From e03eccff973f34842a17398d4f7831f75ce15c4e Mon Sep 17 00:00:00 2001
From: zyuyou <yuyouchow@gmail.com>
Date: Fri, 12 Aug 2022 16:31:01 +0800
Subject: [PATCH 1/7] add otp-25 `maybe_expr` support

---
 gen/org/intellij/erlang/ErlangTypes.java      |  19 +
 .../intellij/erlang/parser/ErlangParser.java  | 154 ++++-
 .../intellij/erlang/parser/_ErlangLexer.java  | 543 +++++++++---------
 .../intellij/erlang/psi/ErlangAttribute.java  |   3 +
 .../erlang/psi/ErlangElseAtomAttribute.java   |  10 +
 .../erlang/psi/ErlangMaybeExpression.java     |  25 +
 .../psi/ErlangMaybeMatchExpression.java       |  13 +
 .../erlang/psi/ErlangMaybeMatchExprs.java     |  16 +
 .../intellij/erlang/psi/ErlangVisitor.java    |  17 +
 .../erlang/psi/impl/ErlangAttributeImpl.java  |   6 +
 .../psi/impl/ErlangElseAtomAttributeImpl.java |  29 +
 .../psi/impl/ErlangMaybeExpressionImpl.java   |  60 ++
 .../impl/ErlangMaybeMatchExpressionImpl.java  |  36 ++
 .../psi/impl/ErlangMaybeMatchExprsImpl.java   |  41 ++
 grammars/erlang.bnf                           |  22 +-
 resources/liveTemplates/erlang.xml            |  26 +
 .../intellij/erlang/ErlangBraceMatcher.java   |   1 +
 .../erlang/editor/ErlangAnnotator.java        |   5 +
 .../erlang/editor/ErlangEnterHandler.java     |  22 +-
 .../editor/ErlangSyntaxHighlighter.java       |   6 +-
 .../formatter/ErlangFormattingBlock.java      |   6 +-
 .../ErlangFormattingModelBuilder.java         |   4 +-
 .../formatter/ErlangIndentProcessor.java      |  13 +-
 src/org/intellij/erlang/parser/Erlang.flex    |   3 +
 .../intellij/erlang/parser/ErlangLexer.java   |   3 +-
 .../erlang/psi/impl/ErlangPsiImplUtil.java    |   9 +
 testData/formatter/bindMaybe-after.erl        |   4 +
 testData/formatter/bindMaybe.erl              |   2 +
 testData/formatter/bindMaybeElse-after.erl    |   6 +
 testData/formatter/bindMaybeElse.erl          |   4 +
 .../formatter/bindMaybeElse__IR_OFF-after.erl |   6 +
 .../bindMaybeFirstElseClause-after.erl        |   6 +
 .../formatter/bindMaybeFirstElseClause.erl    |   5 +
 ...bindMaybeFirstElseClause__IR_OFF-after.erl |   6 +
 .../bindMaybeLastElseClause-after.erl         |   7 +
 .../formatter/bindMaybeLastElseClause.erl     |   6 +
 .../bindMaybeLastElseClause__IR_OFF-after.erl |   7 +
 .../formatter/bindMaybe__IR_OFF-after.erl     |   4 +
 testData/formatter/maybe1-after.erl           |   4 +
 testData/formatter/maybe1.erl                 |   2 +
 testData/formatter/maybe2-after.erl           |   4 +
 testData/formatter/maybe2.erl                 |   3 +
 testData/formatter/maybe3-after.erl           |   6 +
 testData/formatter/maybe3.erl                 |   4 +
 testData/formatter/maybe4-after.erl           |   6 +
 testData/formatter/maybe4.erl                 |   5 +
 testData/formatter/maybe5-after.erl           |   7 +
 testData/formatter/maybe5.erl                 |   6 +
 testData/parser/304.txt                       |   4 +-
 .../completion/ErlangCompletionTest.java      |   2 +-
 .../formatting/ErlangFormattingTest.java      |  31 +
 51 files changed, 927 insertions(+), 312 deletions(-)
 create mode 100644 gen/org/intellij/erlang/psi/ErlangElseAtomAttribute.java
 create mode 100644 gen/org/intellij/erlang/psi/ErlangMaybeExpression.java
 create mode 100644 gen/org/intellij/erlang/psi/ErlangMaybeMatchExpression.java
 create mode 100644 gen/org/intellij/erlang/psi/ErlangMaybeMatchExprs.java
 create mode 100644 gen/org/intellij/erlang/psi/impl/ErlangElseAtomAttributeImpl.java
 create mode 100644 gen/org/intellij/erlang/psi/impl/ErlangMaybeExpressionImpl.java
 create mode 100644 gen/org/intellij/erlang/psi/impl/ErlangMaybeMatchExpressionImpl.java
 create mode 100644 gen/org/intellij/erlang/psi/impl/ErlangMaybeMatchExprsImpl.java
 create mode 100644 testData/formatter/bindMaybe-after.erl
 create mode 100644 testData/formatter/bindMaybe.erl
 create mode 100644 testData/formatter/bindMaybeElse-after.erl
 create mode 100644 testData/formatter/bindMaybeElse.erl
 create mode 100644 testData/formatter/bindMaybeElse__IR_OFF-after.erl
 create mode 100644 testData/formatter/bindMaybeFirstElseClause-after.erl
 create mode 100644 testData/formatter/bindMaybeFirstElseClause.erl
 create mode 100644 testData/formatter/bindMaybeFirstElseClause__IR_OFF-after.erl
 create mode 100644 testData/formatter/bindMaybeLastElseClause-after.erl
 create mode 100644 testData/formatter/bindMaybeLastElseClause.erl
 create mode 100644 testData/formatter/bindMaybeLastElseClause__IR_OFF-after.erl
 create mode 100644 testData/formatter/bindMaybe__IR_OFF-after.erl
 create mode 100644 testData/formatter/maybe1-after.erl
 create mode 100644 testData/formatter/maybe1.erl
 create mode 100644 testData/formatter/maybe2-after.erl
 create mode 100644 testData/formatter/maybe2.erl
 create mode 100644 testData/formatter/maybe3-after.erl
 create mode 100644 testData/formatter/maybe3.erl
 create mode 100644 testData/formatter/maybe4-after.erl
 create mode 100644 testData/formatter/maybe4.erl
 create mode 100644 testData/formatter/maybe5-after.erl
 create mode 100644 testData/formatter/maybe5.erl

diff --git a/gen/org/intellij/erlang/ErlangTypes.java b/gen/org/intellij/erlang/ErlangTypes.java
index 8b3167156..4e2cf686d 100644
--- a/gen/org/intellij/erlang/ErlangTypes.java
+++ b/gen/org/intellij/erlang/ErlangTypes.java
@@ -43,6 +43,7 @@ public interface ErlangTypes {
   IElementType ERL_CONFIG_CALL_EXPRESSION = new ErlangCompositeElementType("ERL_CONFIG_CALL_EXPRESSION");
   IElementType ERL_CONFIG_EXPRESSION = new ErlangCompositeElementType("ERL_CONFIG_EXPRESSION");
   IElementType ERL_CR_CLAUSE = new ErlangCompositeElementType("ERL_CR_CLAUSE");
+  IElementType ERL_ELSE_ATOM_ATTRIBUTE = new ErlangCompositeElementType("ERL_ELSE_ATOM_ATTRIBUTE");
   IElementType ERL_EXPORT = new ErlangCompositeElementType("ERL_EXPORT");
   IElementType ERL_EXPORT_FUNCTION = new ErlangCompositeElementType("ERL_EXPORT_FUNCTION");
   IElementType ERL_EXPORT_FUNCTIONS = new ErlangCompositeElementType("ERL_EXPORT_FUNCTIONS");
@@ -92,6 +93,9 @@ public interface ErlangTypes {
   IElementType ERL_MAP_TUPLE = new ErlangCompositeElementType("ERL_MAP_TUPLE");
   IElementType ERL_MAP_TYPE = new ErlangCompositeElementType("ERL_MAP_TYPE");
   IElementType ERL_MAX_EXPRESSION = new ErlangCompositeElementType("ERL_MAX_EXPRESSION");
+  IElementType ERL_MAYBE_EXPRESSION = new ErlangCompositeElementType("ERL_MAYBE_EXPRESSION");
+  IElementType ERL_MAYBE_MATCH_EXPRESSION = new ErlangCompositeElementType("ERL_MAYBE_MATCH_EXPRESSION");
+  IElementType ERL_MAYBE_MATCH_EXPRS = new ErlangCompositeElementType("ERL_MAYBE_MATCH_EXPRS");
   IElementType ERL_MODEL_FIELD_LIST = new ErlangCompositeElementType("ERL_MODEL_FIELD_LIST");
   IElementType ERL_MODULE = ErlangElementTypeFactory.factory("ERL_MODULE");
   IElementType ERL_MODULE_REF = new ErlangCompositeElementType("ERL_MODULE_REF");
@@ -165,12 +169,14 @@ public interface ErlangTypes {
   IElementType ERL_DOT = new ErlangTokenType(".");
   IElementType ERL_DOT_DOT = new ErlangTokenType("..");
   IElementType ERL_DOT_DOT_DOT = new ErlangTokenType("...");
+  IElementType ERL_ELSE = new ErlangTokenType("else");
   IElementType ERL_END = new ErlangTokenType("end");
   IElementType ERL_FLOAT = new ErlangTokenType("float");
   IElementType ERL_FUN = new ErlangTokenType("fun");
   IElementType ERL_IF = new ErlangTokenType("if");
   IElementType ERL_INTEGER = new ErlangTokenType("integer");
   IElementType ERL_MATCH = new ErlangTokenType(":=");
+  IElementType ERL_MAYBE = new ErlangTokenType("maybe");
   IElementType ERL_NOT = new ErlangTokenType("not");
   IElementType ERL_OF = new ErlangTokenType("of");
   IElementType ERL_OP_AR_DIV = new ErlangTokenType("/");
@@ -187,6 +193,7 @@ public interface ErlangTypes {
   IElementType ERL_OP_LT = new ErlangTokenType("<");
   IElementType ERL_OP_LT_EQ = new ErlangTokenType("<=");
   IElementType ERL_OP_LT_MINUS = new ErlangTokenType("<-");
+  IElementType ERL_OP_MAYBE_EQ = new ErlangTokenType("?=");
   IElementType ERL_OP_MINUS = new ErlangTokenType("-");
   IElementType ERL_OP_MINUS_MINUS = new ErlangTokenType("--");
   IElementType ERL_OP_OR = new ErlangTokenType("|");
@@ -311,6 +318,9 @@ else if (type == ERL_CONFIG_EXPRESSION) {
       else if (type == ERL_CR_CLAUSE) {
         return new ErlangCrClauseImpl(node);
       }
+      else if (type == ERL_ELSE_ATOM_ATTRIBUTE) {
+        return new ErlangElseAtomAttributeImpl(node);
+      }
       else if (type == ERL_EXPORT) {
         return new ErlangExportImpl(node);
       }
@@ -455,6 +465,15 @@ else if (type == ERL_MAP_TYPE) {
       else if (type == ERL_MAX_EXPRESSION) {
         return new ErlangMaxExpressionImpl(node);
       }
+      else if (type == ERL_MAYBE_EXPRESSION) {
+        return new ErlangMaybeExpressionImpl(node);
+      }
+      else if (type == ERL_MAYBE_MATCH_EXPRESSION) {
+        return new ErlangMaybeMatchExpressionImpl(node);
+      }
+      else if (type == ERL_MAYBE_MATCH_EXPRS) {
+        return new ErlangMaybeMatchExprsImpl(node);
+      }
       else if (type == ERL_MODEL_FIELD_LIST) {
         return new ErlangModelFieldListImpl(node);
       }
diff --git a/gen/org/intellij/erlang/parser/ErlangParser.java b/gen/org/intellij/erlang/parser/ErlangParser.java
index 2bd74828c..a5062162c 100644
--- a/gen/org/intellij/erlang/parser/ErlangParser.java
+++ b/gen/org/intellij/erlang/parser/ErlangParser.java
@@ -46,13 +46,14 @@ static boolean parse_root_(IElementType t, PsiBuilder b, int l) {
       ERL_CONFIG_EXPRESSION, ERL_EXPRESSION, ERL_FUNCTION_CALL_EXPRESSION, ERL_FUN_EXPRESSION,
       ERL_GENERIC_FUNCTION_CALL_EXPRESSION, ERL_GLOBAL_FUNCTION_CALL_EXPRESSION, ERL_IF_EXPRESSION, ERL_LC_EXPRESSION,
       ERL_LIST_COMPREHENSION, ERL_LIST_EXPRESSION, ERL_LIST_OP_EXPRESSION, ERL_MAP_EXPRESSION,
-      ERL_MAX_EXPRESSION, ERL_MULTIPLICATIVE_EXPRESSION, ERL_ORELSE_EXPRESSION, ERL_PARENTHESIZED_EXPRESSION,
-      ERL_PREFIX_EXPRESSION, ERL_QUALIFIED_EXPRESSION, ERL_RECEIVE_EXPRESSION, ERL_RECORD_EXPRESSION,
-      ERL_SEND_EXPRESSION, ERL_STRING_LITERAL, ERL_TRY_EXPRESSION, ERL_TUPLE_EXPRESSION),
+      ERL_MAX_EXPRESSION, ERL_MAYBE_EXPRESSION, ERL_MAYBE_MATCH_EXPRESSION, ERL_MULTIPLICATIVE_EXPRESSION,
+      ERL_ORELSE_EXPRESSION, ERL_PARENTHESIZED_EXPRESSION, ERL_PREFIX_EXPRESSION, ERL_QUALIFIED_EXPRESSION,
+      ERL_RECEIVE_EXPRESSION, ERL_RECORD_EXPRESSION, ERL_SEND_EXPRESSION, ERL_STRING_LITERAL,
+      ERL_TRY_EXPRESSION, ERL_TUPLE_EXPRESSION),
   };
 
   /* ********************************************************** */
-  // '+' |'-' | bor | bxor | bsl | bsr | or | xor
+  // '+' | '-' | bor | bxor | bsl | bsr | or | xor
   static boolean add_op(PsiBuilder b, int l) {
     if (!recursion_guard_(b, l, "add_op")) return false;
     boolean r;
@@ -1442,7 +1443,7 @@ public static boolean clause_guard(PsiBuilder b, int l) {
   }
 
   /* ********************************************************** */
-  // '==' | '/=' |'=<' |'<' |'>=' |'>' |'=:=' |'=/='
+  // '==' | '/=' | '=<' |'<' | '>=' | '>' | '=:=' | '=/='
   static boolean comp_op(PsiBuilder b, int l) {
     if (!recursion_guard_(b, l, "comp_op")) return false;
     boolean r;
@@ -1908,22 +1909,11 @@ private static boolean cr_clauses_1_0(PsiBuilder b, int l) {
   }
 
   /* ********************************************************** */
-  // &'else' atom_name
+  // 'else'
   public static boolean else_atom_attribute(PsiBuilder b, int l) {
     if (!recursion_guard_(b, l, "else_atom_attribute")) return false;
     boolean r;
-    Marker m = enter_section_(b, l, _NONE_, ERL_ATOM_ATTRIBUTE, "<attribute>");
-    r = else_atom_attribute_0(b, l + 1);
-    r = r && consumeToken(b, ERL_ATOM_NAME);
-    exit_section_(b, l, m, r, false, null);
-    return r;
-  }
-
-  // &'else'
-  private static boolean else_atom_attribute_0(PsiBuilder b, int l) {
-    if (!recursion_guard_(b, l, "else_atom_attribute_0")) return false;
-    boolean r;
-    Marker m = enter_section_(b, l, _AND_);
+    Marker m = enter_section_(b, l, _NONE_, ERL_ELSE_ATOM_ATTRIBUTE, "<attribute>");
     r = consumeToken(b, "else");
     exit_section_(b, l, m, r, false, null);
     return r;
@@ -2187,7 +2177,7 @@ private static boolean exprs_1_0(PsiBuilder b, int l) {
   }
 
   /* ********************************************************** */
-  // !(')' | ',' | '->' | '.' | ':-' | ';' | '}' | after | catch | end | of | atom '(')
+  // !(')' | ',' | '->' | '.' | ':-' | ';' | '}' | after | catch | else | end | of | atom '(')
   static boolean exprs_recover(PsiBuilder b, int l) {
     if (!recursion_guard_(b, l, "exprs_recover")) return false;
     boolean r;
@@ -2197,7 +2187,7 @@ static boolean exprs_recover(PsiBuilder b, int l) {
     return r;
   }
 
-  // ')' | ',' | '->' | '.' | ':-' | ';' | '}' | after | catch | end | of | atom '('
+  // ')' | ',' | '->' | '.' | ':-' | ';' | '}' | after | catch | else | end | of | atom '('
   private static boolean exprs_recover_0(PsiBuilder b, int l) {
     if (!recursion_guard_(b, l, "exprs_recover_0")) return false;
     boolean r;
@@ -2211,16 +2201,17 @@ private static boolean exprs_recover_0(PsiBuilder b, int l) {
     if (!r) r = consumeToken(b, ERL_CURLY_RIGHT);
     if (!r) r = consumeToken(b, ERL_AFTER);
     if (!r) r = consumeToken(b, ERL_CATCH);
+    if (!r) r = consumeToken(b, ERL_ELSE);
     if (!r) r = consumeToken(b, ERL_END);
     if (!r) r = consumeToken(b, ERL_OF);
-    if (!r) r = exprs_recover_0_11(b, l + 1);
+    if (!r) r = exprs_recover_0_12(b, l + 1);
     exit_section_(b, m, null, r);
     return r;
   }
 
   // atom '('
-  private static boolean exprs_recover_0_11(PsiBuilder b, int l) {
-    if (!recursion_guard_(b, l, "exprs_recover_0_11")) return false;
+  private static boolean exprs_recover_0_12(PsiBuilder b, int l) {
+    if (!recursion_guard_(b, l, "exprs_recover_0_12")) return false;
     boolean r;
     Marker m = enter_section_(b);
     r = atom(b, l + 1);
@@ -2345,7 +2336,7 @@ private static boolean form_10(PsiBuilder b, int l) {
   }
 
   /* ********************************************************** */
-  // !('+' | '-' | '<<' | '?' | '[' | '{' | atom_name | single_quote | bnot | char | float | integer | not | string | var | '#'| '.')
+  // !('+' | '-' | '<<' | '?' | '[' | '{' | atom_name | single_quote | bnot | char | float | integer | not | string | var | '#' | '.')
   static boolean form_recover(PsiBuilder b, int l) {
     if (!recursion_guard_(b, l, "form_recover")) return false;
     boolean r;
@@ -2355,7 +2346,7 @@ static boolean form_recover(PsiBuilder b, int l) {
     return r;
   }
 
-  // '+' | '-' | '<<' | '?' | '[' | '{' | atom_name | single_quote | bnot | char | float | integer | not | string | var | '#'| '.'
+  // '+' | '-' | '<<' | '?' | '[' | '{' | atom_name | single_quote | bnot | char | float | integer | not | string | var | '#' | '.'
   private static boolean form_recover_0(PsiBuilder b, int l) {
     if (!recursion_guard_(b, l, "form_recover_0")) return false;
     boolean r;
@@ -4007,6 +3998,41 @@ static boolean marked_lc_tail(PsiBuilder b, int l) {
     return r || p;
   }
 
