config/Param: add method With()

src/LogInit.cxx

@@ -93,7 +93,7 @@ log_init_file(int line)
 }
 
 static inline LogLevel
-parse_log_level(const char *value, int line)
+parse_log_level(const char *value)
 {
 	if (0 == strcmp(value, "default"))
 		return LogLevel::DEFAULT;
@@ -102,8 +102,7 @@ parse_log_level(const char *value, int line)
 	else if (0 == strcmp(value, "verbose"))
 		return LogLevel::DEBUG;
 	else
-		throw FormatRuntimeError("unknown log level \"%s\" at line %d",
+		throw FormatRuntimeError("unknown log level \"%s\"", value);
-					 value, line);
 }
 
 #endif
@@ -132,9 +131,12 @@ log_init(const ConfigData &config, bool verbose, bool use_stdout)
 #else
 	if (verbose)
 		SetLogThreshold(LogLevel::DEBUG);
-	else if (const auto &param = config.GetParam(ConfigOption::LOG_LEVEL))
+	else
-		SetLogThreshold(parse_log_level(param->value.c_str(),
+		SetLogThreshold(config.With(ConfigOption::LOG_LEVEL, [](const char *s){
-						param->line));
+			return s != nullptr
+				? parse_log_level(s)
+				: LogLevel::DEFAULT;
+		}));
 
 	if (use_stdout) {
 		out_fd = STDOUT_FILENO;

src/Main.cxx

@@ -282,20 +282,23 @@ initialize_decoder_and_player(Instance &instance,
 	size_t buffer_size;
 	param = config.GetParam(ConfigOption::AUDIO_BUFFER_SIZE);
 	if (param != nullptr) {
+		buffer_size = param->With([](const char *s){
 			char *test;
-		long tmp = strtol(param->value.c_str(), &test, 10);
+			long tmp = strtol(s, &test, 10);
 			if (*test != '\0' || tmp <= 0 || tmp == LONG_MAX)
 				throw FormatRuntimeError("buffer size \"%s\" is not a "
-						 "positive integer, line %i",
+							 "positive integer", s);
-						 param->value.c_str(), param->line);
+			size_t result = tmp * KILOBYTE;
-		buffer_size = tmp * KILOBYTE;
 
-		if (buffer_size < MIN_BUFFER_SIZE) {
+			if (result < MIN_BUFFER_SIZE) {
 				FormatWarning(config_domain, "buffer size %lu is too small, using %lu bytes instead",
-				      (unsigned long)buffer_size,
+					      (unsigned long)result,
 					      (unsigned long)MIN_BUFFER_SIZE);
-			buffer_size = MIN_BUFFER_SIZE;
+				result = MIN_BUFFER_SIZE;
 			}
+
+			return result;
+		});
 	} else
 		buffer_size = DEFAULT_BUFFER_SIZE;
 
@@ -309,17 +312,12 @@ initialize_decoder_and_player(Instance &instance,
 		config.GetPositive(ConfigOption::MAX_PLAYLIST_LENGTH,
 				   DEFAULT_PLAYLIST_MAX_LENGTH);
 
-	AudioFormat configured_audio_format = AudioFormat::Undefined();
+	AudioFormat configured_audio_format = config.With(ConfigOption::AUDIO_OUTPUT_FORMAT, [](const char *s){
-	param = config.GetParam(ConfigOption::AUDIO_OUTPUT_FORMAT);
+		if (s == nullptr)
-	if (param != nullptr) {
+			return AudioFormat::Undefined();
-		try {
+
-			configured_audio_format = ParseAudioFormat(param->value.c_str(),
+		return ParseAudioFormat(s, true);
-								   true);
+	});
-		} catch (...) {
-			std::throw_with_nested(FormatRuntimeError("error parsing line %i",
-								  param->line));
-		}
-	}
 
 	instance.partitions.emplace_back(instance,
 					 "default",
@@ -329,15 +327,11 @@ initialize_decoder_and_player(Instance &instance,
 					 replay_gain_config);
 	auto &partition = instance.partitions.back();
 
-	try {
+	partition.replay_gain_mode = config.With(ConfigOption::REPLAYGAIN, [](const char *s){
-		param = config.GetParam(ConfigOption::REPLAYGAIN);
+		return s != nullptr
-		if (param != nullptr)
+			? FromString(s)
-			partition.replay_gain_mode =
+			: ReplayGainMode::OFF;
-				FromString(param->value.c_str());
+	});
-	} catch (...) {
-		std::throw_with_nested(FormatRuntimeError("Failed to parse line %i",
-							  param->line));
-	}
 }
 
 inline void

src/Permission.cxx

@@ -82,44 +82,39 @@ static unsigned parsePermissions(const char *string)
 void
 initPermissions(const ConfigData &config)
 {
-	unsigned permission;
-
 	permission_default = PERMISSION_READ | PERMISSION_ADD |
 	    PERMISSION_CONTROL | PERMISSION_ADMIN;
 
 	for (const auto &param : config.GetParamList(ConfigOption::PASSWORD)) {
 		permission_default = 0;
 
