Raise specific exception #6

Author: obenjiro

src/exceptions.js

@@ -0,0 +1,33 @@
+function GrammarParseError() {
+    var temp = Error.apply(this, arguments);
+    temp.name = this.name = 'GrammarParseError';
+    this.stack = temp.stack;
+    this.message = temp.message;
+}
+GrammarParseError.prototype = Object.create(Error.prototype, {
+    constructor: {
+        value: GrammarParseError,
+        writable: true,
+        configurable: true
+    }
+});
+
+function TextParseError() {
+    var temp = Error.apply(this, arguments);
+    temp.name = this.name = 'TextParseError';
+    this.stack = temp.stack;
+    this.message = temp.message;
+}
+TextParseError.prototype = Object.create(Error.prototype, {
+    constructor: {
+        value: TextParseError,
+        writable: true,
+        configurable: true
+    }
+});
+
+
+module.exports = {
+	GrammarParseError: GrammarParseError,
+	TextParseError: TextParseError
+}

src/speg.js

@@ -1,6 +1,7 @@
 var SPEG_actions_visitor = require('./speg_visitor').SPEG_actions_visitor;
 var SPEG_parser = require('./speg_parser');
 var rd = require('./rd_parser');
+var ex = require('./exceptions');
 
 function SPEG() {
     this.parser = new SPEG_parser();
@@ -14,7 +15,7 @@ SPEG.prototype.parse_grammar = function(grammar) {
     if (speg_ast) {
         this.speg_parser = this.visitor.visit(speg_ast);
     } else {
-        throw Error('Failed to parse grammar: \n\n' + this.parser.get_last_error());
+        throw new ex.GrammarParseError('Failed to parse grammar: \n\n' + this.parser.get_last_error());
     }
 };
 
@@ -28,7 +29,7 @@ SPEG.prototype.parse_text = function(text) {
         if (ast) {
             return ast;
         } else {
-            throw Error('Failed to parse text: \n\n' + rd.get_last_error(state))
+            throw new ex.TextParseError('Failed to parse text: \n\n' + rd.get_last_error(state))
         }
     } else {
         throw Error('You need grammar to parse text. Call parseGrammar first');
@@ -47,10 +48,10 @@ SPEG.prototype.parse = function(grammar, text) {
         if (ast) {
             return ast;
         } else {
-            throw Error('Failed to parse text: \n\n' + rd.get_last_error(state))
+            throw new ex.TextParseError('Failed to parse text: \n\n' + rd.get_last_error(state))
         }
     } else {
-        throw Error('Failed to parse grammar: \n\n' + this.parser.get_last_error())
+        throw new ex.GrammarParseError('Failed to parse grammar: \n\n' + this.parser.get_last_error())
     }
 };
 

test/exceptions.spec.js

@@ -0,0 +1,38 @@
+var should = require('chai').should();
+var expect = require('chai').expect;
+var simplepeg = require('./../src/speg');
+var ex = require('./../src/exceptions');
+
+describe('exceptions - ', function() {
+    it('should throw correct error when grammar is wrong',function() {
+        expect(function() {
+            var parser = new simplepeg.SPEG();
+            parser.parse_grammar('!!!');
+        }).to.throw(ex.GrammarParseError);
+    });
+    it('should throw correct error when text is wrong',function() {
+        expect(function() {
+            var parser = new simplepeg.SPEG();
+            parser.parse_grammar('GRAMMAR test a -> "A";');
+            parser.parse_text('B');
+        }).to.throw(ex.TextParseError);
+    });
+    it('should throw when text called before grammar',function() {
+        expect(function() {
+            var parser = new simplepeg.SPEG();
+            parser.parse_text('B');
+        }).to.throw(Error);
+    });
+    it('should (speg.parse) throw correct error when grammar is wrong',function() {
+        expect(function() {
+            var parser = new simplepeg.SPEG();
+            parser.parse('!!!', 'B');
+        }).to.throw(ex.GrammarParseError);
+    });
+    it('should (speg.parse) throw correct error when text is wrong',function() {
+        expect(function() {
+            var parser = new simplepeg.SPEG();
+            parser.parse('GRAMMAR test a -> "A";', 'B');
+        }).to.throw(ex.TextParseError);
+    });
+});