+  /* ********************************************************** */
+  // maybe maybe_match_exprs [else cr_clauses] end
+  public static boolean maybe_expression(PsiBuilder b, int l) {
+    if (!recursion_guard_(b, l, "maybe_expression")) return false;
+    if (!nextTokenIs(b, "<expression>", ERL_MAYBE)) return false;
+    boolean r, p;
+    Marker m = enter_section_(b, l, _NONE_, ERL_MAYBE_EXPRESSION, "<expression>");
+    r = consumeToken(b, ERL_MAYBE);
+    p = r; // pin = 1
+    r = r && report_error_(b, maybe_match_exprs(b, l + 1));
+    r = p && report_error_(b, maybe_expression_2(b, l + 1)) && r;
+    r = p && consumeToken(b, ERL_END) && r;
+    exit_section_(b, l, m, r, p, null);
+    return r || p;
+  }
+
+  // [else cr_clauses]
+  private static boolean maybe_expression_2(PsiBuilder b, int l) {
+    if (!recursion_guard_(b, l, "maybe_expression_2")) return false;
+    maybe_expression_2_0(b, l + 1);
+    return true;
+  }
+
+  // else cr_clauses
+  private static boolean maybe_expression_2_0(PsiBuilder b, int l) {
+    if (!recursion_guard_(b, l, "maybe_expression_2_0")) return false;
+    boolean r, p;
+    Marker m = enter_section_(b, l, _NONE_);
+    r = consumeToken(b, ERL_ELSE);
+    p = r; // pin = 1
+    r = r && cr_clauses(b, l + 1);
+    exit_section_(b, l, m, r, p, null);
+    return r || p;
+  }
+
   /* ********************************************************** */
   // function_clause_head clause_guard? clause_body
   static boolean maybe_macro_function_clause(PsiBuilder b, int l) {
@@ -4027,6 +4053,80 @@ private static boolean maybe_macro_function_clause_1(PsiBuilder b, int l) {
     return true;
   }
 
+  /* ********************************************************** */
+  // expression '?=' expression
+  public static boolean maybe_match_expression(PsiBuilder b, int l) {
+    if (!recursion_guard_(b, l, "maybe_match_expression")) return false;
+    boolean r;
+    Marker m = enter_section_(b, l, _NONE_, ERL_MAYBE_MATCH_EXPRESSION, "<expression>");
+    r = expression(b, l + 1, -1);
+    r = r && consumeToken(b, ERL_OP_MAYBE_EQ);
+    r = r && expression(b, l + 1, -1);
+    exit_section_(b, l, m, r, false, null);
+    return r;
+  }
+
+  /* ********************************************************** */
+  // (maybe_match_expression | expression) [',' maybe_match_exprs] (exprs_tail)*
+  public static boolean maybe_match_exprs(PsiBuilder b, int l) {
+    if (!recursion_guard_(b, l, "maybe_match_exprs")) return false;
+    boolean r;
+    Marker m = enter_section_(b, l, _NONE_, ERL_MAYBE_MATCH_EXPRS, "<maybe match exprs>");
+    r = maybe_match_exprs_0(b, l + 1);
+    r = r && maybe_match_exprs_1(b, l + 1);
+    r = r && maybe_match_exprs_2(b, l + 1);
+    exit_section_(b, l, m, r, false, ErlangParser::exprs_recover);
+    return r;
+  }
+
+  // maybe_match_expression | expression
+  private static boolean maybe_match_exprs_0(PsiBuilder b, int l) {
+    if (!recursion_guard_(b, l, "maybe_match_exprs_0")) return false;
+    boolean r;
+    r = maybe_match_expression(b, l + 1);
+    if (!r) r = expression(b, l + 1, -1);
+    return r;
+  }
+
+  // [',' maybe_match_exprs]
+  private static boolean maybe_match_exprs_1(PsiBuilder b, int l) {
+    if (!recursion_guard_(b, l, "maybe_match_exprs_1")) return false;
+    maybe_match_exprs_1_0(b, l + 1);
+    return true;
+  }
+
+  // ',' maybe_match_exprs
+  private static boolean maybe_match_exprs_1_0(PsiBuilder b, int l) {
+    if (!recursion_guard_(b, l, "maybe_match_exprs_1_0")) return false;
+    boolean r;
+    Marker m = enter_section_(b);
+    r = consumeToken(b, ERL_COMMA);
+    r = r && maybe_match_exprs(b, l + 1);
+    exit_section_(b, m, null, r);
+    return r;
+  }
+
+  // (exprs_tail)*
+  private static boolean maybe_match_exprs_2(PsiBuilder b, int l) {
+    if (!recursion_guard_(b, l, "maybe_match_exprs_2")) return false;
+    while (true) {
+      int c = current_position_(b);
+      if (!maybe_match_exprs_2_0(b, l + 1)) break;
+      if (!empty_element_parsed_guard_(b, "maybe_match_exprs_2", c)) break;
+    }
+    return true;
+  }
+
+  // (exprs_tail)
+  private static boolean maybe_match_exprs_2_0(PsiBuilder b, int l) {
+    if (!recursion_guard_(b, l, "maybe_match_exprs_2_0")) return false;
+    boolean r;
+    Marker m = enter_section_(b);
+    r = exprs_tail(b, l + 1);
+    exit_section_(b, m, null, r);
+    return r;
+  }
+
   /* ********************************************************** */
   // q_var ['::' top_type]
   public static boolean model_field(PsiBuilder b, int l) {
@@ -4154,7 +4254,7 @@ static boolean module_tail(PsiBuilder b, int l) {
   }
 
   /* ********************************************************** */
-  // '/' |'*' | div | rem  | band | and
+  // '/' | '*' | div | rem  | band | and
   static boolean mult_op(PsiBuilder b, int l) {
     if (!recursion_guard_(b, l, "mult_op")) return false;
     boolean r;
@@ -6218,6 +6318,7 @@ private static boolean qualified_expression_3(PsiBuilder b, int l) {
   //   | receive_expression
   //   | fun_expression
   //   | try_expression
+  //   | maybe_expression
   //   | binary_expression
   //   | begin_end_expression
   public static boolean max_expression(PsiBuilder b, int l) {
@@ -6236,6 +6337,7 @@ public static boolean max_expression(PsiBuilder b, int l) {
     if (!r) r = receive_expression(b, l + 1);
     if (!r) r = fun_expression(b, l + 1);
     if (!r) r = try_expression(b, l + 1);
+    if (!r) r = maybe_expression(b, l + 1);
     if (!r) r = binary_expression(b, l + 1);
     if (!r) r = begin_end_expression(b, l + 1);
     exit_section_(b, l, m, r, false, null);
diff --git a/gen/org/intellij/erlang/parser/_ErlangLexer.java b/gen/org/intellij/erlang/parser/_ErlangLexer.java
index f1bb0e6b1..6894e781c 100644
--- a/gen/org/intellij/erlang/parser/_ErlangLexer.java
+++ b/gen/org/intellij/erlang/parser/_ErlangLexer.java
@@ -53,11 +53,11 @@ public static int ZZ_CMAP(int ch) {
 
   /* The ZZ_CMAP_A table has 384 entries */
   static final char ZZ_CMAP_A[] = zzUnpackCMap(
-    "\1\1\10\0\1\1\1\6\2\0\1\4\21\0\2\1\1\3\1\22\1\2\1\41\1\5\1\0\1\33\1\67\1\70"+
-    "\1\62\1\61\1\43\1\14\1\15\1\63\10\17\2\11\1\56\1\72\1\60\1\42\1\57\1\73\1"+
+    "\1\1\10\0\1\1\1\6\2\0\1\4\21\0\2\1\1\3\1\22\1\2\1\41\1\5\1\0\1\33\1\70\1\71"+
+    "\1\64\1\63\1\43\1\14\1\15\1\65\10\17\2\11\1\60\1\73\1\62\1\42\1\61\1\67\1"+
     "\20\4\7\1\12\25\7\1\34\1\16\1\36\1\21\1\44\1\40\1\45\1\23\1\53\1\24\1\13\1"+
-    "\25\1\50\1\47\1\51\2\10\1\66\1\64\1\26\1\52\2\10\1\27\1\30\1\31\1\54\1\32"+
-    "\1\46\1\65\1\55\1\10\1\35\1\71\1\37\42\0\1\1\337\0");
+    "\25\1\50\1\47\1\51\2\10\1\57\1\56\1\26\1\52\2\10\1\27\1\30\1\31\1\54\1\32"+
+    "\1\46\1\66\1\55\1\10\1\35\1\72\1\37\42\0\1\1\337\0");
 
   /** 
    * Translates DFA states to action switch labels.
@@ -67,23 +67,23 @@ public static int ZZ_CMAP(int ch) {
   private static final String ZZ_ACTION_PACKED_0 =
     "\2\0\1\1\1\2\1\3\1\4\1\5\1\6\1\7"+
     "\1\10\1\7\1\11\1\12\1\1\6\7\1\13\1\14"+
-    "\1\15\1\16\1\17\1\20\1\21\1\22\5\7\1\23"+
+    "\1\15\1\16\1\17\1\20\1\21\1\22\6\7\1\23"+
     "\1\24\1\25\1\26\1\27\1\30\1\7\1\31\1\32"+
     "\1\33\1\34\1\35\1\7\1\1\1\36\1\37\1\5"+
-    "\1\40\1\0\1\10\1\0\1\7\1\41\1\42\1\43"+
+    "\1\40\1\0\1\10\1\0\2\7\1\41\1\42\1\43"+
     "\2\0\1\44\14\7\2\20\1\45\1\0\1\46\1\47"+
-    "\1\0\3\7\1\50\1\51\1\52\1\7\1\53\1\54"+
+    "\1\0\3\7\1\50\1\51\1\52\2\7\1\53\1\54"+
     "\1\55\1\56\1\57\1\60\1\61\1\62\1\63\1\7"+
-    "\1\64\2\0\1\40\1\65\2\10\1\66\1\67\1\70"+
-    "\2\7\1\71\1\72\1\7\1\73\1\7\1\74\1\75"+
-    "\1\76\1\7\1\77\1\100\1\20\1\0\1\101\1\102"+
-    "\1\7\1\103\4\7\1\104\1\0\1\7\1\105\1\106"+
-    "\1\107\1\7\1\20\2\7\1\110\1\7\1\111\1\7"+
-    "\1\66\1\0\1\112\1\7\1\113\2\7\1\114\2\7"+
-    "\1\115\1\116\1\117";
+    "\1\64\1\65\2\0\1\40\1\66\2\10\1\67\1\70"+
+    "\1\7\1\71\2\7\1\72\1\73\1\7\1\74\1\7"+
+    "\1\75\1\76\1\77\1\7\1\100\1\101\1\20\1\0"+
+    "\1\102\1\103\1\7\1\104\5\7\1\105\1\0\1\106"+
+    "\1\7\1\107\1\110\1\111\1\7\1\20\2\7\1\112"+
+    "\1\7\1\113\2\7\1\67\1\0\1\114\1\7\1\115"+
+    "\2\7\1\116\1\117\2\7\1\120\1\121\1\122";
 
   private static int [] zzUnpackAction() {
-    int [] result = new int[157];
+    int [] result = new int[166];
     int offset = 0;
     offset = zzUnpackAction(ZZ_ACTION_PACKED_0, offset, result);
     return result;
@@ -112,25 +112,26 @@ private static int zzUnpackAction(String packed, int offset, int [] result) {
     "\0\u01a4\0\u01e0\0\u021c\0\u0258\0\u0294\0\u02d0\0\u030c\0\u0348"+
     "\0\u0384\0\u03c0\0\u03fc\0\u0438\0\u0474\0\170\0\170\0\170"+
     "\0\170\0\u04b0\0\u04ec\0\170\0\u0528\0\u0564\0\u05a0\0\u05dc"+
-    "\0\u0618\0\u0654\0\u0690\0\u06cc\0\u0708\0\170\0\u0744\0\u0780"+
-    "\0\170\0\170\0\u07bc\0\170\0\170\0\u07f8\0\u0834\0\170"+
-    "\0\u0870\0\u08ac\0\u08e8\0\u0924\0\u0960\0\u099c\0\u09d8\0\170"+
-    "\0\170\0\u0a14\0\u02d0\0\u0a50\0\170\0\u0a8c\0\u0ac8\0\u0b04"+
-    "\0\u0b40\0\u0b7c\0\u0bb8\0\u0bf4\0\u0c30\0\u0c6c\0\u0ca8\0\u0ce4"+
-    "\0\170\0\170\0\u0d20\0\170\0\u0d5c\0\170\0\170\0\u0d98"+
-    "\0\u0dd4\0\u0e10\0\u0e4c\0\u01a4\0\u01a4\0\u0e88\0\u0ec4\0\170"+
-    "\0\170\0\170\0\170\0\170\0\170\0\170\0\170\0\170"+
-    "\0\u0f00\0\170\0\u0834\0\u0f3c\0\u0f78\0\u0fb4\0\u0924\0\u0ff0"+
-    "\0\u102c\0\u01a4\0\170\0\u1068\0\u10a4\0\u01a4\0\u01a4\0\u10e0"+
-    "\0\u01a4\0\u111c\0\u01a4\0\u01a4\0\u01a4\0\u1158\0\u01a4\0\u01a4"+
-    "\0\u1194\0\u11d0\0\170\0\170\0\u120c\0\u1248\0\u1284\0\u12c0"+
-    "\0\u12fc\0\u1338\0\u01a4\0\u1374\0\u13b0\0\u01a4\0\u01a4\0\u01a4"+
-    "\0\u13ec\0\u1428\0\u1464\0\u14a0\0\u01a4\0\u14dc\0\u01a4\0\u1518"+
-    "\0\u1554\0\u1554\0\u01a4\0\u1590\0\u01a4\0\u15cc\0\u1608\0\u01a4"+
-    "\0\u1644\0\u1680\0\u01a4\0\u01a4\0\u01a4";
+    "\0\u0618\0\u0654\0\u0690\0\u06cc\0\u0708\0\u0744\0\170\0\u0780"+
+    "\0\u07bc\0\u07f8\0\170\0\170\0\u0834\0\170\0\u0870\0\u08ac"+
+    "\0\170\0\u08e8\0\u0924\0\u0960\0\u099c\0\u09d8\0\u0a14\0\u0a50"+
+    "\0\u0a8c\0\170\0\170\0\u0ac8\0\u02d0\0\u0b04\0\170\0\u0b40"+
+    "\0\u0b7c\0\u0bb8\0\u0bf4\0\u0c30\0\u0c6c\0\u0ca8\0\u0ce4\0\u0d20"+
+    "\0\u0d5c\0\u0d98\0\170\0\170\0\u0dd4\0\170\0\u0e10\0\170"+
+    "\0\170\0\u0e4c\0\u0e88\0\u0ec4\0\u0f00\0\u01a4\0\u01a4\0\u0f3c"+
+    "\0\u0f78\0\u0fb4\0\170\0\170\0\170\0\170\0\170\0\170"+
+    "\0\170\0\170\0\170\0\u0ff0\0\170\0\170\0\u08ac\0\u102c"+
+    "\0\u1068\0\u10a4\0\u099c\0\u10e0\0\u111c\0\u01a4\0\u1158\0\170"+
+    "\0\u1194\0\u11d0\0\u01a4\0\u01a4\0\u120c\0\u01a4\0\u1248\0\u01a4"+
+    "\0\u01a4\0\u01a4\0\u1284\0\u01a4\0\u01a4\0\u12c0\0\u12fc\0\170"+
+    "\0\170\0\u1338\0\u1374\0\u13b0\0\u13ec\0\u1428\0\u1464\0\u14a0"+
+    "\0\u01a4\0\u14dc\0\u01a4\0\u1518\0\u01a4\0\u01a4\0\u01a4\0\u1554"+
+    "\0\u1590\0\u15cc\0\u1608\0\u01a4\0\u1644\0\u01a4\0\u1680\0\u16bc"+
+    "\0\u16f8\0\u16f8\0\u01a4\0\u1734\0\u01a4\0\u1770\0\u17ac\0\u01a4"+
+    "\0\u01a4\0\u17e8\0\u1824\0\u01a4\0\u01a4\0\u01a4";
 