-		const char *separator = strchr(param.value.c_str(),
+		param.With([](const char *value){
+			const char *separator = strchr(value,
 						       PERMISSION_PASSWORD_CHAR);
 
 			if (separator == NULL)
-			throw FormatRuntimeError("\"%c\" not found in password string "
+				throw FormatRuntimeError("\"%c\" not found in password string",
-						 "\"%s\", line %i",
+							 PERMISSION_PASSWORD_CHAR);
-						 PERMISSION_PASSWORD_CHAR,
-						 param.value.c_str(),
-						 param.line);
 
-		std::string password(param.value.c_str(), separator);
+			std::string password(value, separator);
-
-		permission = parsePermissions(separator + 1);
 
+			unsigned permission = parsePermissions(separator + 1);
 			permission_passwords.insert(std::make_pair(std::move(password),
 								   permission));
+		});
 	}
 
-	const ConfigParam *param;
+	config.With(ConfigOption::DEFAULT_PERMS, [](const char *value){
-	param = config.GetParam(ConfigOption::DEFAULT_PERMS);
+		if (value != nullptr)
-
+			permission_default = parsePermissions(value);
-	if (param)
+	});
-		permission_default = parsePermissions(param->value.c_str());
 
 #ifdef HAVE_UN
-	param = config.GetParam(ConfigOption::LOCAL_PERMISSIONS);
+	local_permissions = config.With(ConfigOption::LOCAL_PERMISSIONS, [](const char *value){
-	if (param != nullptr)
+		return value != nullptr
-		local_permissions = parsePermissions(param->value.c_str());
+			? parsePermissions(value)
-	else
+			: permission_default;
-		local_permissions = permission_default;
+	});
 #endif
 }
 

src/ReplayGainGlobal.cxx

@@ -43,29 +43,22 @@ ParsePreamp(const char *s)
 	return pow(10, f / 20.0);
 }
 
-static float
-ParsePreamp(const ConfigParam &p)
-{
-	try {
-		return ParsePreamp(p.value.c_str());
-	} catch (...) {
-		std::throw_with_nested(FormatRuntimeError("Failed to parse line %i",
-							  p.line));
-	}
-}
-
 ReplayGainConfig
 LoadReplayGainConfig(const ConfigData &config)
 {
 	ReplayGainConfig replay_gain_config;
 
-	const auto *param = config.GetParam(ConfigOption::REPLAYGAIN_PREAMP);
+	replay_gain_config.preamp = config.With(ConfigOption::REPLAYGAIN_PREAMP, [](const char *s){
-	if (param)
+		return s != nullptr
-		replay_gain_config.preamp = ParsePreamp(*param);
+			? ParsePreamp(s)
+			: 1.0;
+	});
 
-	param = config.GetParam(ConfigOption::REPLAYGAIN_MISSING_PREAMP);
+	replay_gain_config.missing_preamp = config.With(ConfigOption::REPLAYGAIN_MISSING_PREAMP, [](const char *s){
-	if (param)
+		return s != nullptr
-		replay_gain_config.missing_preamp = ParsePreamp(*param);
+			? ParsePreamp(s)
+			: 1.0;
+	});
 
 	replay_gain_config.limit = config.GetBool(ConfigOption::REPLAYGAIN_LIMIT,
 						  ReplayGainConfig::DEFAULT_LIMIT);

src/config/Data.hxx

@@ -54,6 +54,14 @@ struct ConfigData {
 		return list.empty() ? nullptr : &list.front();
 	}
 
+	template<typename F>
+	auto With(ConfigOption option, F &&f) const {
+		const auto *param = GetParam(option);
+		return param != nullptr
+			? param->With(std::forward<F>(f))
+			: f(nullptr);
+	}
+
 	gcc_pure
 	const char *GetString(ConfigOption option,
 			      const char *default_value=nullptr) const noexcept;

src/config/Param.hxx

@@ -66,6 +66,19 @@ struct ConfigParam {
 	 */
 	[[noreturn]]
 	void ThrowWithNested() const;
+
+	/**
+	 * Invoke a function with the configured value; if the
+	 * function throws, call ThrowWithNested().
+	 */
+	template<typename F>
+	auto With(F &&f) const {
+		try {
+			return f(value.c_str());
+		} catch (...) {
+			ThrowWithNested();
+		}
+	}
 };
 
 #endif