config/Data: use std::forward_list to manage params and blocks

src/Listen.cxx

@@ -88,14 +88,13 @@ listen_global_init(const ConfigData &config, ClientListener &listener)
 		return;
 #endif
 
-	for (const auto *param = config.GetParam(ConfigOption::BIND_TO_ADDRESS);
-	     param != nullptr; param = param->next) {
+	for (const auto &param : config.GetParamList(ConfigOption::BIND_TO_ADDRESS)) {
 		try {
-			listen_add_config_param(listener, port, param);
+			listen_add_config_param(listener, port, &param);
 		} catch (...) {
 			std::throw_with_nested(FormatRuntimeError("Failed to listen on %s (line %i)",
-								  param->value.c_str(),
-								  param->line));
+								  param.value.c_str(),
+								  param.line));
 		}
 	}
 

src/Permission.cxx

@@ -91,37 +91,32 @@ void
 initPermissions(const ConfigData &config)
 {
 	unsigned permission;
-	const ConfigParam *param;
 
 	permission_default = PERMISSION_READ | PERMISSION_ADD |
 	    PERMISSION_CONTROL | PERMISSION_ADMIN;
 
-	param = config.GetParam(ConfigOption::PASSWORD);
-
-	if (param) {
+	for (const auto &param : config.GetParamList(ConfigOption::PASSWORD)) {
 		permission_default = 0;
 
-		do {
-			const char *separator =
-				strchr(param->value.c_str(),
-				       PERMISSION_PASSWORD_CHAR);
+		const char *separator = strchr(param.value.c_str(),
+					       PERMISSION_PASSWORD_CHAR);
 
-			if (separator == NULL)
-				throw FormatRuntimeError("\"%c\" not found in password string "
-							 "\"%s\", line %i",
-							 PERMISSION_PASSWORD_CHAR,
-							 param->value.c_str(),
-							 param->line);
+		if (separator == NULL)
+			throw FormatRuntimeError("\"%c\" not found in password string "
+						 "\"%s\", line %i",
+						 PERMISSION_PASSWORD_CHAR,
+						 param.value.c_str(),
+						 param.line);
 
-			std::string password(param->value.c_str(), separator);
+		std::string password(param.value.c_str(), separator);
 
-			permission = parsePermissions(separator + 1);
+		permission = parsePermissions(separator + 1);
 
-			permission_passwords.insert(std::make_pair(std::move(password),
-								   permission));
-		} while ((param = param->next) != nullptr);
+		permission_passwords.insert(std::make_pair(std::move(password),
+							   permission));
 	}
 
+	const ConfigParam *param;
 	param = config.GetParam(ConfigOption::DEFAULT_PERMS);
 
 	if (param)

src/config/Block.cxx

@@ -78,11 +78,6 @@ BlockParam::GetBoolValue() const
 	return value2;
 }
 
-ConfigBlock::~ConfigBlock()
-{
-	delete next;
-}
-
 const BlockParam *
 ConfigBlock::GetBlockParam(const char *name) const noexcept
 {

src/config/Block.hxx

@@ -55,12 +55,6 @@ struct BlockParam {
 };
 
 struct ConfigBlock {
-	/**
-	 * The next #ConfigBlock with the same name.  The destructor
-	 * deletes the whole chain.
-	 */
-	ConfigBlock *next = nullptr;
-
 	int line;
 
 	std::vector<BlockParam> block_params;
@@ -74,11 +68,8 @@ struct ConfigBlock {
 	explicit ConfigBlock(int _line=-1)
 		:line(_line) {}
 
-	ConfigBlock(const ConfigBlock &) = delete;
-
-	~ConfigBlock();
-
-	ConfigBlock &operator=(const ConfigBlock &) = delete;
+	ConfigBlock(ConfigBlock &&) = default;
+	ConfigBlock &operator=(ConfigBlock &&) = default;
 
 	/**
 	 * Determine if this is a "null" instance, i.e. an empty

src/config/Data.cxx

@@ -19,8 +19,6 @@
 
 #include "config.h"
 #include "Data.hxx"
-#include "Param.hxx"
-#include "Block.hxx"
 #include "Parser.hxx"
 #include "fs/AllocatedPath.hxx"
 #include "util/RuntimeError.hxx"
@@ -31,35 +29,36 @@
 void
 ConfigData::Clear()
 {
-	for (auto &i : params) {
-		delete i;
-		i = nullptr;
-	}
+	for (auto &i : params)
+		i.clear();
 
