sticker/Song: add enum StickerOperator to sticker_song_find()

Makefile.am

@@ -356,6 +356,7 @@ libmpd_a_SOURCES += \
 	src/command/StickerCommands.cxx src/command/StickerCommands.hxx \
 	src/lib/sqlite/Domain.cxx src/lib/sqlite/Domain.hxx \
 	src/lib/sqlite/Util.hxx \
+	src/sticker/Match.hxx \
 	src/sticker/StickerDatabase.cxx src/sticker/StickerDatabase.hxx \
 	src/sticker/StickerPrint.cxx src/sticker/StickerPrint.hxx \
 	src/sticker/SongSticker.cxx src/sticker/SongSticker.hxx

src/command/StickerCommands.cxx

@@ -143,6 +143,9 @@ handle_sticker_song(Client &client, ConstBuffer<const char *> args)
 
 		const char *const base_uri = args[2];
 
+		StickerOperator op = StickerOperator::EXISTS;
+		const char *value = nullptr;
+
 		bool success;
 		struct sticker_song_find_data data = {
 			client,
@@ -150,6 +153,7 @@ handle_sticker_song(Client &client, ConstBuffer<const char *> args)
 		};
 
 		success = sticker_song_find(*db, base_uri, data.name,
+					    op, value,
 					    sticker_song_find_print_cb, &data,
 					    error);
 		if (!success) {

src/sticker/Match.hxx

@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_STICKER_MATCH_HXX
+#define MPD_STICKER_MATCH_HXX
+
+enum class StickerOperator {
+	/**
+	 * Matches if a sticker with the specified name exists.  The
+	 * "value" parameter is ignored (must be nullptr).
+	 */
+	EXISTS,
+};
+
+#endif

src/sticker/SongSticker.cxx

@@ -97,6 +97,7 @@ sticker_song_find_cb(const char *uri, const char *value, void *user_data)
 
 bool
 sticker_song_find(const Database &db, const char *base_uri, const char *name,
+		  StickerOperator op, const char *value,
 		  void (*func)(const LightSong &song, const char *value,
 			       void *user_data),
 		  void *user_data,
@@ -119,7 +120,7 @@ sticker_song_find(const Database &db, const char *base_uri, const char *name,
 
 	data.base_uri_length = strlen(data.base_uri);
 
-	bool success = sticker_find("song", data.base_uri, name,
+	bool success = sticker_find("song", data.base_uri, name, op, value,
 				    sticker_song_find_cb, &data,
 				    error);
 	free(allocated);

src/sticker/SongSticker.hxx

@@ -20,6 +20,7 @@
 #ifndef MPD_SONG_STICKER_HXX
 #define MPD_SONG_STICKER_HXX
 
+#include "Match.hxx"
 #include "Compiler.h"
 
 #include <string>
@@ -30,7 +31,8 @@ class Database;
 class Error;
 
 /**
- * Returns one value from a song's sticker record.
+ * Returns one value from a song's sticker record.  The caller must
+ * free the return value with g_free().
  */
 gcc_pure
 std::string
@@ -81,6 +83,7 @@ sticker_song_get(const LightSong &song, Error &error);
  */
 bool
 sticker_song_find(const Database &db, const char *base_uri, const char *name,
+		  StickerOperator op, const char *value,
 		  void (*func)(const LightSong &song, const char *value,
 			       void *user_data),
 		  void *user_data,

src/sticker/StickerDatabase.cxx

@@ -370,6 +370,7 @@ sticker_load(const char *type, const char *uri, Error &error)
 
 static sqlite3_stmt *
 BindFind(const char *type, const char *base_uri, const char *name,
+	 StickerOperator op, const char *value,
 	 Error &error)
 {
 	assert(type != nullptr);
@@ -378,12 +379,21 @@ BindFind(const char *type, const char *base_uri, const char *name,
 	if (base_uri == nullptr)
 		base_uri = "";
 
-	return BindAllOrNull(error, sticker_stmt[STICKER_SQL_FIND],
-			     type, base_uri, name);
+	switch (op) {
+	case StickerOperator::EXISTS:
+		return BindAllOrNull(error, sticker_stmt[STICKER_SQL_FIND],
+				     type, base_uri, name);
+	}
+
+	(void)value;
+
+	assert(false);
+	gcc_unreachable();
 }
 
 bool
 sticker_find(const char *type, const char *base_uri, const char *name,
+	     StickerOperator op, const char *value,
 	     void (*func)(const char *uri, const char *value,
 			  void *user_data),
 	     void *user_data,
@@ -392,7 +402,8 @@ sticker_find(const char *type, const char *base_uri, const char *name,
 	assert(func != nullptr);
 	assert(sticker_enabled());
 
-	sqlite3_stmt *const stmt = BindFind(type, base_uri, name, error);
+	sqlite3_stmt *const stmt = BindFind(type, base_uri, name, op, value,
+					    error);
 	if (stmt == nullptr)
 		return false;
 

src/sticker/StickerDatabase.hxx

@@ -42,6 +42,7 @@
 #ifndef MPD_STICKER_DATABASE_HXX
 #define MPD_STICKER_DATABASE_HXX
 
+#include "Match.hxx"
 #include "Compiler.h"
 
 #include <string>
@@ -154,11 +155,14 @@ sticker_load(const char *type, const char *uri,
  * @param base_uri the URI prefix of the resources, or nullptr if all
  * resources should be searched
  * @param name the name of the sticker
+ * @param op the comparison operator
+ * @param value the operand
  * @return true on success (even if no sticker was found), false on
  * failure
  */
 bool
 sticker_find(const char *type, const char *base_uri, const char *name,
+	     StickerOperator op, const char *value,
 	     void (*func)(const char *uri, const char *value,
 			  void *user_data),
 	     void *user_data,