   private static int [] zzUnpackRowMap() {
-    int [] result = new int[157];
+    int [] result = new int[166];
     int offset = 0;
     offset = zzUnpackRowMap(ZZ_ROWMAP_PACKED_0, offset, result);
     return result;
@@ -158,120 +159,129 @@ private static int zzUnpackRowMap(String packed, int offset, int [] result) {
     "\2\3\1\16\1\17\1\20\1\21\1\22\1\23\1\11"+
     "\1\24\1\11\1\25\1\26\1\27\1\30\1\31\1\3"+
     "\1\32\1\33\1\34\1\10\1\35\1\36\2\11\1\37"+
-    "\1\40\1\41\2\11\1\42\1\43\1\44\1\45\1\46"+
-    "\1\47\1\11\1\50\1\11\1\51\1\52\1\53\1\54"+
-    "\1\55\16\56\1\57\14\56\1\60\40\56\75\0\1\4"+
-    "\4\0\1\4\70\0\1\61\70\0\4\62\1\0\1\63"+
-    "\1\0\65\62\7\0\5\10\3\0\2\10\2\0\10\10"+
-    "\11\0\12\10\6\0\3\10\14\0\5\11\3\0\2\11"+
-    "\2\0\10\11\11\0\12\11\6\0\3\11\7\0\1\64"+
-    "\6\0\1\65\3\0\1\66\1\0\1\65\63\0\5\11"+
-    "\3\0\2\11\2\0\3\11\1\67\4\11\11\0\12\11"+
-    "\6\0\3\11\21\0\1\70\42\0\1\71\31\0\1\72"+
-    "\56\0\16\73\1\74\3\73\1\75\51\73\7\0\4\11"+
-    "\1\76\3\0\2\11\2\0\3\11\1\77\1\11\1\100"+
-    "\2\11\11\0\1\11\1\101\4\11\1\102\3\11\6\0"+
-    "\1\11\1\103\1\11\14\0\5\11\3\0\2\11\2\0"+
-    "\10\11\11\0\5\11\1\104\4\11\6\0\3\11\14\0"+
-    "\5\11\3\0\2\11\2\0\10\11\11\0\10\11\1\105"+
-    "\1\11\6\0\3\11\14\0\5\11\3\0\2\11\2\0"+
-    "\10\11\11\0\6\11\1\106\3\11\6\0\3\11\14\0"+
-    "\4\11\1\107\3\0\2\11\2\0\10\11\11\0\12\11"+
-    "\6\0\3\11\14\0\5\11\3\0\2\11\2\0\4\11"+
-    "\1\110\3\11\11\0\12\11\6\0\3\11\40\0\1\111"+
-    "\40\0\6\112\1\0\7\112\1\113\55\112\42\0\1\114"+
-    "\13\0\1\115\1\116\1\117\2\0\1\120\17\0\5\11"+
-    "\3\0\2\11\2\0\2\11\1\121\1\122\4\11\11\0"+
-    "\12\11\6\0\3\11\14\0\5\11\3\0\2\11\2\0"+
-    "\10\11\11\0\3\11\1\123\6\11\6\0\3\11\14\0"+
-    "\5\11\3\0\2\11\2\0\2\11\1\124\5\11\11\0"+
-    "\12\11\6\0\3\11\14\0\5\11\3\0\2\11\2\0"+
-    "\2\11\1\125\1\11\1\126\3\11\11\0\12\11\6\0"+
-    "\3\11\14\0\5\11\3\0\2\11\2\0\10\11\11\0"+
-    "\1\11\1\127\10\11\6\0\3\11\47\0\1\130\13\0"+
-    "\1\131\57\0\1\132\14\0\1\133\30\0\1\134\25\0"+
-    "\1\135\15\0\1\136\74\0\1\137\54\0\1\140\40\0"+
-    "\5\11\3\0\2\11\2\0\10\11\11\0\6\11\1\141"+
-    "\3\11\6\0\3\11\76\0\1\142\2\0\16\56\1\143"+
-    "\14\56\1\0\40\56\5\0\1\56\5\0\1\56\1\0"+
-    "\3\56\1\0\1\144\23\56\27\0\4\61\1\0\1\61"+
-    "\1\0\65\61\4\62\1\0\1\62\1\0\65\62\4\145"+
-    "\1\0\1\146\1\0\65\145\7\0\5\147\3\0\1\147"+
-    "\3\0\10\147\12\0\11\147\6\0\3\147\7\0\1\64"+
-    "\6\0\1\150\3\0\1\66\1\0\1\150\65\0\1\151"+
-    "\5\0\1\151\63\0\5\11\3\0\2\11\2\0\1\11"+
-    "\1\152\6\11\11\0\12\11\6\0\3\11\22\0\1\153"+
-    "\56\0\74\73\7\0\5\11\3\0\2\11\2\0\10\11"+
-    "\11\0\4\11\1\154\5\11\6\0\3\11\14\0\5\11"+
-    "\3\0\2\11\2\0\10\11\11\0\6\11\1\155\3\11"+
-    "\6\0\3\11\14\0\5\11\3\0\2\11\2\0\4\11"+
-    "\1\156\3\11\11\0\12\11\6\0\2\11\1\157\14\0"+
-    "\5\11\3\0\2\11\2\0\3\11\1\160\4\11\11\0"+
-    "\12\11\6\0\3\11\14\0\5\11\3\0\2\11\2\0"+
-    "\4\11\1\161\3\11\11\0\12\11\6\0\3\11\14\0"+
+    "\1\40\1\41\2\11\1\42\1\11\1\43\1\44\1\45"+
+    "\1\46\1\47\1\50\1\51\1\52\1\53\1\54\1\55"+
+    "\1\56\16\57\1\60\14\57\1\61\40\57\75\0\1\4"+
+    "\4\0\1\4\70\0\1\62\70\0\4\63\1\0\1\64"+
+    "\1\0\65\63\7\0\5\10\3\0\2\10\2\0\10\10"+
+    "\11\0\14\10\6\0\1\10\14\0\5\11\3\0\2\11"+
+    "\2\0\10\11\11\0\14\11\6\0\1\11\7\0\1\65"+
+    "\6\0\1\66\3\0\1\67\1\0\1\66\63\0\5\11"+
+    "\3\0\2\11\2\0\3\11\1\70\4\11\11\0\13\11"+
+    "\1\71\6\0\1\11\21\0\1\72\44\0\1\73\27\0"+
+    "\1\74\56\0\16\75\1\76\3\75\1\77\51\75\7\0"+
+    "\4\11\1\100\3\0\2\11\2\0\3\11\1\101\1\11"+
+    "\1\102\2\11\11\0\1\11\1\103\4\11\1\104\5\11"+
+    "\6\0\1\105\14\0\5\11\3\0\2\11\2\0\10\11"+
+    "\11\0\5\11\1\106\6\11\6\0\1\11\14\0\5\11"+
+    "\3\0\2\11\2\0\10\11\11\0\10\11\1\107\3\11"+
+    "\6\0\1\11\14\0\5\11\3\0\2\11\2\0\10\11"+
+    "\11\0\6\11\1\110\5\11\6\0\1\11\14\0\4\11"+
+    "\1\111\3\0\2\11\2\0\10\11\11\0\14\11\6\0"+
+    "\1\11\14\0\5\11\3\0\2\11\2\0\4\11\1\112"+
+    "\3\11\11\0\14\11\6\0\1\11\40\0\1\113\40\0"+
+    "\6\114\1\0\7\114\1\115\55\114\42\0\1\116\15\0"+
+    "\1\117\1\120\1\121\2\0\1\122\15\0\5\11\3\0"+
+    "\2\11\2\0\2\11\1\123\1\124\4\11\11\0\14\11"+
+    "\6\0\1\11\14\0\5\11\3\0\2\11\2\0\10\11"+
+    "\11\0\3\11\1\125\10\11\6\0\1\11\14\0\5\11"+
+    "\3\0\2\11\2\0\2\11\1\126\5\11\11\0\14\11"+
+    "\6\0\1\11\14\0\5\11\3\0\2\11\2\0\2\11"+
+    "\1\127\1\11\1\130\3\11\11\0\14\11\6\0\1\11"+
+    "\14\0\5\11\3\0\2\11\2\0\10\11\11\0\1\11"+
+    "\1\131\12\11\6\0\1\11\14\0\5\11\3\0\2\11"+
+    "\2\0\10\11\11\0\1\11\1\132\12\11\6\0\1\11"+
+    "\47\0\1\133\15\0\1\134\55\0\1\135\16\0\1\136"+
+    "\26\0\1\137\25\0\1\140\17\0\1\141\74\0\1\142"+
+    "\52\0\1\143\40\0\5\11\3\0\2\11\2\0\10\11"+
+    "\11\0\6\11\1\144\5\11\6\0\1\11\47\0\1\145"+
+    "\123\0\1\146\1\0\16\57\1\147\14\57\1\0\40\57"+
+    "\5\0\1\57\5\0\1\57\1\0\3\57\1\0\1\150"+
+    "\23\57\27\0\4\62\1\0\1\62\1\0\65\62\4\63"+
+    "\1\0\1\63\1\0\65\63\4\151\1\0\1\152\1\0"+
+    "\65\151\7\0\5\153\3\0\1\153\3\0\10\153\12\0"+
+    "\13\153\6\0\1\153\7\0\1\65\6\0\1\154\3\0"+
+    "\1\67\1\0\1\154\65\0\1\155\5\0\1\155\63\0"+
+    "\5\11\3\0\2\11\2\0\1\11\1\156\6\11\11\0"+
+    "\14\11\6\0\1\11\14\0\5\11\3\0\2\11\2\0"+
+    "\5\11\1\157\2\11\11\0\14\11\6\0\1\11\22\0"+
+    "\1\160\56\0\74\75\7\0\5\11\3\0\2\11\2\0"+
+    "\10\11\11\0\4\11\1\161\7\11\6\0\1\11\14\0"+
     "\5\11\3\0\2\11\2\0\10\11\11\0\6\11\1\162"+
-    "\3\11\6\0\3\11\14\0\5\11\3\0\2\11\2\0"+
-    "\7\11\1\163\11\0\12\11\6\0\3\11\14\0\5\11"+
-    "\3\0\2\11\2\0\3\11\1\164\4\11\11\0\12\11"+
-    "\6\0\3\11\14\0\5\11\3\0\2\11\2\0\6\11"+
-    "\1\165\1\11\11\0\12\11\6\0\3\11\14\0\5\11"+
-    "\3\0\2\11\2\0\10\11\11\0\7\11\1\166\2\11"+
-    "\6\0\1\167\2\11\14\0\5\11\3\0\2\11\2\0"+
-    "\10\11\11\0\11\11\1\170\6\0\3\11\6\0\1\112"+
-    "\3\0\2\112\4\0\1\112\1\0\2\112\1\171\1\0"+
-    "\1\172\23\112\71\0\1\173\73\0\1\174\40\0\5\11"+
-    "\3\0\2\11\2\0\6\11\1\175\1\11\11\0\12\11"+
-    "\6\0\3\11\14\0\5\11\3\0\2\11\2\0\1\11"+
-    "\1\176\6\11\11\0\12\11\6\0\3\11\14\0\4\11"+
-    "\1\177\3\0\2\11\2\0\10\11\11\0\12\11\6\0"+
-    "\3\11\14\0\4\11\1\200\3\0\2\11\2\0\10\11"+
-    "\11\0\12\11\6\0\3\11\14\0\5\11\3\0\2\11"+
-    "\2\0\5\11\1\201\1\202\1\11\11\0\12\11\6\0"+
-    "\3\11\14\0\5\11\3\0\2\11\2\0\4\11\1\203"+
-    "\3\11\11\0\12\11\6\0\3\11\14\0\1\56\2\0"+
-    "\1\56\3\0\1\56\1\0\2\56\12\0\1\56\1\0"+
-    "\1\56\5\0\1\56\27\0\4\145\1\0\1\145\1\0"+
-    "\65\145\4\146\1\0\1\146\1\0\65\146\11\0\1\150"+
-    "\3\0\1\66\1\0\1\150\65\0\1\151\2\204\3\0"+
-    "\1\151\63\0\5\11\3\0\2\11\2\0\10\11\11\0"+
-    "\5\11\1\205\4\11\6\0\3\11\14\0\5\11\3\0"+
-    "\2\11\2\0\6\11\1\206\1\11\11\0\12\11\6\0"+
-    "\3\11\14\0\5\11\3\0\2\11\2\0\1\11\1\207"+
-    "\6\11\11\0\12\11\6\0\3\11\14\0\5\11\3\0"+
-    "\2\11\2\0\4\11\1\210\3\11\11\0\12\11\6\0"+
-    "\3\11\14\0\4\11\1\211\3\0\2\11\2\0\10\11"+
-    "\11\0\12\11\6\0\3\11\24\0\1\212\63\0\1\112"+
-    "\2\0\1\112\3\0\1\112\1\0\2\112\12\0\1\112"+
-    "\1\0\1\112\5\0\1\112\36\0\4\11\1\213\3\0"+
-    "\2\11\2\0\10\11\11\0\12\11\6\0\3\11\14\0"+
-    "\5\11\3\0\2\11\2\0\10\11\11\0\1\11\1\214"+
-    "\10\11\6\0\3\11\14\0\5\11\3\0\2\11\2\0"+
-    "\3\11\1\215\4\11\11\0\12\11\6\0\3\11\14\0"+
-    "\5\11\3\0\2\11\2\0\10\11\11\0\12\11\6\0"+
-    "\2\11\1\216\14\0\4\11\1\217\3\0\2\11\2\0"+
-    "\10\11\11\0\12\11\6\0\3\11\14\0\5\11\3\0"+
-    "\2\11\2\0\10\11\11\0\7\11\1\220\2\11\6\0"+
-    "\3\11\16\0\1\221\2\0\1\222\2\0\1\221\41\0"+
-    "\1\222\21\0\5\11\3\0\2\11\2\0\3\11\1\223"+
-    "\4\11\11\0\12\11\6\0\3\11\14\0\5\11\3\0"+
-    "\2\11\2\0\10\11\11\0\5\11\1\224\4\11\6\0"+
-    "\3\11\24\0\1\112\63\0\5\11\3\0\2\11\2\0"+
-    "\4\11\1\225\3\11\11\0\12\11\6\0\3\11\14\0"+
-    "\5\11\3\0\2\11\2\0\10\11\11\0\12\11\6\0"+
-    "\2\11\1\226\14\0\5\11\3\0\2\11\2\0\5\11"+
-    "\1\227\2\11\11\0\12\11\6\0\3\11\14\0\5\11"+
-    "\3\0\2\11\2\0\10\11\11\0\3\11\1\230\6\11"+
-    "\6\0\3\11\16\0\1\221\5\0\1\221\63\0\5\11"+
-    "\3\0\2\11\2\0\7\11\1\231\11\0\12\11\6\0"+
-    "\3\11\14\0\5\11\3\0\2\11\2\0\5\11\1\232"+
-    "\2\11\11\0\12\11\6\0\3\11\14\0\4\11\1\233"+
-    "\3\0\2\11\2\0\10\11\11\0\12\11\6\0\3\11"+
-    "\14\0\4\11\1\234\3\0\2\11\2\0\10\11\11\0"+
-    "\12\11\6\0\3\11\14\0\5\11\3\0\2\11\2\0"+
-    "\10\11\11\0\6\11\1\235\3\11\6\0\3\11\5\0";
+    "\5\11\6\0\1\11\14\0\5\11\3\0\2\11\2\0"+
+    "\4\11\1\163\3\11\11\0\13\11\1\164\6\0\1\11"+
+    "\14\0\5\11\3\0\2\11\2\0\3\11\1\165\4\11"+
+    "\11\0\14\11\6\0\1\11\14\0\5\11\3\0\2\11"+
+    "\2\0\4\11\1\166\3\11\11\0\14\11\6\0\1\11"+
+    "\14\0\5\11\3\0\2\11\2\0\10\11\11\0\6\11"+
+    "\1\167\5\11\6\0\1\11\14\0\5\11\3\0\2\11"+
+    "\2\0\7\11\1\170\11\0\14\11\6\0\1\11\14\0"+
+    "\5\11\3\0\2\11\2\0\3\11\1\171\4\11\11\0"+
+    "\14\11\6\0\1\11\14\0\5\11\3\0\2\11\2\0"+
+    "\6\11\1\172\1\11\11\0\14\11\6\0\1\11\14\0"+
+    "\5\11\3\0\2\11\2\0\10\11\11\0\7\11\1\173"+
+    "\2\11\1\174\1\11\6\0\1\11\14\0\5\11\3\0"+
+    "\2\11\2\0\10\11\11\0\11\11\1\175\2\11\6\0"+
+    "\1\11\6\0\1\114\3\0\2\114\4\0\1\114\1\0"+
+    "\2\114\1\176\1\0\1\177\23\114\71\0\1\200\73\0"+
+    "\1\201\40\0\5\11\3\0\2\11\2\0\6\11\1\202"+
+    "\1\11\11\0\14\11\6\0\1\11\14\0\5\11\3\0"+
+    "\2\11\2\0\1\11\1\203\6\11\11\0\14\11\6\0"+
+    "\1\11\14\0\4\11\1\204\3\0\2\11\2\0\10\11"+
+    "\11\0\14\11\6\0\1\11\14\0\4\11\1\205\3\0"+
+    "\2\11\2\0\10\11\11\0\14\11\6\0\1\11\14\0"+
+    "\5\11\3\0\2\11\2\0\5\11\1\206\1\207\1\11"+
+    "\11\0\14\11\6\0\1\11\14\0\5\11\3\0\2\11"+
+    "\2\0\10\11\11\0\11\11\1\210\2\11\6\0\1\11"+
+    "\14\0\5\11\3\0\2\11\2\0\4\11\1\211\3\11"+
+    "\11\0\14\11\6\0\1\11\14\0\1\57\2\0\1\57"+
+    "\3\0\1\57\1\0\2\57\12\0\1\57\1\0\1\57"+
+    "\5\0\1\57\27\0\4\151\1\0\1\151\1\0\65\151"+
+    "\4\152\1\0\1\152\1\0\65\152\11\0\1\154\3\0"+
+    "\1\67\1\0\1\154\65\0\1\155\2\212\3\0\1\155"+
+    "\63\0\4\11\1\213\3\0\2\11\2\0\10\11\11\0"+
+    "\14\11\6\0\1\11\14\0\5\11\3\0\2\11\2\0"+
+    "\10\11\11\0\5\11\1\214\6\11\6\0\1\11\14\0"+
+    "\5\11\3\0\2\11\2\0\6\11\1\215\1\11\11\0"+
+    "\14\11\6\0\1\11\14\0\5\11\3\0\2\11\2\0"+
+    "\1\11\1\216\6\11\11\0\14\11\6\0\1\11\14\0"+
+    "\5\11\3\0\2\11\2\0\4\11\1\217\3\11\11\0"+
+    "\14\11\6\0\1\11\14\0\4\11\1\220\3\0\2\11"+
+    "\2\0\10\11\11\0\14\11\6\0\1\11\24\0\1\221"+
+    "\63\0\1\114\2\0\1\114\3\0\1\114\1\0\2\114"+
+    "\12\0\1\114\1\0\1\114\5\0\1\114\36\0\4\11"+
+    "\1\222\3\0\2\11\2\0\10\11\11\0\14\11\6\0"+
+    "\1\11\14\0\5\11\3\0\2\11\2\0\10\11\11\0"+
+    "\1\11\1\223\12\11\6\0\1\11\14\0\5\11\3\0"+
+    "\2\11\2\0\3\11\1\224\4\11\11\0\14\11\6\0"+
+    "\1\11\14\0\5\11\3\0\2\11\2\0\10\11\11\0"+
+    "\13\11\1\225\6\0\1\11\14\0\4\11\1\226\3\0"+
+    "\2\11\2\0\10\11\11\0\14\11\6\0\1\11\14\0"+
+    "\5\11\3\0\2\11\2\0\10\11\11\0\7\11\1\227"+
+    "\4\11\6\0\1\11\14\0\5\11\3\0\2\11\2\0"+
+    "\1\230\7\11\11\0\14\11\6\0\1\11\16\0\1\231"+
+    "\2\0\1\232\2\0\1\231\43\0\1\232\17\0\5\11"+
+    "\3\0\2\11\2\0\3\11\1\233\4\11\11\0\14\11"+
+    "\6\0\1\11\14\0\5\11\3\0\2\11\2\0\10\11"+
+    "\11\0\5\11\1\234\6\11\6\0\1\11\24\0\1\114"+
+    "\63\0\5\11\3\0\2\11\2\0\4\11\1\235\3\11"+
+    "\11\0\14\11\6\0\1\11\14\0\5\11\3\0\2\11"+
+    "\2\0\10\11\11\0\13\11\1\236\6\0\1\11\14\0"+
+    "\5\11\3\0\2\11\2\0\5\11\1\237\2\11\11\0"+
+    "\14\11\6\0\1\11\14\0\5\11\3\0\2\11\2\0"+
+    "\10\11\11\0\3\11\1\240\10\11\6\0\1\11\14\0"+
+    "\4\11\1\241\3\0\2\11\2\0\10\11\11\0\14\11"+
+    "\6\0\1\11\16\0\1\231\5\0\1\231\63\0\5\11"+
+    "\3\0\2\11\2\0\7\11\1\242\11\0\14\11\6\0"+
+    "\1\11\14\0\5\11\3\0\2\11\2\0\5\11\1\243"+
+    "\2\11\11\0\14\11\6\0\1\11\14\0\4\11\1\244"+
+    "\3\0\2\11\2\0\10\11\11\0\14\11\6\0\1\11"+
+    "\14\0\4\11\1\245\3\0\2\11\2\0\10\11\11\0"+
+    "\14\11\6\0\1\11\14\0\5\11\3\0\2\11\2\0"+
+    "\10\11\11\0\6\11\1\246\5\11\6\0\1\11\5\0";
 
   private static int [] zzUnpackTrans() {
-    int [] result = new int[5820];
+    int [] result = new int[6240];
     int offset = 0;
     offset = zzUnpackTrans(ZZ_TRANS_PACKED_0, offset, result);
     return result;
@@ -310,14 +320,14 @@ private static int zzUnpackTrans(String packed, int offset, int [] result) {
 
   private static final String ZZ_ATTRIBUTE_PACKED_0 =
     "\2\0\1\11\2\1\1\11\17\1\4\11\2\1\1\11"+
-    "\11\1\1\11\2\1\2\11\1\1\2\11\2\1\1\11"+
-    "\3\1\1\0\1\1\1\0\1\1\2\11\1\1\2\0"+
+    "\12\1\1\11\3\1\2\11\1\1\1\11\2\1\1\11"+
+    "\3\1\1\0\1\1\1\0\2\1\2\11\1\1\2\0"+
     "\1\11\13\1\2\11\1\1\1\11\1\0\2\11\1\0"+
-    "\7\1\11\11\1\1\1\11\2\0\6\1\1\11\16\1"+
-    "\1\0\2\11\7\1\1\0\15\1\1\0\13\1";
+    "\10\1\11\11\1\1\2\11\2\0\7\1\1\11\16\1"+
+    "\1\0\2\11\10\1\1\0\17\1\1\0\14\1";
 