-	for (auto &i : blocks) {
-		delete i;
-		i = nullptr;
-	}
+	for (auto &i : blocks)
+		i.clear();
 }
 
-gcc_nonnull_all
-static void
-Append(ConfigParam *&head, ConfigParam *p)
+template<typename T>
+gcc_pure
+static auto
+FindLast(const std::forward_list<T> &list)
 {
-	assert(p->next == nullptr);
-
-	auto **i = &head;
-	while (*i != nullptr)
-		i = &(*i)->next;
+	auto i = list.before_begin();
+	while (std::next(i) != list.end())
+		++i;
+	return i;
+}
 
-	*i = p;
+template<typename T>
+static auto
+Append(std::forward_list<T> &list, T &&src)
+{
+	return list.emplace_after(FindLast(list), std::move(src));
 }
 
 void
 ConfigData::AddParam(ConfigOption option,
 		     std::unique_ptr<ConfigParam> param) noexcept
 {
-	Append(params[size_t(option)], param.release());
+	Append(GetParamList(option), std::move(*param));
 }
 
 const char *
@@ -143,39 +142,25 @@ ConfigData::GetBool(ConfigOption option, bool default_value) const
 	return value;
 }
 
-gcc_nonnull_all
-static void
-Append(ConfigBlock *&head, ConfigBlock *p)
-{
-	assert(p->next == nullptr);
-
-	auto **i = &head;
-	while (*i != nullptr)
-		i = &(*i)->next;
-
-	*i = p;
-}
-
-void
+ConfigBlock &
 ConfigData::AddBlock(ConfigBlockOption option,
 		     std::unique_ptr<ConfigBlock> block) noexcept
 {
-	Append(blocks[size_t(option)], block.release());
+	return *Append(GetBlockList(option), std::move(*block));
 }
 
 const ConfigBlock *
 ConfigData::FindBlock(ConfigBlockOption option,
 		      const char *key, const char *value) const
 {
-	for (const auto *block = GetBlock(option);
-	     block != nullptr; block = block->next) {
-		const char *value2 = block->GetBlockValue(key);
+	for (const auto &block : GetBlockList(option)) {
+		const char *value2 = block.GetBlockValue(key);
 		if (value2 == nullptr)
 			throw FormatRuntimeError("block without '%s' in line %d",
-						 key, block->line);
+						 key, block.line);
 
 		if (StringIsEqual(value2, value))
-			return block;
+			return &block;
 	}
 
 	return nullptr;
@@ -189,8 +174,7 @@ ConfigData::MakeBlock(ConfigBlockOption option,
 	if (block == nullptr) {
 		auto new_block = std::make_unique<ConfigBlock>();
 		new_block->AddBlockParam(key, value);
-		block = new_block.get();
-		AddBlock(option, std::move(new_block));
+		block = &AddBlock(option, std::move(new_block));
 	}
 
 	return *block;

src/config/Data.hxx

@@ -21,9 +21,12 @@
 #define MPD_CONFIG_DATA_HXX
 
 #include "Option.hxx"
+#include "Param.hxx"
+#include "Block.hxx"
 
 #include <array>
 #include <chrono>
+#include <forward_list>
 #include <memory>
 
 struct ConfigParam;
@@ -31,17 +34,26 @@ struct ConfigBlock;
 class AllocatedPath;
 
 struct ConfigData {
-	std::array<ConfigParam *, std::size_t(ConfigOption::MAX)> params{{nullptr}};
-	std::array<ConfigBlock *, std::size_t(ConfigBlockOption::MAX)> blocks{{nullptr}};
+	std::array<std::forward_list<ConfigParam>, std::size_t(ConfigOption::MAX)> params;
+	std::array<std::forward_list<ConfigBlock>, std::size_t(ConfigBlockOption::MAX)> blocks;
 
 	void Clear();
 
+	auto &GetParamList(ConfigOption option) noexcept {
+		return params[size_t(option)];
+	}
+
+	const auto &GetParamList(ConfigOption option) const noexcept {
+		return params[size_t(option)];
+	}
+
 	void AddParam(ConfigOption option,
 		      std::unique_ptr<ConfigParam> param) noexcept;
 
 	gcc_pure
 	const ConfigParam *GetParam(ConfigOption option) const noexcept {
-		return params[size_t(option)];
+		const auto &list = GetParamList(option);
+		return list.empty() ? nullptr : &list.front();
 	}
 
 	gcc_pure
@@ -81,12 +93,21 @@ struct ConfigData {
 
 	bool GetBool(ConfigOption option, bool default_value) const;
 
