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-rw-r--r--src/DatabaseHelpers.cxx78
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diff --git a/src/DatabaseHelpers.cxx b/src/DatabaseHelpers.cxx
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+/*
+ * Copyright (C) 2003-2012 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.
+ */
+
+#include "DatabaseHelpers.hxx"
+#include "DatabasePlugin.hxx"
+#include "song.h"
+#include "tag.h"
+
+#include <functional>
+#include <set>
+
+#include <string.h>
+
+struct StringLess {
+ gcc_pure
+ bool operator()(const char *a, const char *b) const {
+ return strcmp(a, b) < 0;
+ }
+};
+
+typedef std::set<const char *, StringLess> StringSet;
+
+static bool
+CollectTags(StringSet &set, enum tag_type tag_type, song &song)
+{
+ struct tag *tag = song.tag;
+ if (tag == nullptr)
+ return true;
+
+ bool found = false;
+ for (unsigned i = 0; i < tag->num_items; ++i) {
+ if (tag->items[i]->type == tag_type) {
+ set.insert(tag->items[i]->value);
+ found = true;
+ }
+ }
+
+ if (!found)
+ set.insert("");
+
+ return true;
+}
+
+bool
+VisitUniqueTags(const Database &db, const DatabaseSelection &selection,
+ enum tag_type tag_type,
+ VisitString visit_string,
+ GError **error_r)
+{
+ StringSet set;
+
+ using namespace std::placeholders;
+ const auto f = std::bind(CollectTags, std::ref(set), tag_type, _1);
+ if (!db.Visit(selection, f, error_r))
+ return false;
+
+ for (auto value : set)
+ if (!visit_string(value, error_r))
+ return false;
+
+ return true;
+}