   private static int [] zzUnpackAttribute() {
-    int [] result = new int[157];
+    int [] result = new int[166];
     int offset = 0;
     offset = zzUnpackAttribute(ZZ_ATTRIBUTE_PACKED_0, offset, result);
     return result;
@@ -626,397 +636,412 @@ else if (zzAtEOF) {
             { yybegin(YYINITIAL); return com.intellij.psi.TokenType.BAD_CHARACTER;
             } 
             // fall through
-          case 80: break;
+          case 83: break;
           case 2: 
             { return com.intellij.psi.TokenType.WHITE_SPACE;
             } 
             // fall through
-          case 81: break;
+          case 84: break;
           case 3: 
             { return ERL_RADIX;
             } 
             // fall through
-          case 82: break;
+          case 85: break;
           case 4: 
             { return ERL_OP_EXL;
             } 
             // fall through
-          case 83: break;
+          case 86: break;
           case 5: 
             { return ERL_COMMENT;
             } 
             // fall through
-          case 84: break;
+          case 87: break;
           case 6: 
             { return ERL_VAR;
             } 
             // fall through
-          case 85: break;
+          case 88: break;
           case 7: 
             { return ERL_ATOM_NAME;
             } 
             // fall through
-          case 86: break;
+          case 89: break;
           case 8: 
             { return ERL_INTEGER;
             } 
             // fall through
-          case 87: break;
+          case 90: break;
           case 9: 
             { return ERL_OP_MINUS;
             } 
             // fall through
-          case 88: break;
+          case 91: break;
           case 10: 
             { return ERL_DOT;
             } 
             // fall through
-          case 89: break;
+          case 92: break;
           case 11: 
             { yybegin(IN_QUOTES); return ERL_SINGLE_QUOTE;
             } 
             // fall through
-          case 90: break;
+          case 93: break;
           case 12: 
             { return ERL_BRACKET_LEFT;
             } 
             // fall through
-          case 91: break;
+          case 94: break;
           case 13: 
             { return ERL_CURLY_LEFT;
             } 
             // fall through
-          case 92: break;
+          case 95: break;
           case 14: 
             { return ERL_BRACKET_RIGHT;
             } 
             // fall through
-          case 93: break;
+          case 96: break;
           case 15: 
             { return ERL_CURLY_RIGHT;
             } 
             // fall through
-          case 94: break;
+          case 97: break;
           case 16: 
             { return ERL_CHAR;
             } 
             // fall through
-          case 95: break;
+          case 98: break;
           case 17: 
             { return ERL_OP_EQ;
             } 
             // fall through
-          case 96: break;
+          case 99: break;
           case 18: 
             { return ERL_COMMA;
             } 
             // fall through
-          case 97: break;
+          case 100: break;
           case 19: 
             { return ERL_COLON;
             } 
             // fall through
-          case 98: break;
+          case 101: break;
           case 20: 
             { return ERL_OP_GT;
             } 
             // fall through
-          case 99: break;
+          case 102: break;
           case 21: 
             { return ERL_OP_LT;
             } 
             // fall through
-          case 100: break;
+          case 103: break;
           case 22: 
             { return ERL_OP_PLUS;
             } 
             // fall through
-          case 101: break;
+          case 104: break;
           case 23: 
             { return ERL_OP_AR_MUL;
             } 
             // fall through
-          case 102: break;
+          case 105: break;
           case 24: 
             { return ERL_OP_AR_DIV;
             } 
             // fall through
-          case 103: break;
+          case 106: break;
           case 25: 
-            { return ERL_PAR_LEFT;
+            { return ERL_QMARK;
             } 
             // fall through
-          case 104: break;
+          case 107: break;
           case 26: 
-            { return ERL_PAR_RIGHT;
+            { return ERL_PAR_LEFT;
             } 
             // fall through
-          case 105: break;
+          case 108: break;
           case 27: 
-            { return ERL_OP_OR;
+            { return ERL_PAR_RIGHT;
             } 
             // fall through
-          case 106: break;
+          case 109: break;
           case 28: 
-            { return ERL_SEMI;
+            { return ERL_OP_OR;
             } 
             // fall through
-          case 107: break;
+          case 110: break;
           case 29: 
-            { return ERL_QMARK;
+            { return ERL_SEMI;
             } 
             // fall through
-          case 108: break;
+          case 111: break;
           case 30: 
             { yybegin(YYINITIAL); return ERL_SINGLE_QUOTE;
             } 
             // fall through
-          case 109: break;
+          case 112: break;
           case 31: 
             { return getTokenStart() == 0 ? ERL_SHEBANG : com.intellij.psi.TokenType.ERROR_ELEMENT;
             } 
             // fall through
-          case 110: break;
+          case 113: break;
           case 32: 
             { return ERL_FUNCTION_DOC_COMMENT;
             } 
             // fall through
-          case 111: break;
+          case 114: break;
           case 33: 
             { return ERL_OP_MINUS_MINUS;
             } 
             // fall through
-          case 112: break;
+          case 115: break;
           case 34: 
             { return ERL_ARROW;
             } 
             // fall through
-          case 113: break;
+          case 116: break;
           case 35: 
             { return ERL_DOT_DOT;
             } 
             // fall through
-          case 114: break;
+          case 117: break;
           case 36: 
             { return ERL_STRING;
             } 
             // fall through
-          case 115: break;
+          case 118: break;
           case 37: 
             { return ERL_OP_EQ_EQ;
             } 
             // fall through
-          case 116: break;
+          case 119: break;
           case 38: 
             { return ERL_ASSOC;
             } 
             // fall through
-          case 117: break;
+          case 120: break;
           case 39: 
             { return ERL_OP_EQ_LT;
             } 
             // fall through
-          case 118: break;
+          case 121: break;
           case 40: 
             { return ERL_IF;
             } 
             // fall through
-          case 119: break;
+          case 122: break;
           case 41: 
             { return ERL_OF;
             } 
             // fall through
-          case 120: break;
+          case 123: break;
           case 42: 
             { return ERL_OR;
             } 
             // fall through
-          case 121: break;
+          case 124: break;
           case 43: 
             { return ERL_MATCH;
             } 
             // fall through
-          case 122: break;
+          case 125: break;
           case 44: 
             { return ERL_COLON_COLON;
             } 
             // fall through
-          case 123: break;
+          case 126: break;
           case 45: 
             { return ERL_OP_GT_EQ;
             } 
             // fall through
-          case 124: break;
+          case 127: break;
           case 46: 
             { return ERL_BIN_END;
             } 
             // fall through
-          case 125: break;
+          case 128: break;
           case 47: 
             { return ERL_OP_LT_MINUS;
             } 
             // fall through
-          case 126: break;
+          case 129: break;
           case 48: 
             { return ERL_OP_LT_EQ;
             } 
             // fall through
-          case 127: break;
+          case 130: break;
           case 49: 
             { return ERL_BIN_START;
             } 
             // fall through
-          case 128: break;
+          case 131: break;
           case 50: 
             { return ERL_OP_PLUS_PLUS;
             } 
             // fall through
-          case 129: break;
+          case 132: break;
           case 51: 
             { return ERL_OP_DIV_EQ;
             } 
             // fall through
-          case 130: break;
+          case 133: break;
           case 52: 
-            { return ERL_OR_OR;
+            { return ERL_OP_MAYBE_EQ;
             } 
             // fall through
-          case 131: break;
+          case 134: break;
           case 53: 
-            { return ERL_MODULE_DOC_COMMENT;
+            { return ERL_OR_OR;
             } 
             // fall through
-          case 132: break;
+          case 135: break;
           case 54: 
-            { return ERL_FLOAT;
+            { return ERL_MODULE_DOC_COMMENT;
             } 
             // fall through
-          case 133: break;
+          case 136: break;
           case 55: 
-            { return ERL_END;
+            { return ERL_FLOAT;
             } 
             // fall through
-          case 134: break;
+          case 137: break;
           case 56: 
-            { return ERL_DOT_DOT_DOT;
+            { return ERL_END;
             } 
             // fall through
-          case 135: break;
+          case 138: break;
           case 57: 
-            { return ERL_BSR;
+            { return ERL_DOT_DOT_DOT;
             } 
             // fall through
-          case 136: break;
+          case 139: break;
           case 58: 
-            { return ERL_BSL;
+            { return ERL_BSR;
             } 
             // fall through
-          case 137: break;
+          case 140: break;
           case 59: 
-            { return ERL_BOR;
+            { return ERL_BSL;
             } 
             // fall through
-          case 138: break;
+          case 141: break;
           case 60: 
-            { return ERL_DIV;
+            { return ERL_BOR;
             } 
             // fall through
-          case 139: break;
+          case 142: break;
           case 61: 
-            { return ERL_FUN;
+            { return ERL_DIV;
             } 
             // fall through
-          case 140: break;
+          case 143: break;
           case 62: 
-            { return ERL_NOT;
+            { return ERL_FUN;
             } 
             // fall through
-          case 141: break;
+          case 144: break;
           case 63: 
-            { return ERL_REM;
+            { return ERL_NOT;
             } 
             // fall through
-          case 142: break;
+          case 145: break;
           case 64: 
-            { return ERL_TRY;
+            { return ERL_REM;
             } 
             // fall through
-          case 143: break;
+          case 146: break;
           case 65: 
-            { return ERL_OP_EQ_COL_EQ;
+            { return ERL_TRY;
             } 
             // fall through
-          case 144: break;
+          case 147: break;
           case 66: 
-            { return ERL_OP_EQ_DIV_EQ;
+            { return ERL_OP_EQ_COL_EQ;
             } 
             // fall through
-          case 145: break;
+          case 148: break;
           case 67: 
-            { return ERL_AND;
+            { return ERL_OP_EQ_DIV_EQ;
             } 
             // fall through
-          case 146: break;
+          case 149: break;
           case 68: 
-            { return ERL_XOR;
+            { return ERL_AND;
             } 
             // fall through
-          case 147: break;
+          case 150: break;
           case 69: 
-            { return ERL_BNOT;
+            { return ERL_XOR;
             } 
             // fall through
-          case 148: break;
+          case 151: break;
           case 70: 
-            { return ERL_BAND;
+            { return ERL_ELSE;
             } 
             // fall through
-          case 149: break;
+          case 152: break;
           case 71: 
-            { return ERL_BXOR;
+            { return ERL_BNOT;
             } 
             // fall through
-          case 150: break;
+          case 153: break;
           case 72: 
-            { return ERL_WHEN;
+            { return ERL_BAND;
             } 
             // fall through
-          case 151: break;
+          case 154: break;
           case 73: 
-            { return ERL_CASE;
+            { return ERL_BXOR;
             } 
             // fall through
-          case 152: break;
+          case 155: break;
           case 74: 
-            { return ERL_BEGIN;
+            { return ERL_WHEN;
             } 
             // fall through
-          case 153: break;
+          case 156: break;
           case 75: 
-            { return ERL_AFTER;
+            { return ERL_CASE;
             } 
             // fall through
-          case 154: break;
+          case 157: break;
           case 76: 
-            { return ERL_CATCH;
+            { return ERL_BEGIN;
             } 
             // fall through
-          case 155: break;
+          case 158: break;
           case 77: 
-            { return ERL_ORELSE;
+            { return ERL_AFTER;
             } 
             // fall through
-          case 156: break;
+          case 159: break;
           case 78: 
-            { return ERL_RECEIVE;
+            { return ERL_CATCH;
             } 
             // fall through
-          case 157: break;
+          case 160: break;
           case 79: 
+            { return ERL_MAYBE;
+            } 
+            // fall through
+          case 161: break;
+          case 80: 
+            { return ERL_ORELSE;
+            } 
+            // fall through
+          case 162: break;
+          case 81: 
+            { return ERL_RECEIVE;
+            } 
+            // fall through
+          case 163: break;
+          case 82: 
             { return ERL_ANDALSO;
             } 
             // fall through
-          case 158: break;
+          case 164: break;
           default:
             zzScanError(ZZ_NO_MATCH);
           }
diff --git a/gen/org/intellij/erlang/psi/ErlangAttribute.java b/gen/org/intellij/erlang/psi/ErlangAttribute.java
index 84de87e2f..4cc338646 100644
--- a/gen/org/intellij/erlang/psi/ErlangAttribute.java
+++ b/gen/org/intellij/erlang/psi/ErlangAttribute.java
@@ -16,6 +16,9 @@ public interface ErlangAttribute extends ErlangCompositeElement {
   @Nullable
   ErlangCallbackSpec getCallbackSpec();
 
+  @Nullable
+  ErlangElseAtomAttribute getElseAtomAttribute();
+
   @Nullable
   ErlangExport getExport();
 
diff --git a/gen/org/intellij/erlang/psi/ErlangElseAtomAttribute.java b/gen/org/intellij/erlang/psi/ErlangElseAtomAttribute.java
new file mode 100644
index 000000000..41577707e
--- /dev/null
+++ b/gen/org/intellij/erlang/psi/ErlangElseAtomAttribute.java
@@ -0,0 +1,10 @@
+// This is a generated file. Not intended for manual editing.
+package org.intellij.erlang.psi;
+
+import java.util.List;
+import org.jetbrains.annotations.*;
+import com.intellij.psi.PsiElement;
+
+public interface ErlangElseAtomAttribute extends ErlangMetaAttribute {
+
+}
diff --git a/gen/org/intellij/erlang/psi/ErlangMaybeExpression.java b/gen/org/intellij/erlang/psi/ErlangMaybeExpression.java
new file mode 100644
index 000000000..a93bcccee
--- /dev/null
+++ b/gen/org/intellij/erlang/psi/ErlangMaybeExpression.java
@@ -0,0 +1,25 @@
+// This is a generated file. Not intended for manual editing.
+package org.intellij.erlang.psi;
+
+import java.util.List;
+import org.jetbrains.annotations.*;
+import com.intellij.psi.PsiElement;
+
+public interface ErlangMaybeExpression extends ErlangExpression, ErlangClauseOwner {
+
+  @NotNull
+  List<ErlangCrClause> getCrClauseList();
+
+  @Nullable
+  ErlangMaybeMatchExprs getMaybeMatchExprs();
+
+  @Nullable
+  PsiElement getElse();
+
+  @Nullable
+  PsiElement getEnd();
+
+  @NotNull
+  PsiElement getMaybe();
+
+}
diff --git a/gen/org/intellij/erlang/psi/ErlangMaybeMatchExpression.java b/gen/org/intellij/erlang/psi/ErlangMaybeMatchExpression.java
new file mode 100644
index 000000000..3fccfbb38
--- /dev/null
+++ b/gen/org/intellij/erlang/psi/ErlangMaybeMatchExpression.java
@@ -0,0 +1,13 @@
+// This is a generated file. Not intended for manual editing.
+package org.intellij.erlang.psi;
+
+import java.util.List;
+import org.jetbrains.annotations.*;
+import com.intellij.psi.PsiElement;
+
+public interface ErlangMaybeMatchExpression extends ErlangFakeBinaryExpression {
+
+  @NotNull
+  PsiElement getOpMaybeEq();
+
+}
diff --git a/gen/org/intellij/erlang/psi/ErlangMaybeMatchExprs.java b/gen/org/intellij/erlang/psi/ErlangMaybeMatchExprs.java
new file mode 100644
index 000000000..ce49a5a6e
--- /dev/null
+++ b/gen/org/intellij/erlang/psi/ErlangMaybeMatchExprs.java
@@ -0,0 +1,16 @@
+// This is a generated file. Not intended for manual editing.
+package org.intellij.erlang.psi;
+
+import java.util.List;
+import org.jetbrains.annotations.*;
+import com.intellij.psi.PsiElement;
+
+public interface ErlangMaybeMatchExprs extends ErlangCompositeElement {
+
+  @NotNull
+  List<ErlangExpression> getExpressionList();
+
+  @Nullable
+  ErlangMaybeMatchExprs getMaybeMatchExprs();
+
+}
diff --git a/gen/org/intellij/erlang/psi/ErlangVisitor.java b/gen/org/intellij/erlang/psi/ErlangVisitor.java
index 1de165dc8..34b33c217 100644
--- a/gen/org/intellij/erlang/psi/ErlangVisitor.java
+++ b/gen/org/intellij/erlang/psi/ErlangVisitor.java
@@ -140,6 +140,10 @@ public void visitCrClause(@NotNull ErlangCrClause o) {
     visitCompositeElement(o);
   }
 
+  public void visitElseAtomAttribute(@NotNull ErlangElseAtomAttribute o) {
+    visitMetaAttribute(o);
+  }
+
   public void visitExport(@NotNull ErlangExport o) {
     visitMetaAttribute(o);
   }
@@ -340,6 +344,19 @@ public void visitMaxExpression(@NotNull ErlangMaxExpression o) {
     visitExpression(o);
   }
 
+  public void visitMaybeExpression(@NotNull ErlangMaybeExpression o) {
+    visitExpression(o);
+    // visitClauseOwner(o);
+  }
+
+  public void visitMaybeMatchExpression(@NotNull ErlangMaybeMatchExpression o) {
+    visitFakeBinaryExpression(o);
+  }
+
+  public void visitMaybeMatchExprs(@NotNull ErlangMaybeMatchExprs o) {
+    visitCompositeElement(o);
+  }
+
   public void visitModelFieldList(@NotNull ErlangModelFieldList o) {
     visitCompositeElement(o);
   }
diff --git a/gen/org/intellij/erlang/psi/impl/ErlangAttributeImpl.java b/gen/org/intellij/erlang/psi/impl/ErlangAttributeImpl.java
index fa53f0303..59ee11efe 100644
--- a/gen/org/intellij/erlang/psi/impl/ErlangAttributeImpl.java
+++ b/gen/org/intellij/erlang/psi/impl/ErlangAttributeImpl.java
@@ -44,6 +44,12 @@ public ErlangCallbackSpec getCallbackSpec() {
     return PsiTreeUtil.getChildOfType(this, ErlangCallbackSpec.class);
   }
 