-	void AddBlock(ConfigBlockOption option,
-		      std::unique_ptr<ConfigBlock> block) noexcept;
+	auto &GetBlockList(ConfigBlockOption option) noexcept {
+		return blocks[size_t(option)];
+	}
+
+	const auto &GetBlockList(ConfigBlockOption option) const noexcept {
+		return blocks[size_t(option)];
+	}
+
+	ConfigBlock &AddBlock(ConfigBlockOption option,
+			      std::unique_ptr<ConfigBlock> block) noexcept;
 
 	gcc_pure
 	const ConfigBlock *GetBlock(ConfigBlockOption option) const noexcept {
-		return blocks[size_t(option)];
+		const auto &list = GetBlockList(option);
+		return list.empty() ? nullptr : &list.front();
 	}
 
 	/**

src/config/Global.cxx

@@ -72,9 +72,9 @@ Check(const ConfigBlock &block)
 
 void config_global_check(void)
 {
-	for (auto i : config_data.blocks)
-		for (const auto *p = i; p != nullptr; p = p->next)
-			Check(*p);
+	for (const auto &list : config_data.blocks)
+		for (const auto &block : list)
+			Check(block);
 }
 
 const char *

src/config/Param.cxx

@@ -25,11 +25,6 @@
 
 #include <stdexcept>
 
-ConfigParam::~ConfigParam()
-{
-	delete next;
-}
-
 AllocatedPath
 ConfigParam::GetPath() const
 {

src/config/Param.hxx

@@ -28,12 +28,6 @@
 class AllocatedPath;
 
 struct ConfigParam {
-	/**
-	 * The next ConfigParam with the same name.  The destructor
-	 * deletes the whole chain.
-	 */
-	ConfigParam *next = nullptr;
-
 	std::string value;
 
 	int line;
@@ -46,11 +40,8 @@ struct ConfigParam {
 	explicit ConfigParam(V &&_value, int _line=-1) noexcept
 		:value(std::forward<V>(_value)), line(_line) {}
 
-	ConfigParam(const ConfigParam &) = delete;
-
-	~ConfigParam();
-
-	ConfigParam &operator=(const ConfigParam &) = delete;
+	ConfigParam(ConfigParam &&) = default;
+	ConfigParam &operator=(ConfigParam &&) = default;
 
 	/**
 	 * Determine if this is a "null" instance, i.e. an empty

src/neighbor/Glue.cxx

@@ -53,17 +53,16 @@ void
 NeighborGlue::Init(const ConfigData &config,
 		   EventLoop &loop, NeighborListener &listener)
 {
-	for (const auto *block = config.GetBlock(ConfigBlockOption::NEIGHBORS);
-	     block != nullptr; block = block->next) {
-		block->SetUsed();
+	for (const auto &block : config.GetBlockList(ConfigBlockOption::NEIGHBORS)) {
+		block.SetUsed();
 
 		try {
 			explorers.emplace_front(CreateNeighborExplorer(loop,
 								       listener,
-								       *block));
+								       block));
 		} catch (...) {
 			std::throw_with_nested(FormatRuntimeError("Line %i: ",
-								  block->line));
+								  block.line));
 		}
 	}
 }

src/output/MultipleOutputs.cxx

@@ -91,13 +91,12 @@ MultipleOutputs::Configure(EventLoop &event_loop,
 			   const ReplayGainConfig &replay_gain_config,
 			   AudioOutputClient &client)
 {
-	for (const auto *param = config.GetBlock(ConfigBlockOption::AUDIO_OUTPUT);
-	     param != nullptr; param = param->next) {
-		param->SetUsed();
+	for (const auto &block : config.GetBlockList(ConfigBlockOption::AUDIO_OUTPUT)) {
+		block.SetUsed();
 		auto *output = LoadOutputControl(event_loop,
 						 replay_gain_config,
 						 mixer_listener,
-						 client, *param);
+						 client, block);
 		if (FindByName(output->GetName()) != nullptr)
 			throw FormatRuntimeError("output devices with identical "
 						 "names: %s", output->GetName());