CommandLine: new command line parser

This implementation behaves mostly identical to old parser.
Few observable differences:
- There are no option groups (single group is used for all options)
- Option --stdout is hidden (it has been obsolete for a long time)
- MPD executable name (mpd) is hardcoded for simplicity

src/util/OptionDef.hxx

@@ -0,0 +1,63 @@
+/*
+ * 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_UTIL_OPTIONDEF_HXX
+#define MPD_UTIL_OPTIONDEF_HXX
+
+/**
+ * Command line option definition.
+ */
+class OptionDef
+{
+	const char *long_option;
+	char short_option;
+	const char *desc;
+public:
+	constexpr OptionDef(const char *_long_option, const char *_desc)
+		: long_option(_long_option),
+		  short_option(0),
+		  desc(_desc) { }
+
+	constexpr OptionDef(const char *_long_option,
+			    char _short_option, const char *_desc)
+		: long_option(_long_option),
+		  short_option(_short_option),
+		  desc(_desc) { }
+
+	bool HasLongOption() const { return long_option != nullptr; }
+	bool HasShortOption() const { return short_option != 0; }
+	bool HasDescription() const { return desc != nullptr; }
+
+	const char *GetLongOption() const {
+		assert(HasLongOption());
+		return long_option;
+	}
+
+	char GetShortOption() const {
+		assert(HasShortOption());
+		return short_option;
+	}
+
+	const char *GetDescription() const {
+		assert(HasDescription());
+		return desc;
+	}
+};
+
+#endif

src/util/OptionParser.cxx

@@ -0,0 +1,59 @@
+/*
+ * 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.
+ */
+
+#include "OptionParser.hxx"
+#include "OptionDef.hxx"
+
+#include <string.h>
+
+bool OptionParser::CheckOption(const OptionDef &opt)
+{
+	assert(option != nullptr);
+
+	if (is_long)
+		return opt.HasLongOption() &&
+		       strcmp(option, opt.GetLongOption()) == 0;
+
+	return opt.HasShortOption() &&
+	       option[0] == opt.GetShortOption() &&
+	       option[1] == '\0';
+}
+
+bool OptionParser::ParseNext()
+{
+	assert(HasEntries());
+	char *arg = *argv;
+	++argv;
+	--argc;
+	if (arg[0] == '-') {
+		if (arg[1] == '-') {
+			option = arg + 2;
+			is_long = true;
+		}
+		else {
+			option = arg + 1;
+			is_long = false;
+		}
+		option_raw = arg;
+		return true;
+	}
+	option = nullptr;
+	option_raw = nullptr;
+	return false;
+}

src/util/OptionParser.hxx

@@ -0,0 +1,88 @@
+/*
+ * 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_UTIL_OPTIONPARSER_HXX
+#define MPD_UTIL_OPTIONPARSER_HXX
+
+#include <assert.h>
+
+class OptionDef;
+
+/**
+ * Command line option parser.
+ */
+class OptionParser
+{
+	int argc;
+	char **argv;
+	char *option;
+	char *option_raw;
+	bool is_long;
+public:
+	/**
+	 * Constructs #OptionParser.
+	 */
+	OptionParser(int _argc, char **_argv)
+		: argc(_argc - 1), argv(_argv + 1),
+		  option(nullptr), option_raw(nullptr), is_long(false) { }
+
+	/**
+	 * Checks if there are command line entries to process.
+	 */
+	bool HasEntries() const { return argc > 0; }
+
+	/**
+	 * Gets the last parsed option.
+	 */
+	char *GetOption() {
+		assert(option_raw != nullptr);
+		return option_raw;
+	}
+
+	/**
+	 * Checks if current option is a specified option.
+	 */
+	bool CheckOption(const OptionDef& opt);
+
+	/**
+	 * Checks if current option is a specified option
+	 * or specified alternative option.
+	 */
+	bool CheckOption(const OptionDef& opt, const OptionDef &alt_opt) {
+		return CheckOption(opt) || CheckOption(alt_opt);
+	}
+
+	/**
+	 * Parses current command line entry.
+	 * Returns true on success, false otherwise.
+	 * Regardless of result, advances current position to the next
+	 * command line entry. 
+	 */
+	bool ParseNext();
+
+	/**
+	 * Checks if specified string is a command line option.
+	 */
+	static bool IsOption(const char *s) {
+		assert(s != nullptr);
+		return s[0] == '-';
+	}
+};
+
+#endif