+  @Override
+  @Nullable
+  public ErlangElseAtomAttribute getElseAtomAttribute() {
+    return PsiTreeUtil.getChildOfType(this, ErlangElseAtomAttribute.class);
+  }
+
   @Override
   @Nullable
   public ErlangExport getExport() {
diff --git a/gen/org/intellij/erlang/psi/impl/ErlangElseAtomAttributeImpl.java b/gen/org/intellij/erlang/psi/impl/ErlangElseAtomAttributeImpl.java
new file mode 100644
index 000000000..e7aa377be
--- /dev/null
+++ b/gen/org/intellij/erlang/psi/impl/ErlangElseAtomAttributeImpl.java
@@ -0,0 +1,29 @@
+// This is a generated file. Not intended for manual editing.
+package org.intellij.erlang.psi.impl;
+
+import java.util.List;
+import org.jetbrains.annotations.*;
+import com.intellij.lang.ASTNode;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiElementVisitor;
+import com.intellij.psi.util.PsiTreeUtil;
+import static org.intellij.erlang.ErlangTypes.*;
+import org.intellij.erlang.psi.*;
+
+public class ErlangElseAtomAttributeImpl extends ErlangCompositeElementImpl implements ErlangElseAtomAttribute {
+
+  public ErlangElseAtomAttributeImpl(ASTNode node) {
+    super(node);
+  }
+
+  public void accept(@NotNull ErlangVisitor visitor) {
+    visitor.visitElseAtomAttribute(this);
+  }
+
+  @Override
+  public void accept(@NotNull PsiElementVisitor visitor) {
+    if (visitor instanceof ErlangVisitor) accept((ErlangVisitor)visitor);
+    else super.accept(visitor);
+  }
+
+}
diff --git a/gen/org/intellij/erlang/psi/impl/ErlangMaybeExpressionImpl.java b/gen/org/intellij/erlang/psi/impl/ErlangMaybeExpressionImpl.java
new file mode 100644
index 000000000..6cd933ced
--- /dev/null
+++ b/gen/org/intellij/erlang/psi/impl/ErlangMaybeExpressionImpl.java
@@ -0,0 +1,60 @@
+// This is a generated file. Not intended for manual editing.
+package org.intellij.erlang.psi.impl;
+
+import java.util.List;
+import org.jetbrains.annotations.*;
+import com.intellij.lang.ASTNode;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiElementVisitor;
+import com.intellij.psi.util.PsiTreeUtil;
+import static org.intellij.erlang.ErlangTypes.*;
+import org.intellij.erlang.psi.*;
+
+public class ErlangMaybeExpressionImpl extends ErlangExpressionImpl implements ErlangMaybeExpression {
+
+  public ErlangMaybeExpressionImpl(ASTNode node) {
+    super(node);
+  }
+
+  @Override
+  public void accept(@NotNull ErlangVisitor visitor) {
+    visitor.visitMaybeExpression(this);
+  }
+
+  @Override
+  public void accept(@NotNull PsiElementVisitor visitor) {
+    if (visitor instanceof ErlangVisitor) accept((ErlangVisitor)visitor);
+    else super.accept(visitor);
+  }
+
+  @Override
+  @NotNull
+  public List<ErlangCrClause> getCrClauseList() {
+    return PsiTreeUtil.getChildrenOfTypeAsList(this, ErlangCrClause.class);
+  }
+
+  @Override
+  @Nullable
+  public ErlangMaybeMatchExprs getMaybeMatchExprs() {
+    return PsiTreeUtil.getChildOfType(this, ErlangMaybeMatchExprs.class);
+  }
+
+  @Override
+  @Nullable
+  public PsiElement getElse() {
+    return findChildByType(ERL_ELSE);
+  }
+
+  @Override
+  @Nullable
+  public PsiElement getEnd() {
+    return findChildByType(ERL_END);
+  }
+
+  @Override
+  @NotNull
+  public PsiElement getMaybe() {
+    return notNullChild(findChildByType(ERL_MAYBE));
+  }
+
+}
diff --git a/gen/org/intellij/erlang/psi/impl/ErlangMaybeMatchExpressionImpl.java b/gen/org/intellij/erlang/psi/impl/ErlangMaybeMatchExpressionImpl.java
new file mode 100644
index 000000000..b442d106e
--- /dev/null
+++ b/gen/org/intellij/erlang/psi/impl/ErlangMaybeMatchExpressionImpl.java
@@ -0,0 +1,36 @@
+// This is a generated file. Not intended for manual editing.
+package org.intellij.erlang.psi.impl;
+
+import java.util.List;
+import org.jetbrains.annotations.*;
+import com.intellij.lang.ASTNode;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiElementVisitor;
+import com.intellij.psi.util.PsiTreeUtil;
+import static org.intellij.erlang.ErlangTypes.*;
+import org.intellij.erlang.psi.*;
+
+public class ErlangMaybeMatchExpressionImpl extends ErlangFakeBinaryExpressionImpl implements ErlangMaybeMatchExpression {
+
+  public ErlangMaybeMatchExpressionImpl(ASTNode node) {
+    super(node);
+  }
+
+  @Override
+  public void accept(@NotNull ErlangVisitor visitor) {
+    visitor.visitMaybeMatchExpression(this);
+  }
+
+  @Override
+  public void accept(@NotNull PsiElementVisitor visitor) {
+    if (visitor instanceof ErlangVisitor) accept((ErlangVisitor)visitor);
+    else super.accept(visitor);
+  }
+
+  @Override
+  @NotNull
+  public PsiElement getOpMaybeEq() {
+    return notNullChild(findChildByType(ERL_OP_MAYBE_EQ));
+  }
+
+}
diff --git a/gen/org/intellij/erlang/psi/impl/ErlangMaybeMatchExprsImpl.java b/gen/org/intellij/erlang/psi/impl/ErlangMaybeMatchExprsImpl.java
new file mode 100644
index 000000000..2c92648d3
--- /dev/null
+++ b/gen/org/intellij/erlang/psi/impl/ErlangMaybeMatchExprsImpl.java
@@ -0,0 +1,41 @@
+// This is a generated file. Not intended for manual editing.
+package org.intellij.erlang.psi.impl;
+
+import java.util.List;
+import org.jetbrains.annotations.*;
+import com.intellij.lang.ASTNode;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiElementVisitor;
+import com.intellij.psi.util.PsiTreeUtil;
+import static org.intellij.erlang.ErlangTypes.*;
+import org.intellij.erlang.psi.*;
+
+public class ErlangMaybeMatchExprsImpl extends ErlangCompositeElementImpl implements ErlangMaybeMatchExprs {
+
+  public ErlangMaybeMatchExprsImpl(ASTNode node) {
+    super(node);
+  }
+
+  public void accept(@NotNull ErlangVisitor visitor) {
+    visitor.visitMaybeMatchExprs(this);
+  }
+
+  @Override
+  public void accept(@NotNull PsiElementVisitor visitor) {
+    if (visitor instanceof ErlangVisitor) accept((ErlangVisitor)visitor);
+    else super.accept(visitor);
+  }
+
+  @Override
+  @NotNull
+  public List<ErlangExpression> getExpressionList() {
+    return PsiTreeUtil.getChildrenOfTypeAsList(this, ErlangExpression.class);
+  }
+
+  @Override
+  @Nullable
+  public ErlangMaybeMatchExprs getMaybeMatchExprs() {
+    return PsiTreeUtil.getChildOfType(this, ErlangMaybeMatchExprs.class);
+  }
+
+}
diff --git a/grammars/erlang.bnf b/grammars/erlang.bnf
index 9e350b5fe..0aa4d0e28 100644
--- a/grammars/erlang.bnf
+++ b/grammars/erlang.bnf
@@ -39,6 +39,7 @@
   OP_EQ           = "="
   OP_EXL          = "!"
   OP_LT_MINUS     = "<-"
+  OP_MAYBE_EQ     = "?="
 
   BIN_START       = "<<"
   BIN_END         = ">>"
@@ -65,7 +66,7 @@
   ASSOC           = "=>"
   ]
 
-  extends("assignment_expression|send_expression|orelse_expression|andalso_expression|comp_op_expression|list_op_expression|additive_expression|multiplicative_expression")=fake_binary_expression
+  extends("assignment_expression|maybe_match_expression|send_expression|orelse_expression|andalso_expression|comp_op_expression|list_op_expression|additive_expression|multiplicative_expression")=fake_binary_expression
   extends(".*_(expression|comprehension|literal)")=expression
 
   name(".*_(expression|comprehension|literal)")=expression
@@ -82,7 +83,7 @@
   extends("behaviour|type_definition|include|include_lib|callback_spec|callback_function")="org.intellij.erlang.psi.impl.ErlangStubbedPsiElementBase<?>"
   elementTypeFactory("function|behaviour|module|record_definition|type_definition|macros_definition|include|include_lib|callback_spec|callback_function|specification")="org.intellij.erlang.ErlangElementTypeFactory.factory"
 
-  implements("case_expression|try_expression|receive_expression")="org.intellij.erlang.psi.ErlangClauseOwner"
+  implements("case_expression|try_expression|receive_expression|maybe_expression")="org.intellij.erlang.psi.ErlangClauseOwner"
 }
 
 forms ::= console_expression | application_file_expression | form_with_period *
@@ -92,7 +93,7 @@ private console_expression_or_empty ::= exprs period | empty {pin(".*")=1}
 private empty ::= ()
 private form_with_period ::= form period {recoverWhile=form_recover pin=1}
 private left period ::= '.' | <<isModeOn "ELSE">> <<exitMode "ELSE">>
-private form_recover ::= !('+' | '-' | '<<' | '?' | '[' | '{' | atom_name | single_quote | bnot | char | float | integer | not | string | var | '#'| '.')
+private form_recover ::= !('+' | '-' | '<<' | '?' | '[' | '{' | atom_name | single_quote | bnot | char | float | integer | not | string | var | '#' | '.')
 private form ::=
     is_config config_expression
   | function
@@ -219,7 +220,7 @@ type_ref ::= q_atom {
 }
 
 ifdef_ifndef_undef_attribute ::= &('ifdef'|'ifndef'|'undef') atom_name '(' macros_name ')' {pin=2 elementType=atom_attribute}
-else_atom_attribute ::= &'else' atom_name {elementType=atom_attribute}
+else_atom_attribute ::= 'else' {pin=1}
 on_load ::= &'on_load' atom_name '(' function_with_arity ')'{pin=2 elementType=atom_attribute}
 atom_attribute ::= atom_name ['(' typed_attr_val ')' | typed_attr_val | attr_val] {methods=[getName]}
 export_functions ::= '[' export_function_list? ']' {pin=1}
@@ -439,6 +440,7 @@ max_expression ::=
   | receive_expression
   | fun_expression
   | try_expression
+  | maybe_expression
   | binary_expression
   | begin_end_expression
 
@@ -571,6 +573,10 @@ try_clauses ::= try_clause (';' try_clause)*
 try_clause ::= <<guarded try_argument_definition>> clause_guard? clause_body {pin=1}
 private try_argument_definition ::= [argument_definition ':'] argument_definition
 
+maybe_expression ::= maybe maybe_match_exprs [else cr_clauses] end {pin(".*")=1}
+maybe_match_exprs ::= (maybe_match_expression | expression) [',' maybe_match_exprs] (exprs_tail)* {pin=3 recoverWhile=exprs_recover}
+maybe_match_expression ::= expression '?=' expression { rightAssociative=true }
+
 argument_list ::= '(' call_exprs? ')'
 
 fake fake_binary_expression ::= expression+ {
@@ -582,7 +588,7 @@ fake fake_binary_expression ::= expression+ {
 
 private exprs ::= expression (exprs_tail)* {pin=2 recoverWhile=exprs_recover}
 private exprs_tail ::= ',' expression {pin=1 recoverWhile=exprs_recover}
-private exprs_recover ::= !(')' | ',' | '->' | '.' | ':-' | ';' | '}' | after | catch | end | of | atom '(')
+private exprs_recover ::= !(')' | ',' | '->' | '.' | ':-' | ';' | '}' | after | catch | else | end | of | atom '(')
 guard ::= exprs (';' exprs)* {pin(".*")=1}
 private atomic ::= q_atom !'(' | integer | (string_literal | macros)+ | float | char
 string_literal ::= string {
@@ -591,10 +597,10 @@ string_literal ::= string {
 }
 
 private prefix_op ::= '+' | '-' | bnot | not
-private mult_op ::= '/' |'*' | div | rem  | band | and
-private add_op ::= '+' |'-' | bor | bxor | bsl | bsr | or | xor
+private mult_op ::= '/' | '*' | div | rem  | band | and
+private add_op ::= '+' | '-' | bor | bxor | bsl | bsr | or | xor
 private list_op ::= '++' | '--'
-private comp_op ::= '==' | '/=' |'=<' |'<' |'>=' |'>' |'=:=' |'=/='
+private comp_op ::= '==' | '/=' | '=<' |'<' | '>=' | '>' | '=:=' | '=/='
 
 rule ::= rule_clause (';' rule_clause)* {pin(".*")=1}
 rule_clause ::= q_atom argument_list clause_guard? rule_body
diff --git a/resources/liveTemplates/erlang.xml b/resources/liveTemplates/erlang.xml
index 32f606bc8..c0c2e25fc 100644
--- a/resources/liveTemplates/erlang.xml
+++ b/resources/liveTemplates/erlang.xml
@@ -98,6 +98,32 @@
         <option name="OTHER" value="false" />
       </context>
     </template>
+    <template name="maybe" value="maybe&#10;    $EXPR$&#10;end" description="maybe...end" toReformat="false" toShortenFQNames="true">
+      <variable name="EXPR" expression="completeSmart()" defaultValue="" alwaysStopAt="false" />
+      <context>
+        <option name="ERLANG_STATEMENT" value="true" />
+        <option name="ERLANG_EXPRESSION" value="true" />
+        <option name="OTHER" value="false" />
+      </context>
+    </template>
+    <template name="mayel" value="maybe&#10;    $EXPR$&#10;else&#10;    $PATTERN$ -&gt; $END$&#10;end" description="maybe...else...end" toReformat="false" toShortenFQNames="true">
+      <variable name="EXPR" expression="completeSmart()" defaultValue="" alwaysStopAt="true" />
+      <variable name="PATTERN" expression="" defaultValue="" alwaysStopAt="true" />
+      <context>
+        <option name="ERLANG_STATEMENT" value="true" />
+        <option name="ERLANG_EXPRESSION" value="true" />
+        <option name="OTHER" value="false" />
+      </context>
+    </template>
+    <template name="M" value="maybe&#10;    $EXPR$&#10;else&#10;    $PATTERN$ -&gt; $END$&#10;end" description="surround with maybe...else...end" toReformat="false" toShortenFQNames="true">
+      <variable name="EXPR" expression="complete()" defaultValue="" alwaysStopAt="true" />
+      <variable name="PATTERN" expression="" defaultValue="" alwaysStopAt="true" />
+      <context>
+        <option name="ERLANG_STATEMENT" value="true" />
+        <option name="ERLANG_EXPRESSION" value="true" />
+        <option name="OTHER" value="false" />
+      </context>
+    </template>
     <template name="spec" value="-spec $NAME$/$ARITY$ :: ($ARGUMENTS$) -&gt; $RESULT$.$END$" description="define spec" toReformat="false" toShortenFQNames="true">
       <variable name="NAME" expression="" defaultValue="" alwaysStopAt="true" />
       <variable name="ARITY" expression="" defaultValue="" alwaysStopAt="true" />
diff --git a/src/org/intellij/erlang/ErlangBraceMatcher.java b/src/org/intellij/erlang/ErlangBraceMatcher.java
index 0303d8011..59d6c3378 100755
--- a/src/org/intellij/erlang/ErlangBraceMatcher.java
+++ b/src/org/intellij/erlang/ErlangBraceMatcher.java
@@ -36,6 +36,7 @@ public class ErlangBraceMatcher implements PairedBraceMatcher {
     new BracePair(ErlangTypes.ERL_TRY, ErlangTypes.ERL_END, true),
     new BracePair(ErlangTypes.ERL_FUN, ErlangTypes.ERL_END, true),
     new BracePair(ErlangTypes.ERL_RECEIVE, ErlangTypes.ERL_END, true),
+    new BracePair(ErlangTypes.ERL_MAYBE, ErlangTypes.ERL_END, true),
   };
 
   @NotNull
diff --git a/src/org/intellij/erlang/editor/ErlangAnnotator.java b/src/org/intellij/erlang/editor/ErlangAnnotator.java
index 4f229fc4d..37e3469b1 100644
--- a/src/org/intellij/erlang/editor/ErlangAnnotator.java
+++ b/src/org/intellij/erlang/editor/ErlangAnnotator.java
@@ -104,6 +104,11 @@ public void visitTypeDefinition(@NotNull ErlangTypeDefinition o) {
         markFirstChild(o, annotationHolder, ErlangSyntaxHighlighter.ATTRIBUTE);
       }
 
+      @Override
+      public void visitElseAtomAttribute(@NotNull ErlangElseAtomAttribute o) {
+        markFirstChild(o, annotationHolder, ErlangSyntaxHighlighter.ATTRIBUTE);
+      }
+
       @Override
       public void visitMacrosName(@NotNull ErlangMacrosName o) {
         PsiElement firstChild = o.getFirstChild();
diff --git a/src/org/intellij/erlang/editor/ErlangEnterHandler.java b/src/org/intellij/erlang/editor/ErlangEnterHandler.java
index 4ccfe1dc8..ad233e3db 100644
--- a/src/org/intellij/erlang/editor/ErlangEnterHandler.java
+++ b/src/org/intellij/erlang/editor/ErlangEnterHandler.java
@@ -52,7 +52,8 @@ public Result preprocessEnter(@NotNull PsiFile file, @NotNull Editor editor, @No
         completeCaseOf(file, editor) ||
         completeReceive(file, editor) ||
         completeIf(file, editor) ||
-        completeTry(file, editor)) {
+        completeTry(file, editor) ||
+        completeMaybe(file, editor)) {
       return Result.Stop;
     }
 
@@ -81,6 +82,11 @@ private static boolean completeTry(@NotNull PsiFile file, @NotNull Editor editor
            completeExpression(file, editor, ErlangTypes.ERL_OF, ErlangTryExpression.class);
   }
 
+  private static boolean completeMaybe(@NotNull PsiFile file, @NotNull Editor editor) {
+    return completeExpression(file, editor, ErlangTypes.ERL_MAYBE, ErlangMaybeExpression.class) ||
+           completeExpression(file, editor, ErlangTypes.ERL_ELSE, ErlangMaybeExpression.class);
+  }
+
   private static boolean completeExpression(@NotNull PsiFile file,
                                             @NotNull Editor editor,
                                             @NotNull IElementType lastElementType,
@@ -142,6 +148,7 @@ private static boolean hasEnd(PsiElement element) {
 
   private static boolean needCommaAfter(@NotNull PsiElement parent) {
     if (parent instanceof ErlangBeginEndExpression) return needCommaAfter((ErlangBeginEndExpression) parent);
+    if (parent instanceof ErlangMaybeExpression)    return needCommaAfter((ErlangMaybeExpression) parent);
     if (parent instanceof ErlangClauseOwner)        return needCommaAfter((ErlangClauseOwner) parent);
     if (parent instanceof ErlangIfExpression)       return needCommaAfter((ErlangIfExpression) parent);
     return false;
@@ -174,13 +181,24 @@ private static boolean needCommaAfter(@NotNull ErlangIfExpression ifExpression)
       PsiTreeUtil.findChildOfType(firstIfClause, ErlangIfExpression.class) != null;
   }
 
+  private static boolean needCommaAfter(@NotNull ErlangMaybeExpression maybeExpression) {
+    ErlangMaybeMatchExprs maybeMatchExprs = maybeExpression.getMaybeMatchExprs();
+    if (maybeMatchExprs == null) return false;
+
+    ErlangExpression expression = PsiTreeUtil.getChildOfType(maybeMatchExprs, ErlangExpression.class);
+    if(expression == null) return false;
+
+    return true;
+  }
+
   private static boolean shouldEndWithEnd(@NotNull PsiElement element) {
     return element instanceof ErlangBeginEndExpression ||
            element instanceof ErlangCaseExpression ||
            element instanceof ErlangIfExpression ||
            element instanceof ErlangReceiveExpression ||
            element instanceof ErlangFunExpression && PsiTreeUtil.getChildOfType(element, ErlangFunClauses.class) != null ||
-           element instanceof ErlangTryExpression;
+           element instanceof ErlangTryExpression ||
+           element instanceof ErlangMaybeExpression;
   }
 
