fs/Path: rename to AllocatedPath

The new class Path only holds a string pointer without being
responsible for allocation/deallocation.  The FileSystem.hxx library
accepts Path arguments instead of AllocatedPath, to avoid forcing
callers to allocate another string object.

src/fs/AllocatedPath.hxx

@@ -0,0 +1,226 @@
+/*
+ * Copyright (C) 2003-2013 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_FS_ALLOCATED_PATH_HXX
+#define MPD_FS_ALLOCATED_PATH_HXX
+
+#include "check.h"
+#include "Compiler.h"
+#include "Traits.hxx"
+#include "Path.hxx"
+
+#ifdef WIN32
+#include <glib.h>
+#endif
+
+#include <utility>
+#include <string>
+
+#include <assert.h>
+
+class Error;
+
+/**
+ * A path name in the native file system character set.
+ *
+ * This class manages the memory chunk where this path string is
+ * stored.
+ */
+class AllocatedPath {
+	typedef std::string string;
+
+	typedef PathTraits::value_type value_type;
+	typedef PathTraits::pointer pointer;
+	typedef PathTraits::const_pointer const_pointer;
+
+	string value;
+
+	struct Donate {};
+
+	/**
+	 * Donate the allocated pointer to a new #AllocatedPath object.
+	 */
+	AllocatedPath(Donate, pointer _value);
+
+	AllocatedPath(const_pointer _value):value(_value) {}
+
+public:
+	/**
+	 * Copy a #AllocatedPath object.
+	 */
+	AllocatedPath(const AllocatedPath &) = default;
+
+	/**
+	 * Move a #AllocatedPath object.
+	 */
+	AllocatedPath(AllocatedPath &&other):value(std::move(other.value)) {}
+
+	~AllocatedPath();
+
+	/**
+	 * Return a "nulled" instance.  Its IsNull() method will
+	 * return true.  Such an object must not be used.
+	 *
+	 * @see IsNull()
+	 */
+	gcc_const
+	static AllocatedPath Null() {
+		return AllocatedPath("");
+	}
+
+	gcc_pure
+	operator Path() const {
+		return Path::FromFS(c_str());
+	}
+
+	/**
+	 * Join two path components with the path separator.
+	 */
+	gcc_pure gcc_nonnull_all
+	static AllocatedPath Build(const_pointer a, const_pointer b);
+
+	gcc_pure gcc_nonnull_all
+	static AllocatedPath Build(const_pointer a, const AllocatedPath &b) {
+		return Build(a, b.c_str());
+	}
+
+	gcc_pure gcc_nonnull_all
+	static AllocatedPath Build(const AllocatedPath &a, const_pointer b) {
+		return Build(a.c_str(), b);
+	}
+
+	gcc_pure
+	static AllocatedPath Build(const AllocatedPath &a,
+				   const AllocatedPath &b) {
+		return Build(a.c_str(), b.c_str());
+	}
+
+	/**
+	 * Convert a C string that is already in the filesystem
+	 * character set to a #Path instance.
+	 */
+	gcc_pure
+	static AllocatedPath FromFS(const_pointer fs) {
+		return AllocatedPath(fs);
+	}
+
+	/**
+	 * Convert a UTF-8 C string to a #AllocatedPath instance.
+	 * Returns return a "nulled" instance on error.
+	 */
+	gcc_pure gcc_nonnull_all
+	static AllocatedPath FromUTF8(const char *path_utf8);
+
+	gcc_pure gcc_nonnull_all
+	static AllocatedPath FromUTF8(const char *path_utf8, Error &error);
+
+	/**
+	 * Copy a #AllocatedPath object.
+	 */
+	AllocatedPath &operator=(const AllocatedPath &) = default;
+
+	/**
+	 * Move a #AllocatedPath object.
+	 */
+	AllocatedPath &operator=(AllocatedPath &&other) {
+		value = std::move(other.value);
+		return *this;
+	}
+
+	/**
+	 * Check if this is a "nulled" instance.  A "nulled" instance
+	 * must not be used.
+	 */
+	bool IsNull() const {
+		return value.empty();
+	}
+
+	/**
+	 * Clear this object's value, make it "nulled".
+	 *
+	 * @see IsNull()
+	 */
+	void SetNull() {
+		value.clear();
+	}
+
+	/**
+	 * @return the length of this string in number of "value_type"
+	 * elements (which may not be the number of characters).
+	 */
+	gcc_pure
+	size_t length() const {
+		return value.length();
+	}
+
+	/**
+	 * Returns the value as a const C string.  The returned
+	 * pointer is invalidated whenever the value of life of this
+	 * instance ends.
+	 */
+	gcc_pure
+	const_pointer c_str() const {
+		return value.c_str();
+	}
+
+	/**
+	 * Returns a pointer to the raw value, not necessarily
+	 * null-terminated.
+	 */
+	gcc_pure
+	const_pointer data() const {
+		return value.data();
+	}
+
+	/**
+	 * Convert the path to UTF-8.
+	 * Returns empty string on error or if this instance is "nulled"
+	 * (#IsNull returns true).
+	 */
+	gcc_pure
+	std::string ToUTF8() const;
+
+	/**
+	 * Gets directory name of this path.
+	 * Returns a "nulled" instance on error.
+	 */
+	gcc_pure
+	AllocatedPath GetDirectoryName() const;
+
+	/**
+	 * Determine the relative part of the given path to this
+	 * object, not including the directory separator.  Returns an
+	 * empty string if the given path equals this object or
+	 * nullptr on mismatch.
+	 */
+	gcc_pure
+	const char *RelativeFS(const char *other_fs) const;
+
+	/**
+	 * Chop trailing directory separators.
+	 */
+	void ChopSeparators();
+
+	gcc_pure
+	bool IsAbsolute() {
+		return PathTraits::IsAbsoluteFS(c_str());
+	}
+};
+
+#endif