(wip) song/DirectorySongFilter: new filter

doc/protocol.rst

@@ -213,6 +213,8 @@ of:
   songs in the given directory (relative to the music
   directory).
 
+- ``(directory 'VALUE')``: non-recursive version of ``(base 'VALUE')``.
+
 - ``(modified-since 'VALUE')``: compares the
   file's time stamp with the given value (ISO 8601 or UNIX
   time stamp).

src/db/Selection.cxx

@@ -3,17 +3,19 @@
 
 #include "Selection.hxx"
 #include "song/Filter.hxx"
+#include "song/BaseSongFilter.hxx"
 
 DatabaseSelection::DatabaseSelection(const char *_uri, bool _recursive,
 				     const SongFilter *_filter) noexcept
 	:uri(_uri), filter(_filter), recursive(_recursive)
 {
 	/* optimization: if the caller didn't specify a base URI, pick
 	   the one from SongFilter */
-	if (uri.empty() && filter != nullptr) {
-		auto base = filter->GetBase();
-		if (base != nullptr)
-			uri = base;
+	if (filter != nullptr) {
+		Base base = filter->GetBase();
+		if (uri.empty() && base.uri != nullptr)
+			uri = base.uri;
+		recursive = base.recursive;
 	}
 }
 

src/song/BaseSongFilter.hxx

@@ -8,18 +8,24 @@
 
 class BaseSongFilter final : public ISongFilter {
 	std::string value;
+  bool recursive;
 
 public:
+
 	BaseSongFilter(const BaseSongFilter &) = default;
 
 	template<typename V>
-	explicit BaseSongFilter(V &&_value)
-		:value(std::forward<V>(_value)) {}
+	explicit BaseSongFilter(V &&_value, bool _recursive)
+		:value(std::forward<V>(_value)), recursive(_recursive) {}
 
 	const char *GetValue() const noexcept {
 		return value.c_str();
 	}
 
+  bool IsRecursive() const noexcept {
+    return recursive;
+  }
+
 	ISongFilterPtr Clone() const noexcept override {
 		return std::make_unique<BaseSongFilter>(*this);
 	}

src/song/Filter.cxx

@@ -43,6 +43,7 @@ enum {
 	LOCATE_TAG_FILE_TYPE,
 	LOCATE_TAG_ANY_TYPE,
 	LOCATE_TAG_ADDED_SINCE,
+	LOCATE_TAG_DIRECTORY_TYPE,
 };
 
 /**
@@ -62,6 +63,9 @@ locate_parse_type(const char *str) noexcept
 	if (strcmp(str, "base") == 0)
 		return LOCATE_TAG_BASE_TYPE;
 
+	if (strcmp(str, "directory") == 0)
+		return LOCATE_TAG_DIRECTORY_TYPE;
+
 	if (strcmp(str, "modified-since") == 0)
 		return LOCATE_TAG_MODIFIED_SINCE;
 
@@ -385,7 +389,13 @@ SongFilter::ParseExpression(const char *&s, bool fold_case, bool strip_diacritic
 			throw std::runtime_error("')' expected");
 		s = StripLeft(s + 1);
 
-		return std::make_unique<BaseSongFilter>(std::move(value));
+		return std::make_unique<BaseSongFilter>(std::move(value), true);
+	} else if (type == LOCATE_TAG_DIRECTORY_TYPE) {
+		auto value = ExpectQuoted(s);
+		if (*s != ')')
+			throw std::runtime_error("')' expected");
+		s = StripLeft(s + 1);
+		return std::make_unique<BaseSongFilter>(std::move(value), false);
 	} else if (type == LOCATE_TAG_AUDIO_FORMAT) {
 		bool mask;
 		if (s[0] == '=' && s[1] == '=')
@@ -456,7 +466,13 @@ SongFilter::Parse(const char *tag_string, const char *value, bool fold_case, boo
 		if (!uri_safe_local(value))
 			throw std::runtime_error("Bad URI");
 
-		and_filter.AddItem(std::make_unique<BaseSongFilter>(value));
+		and_filter.AddItem(std::make_unique<BaseSongFilter>(value, true));
+		break;
+
+	case LOCATE_TAG_DIRECTORY_TYPE:
+		if (!uri_safe_local(value))
+			throw std::runtime_error("Bad URI");
+		and_filter.AddItem(std::make_unique<BaseSongFilter>(value, false));
 		break;
 
 	case LOCATE_TAG_MODIFIED_SINCE:
@@ -557,16 +573,15 @@ SongFilter::HasFoldCase() const noexcept
 		});
 }
 
-const char *
+const Base
 SongFilter::GetBase() const noexcept
 {
 	for (const auto &i : and_filter.GetItems()) {
 		const auto *f = dynamic_cast<const BaseSongFilter *>(i.get());
 		if (f != nullptr)
-			return f->GetValue();
+			return Base{f->GetValue(), f->IsRecursive()};
 	}
-
-	return nullptr;
+	return Base{nullptr, true};
 }
 
 SongFilter
@@ -586,7 +601,7 @@ SongFilter::WithoutBasePrefix(const std::string_view prefix) const noexcept
 					++s;
 
 					if (*s != 0)
-						result.and_filter.AddItem(std::make_unique<BaseSongFilter>(s));
+						result.and_filter.AddItem(std::make_unique<BaseSongFilter>(s, f->IsRecursive()));
 
 					continue;
 				}

src/song/Filter.hxx

@@ -29,6 +29,11 @@
 enum TagType : uint8_t;
 struct LightSong;
 
+/**
+ * Base URI and recursive flag.
+ */
+struct Base { const char *uri; bool recursive; };
+
 class SongFilter {
 	AndSongFilter and_filter;
 
@@ -80,11 +85,11 @@ public:
 	bool HasFoldCase() const noexcept;
 
 	/**
-	 * Returns the "base" specification (if there is one) or
-	 * nullptr.
+	 * Returns the "base" specification, containing URI (if any) and
+	 * recursive flag (default to true).
 	 */
 	[[gnu::pure]]
-	const char *GetBase() const noexcept;
+	const Base GetBase() const noexcept;
 
 	/**
 	 * Create a copy of the filter with the given prefix stripped