   @Nullable
diff --git a/src/org/intellij/erlang/editor/ErlangSyntaxHighlighter.java b/src/org/intellij/erlang/editor/ErlangSyntaxHighlighter.java
index ef18adea5..6bf290491 100644
--- a/src/org/intellij/erlang/editor/ErlangSyntaxHighlighter.java
+++ b/src/org/intellij/erlang/editor/ErlangSyntaxHighlighter.java
@@ -75,7 +75,7 @@ public Lexer getHighlightingLexer() {
     if (type == ERL_INTEGER || type == ERL_FLOAT) {
       return pack(NUMBER);
     }
-    if (type == ERL_OP_EQ) {
+    if (type == ERL_OP_EQ || type == ERL_OP_MAYBE_EQ) {
       return pack(OP_SIGN);
     }
     if (type == ERL_PAR_LEFT || type == ERL_PAR_RIGHT) {
@@ -106,6 +106,8 @@ public Lexer getHighlightingLexer() {
         ERL_IF == type ||
         ERL_RECEIVE == type ||
         ERL_TRY == type ||
+        ERL_ELSE == type ||
+        ERL_MAYBE == type ||
         ERL_DOT == type ||
         ERL_ANDALSO == type ||
         ERL_ORELSE == type ||
@@ -125,6 +127,6 @@ public Lexer getHighlightingLexer() {
       ) {
       return pack(KEYWORD);
     }
-    return EMPTY;
+    return TextAttributesKey.EMPTY_ARRAY;
   }
 }
diff --git a/src/org/intellij/erlang/formatter/ErlangFormattingBlock.java b/src/org/intellij/erlang/formatter/ErlangFormattingBlock.java
index 87ba696f7..27b840d0d 100644
--- a/src/org/intellij/erlang/formatter/ErlangFormattingBlock.java
+++ b/src/org/intellij/erlang/formatter/ErlangFormattingBlock.java
@@ -54,6 +54,7 @@ public class ErlangFormattingBlock extends AbstractBlock {
     ERL_TOP_TYPE_CLAUSE,
     ERL_FUN_CLAUSES,
     ERL_TRY_EXPRESSIONS_CLAUSE,
+    ERL_MAYBE_MATCH_EXPRS,
     ERL_TYPE_SIG_GUARD,
     ERL_TOP_TYPE_CLAUSE
   );
@@ -354,13 +355,14 @@ private Indent getChildIndent(@Nullable IElementType type, int newChildIndex) {
       type == ERL_IF_EXPRESSION && newChildIndex == 1 ||
       type == ERL_CASE_EXPRESSION && newChildIndex == 1 ||
       type == ERL_BEGIN_END_EXPRESSION && newChildIndex == 1 ||
+      type == ERL_MAYBE_EXPRESSION && (newChildIndex == 1 || newChildIndex == 3 || newChildIndex == 5) ||
       type == ERL_FUN_EXPRESSION && newChildIndex == 1 ||
       type == ERL_RECEIVE_EXPRESSION && (newChildIndex == 1 || newChildIndex == 3 || newChildIndex == 5) ||
       type == ERL_TRY_EXPRESSION && (newChildIndex == 1 || newChildIndex == 3 || newChildIndex == 5)) {
       return Indent.getNormalIndent(myErlangSettings.INDENT_RELATIVE);
     }
 
-    if (type == ERL_IF_EXPRESSION || type == ERL_CASE_EXPRESSION ||
+    if (type == ERL_IF_EXPRESSION || type == ERL_CASE_EXPRESSION || type == ERL_MAYBE_EXPRESSION ||
       type == ERL_RECEIVE_EXPRESSION || type == ERL_BEGIN_END_EXPRESSION || type == ERL_FUN_EXPRESSION) {
       IElementType previousElement = getPreviousElementType(newChildIndex);
       if (previousElement != null &&
@@ -371,6 +373,8 @@ private Indent getChildIndent(@Nullable IElementType type, int newChildIndex) {
 
     if (type == ERL_BEGIN_END_BODY) return Indent.getNoneIndent();
 
+    if (type == ERL_MAYBE_MATCH_EXPRS) return Indent.getNoneIndent();
+
     if (type == ERL_TRY_EXPRESSIONS_CLAUSE && newChildIndex == 1) return Indent.getNoneIndent();
 
     if (BLOCKS_TOKEN_SET.contains(type) || type == ERL_TYPED_RECORD_FIELDS) {
diff --git a/src/org/intellij/erlang/formatter/ErlangFormattingModelBuilder.java b/src/org/intellij/erlang/formatter/ErlangFormattingModelBuilder.java
index 860815df7..e98978085 100644
--- a/src/org/intellij/erlang/formatter/ErlangFormattingModelBuilder.java
+++ b/src/org/intellij/erlang/formatter/ErlangFormattingModelBuilder.java
@@ -45,8 +45,8 @@ public class ErlangFormattingModelBuilder implements FormattingModelBuilder {
   private static SpacingBuilder createSpacingBuilder(@NotNull CommonCodeStyleSettings settings, @NotNull ErlangCodeStyleSettings erlangSettings) {
     TokenSet rules = TokenSet.create(ERL_RULE, ERL_RECORD_DEFINITION, ERL_INCLUDE, ERL_MACROS_DEFINITION, ERL_ATTRIBUTE);
     TokenSet keywords = TokenSet.create(
-      ERL_AFTER, ERL_WHEN, ERL_BEGIN, ERL_END, ERL_OF, ERL_CASE, ERL_CATCH, ERL_IF, ERL_RECEIVE,
-      ERL_TRY, ERL_DIV, ERL_REM, ERL_OR, ERL_XOR, ERL_BOR, ERL_BXOR, ERL_BSL, ERL_BSR, ERL_AND, ERL_BAND);
+      ERL_AFTER, ERL_WHEN, ERL_BEGIN, ERL_END, ERL_OF, ERL_CASE, ERL_CATCH, ERL_ELSE, ERL_IF, ERL_RECEIVE,
+      ERL_TRY, ERL_MAYBE, ERL_DIV, ERL_REM, ERL_OR, ERL_XOR, ERL_BOR, ERL_BXOR, ERL_BSL, ERL_BSR, ERL_AND, ERL_BAND);
 
     //noinspection SuspiciousNameCombination
     return new SpacingBuilder(settings.getRootSettings(), ErlangLanguage.INSTANCE)
diff --git a/src/org/intellij/erlang/formatter/ErlangIndentProcessor.java b/src/org/intellij/erlang/formatter/ErlangIndentProcessor.java
index 689221286..71ff1a28d 100644
--- a/src/org/intellij/erlang/formatter/ErlangIndentProcessor.java
+++ b/src/org/intellij/erlang/formatter/ErlangIndentProcessor.java
@@ -25,10 +25,7 @@
 import com.intellij.util.containers.ContainerUtil;
 import org.intellij.erlang.ErlangParserDefinition;
 import org.intellij.erlang.formatter.settings.ErlangCodeStyleSettings;
-import org.intellij.erlang.psi.ErlangArgumentDefinition;
-import org.intellij.erlang.psi.ErlangExpression;
-import org.intellij.erlang.psi.ErlangListOpExpression;
-import org.intellij.erlang.psi.ErlangParenthesizedExpression;
+import org.intellij.erlang.psi.*;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -92,7 +89,7 @@ public Indent getChildIndent(ASTNode node, int binaryExpressionIndex) {
       boolean insideCall = PsiTreeUtil.getParentOfType(node.getPsi(), ErlangArgumentDefinition.class, ErlangParenthesizedExpression.class) != null;
       return insideCall ? Indent.getNormalIndent() : Indent.getNoneIndent();
     }
-    if (parentType == ERL_BEGIN_END_BODY || parentType == ERL_TRY_EXPRESSIONS_CLAUSE) {
+    if (parentType == ERL_BEGIN_END_BODY || parentType == ERL_TRY_EXPRESSIONS_CLAUSE || parentType == ERL_MAYBE_MATCH_EXPRS ) {
       return Indent.getNoneIndent();
     }
     if (parentType == ERL_TRY_CLAUSES || parentType == ERL_FUN_CLAUSES) {
@@ -100,12 +97,12 @@ public Indent getChildIndent(ASTNode node, int binaryExpressionIndex) {
     }
     if (parentType == ERL_CASE_EXPRESSION || parentType == ERL_RECEIVE_EXPRESSION || parentType == ERL_TRY_EXPRESSION ||
         parentType == ERL_BEGIN_END_EXPRESSION || parentType == ERL_IF_EXPRESSION || parentType == ERL_FUN_EXPRESSION || 
-        parentType == ERL_CATCH_EXPRESSION) {
+        parentType == ERL_CATCH_EXPRESSION || parentType == ERL_MAYBE_EXPRESSION ) {
       if (elementType == ERL_CR_CLAUSE || elementType == ERL_IF_CLAUSE || elementType == ERL_BEGIN_END_BODY ||
-        elementType == ERL_TRY_EXPRESSIONS_CLAUSE || elementType == ERL_AFTER_CLAUSE_BODY) {
+        elementType == ERL_TRY_EXPRESSIONS_CLAUSE || elementType == ERL_MAYBE_MATCH_EXPRS || elementType == ERL_AFTER_CLAUSE_BODY) {
         return Indent.getNormalIndent(myErlangSettings.INDENT_RELATIVE);
       }
-      if (elementType == ERL_OF || elementType == ERL_CATCH || elementType == ERL_AFTER || elementType == ERL_END ||
+      if (elementType == ERL_OF || elementType == ERL_CATCH || elementType == ERL_ELSE || elementType == ERL_AFTER || elementType == ERL_END ||
         elementType == ERL_TRY_CLAUSES || elementType == ERL_FUN_CLAUSES) {
         return myErlangSettings.INDENT_RELATIVE ? Indent.getSpaceIndent(0, true) : Indent.getNoneIndent();
       }
diff --git a/src/org/intellij/erlang/parser/Erlang.flex b/src/org/intellij/erlang/parser/Erlang.flex
index 263bde57b..cabd45e8f 100644
--- a/src/org/intellij/erlang/parser/Erlang.flex
+++ b/src/org/intellij/erlang/parser/Erlang.flex
@@ -91,6 +91,8 @@ Variable = (_ {NameChars}) | ({ErlangUppercase} {NameChars})
 <YYINITIAL> "catch"                       { return ERL_CATCH; }
 <YYINITIAL> "if"                          { return ERL_IF; }
 <YYINITIAL> "receive"                     { return ERL_RECEIVE; }
+<YYINITIAL> "maybe"                       { return ERL_MAYBE; }
+<YYINITIAL> "else"                        { return ERL_ELSE; }
 
 <YYINITIAL> ":="                          { return ERL_MATCH; }
 <YYINITIAL> "=>"                          { return ERL_ASSOC; }
@@ -124,6 +126,7 @@ Variable = (_ {NameChars}) | ({ErlangUppercase} {NameChars})
 <YYINITIAL> "++"                           { return ERL_OP_PLUS_PLUS; }
 <YYINITIAL> "--"                           { return ERL_OP_MINUS_MINUS; }
 <YYINITIAL> "="                            { return ERL_OP_EQ; }
+<YYINITIAL> "?="                           { return ERL_OP_MAYBE_EQ; }
 <YYINITIAL> "!"                            { return ERL_OP_EXL; }
 <YYINITIAL> "<-"                           { return ERL_OP_LT_MINUS; }
 <YYINITIAL> "<="                           { return ERL_OP_LT_EQ; }
diff --git a/src/org/intellij/erlang/parser/ErlangLexer.java b/src/org/intellij/erlang/parser/ErlangLexer.java
index fa2c754b2..c987be217 100644
--- a/src/org/intellij/erlang/parser/ErlangLexer.java
+++ b/src/org/intellij/erlang/parser/ErlangLexer.java
@@ -26,7 +26,8 @@
 
 public class ErlangLexer extends LookAheadLexer {
   public static final TokenSet KEYWORDS = TokenSet.create(
-    ERL_AFTER, ERL_WHEN, ERL_BEGIN, ERL_END, ERL_OF, ERL_CASE, ERL_FUN, ERL_CATCH, ERL_IF, ERL_RECEIVE, ERL_TRY);
+    ERL_AFTER, ERL_WHEN, ERL_BEGIN, ERL_END, ERL_OF, ERL_CASE, ERL_FUN, ERL_CATCH, ERL_IF, ERL_RECEIVE, ERL_TRY,
+    ERL_ELSE, ERL_MAYBE);
 
   public ErlangLexer() {
     super(new MergingLexerAdapter(new FlexAdapter(new _ErlangLexer()), COMMENTS));
diff --git a/src/org/intellij/erlang/psi/impl/ErlangPsiImplUtil.java b/src/org/intellij/erlang/psi/impl/ErlangPsiImplUtil.java
index 76cc9796f..55b58fe11 100644
--- a/src/org/intellij/erlang/psi/impl/ErlangPsiImplUtil.java
+++ b/src/org/intellij/erlang/psi/impl/ErlangPsiImplUtil.java
@@ -528,6 +528,7 @@ public static boolean inLeftPartOfAssignment(@NotNull PsiElement psiElement) {
   }
 
   public static boolean inLeftPartOfAssignment(@NotNull PsiElement psiElement, boolean strict) {
+    // '=' assignment
     ErlangAssignmentExpression assignment = PsiTreeUtil.getParentOfType(psiElement, ErlangAssignmentExpression.class, true);
     while (assignment != null) {
       if (PsiTreeUtil.isAncestor(assignment.getLeft(), psiElement, strict)) {
@@ -535,6 +536,14 @@ public static boolean inLeftPartOfAssignment(@NotNull PsiElement psiElement, boo
       }
       assignment = PsiTreeUtil.getParentOfType(assignment, ErlangAssignmentExpression.class, true);
     }
+    // '?=' maybe assignment
+    ErlangMaybeMatchExpression maybeMatchAssignment = PsiTreeUtil.getParentOfType(psiElement, ErlangMaybeMatchExpression.class, true);
+    while (maybeMatchAssignment != null) {
+      if (PsiTreeUtil.isAncestor(maybeMatchAssignment.getLeft(), psiElement, strict)) {
+        return true;
+      }
+      maybeMatchAssignment = PsiTreeUtil.getParentOfType(maybeMatchAssignment, ErlangMaybeMatchExpression.class, true);
+    }
     return false;
   }
 
diff --git a/testData/formatter/bindMaybe-after.erl b/testData/formatter/bindMaybe-after.erl
new file mode 100644
index 000000000..8548e5cdb
--- /dev/null
+++ b/testData/formatter/bindMaybe-after.erl
@@ -0,0 +1,4 @@
+test() ->
+  X = maybe
+        <caret>
+      end
\ No newline at end of file
diff --git a/testData/formatter/bindMaybe.erl b/testData/formatter/bindMaybe.erl
new file mode 100644
index 000000000..df3fd6f43
--- /dev/null
+++ b/testData/formatter/bindMaybe.erl
@@ -0,0 +1,2 @@
+test() ->
+  X = maybe<caret>
\ No newline at end of file
diff --git a/testData/formatter/bindMaybeElse-after.erl b/testData/formatter/bindMaybeElse-after.erl
new file mode 100644
index 000000000..8f4e308c7
--- /dev/null
+++ b/testData/formatter/bindMaybeElse-after.erl
@@ -0,0 +1,6 @@
+test() ->
+  X = maybe
+    fail()
+  else
+        <caret>
+      end,
\ No newline at end of file
diff --git a/testData/formatter/bindMaybeElse.erl b/testData/formatter/bindMaybeElse.erl
new file mode 100644
index 000000000..e4bdc1777
--- /dev/null
+++ b/testData/formatter/bindMaybeElse.erl
@@ -0,0 +1,4 @@
+test() ->
+  X = maybe
+    fail()
+  else<caret>
\ No newline at end of file
diff --git a/testData/formatter/bindMaybeElse__IR_OFF-after.erl b/testData/formatter/bindMaybeElse__IR_OFF-after.erl
new file mode 100644
index 000000000..3c3927214
--- /dev/null
+++ b/testData/formatter/bindMaybeElse__IR_OFF-after.erl
@@ -0,0 +1,6 @@
+test() ->
+  X = maybe
+    fail()
+  else
+    <caret>
+  end,
\ No newline at end of file
diff --git a/testData/formatter/bindMaybeFirstElseClause-after.erl b/testData/formatter/bindMaybeFirstElseClause-after.erl
new file mode 100644
index 000000000..d525493f1
--- /dev/null
+++ b/testData/formatter/bindMaybeFirstElseClause-after.erl
@@ -0,0 +1,6 @@
+test() ->
+  X = maybe
+    fail()
+  else
+    ex -> ok;
+        <caret>
\ No newline at end of file
diff --git a/testData/formatter/bindMaybeFirstElseClause.erl b/testData/formatter/bindMaybeFirstElseClause.erl
new file mode 100644
index 000000000..9efcf7312
--- /dev/null
+++ b/testData/formatter/bindMaybeFirstElseClause.erl
@@ -0,0 +1,5 @@
+test() ->
+  X = maybe
+    fail()
+  else
+    ex -> ok;<caret>
\ No newline at end of file
diff --git a/testData/formatter/bindMaybeFirstElseClause__IR_OFF-after.erl b/testData/formatter/bindMaybeFirstElseClause__IR_OFF-after.erl
new file mode 100644
index 000000000..97c0dd886
--- /dev/null
+++ b/testData/formatter/bindMaybeFirstElseClause__IR_OFF-after.erl
@@ -0,0 +1,6 @@
+test() ->
+  X = maybe
+    fail()
+  else
+    ex -> ok;
+    <caret>
\ No newline at end of file
diff --git a/testData/formatter/bindMaybeLastElseClause-after.erl b/testData/formatter/bindMaybeLastElseClause-after.erl
new file mode 100644
index 000000000..195d896ad
--- /dev/null
+++ b/testData/formatter/bindMaybeLastElseClause-after.erl
@@ -0,0 +1,7 @@
+test() ->
+  X = maybe
+    fail()
+  else
+    ex -> ok;
+    ex -> ok
+      <caret>
\ No newline at end of file
diff --git a/testData/formatter/bindMaybeLastElseClause.erl b/testData/formatter/bindMaybeLastElseClause.erl
new file mode 100644
index 000000000..f7957d14f
--- /dev/null
+++ b/testData/formatter/bindMaybeLastElseClause.erl
@@ -0,0 +1,6 @@
+test() ->
+  X = maybe
+    fail()
+  else
+    ex -> ok;
+    ex -> ok<caret>
\ No newline at end of file
diff --git a/testData/formatter/bindMaybeLastElseClause__IR_OFF-after.erl b/testData/formatter/bindMaybeLastElseClause__IR_OFF-after.erl
new file mode 100644
index 000000000..55ef516cf
--- /dev/null
+++ b/testData/formatter/bindMaybeLastElseClause__IR_OFF-after.erl
@@ -0,0 +1,7 @@
+test() ->
+  X = maybe
+    fail()
+  else
+    ex -> ok;
+    ex -> ok
+  <caret>
\ No newline at end of file
diff --git a/testData/formatter/bindMaybe__IR_OFF-after.erl b/testData/formatter/bindMaybe__IR_OFF-after.erl
new file mode 100644
index 000000000..f8ff02d76
--- /dev/null
+++ b/testData/formatter/bindMaybe__IR_OFF-after.erl
@@ -0,0 +1,4 @@
+test() ->
+  X = maybe
+    <caret>
+  end
\ No newline at end of file
diff --git a/testData/formatter/maybe1-after.erl b/testData/formatter/maybe1-after.erl
new file mode 100644
index 000000000..a84df408c
--- /dev/null
+++ b/testData/formatter/maybe1-after.erl
@@ -0,0 +1,4 @@
+test() ->
+  maybe
+    <caret>
+  end
\ No newline at end of file
diff --git a/testData/formatter/maybe1.erl b/testData/formatter/maybe1.erl
new file mode 100644
index 000000000..f6aab46f3
--- /dev/null
+++ b/testData/formatter/maybe1.erl
@@ -0,0 +1,2 @@
+test() ->
+  maybe<caret>
\ No newline at end of file
diff --git a/testData/formatter/maybe2-after.erl b/testData/formatter/maybe2-after.erl
new file mode 100644
index 000000000..bf039aca8
--- /dev/null
+++ b/testData/formatter/maybe2-after.erl
@@ -0,0 +1,4 @@
+test() ->
+  maybe
+    fail()
+  <caret>
\ No newline at end of file
diff --git a/testData/formatter/maybe2.erl b/testData/formatter/maybe2.erl
new file mode 100644
index 000000000..0184632a2
--- /dev/null
+++ b/testData/formatter/maybe2.erl
@@ -0,0 +1,3 @@
+test() ->
+  maybe
+    fail()<caret>
\ No newline at end of file
diff --git a/testData/formatter/maybe3-after.erl b/testData/formatter/maybe3-after.erl
new file mode 100644
index 000000000..35ae0e213
--- /dev/null
+++ b/testData/formatter/maybe3-after.erl
@@ -0,0 +1,6 @@
+test() ->
+  maybe
+    fail()
+  else
+    <caret>
+  end,
\ No newline at end of file
diff --git a/testData/formatter/maybe3.erl b/testData/formatter/maybe3.erl
new file mode 100644
index 000000000..fd3539907
--- /dev/null
+++ b/testData/formatter/maybe3.erl
@@ -0,0 +1,4 @@
+test() ->
+  maybe
+    fail()
+  else<caret>
\ No newline at end of file
diff --git a/testData/formatter/maybe4-after.erl b/testData/formatter/maybe4-after.erl
new file mode 100644
index 000000000..216828359
--- /dev/null
+++ b/testData/formatter/maybe4-after.erl
@@ -0,0 +1,6 @@
+test() ->
+  maybe
+    fail()
+  else
+    ex -> ok;
+    <caret>
\ No newline at end of file
diff --git a/testData/formatter/maybe4.erl b/testData/formatter/maybe4.erl
new file mode 100644
index 000000000..f28df72d0
--- /dev/null
+++ b/testData/formatter/maybe4.erl
@@ -0,0 +1,5 @@
+test() ->
+  maybe
+    fail()
+  else
+    ex -> ok;<caret>
\ No newline at end of file
diff --git a/testData/formatter/maybe5-after.erl b/testData/formatter/maybe5-after.erl
new file mode 100644
index 000000000..094cd8201
--- /dev/null
+++ b/testData/formatter/maybe5-after.erl
@@ -0,0 +1,7 @@
+test() ->
+  maybe
+    fail()
+  else
+    ex -> ok;
+    ex -> ok
+  <caret>
\ No newline at end of file
diff --git a/testData/formatter/maybe5.erl b/testData/formatter/maybe5.erl
new file mode 100644
index 000000000..15a764051
--- /dev/null
+++ b/testData/formatter/maybe5.erl
@@ -0,0 +1,6 @@
+test() ->
+  maybe
+    fail()
+  else
+    ex -> ok;
+    ex -> ok<caret>
\ No newline at end of file
diff --git a/testData/parser/304.txt b/testData/parser/304.txt
index e574a0919..bb1da98bd 100644
--- a/testData/parser/304.txt
+++ b/testData/parser/304.txt
@@ -69,8 +69,8 @@ ERL_FILE
     PsiElement(.)('.')
   ERL_ATTRIBUTE
     PsiElement(-)('-')
-    ERL_ATOM_ATTRIBUTE
-      PsiElement(atom_name)('else')
+    ERL_ELSE_ATOM_ATTRIBUTE
+      PsiElement(else)('else')
   ERL_MACROS_DEFINITION
     PsiElement(-)('-')
     PsiElement(atom_name)('define')
diff --git a/tests/org/intellij/erlang/completion/ErlangCompletionTest.java b/tests/org/intellij/erlang/completion/ErlangCompletionTest.java
index de6592dfa..7e9ecf99f 100644
--- a/tests/org/intellij/erlang/completion/ErlangCompletionTest.java
+++ b/tests/org/intellij/erlang/completion/ErlangCompletionTest.java
@@ -39,7 +39,7 @@ public void testFunctions() {
 
   public void testFunctionCompletionInTypedList() {
     doTestInclude("foo() -> ok. -record(state, {first = <caret>}).",
-      "begin", "try", "fun", "if",
+      "begin", "try", "fun", "if", "maybe",
       "node", "pid_to_list", "spawn", "binary_to_list",
       "foo");
   }
diff --git a/tests/org/intellij/erlang/formatting/ErlangFormattingTest.java b/tests/org/intellij/erlang/formatting/ErlangFormattingTest.java
index eb0fe1d64..d75f4f839 100644
--- a/tests/org/intellij/erlang/formatting/ErlangFormattingTest.java
+++ b/tests/org/intellij/erlang/formatting/ErlangFormattingTest.java
@@ -237,6 +237,37 @@ public void testUniformBinaryExpressionsStyle() throws Exception {
   public void testBindTryFirstCatchClauseParasite__IR_OFF() throws Exception { doEnterTest(); }
   public void testBindTryLastCatchClauseParasite__IR_OFF()  throws Exception { doEnterTest(); }
 
+  public void testMaybe1() throws Exception { doEnterTest(); }
+  public void testMaybe2() throws Exception { doEnterTest(); }
+  public void testMaybe3() throws Exception { doEnterTest(); }
+  public void testMaybe4() throws Exception { doEnterTest(); }
+  public void testMaybe5() throws Exception { doEnterTest(); }
+
+  public void testMaybeParasite1() throws Exception { doEnterTest(); }
+  public void testMaybeParasite2() throws Exception { doEnterTest(); }
+  public void testMaybeParasite3() throws Exception { doEnterTest(); }
+  public void testMaybeParasite4() throws Exception { doEnterTest(); }
+  public void testMaybeParasite5() throws Exception { doEnterTest(); }
+
+  public void testBindMaybe()                throws Exception { doEnterTest(); }
+  public void testBindMaybeElse()            throws Exception { doEnterTest(); }
+  public void testBindMaybeFirstElseClause() throws Exception { doEnterTest(); }
+  public void testBindMaybeLastElseClause()  throws Exception { doEnterTest(); }
+
+  public void testBindMaybe__IR_OFF()                throws Exception { doEnterTest(); }
+  public void testBindMaybeElse__IR_OFF()            throws Exception { doEnterTest(); }
+  public void testBindMaybeFirstElseClause__IR_OFF() throws Exception { doEnterTest(); }
+  public void testBindMaybeLastElseClause__IR_OFF()  throws Exception { doEnterTest(); }
+
+  public void testBindMaybeParasite()                throws Exception { doEnterTest(); }
+  public void testBindMaybeElseParasite()            throws Exception { doEnterTest(); }
+  public void testBindMaybeFirstElseClauseParasite() throws Exception { doEnterTest(); }
+  public void testBindMaybeLastElseClauseParasite()  throws Exception { doEnterTest(); }
+
+  public void testBindMaybeParasite__IR_OFF()                throws Exception { doEnterTest(); }
+  public void testBindMaybeElseParasite__IR_OFF()            throws Exception { doEnterTest(); }
+  public void testBindMaybeFirstElseClauseParasite__IR_OFF() throws Exception { doEnterTest(); }
+  public void testBindMaybeLastElseClauseParasite__IR_OFF()  throws Exception { doEnterTest(); }
 
   public void testCase1() throws Exception { doEnterTest(); }
   public void testCase2() throws Exception { doEnterTest(); }

From 48fb8cfe06d0ffeac6d974c03ec0f061dda0d2c1 Mon Sep 17 00:00:00 2001
From: zyuyou <yuyouchow@gmail.com>
Date: Fri, 12 Aug 2022 17:11:37 +0800
Subject: [PATCH 2/7] add otp-25 syntax inspection tests

---
 resources/META-INF/ErlangPlugin.xml           |  3 +
 .../inspection/Erlang25SyntaxInspection.java  | 45 ++++++++++++
 .../settings/RebarConfigurationForm.java      |  2 +-
 .../intellij/erlang/sdk/ErlangSdkRelease.java |  1 +
 testData/highlighting/Erlang25SyntaxError.erl |  4 ++
 .../highlighting/Erlang25SyntaxNoError.erl    |  3 +
 testData/mockSdk-R25/lib/.dummy               |  0
 .../Erlang25HighlightingTest.java             | 40 +++++++++++
 .../Erlang25SmallIdeHighlightingTest.java     | 69 +++++++++++++++++++
 .../ErlangHighlightingTestBase.java           |  5 ++
 10 files changed, 171 insertions(+), 1 deletion(-)
 create mode 100644 src/org/intellij/erlang/inspection/Erlang25SyntaxInspection.java
 create mode 100644 testData/highlighting/Erlang25SyntaxError.erl
 create mode 100644 testData/highlighting/Erlang25SyntaxNoError.erl
 create mode 100644 testData/mockSdk-R25/lib/.dummy
 create mode 100644 tests/org/intellij/erlang/highlighting/Erlang25HighlightingTest.java
 create mode 100644 tests/org/intellij/erlang/highlighting/Erlang25SmallIdeHighlightingTest.java

diff --git a/resources/META-INF/ErlangPlugin.xml b/resources/META-INF/ErlangPlugin.xml
index e22705033..995ee643d 100644
--- a/resources/META-INF/ErlangPlugin.xml
+++ b/resources/META-INF/ErlangPlugin.xml
@@ -214,6 +214,9 @@
         <localInspection language="Erlang" shortName="ErlangFunctionAlreadyImported" displayName="Function already imported"
                          groupName="Erlang" enabledByDefault="true" level="ERROR"
                          implementationClass="org.intellij.erlang.inspection.ErlangFunctionAlreadyImportedInspection"/>
+        <localInspection language="Erlang" shortName="Erlang25Syntax" displayName="Erlang 25.0 syntax"
+                         groupName="Erlang" enabledByDefault="true" level="ERROR"
+                         implementationClass="org.intellij.erlang.inspection.Erlang25SyntaxInspection"/>
 
         <!--warnings-->
         <localInspection language="Erlang" shortName="Erlang18Syntax" displayName="Erlang 18.0 syntax"
diff --git a/src/org/intellij/erlang/inspection/Erlang25SyntaxInspection.java b/src/org/intellij/erlang/inspection/Erlang25SyntaxInspection.java
new file mode 100644
index 000000000..b72784614
--- /dev/null
+++ b/src/org/intellij/erlang/inspection/Erlang25SyntaxInspection.java
@@ -0,0 +1,45 @@
+/*
+ * Copyright 2012-2015 Sergey Ignatov
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.intellij.erlang.inspection;
+
+import com.intellij.codeInspection.LocalInspectionToolSession;
+import com.intellij.codeInspection.ProblemsHolder;
+import org.intellij.erlang.psi.ErlangFile;
+import org.intellij.erlang.psi.ErlangMaybeExpression;
+import org.intellij.erlang.psi.ErlangVisitor;
+import org.intellij.erlang.sdk.ErlangSdkRelease;
+import org.intellij.erlang.sdk.ErlangSdkType;
+import org.jetbrains.annotations.NotNull;
+
+public class Erlang25SyntaxInspection extends ErlangInspectionBase {
+  @Override
+  protected boolean canRunOn(@NotNull ErlangFile file) {
+    ErlangSdkRelease release = ErlangSdkType.getRelease(file);
+    return release == null || ErlangSdkRelease.V_25_0.isNewerThan(release);
+  }
+
+  @NotNull
+  @Override
+  protected ErlangVisitor buildErlangVisitor(@NotNull final ProblemsHolder holder, @NotNull LocalInspectionToolSession session) {
+    return new ErlangVisitor() {
+      @Override
+      public void visitMaybeExpression(@NotNull ErlangMaybeExpression o) {
+        registerProblem(holder, o, "`maybe` expression require Erlang/OTP 25.0 with `-enable-feature maybe_expr`");
+      }
+    };
+  }
+}
diff --git a/src/org/intellij/erlang/rebar/settings/RebarConfigurationForm.java b/src/org/intellij/erlang/rebar/settings/RebarConfigurationForm.java
index b59aef27f..ab3ea8a44 100644
--- a/src/org/intellij/erlang/rebar/settings/RebarConfigurationForm.java
+++ b/src/org/intellij/erlang/rebar/settings/RebarConfigurationForm.java
@@ -95,7 +95,7 @@ private static void validateRebarPath(String rebarPath, Consumer<String> consume
 
         String escriptPath = RebarRunningStateUtil.findEscriptExecutable();
         ExtProcessUtil.ExtProcessOutput escript = ExtProcessUtil.execAndGetFirstLine(3000, escriptPath, rebarPath, "--version");
-        String versionWithEscript = rebar.getStdOut();
+        String versionWithEscript = escript.getStdOut();
 
         if (versionWithEscript.startsWith("rebar")) {
           updateUI(consumer, versionWithEscript);
diff --git a/src/org/intellij/erlang/sdk/ErlangSdkRelease.java b/src/org/intellij/erlang/sdk/ErlangSdkRelease.java
index 73c34f14f..c323e683f 100644
--- a/src/org/intellij/erlang/sdk/ErlangSdkRelease.java
+++ b/src/org/intellij/erlang/sdk/ErlangSdkRelease.java
@@ -30,6 +30,7 @@ public final class ErlangSdkRelease {
   public static final ErlangSdkRelease V_R16B = new ErlangSdkRelease("R16B", "5.10.1");
   public static final ErlangSdkRelease V_17_0 = new ErlangSdkRelease("17", "6.0");
   public static final ErlangSdkRelease V_18_0 = new ErlangSdkRelease("18", "7.0");
+  public static final ErlangSdkRelease V_25_0 = new ErlangSdkRelease("25", "13.0");
 
   private static final Pattern VERSION_PATTERN = Pattern.compile("Erlang/OTP (\\S+) \\[erts-(\\S+)]");
 
diff --git a/testData/highlighting/Erlang25SyntaxError.erl b/testData/highlighting/Erlang25SyntaxError.erl
new file mode 100644
index 000000000..dde6e4ebb
--- /dev/null
+++ b/testData/highlighting/Erlang25SyntaxError.erl
@@ -0,0 +1,4 @@
+-module('Erlang25SyntaxError').
+-export([foo/0]).
+foo() ->
+  <error>maybe ok end</error>.
\ No newline at end of file
diff --git a/testData/highlighting/Erlang25SyntaxNoError.erl b/testData/highlighting/Erlang25SyntaxNoError.erl
new file mode 100644
index 000000000..6651e97cb
--- /dev/null
+++ b/testData/highlighting/Erlang25SyntaxNoError.erl
@@ -0,0 +1,3 @@
+-export([foo/0]).
+foo() ->
+  maybe ok end.
\ No newline at end of file
diff --git a/testData/mockSdk-R25/lib/.dummy b/testData/mockSdk-R25/lib/.dummy
new file mode 100644
index 000000000..e69de29bb
diff --git a/tests/org/intellij/erlang/highlighting/Erlang25HighlightingTest.java b/tests/org/intellij/erlang/highlighting/Erlang25HighlightingTest.java
new file mode 100644
index 000000000..01b7f0137
--- /dev/null
+++ b/tests/org/intellij/erlang/highlighting/Erlang25HighlightingTest.java
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2012-2015 Sergey Ignatov
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.intellij.erlang.highlighting;
+
+import com.intellij.openapi.projectRoots.Sdk;
+import com.intellij.testFramework.LightProjectDescriptor;
+import com.intellij.testFramework.fixtures.DefaultLightProjectDescriptor;
+import org.intellij.erlang.sdk.ErlangSdkRelease;
+import org.intellij.erlang.sdk.ErlangSdkType;
+
+public class Erlang25HighlightingTest extends ErlangHighlightingTestBase {
+  @Override
+  protected LightProjectDescriptor getProjectDescriptor() {
+    return new DefaultLightProjectDescriptor() {
+      @Override
+      public Sdk getSdk() {
+        return ErlangSdkType.createMockSdk("testData/mockSdk-R25/", ErlangSdkRelease.V_25_0);
+      }
+    };
+  }
+
+  public void testErlang25SyntaxNoError() {
+    enableErlang25SyntaxInspection();
+    doTest();
+  }
+}
diff --git a/tests/org/intellij/erlang/highlighting/Erlang25SmallIdeHighlightingTest.java b/tests/org/intellij/erlang/highlighting/Erlang25SmallIdeHighlightingTest.java
new file mode 100644
index 000000000..6c07eb121
--- /dev/null
+++ b/tests/org/intellij/erlang/highlighting/Erlang25SmallIdeHighlightingTest.java
@@ -0,0 +1,69 @@
+/*
+ * Copyright 2012-2015 Sergey Ignatov
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.intellij.erlang.highlighting;
+
+import com.intellij.openapi.projectRoots.Sdk;
+import com.intellij.testFramework.LightProjectDescriptor;
+import com.intellij.testFramework.fixtures.DefaultLightProjectDescriptor;
+import org.intellij.erlang.sdk.ErlangSdkForSmallIdes;
+import org.intellij.erlang.sdk.ErlangSdkRelease;
+import org.intellij.erlang.sdk.ErlangSdkType;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Objects;
+
+public class Erlang25SmallIdeHighlightingTest extends ErlangHighlightingTestBase {
+  private static final String SDK_HOME = "testData/mockSdk-R25";
+
+  public Erlang25SmallIdeHighlightingTest() {
+    super(true);
+  }
+
+  @Nullable
+  @Override
+  protected LightProjectDescriptor getProjectDescriptor() {
+    return new DefaultLightProjectDescriptor() {
+      @Override
+      public Sdk getSdk() {
+        return ErlangSdkType.createMockSdk(SDK_HOME, ErlangSdkRelease.V_25_0);
+      }
+    };
+  }
+
+  @Override
+  protected void setUp() throws Exception {
+    super.setUp();
+    // we create an sdk here so that we have sdk version cached
+    ErlangSdkType.createMockSdk(SDK_HOME, ErlangSdkRelease.V_25_0);
+    ErlangSdkForSmallIdes.setUpOrUpdateSdk(getProject(), SDK_HOME);
+  }
+
+  @Override
+  protected void tearDown() throws Exception {
+    ErlangSdkForSmallIdes.setUpOrUpdateSdk(getProject(), "");
+    super.tearDown();
+  }
+  
+  public void testCorrectSdkReleaseIsReported() {
+    assertEquals(ErlangSdkRelease.V_25_0.getOtpRelease(), Objects.requireNonNull(ErlangSdkType.getRelease(getProject())).getOtpRelease());
+  }
+
+  public void testErlang25SyntaxNoError() {
+    enableErlang25SyntaxInspection();
+    doTest();
+  }
+}
\ No newline at end of file
diff --git a/tests/org/intellij/erlang/highlighting/ErlangHighlightingTestBase.java b/tests/org/intellij/erlang/highlighting/ErlangHighlightingTestBase.java
index 3d5e9b52e..787e058b9 100644
--- a/tests/org/intellij/erlang/highlighting/ErlangHighlightingTestBase.java
+++ b/tests/org/intellij/erlang/highlighting/ErlangHighlightingTestBase.java
@@ -130,4 +130,9 @@ protected void enableErlang18SyntaxInspection() {
     //noinspection unchecked
     myFixture.enableInspections(Erlang18SyntaxInspection.class);
   }
+
+  protected void enableErlang25SyntaxInspection() {
+    //noinspection unchecked
+    myFixture.enableInspections(Erlang25SyntaxInspection.class);
+  }
 }

From 688dbc623b0dfd39faa7c85ed4cc360b99211cdd Mon Sep 17 00:00:00 2001
From: zyuyou <yuyouchow@gmail.com>
Date: Fri, 12 Aug 2022 19:27:41 +0800
Subject: [PATCH 3/7] Fix "Setup SDK" button suggests to configure the JDK
 isntead of the Erlang SDK

---
 .../SetupSDKNotificationProvider.java         | 22 ++++++++-----------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/src/org/intellij/erlang/inspection/SetupSDKNotificationProvider.java b/src/org/intellij/erlang/inspection/SetupSDKNotificationProvider.java
index 071fec415..253a1ef08 100644
--- a/src/org/intellij/erlang/inspection/SetupSDKNotificationProvider.java
+++ b/src/org/intellij/erlang/inspection/SetupSDKNotificationProvider.java
@@ -18,14 +18,10 @@
 
 import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.fileEditor.FileEditor;
-import com.intellij.openapi.module.Module;
-import com.intellij.openapi.module.ModuleUtilCore;
 import com.intellij.openapi.options.ShowSettingsUtil;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.project.ProjectBundle;
-import com.intellij.openapi.projectRoots.Sdk;
-import com.intellij.openapi.roots.ModuleRootModificationUtil;
-import com.intellij.openapi.roots.ui.configuration.ProjectSettingsService;
+import com.intellij.openapi.roots.ui.configuration.SdkPopupFactory;
 import com.intellij.openapi.util.Key;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.psi.PsiFile;
@@ -70,6 +66,7 @@ public EditorNotificationPanel createNotificationPanel(@NotNull VirtualFile file
   @NotNull
   private static EditorNotificationPanel createPanel(@NotNull final Project project, @NotNull final PsiFile file) {
     EditorNotificationPanel panel = new EditorNotificationPanel();
+
     panel.setText(ProjectBundle.message("project.sdk.not.defined"));
     panel.createActionLabel(ProjectBundle.message("project.sdk.setup"), () -> {
       if (ErlangSystemUtil.isSmallIde()) {
@@ -77,14 +74,13 @@ private static EditorNotificationPanel createPanel(@NotNull final Project projec
         return;
       }
 
-      Sdk projectSdk = ProjectSettingsService.getInstance(project).chooseAndSetSdk();
-      if (projectSdk == null) return;
-      ApplicationManager.getApplication().runWriteAction(() -> {
-        Module module = ModuleUtilCore.findModuleForPsiElement(file);
-        if (module != null) {
-          ModuleRootModificationUtil.setSdkInherited(module);
-        }
-      });
+      SdkPopupFactory
+        .newBuilder()
+        .withProject(project)
+        .withSdkTypeFilter(type -> type instanceof ErlangSdkType)
+        .updateProjectSdkFromSelection()
+        .buildPopup()
+        .showInFocusCenter();
     });
     return panel;
   }

From 84b91bac9a801ff9a6f65ae7bed71a1205c065c2 Mon Sep 17 00:00:00 2001
From: zyuyou <yuyouchow@gmail.com>
Date: Thu, 15 Dec 2022 02:28:50 +0800
Subject: [PATCH 4/7] Fix basic completion tests error

---
 .../intellij/erlang/psi/impl/ErlangFileImpl.java |  4 ++--
 testData/parser/DialyzerDataflow.txt             | 16 ++++++++--------
 testData/parser/H.txt                            | 12 ++++++------
 .../completion/ErlangCompletionTestBase.java     |  2 ++
 4 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/src/org/intellij/erlang/psi/impl/ErlangFileImpl.java b/src/org/intellij/erlang/psi/impl/ErlangFileImpl.java
index 3b5e718c8..6151e942d 100644
--- a/src/org/intellij/erlang/psi/impl/ErlangFileImpl.java
+++ b/src/org/intellij/erlang/psi/impl/ErlangFileImpl.java
@@ -17,7 +17,7 @@
 package org.intellij.erlang.psi.impl;
 
 import com.intellij.extapi.psi.PsiFileBase;
-import com.intellij.ide.scratch.ScratchFileType;
+import com.intellij.ide.scratch.ScratchUtil;
 import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.fileTypes.FileType;
 import com.intellij.openapi.project.DumbService;
@@ -303,7 +303,7 @@ public PsiElement setName(@NotNull String name) throws IncorrectOperationExcepti
   @Override
   public FileType getFileType() {
     FileType fileType = getViewProvider().getFileType();
-    if ((fileType instanceof ScratchFileType)) return fileType;
+    if(ScratchUtil.isScratch(getViewProvider().getVirtualFile())) return fileType;
     if (!(fileType instanceof ErlangFileType) && ApplicationManager.getApplication().isUnitTestMode()) {
       return getFileTypeForTests();
     }
diff --git a/testData/parser/DialyzerDataflow.txt b/testData/parser/DialyzerDataflow.txt
index 720218668..16b3bf356 100644
--- a/testData/parser/DialyzerDataflow.txt
+++ b/testData/parser/DialyzerDataflow.txt
@@ -776,8 +776,8 @@ ERL_FILE
     PsiElement(.)('.')
   ERL_ATTRIBUTE
     PsiElement(-)('-')
-    ERL_ATOM_ATTRIBUTE
-      PsiElement(atom_name)('else')
+    ERL_ELSE_ATOM_ATTRIBUTE
+      PsiElement(else)('else')
     PsiElement(.)('.')
   ERL_MACROS_DEFINITION
     PsiElement(-)('-')
@@ -45543,8 +45543,8 @@ ERL_FILE
     PsiElement(.)('.')
   ERL_ATTRIBUTE
     PsiElement(-)('-')
-    ERL_ATOM_ATTRIBUTE
-      PsiElement(atom_name)('else')
+    ERL_ELSE_ATOM_ATTRIBUTE
+      PsiElement(else)('else')
     PsiElement(.)('.')
   ERL_FUNCTION
     ERL_FUNCTION_CLAUSE
@@ -58880,8 +58880,8 @@ ERL_FILE
     PsiElement(.)('.')
   ERL_ATTRIBUTE
     PsiElement(-)('-')
-    ERL_ATOM_ATTRIBUTE
-      PsiElement(atom_name)('else')
+    ERL_ELSE_ATOM_ATTRIBUTE
+      PsiElement(else)('else')
     PsiElement(.)('.')
   ERL_FUNCTION
     ERL_FUNCTION_CLAUSE
@@ -58991,8 +58991,8 @@ ERL_FILE
     PsiElement(.)('.')
   ERL_ATTRIBUTE
     PsiElement(-)('-')
-    ERL_ATOM_ATTRIBUTE
-      PsiElement(atom_name)('else')
+    ERL_ELSE_ATOM_ATTRIBUTE
+      PsiElement(else)('else')
     PsiElement(.)('.')
   ERL_FUNCTION
     ERL_FUNCTION_CLAUSE
diff --git a/testData/parser/H.txt b/testData/parser/H.txt
index 1b0f70ef3..8f0440e92 100644
--- a/testData/parser/H.txt
+++ b/testData/parser/H.txt
@@ -21593,8 +21593,8 @@ ERL_FILE
     PsiElement(.)('.')
   ERL_ATTRIBUTE
     PsiElement(-)('-')
-    ERL_ATOM_ATTRIBUTE
-      PsiElement(atom_name)('else')
+    ERL_ELSE_ATOM_ATTRIBUTE
+      PsiElement(else)('else')
     PsiElement(.)('.')
   ERL_FUNCTION
     ERL_FUNCTION_CLAUSE
@@ -34930,8 +34930,8 @@ ERL_FILE
     PsiElement(.)('.')
   ERL_ATTRIBUTE
     PsiElement(-)('-')
-    ERL_ATOM_ATTRIBUTE
-      PsiElement(atom_name)('else')
+    ERL_ELSE_ATOM_ATTRIBUTE
+      PsiElement(else)('else')
     PsiElement(.)('.')
   ERL_FUNCTION
     ERL_FUNCTION_CLAUSE
@@ -35041,8 +35041,8 @@ ERL_FILE
     PsiElement(.)('.')
   ERL_ATTRIBUTE
     PsiElement(-)('-')
-    ERL_ATOM_ATTRIBUTE
-      PsiElement(atom_name)('else')
+    ERL_ELSE_ATOM_ATTRIBUTE
+      PsiElement(else)('else')
     PsiElement(.)('.')
   ERL_FUNCTION
     ERL_FUNCTION_CLAUSE
diff --git a/tests/org/intellij/erlang/completion/ErlangCompletionTestBase.java b/tests/org/intellij/erlang/completion/ErlangCompletionTestBase.java
index 58fad9e09..addf44e1d 100644
--- a/tests/org/intellij/erlang/completion/ErlangCompletionTestBase.java
+++ b/tests/org/intellij/erlang/completion/ErlangCompletionTestBase.java
@@ -18,6 +18,7 @@
 
 import com.intellij.codeInsight.completion.CompletionType;
 import com.intellij.openapi.util.Disposer;
+import com.intellij.openapi.util.registry.Registry;
 import com.intellij.psi.impl.source.tree.injected.InjectedLanguageManagerImpl;
 import com.intellij.testFramework.UsefulTestCase;
 import com.intellij.testFramework.fixtures.CodeInsightTestFixture;
@@ -98,6 +99,7 @@ protected void doTestVariants(String txt, CompletionType type, int count, CheckT
   }
 
   protected void doTestVariantsInner(CompletionType type, int count, CheckType checkType, String... variants) {
+    Registry.get("ide.completion.variant.limit").setValue(2000);
     myFixture.complete(type, count);
     List<String> stringList = myFixture.getLookupElementStrings();
 

From 70fdc3ae296741b4233e30c557c24b61113c2d07 Mon Sep 17 00:00:00 2001
From: zyuyou <zyuyou@163.com>
Date: Thu, 9 Feb 2023 16:24:35 +0800
Subject: [PATCH 5/7] `maybe` expr indent process

---
 src/org/intellij/erlang/formatter/ErlangIndentProcessor.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/org/intellij/erlang/formatter/ErlangIndentProcessor.java b/src/org/intellij/erlang/formatter/ErlangIndentProcessor.java
index 71ff1a28d..73ff20433 100644
--- a/src/org/intellij/erlang/formatter/ErlangIndentProcessor.java
+++ b/src/org/intellij/erlang/formatter/ErlangIndentProcessor.java
@@ -110,7 +110,7 @@ public Indent getChildIndent(ASTNode node, int binaryExpressionIndex) {
         return Indent.getNormalIndent(myErlangSettings.INDENT_RELATIVE);
       }
     }
-    if (ErlangParserDefinition.COMMENTS.contains(elementType) && parentType == ERL_TRY_EXPRESSION) {
+    if (ErlangParserDefinition.COMMENTS.contains(elementType) && (parentType == ERL_TRY_EXPRESSION || parentType == ERL_MAYBE_EXPRESSION)) {
       return Indent.getNormalIndent();
     }
     if (needIndent(parentType)) {

From 1b49afa9ed195db9584e9106e1cb8a5f80dd9558 Mon Sep 17 00:00:00 2001
From: zyuyou <zyuyou@163.com>
Date: Tue, 28 Feb 2023 15:10:00 +0800
Subject: [PATCH 6/7] add block before `ERL_IMPORT_FUNCTIONS`.

---
 src/org/intellij/erlang/formatter/ErlangFormattingBlock.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/org/intellij/erlang/formatter/ErlangFormattingBlock.java b/src/org/intellij/erlang/formatter/ErlangFormattingBlock.java
index 27b840d0d..09af97a11 100644
--- a/src/org/intellij/erlang/formatter/ErlangFormattingBlock.java
+++ b/src/org/intellij/erlang/formatter/ErlangFormattingBlock.java
@@ -65,7 +65,7 @@ public class ErlangFormattingBlock extends AbstractBlock {
     ERL_PARENTHESIZED_EXPRESSION, ERL_ARGUMENT_LIST, ERL_ARGUMENT_DEFINITION_LIST, ERL_FUN_TYPE, ERL_FUN_TYPE_ARGUMENTS
   );
   private static final TokenSet BRACKETS_CONTAINERS = TokenSet.create(
-    ERL_LIST_EXPRESSION, ERL_EXPORT_FUNCTIONS, ERL_EXPORT_TYPES, ERL_BINARY_EXPRESSION
+    ERL_LIST_EXPRESSION, ERL_IMPORT_FUNCTIONS, ERL_EXPORT_FUNCTIONS, ERL_EXPORT_TYPES, ERL_BINARY_EXPRESSION
   );
   private static final TokenSet BINARY_EXPRESSIONS = TokenSet.create(
     ERL_LIST_OP_EXPRESSION, ERL_ASSIGNMENT_EXPRESSION, ERL_SEND_EXPRESSION, //right-assoc

From ed0ec1ebc6a5da0214d5c8a3a1cc51f03fcbe722 Mon Sep 17 00:00:00 2001
From: zyuyou <yuyouchow@gmail.com>
Date: Thu, 14 Sep 2023 00:41:44 +0800
Subject: [PATCH 7/7] Add some formatting tests

---
 testData/formatter/alignedExport-after.erl        | 15 +++++++++++++++
 testData/formatter/alignedExport.erl              | 15 +++++++++++++++
 testData/formatter/alignedImport-after.erl        | 12 ++++++++++++
 testData/formatter/alignedImport.erl              | 12 ++++++++++++
 testData/formatter/maybe6-after.erl               |  4 ++++
 testData/formatter/maybe6.erl                     |  3 +++
 testData/formatter/try6-after.erl                 |  4 ++++
 testData/formatter/try6.erl                       |  3 +++
 .../erlang/formatting/ErlangFormattingTest.java   | 14 ++++++++++++++
 9 files changed, 82 insertions(+)
 create mode 100644 testData/formatter/alignedExport-after.erl
 create mode 100644 testData/formatter/alignedExport.erl
 create mode 100644 testData/formatter/alignedImport-after.erl
 create mode 100644 testData/formatter/alignedImport.erl
 create mode 100644 testData/formatter/maybe6-after.erl
 create mode 100644 testData/formatter/maybe6.erl
 create mode 100644 testData/formatter/try6-after.erl
 create mode 100644 testData/formatter/try6.erl

diff --git a/testData/formatter/alignedExport-after.erl b/testData/formatter/alignedExport-after.erl
new file mode 100644
index 000000000..8b8d418ed
--- /dev/null
+++ b/testData/formatter/alignedExport-after.erl
@@ -0,0 +1,15 @@
+%%  Copyright (c) 2012. Sergey Ignatov.
+-module(aaa).
+-author("ignatov").
+
+%% API
+-export([
+  foo/0,
+  bar/0
+]).
+
+foo() ->
+  bar.
+
+bar() ->
+  foo.
\ No newline at end of file
diff --git a/testData/formatter/alignedExport.erl b/testData/formatter/alignedExport.erl
new file mode 100644
index 000000000..8032f1794
--- /dev/null
+++ b/testData/formatter/alignedExport.erl
@@ -0,0 +1,15 @@
+%%  Copyright (c) 2012. Sergey Ignatov.
+-module(aaa).
+-author("ignatov").
+
+%% API
+-export([
+foo/0,
+                    bar/0
+]).
+
+foo() ->
+  bar.
+
+bar() ->
+  foo.
\ No newline at end of file
diff --git a/testData/formatter/alignedImport-after.erl b/testData/formatter/alignedImport-after.erl
new file mode 100644
index 000000000..28d9e098b
--- /dev/null
+++ b/testData/formatter/alignedImport-after.erl
@@ -0,0 +1,12 @@
+%%  Copyright (c) 2012. Sergey Ignatov.
+-module(aaa).
+-author("ignatov").
+
+%% API
+-import(lists, [
+  nth/2,
+  all/2
+]).
+
+test() ->
+  nth(1, [1, 2, 3]).
\ No newline at end of file
diff --git a/testData/formatter/alignedImport.erl b/testData/formatter/alignedImport.erl
new file mode 100644
index 000000000..9492a4050
--- /dev/null
+++ b/testData/formatter/alignedImport.erl
@@ -0,0 +1,12 @@
+%%  Copyright (c) 2012. Sergey Ignatov.
+-module(aaa).
+-author("ignatov").
+
+%% API
+-import(lists,[
+nth/2,
+              all/2
+]).
+
+test() ->
+  nth(1, [1, 2, 3]).
\ No newline at end of file
diff --git a/testData/formatter/maybe6-after.erl b/testData/formatter/maybe6-after.erl
new file mode 100644
index 000000000..375934db3
--- /dev/null
+++ b/testData/formatter/maybe6-after.erl
@@ -0,0 +1,4 @@
+test() ->
+  maybe
+    <caret>%% comment
+  end.
\ No newline at end of file
diff --git a/testData/formatter/maybe6.erl b/testData/formatter/maybe6.erl
new file mode 100644
index 000000000..aa4a246fd
--- /dev/null
+++ b/testData/formatter/maybe6.erl
@@ -0,0 +1,3 @@
+test() ->
+  maybe<caret>%% comment
+  end.
\ No newline at end of file
diff --git a/testData/formatter/try6-after.erl b/testData/formatter/try6-after.erl
new file mode 100644
index 000000000..1e63db93a
--- /dev/null
+++ b/testData/formatter/try6-after.erl
@@ -0,0 +1,4 @@
+test() ->
+  try
+    <caret>%% comment
+  end.
\ No newline at end of file
diff --git a/testData/formatter/try6.erl b/testData/formatter/try6.erl
new file mode 100644
index 000000000..274b6edb7
--- /dev/null
+++ b/testData/formatter/try6.erl
@@ -0,0 +1,3 @@
+test() ->
+  try<caret>%% comment
+  end.
\ No newline at end of file
diff --git a/tests/org/intellij/erlang/formatting/ErlangFormattingTest.java b/tests/org/intellij/erlang/formatting/ErlangFormattingTest.java
index d75f4f839..32acf2446 100644
--- a/tests/org/intellij/erlang/formatting/ErlangFormattingTest.java
+++ b/tests/org/intellij/erlang/formatting/ErlangFormattingTest.java
@@ -143,6 +143,16 @@ public void testAligned() throws Exception {
     doTest();
   }
 
+  public void testAlignedImport() throws Exception {
+    alignBlocks();
+    doTest();
+  }
+
+  public void testAlignedExport() throws Exception {
+    alignBlocks();
+    doTest();
+  }
+
   public void testFunctionClausesAligned() throws Exception {
     getErlangSettings().ALIGN_FUNCTION_CLAUSES = true;
     doTest();
@@ -206,12 +216,14 @@ public void testUniformBinaryExpressionsStyle() throws Exception {
   public void testTry3() throws Exception { doEnterTest(); }
   public void testTry4() throws Exception { doEnterTest(); }
   public void testTry5() throws Exception { doEnterTest(); }
+  public void testTry6() throws Exception { doEnterTest(); }
 
   public void testTryParasite1() throws Exception { doEnterTest(); }
   public void testTryParasite2() throws Exception { doEnterTest(); }
   public void testTryParasite3() throws Exception { doEnterTest(); }
   public void testTryParasite4() throws Exception { doEnterTest(); }
   public void testTryParasite5() throws Exception { doEnterTest(); }
+  public void testTryParasite6() throws Exception { doEnterTest(); }
 
   public void testBindTry()                 throws Exception { doEnterTest(); }
   public void testBindTryExpr()             throws Exception { doEnterTest(); }
@@ -242,12 +254,14 @@ public void testUniformBinaryExpressionsStyle() throws Exception {
   public void testMaybe3() throws Exception { doEnterTest(); }
   public void testMaybe4() throws Exception { doEnterTest(); }
   public void testMaybe5() throws Exception { doEnterTest(); }
+  public void testMaybe6() throws Exception { doEnterTest(); }
 
   public void testMaybeParasite1() throws Exception { doEnterTest(); }
   public void testMaybeParasite2() throws Exception { doEnterTest(); }
   public void testMaybeParasite3() throws Exception { doEnterTest(); }
   public void testMaybeParasite4() throws Exception { doEnterTest(); }
   public void testMaybeParasite5() throws Exception { doEnterTest(); }
+  public void testMaybeParasite6() throws Exception { doEnterTest(); }
 
   public void testBindMaybe()                throws Exception { doEnterTest(); }
   public void testBindMaybeElse()            throws Exception { doEnterTest(); }