1 files changed, 216 insertions, 0 deletions

diff --git a/src/Bindings/BlockTypeRegistry.h b/src/Bindings/BlockTypeRegistry.h
new file mode 100644
index 000000000..3a85ee510
--- /dev/null
+++ b/src/Bindings/BlockTypeRegistry.h
@@ -0,0 +1,216 @@
+#pragma once
+
+
+
+
+
+#include <map>
+#include <functional>
+
+
+
+
+
+// fwd:
+class cBlockHandler;
+class BlockState;
+
+
+
+
+
+/** Complete information about a single block type.
+The BlockTypeRegistry uses this structure to store the registered information. */
+class BlockInfo
+{
+public:
+
+	/** Callback is used to query block hints dynamically, based on the current BlockState.
+	Useful for example for redstone lamps that can be turned on or off. */
+	using HintCallback = std::function<AString(const AString & aTypeName, const BlockState & aBlockState)>;
+
+
+	/** Creates a new instance with the specified BlockTypeName and handler / hints / callbacks.
+	aPluginName specifies the name of the plugin to associate with the block type (to allow unload / reload). */
+	BlockInfo(
+		const AString & aPluginName,
+		const AString & aBlockTypeName,
+		std::shared_ptr<cBlockHandler> aHandler,
+		const std::map<AString, AString> & aHints = std::map<AString, AString>(),
+		const std::map<AString, HintCallback> & aHintCallbacks = std::map<AString, HintCallback>()
+	);
+
+
+	/** Retrieves the value associated with the specified hint for this specific BlockTypeName and BlockState.
+	Queries hint callbacks first, then static hints if a callback doesn't exist.
+	Returns an empty string if hint not found at all. */
+	AString hintValue(
+		const AString & aHintName,
+		const BlockState & aBlockState
+	);
+
+	// Simple getters:
+	const AString & pluginName() const { return m_PluginName; }
+	const AString & blockTypeName() const { return m_BlockTypeName; }
+	std::shared_ptr<cBlockHandler> handler() const { return m_Handler; }
+
+	/** Sets (creates or updates) a static hint.
+	Hints provided by callbacks are unaffected by this - callbacks are "higher priority", they overwrite anything set here.
+	Logs an info message if the hint is already provided by a hint callback. */
+	void setHint(const AString & aHintKey, const AString & aHintValue);
+
+	/** Removes a hint.
+	Silently ignored if the hint hasn't been previously set. */
+	void removeHint(const AString & aHintKey);
+
+
+private:
+
+	/** The name of the plugin that registered the block. */
+	AString m_PluginName;
+
+	/** The name of the block type, such as "minecraft:redstone_lamp" */
+	AString m_BlockTypeName;
+
+	/** The callbacks to call for various interaction. */
+	std::shared_ptr<cBlockHandler> m_Handler;
+
+	/** Optional static hints for any subsystem to use, such as "IsSnowable" -> "1".
+	Hint callbacks are of higher priority than m_Hints - if a hint is provided by a m_HintCallback, its value in m_Hints is ignored. */
+	std::map<AString, AString> m_Hints;
+
+	/** The callbacks for dynamic evaluation of hints, such as "LightValue" -> function(BlockTypeName, BlockState).
+	Hint callbacks are of higher priority than m_Hints - if a hint is provided by a m_HintCallback, its value in m_Hints is ignored. */
+	std::map<AString, HintCallback> m_HintCallbacks;
+};
+
+
+
+
+
+/** Stores information on all known block types.
+Can dynamically add and remove block types.
+Block types are identified using BlockTypeName.
+Supports unregistering and re-registering the same type by the same plugin.
+Stores the name of the plugin that registered the type, for better plugin error messages ("already registered in X")
+and so that we can unload and reload plugins. */
+class BlockTypeRegistry
+{
+public:
+	// fwd:
+	class AlreadyRegisteredException;
+	class NotRegisteredException;
+
+
+	/** Creates an empty new instance of the block type registry */
+	BlockTypeRegistry() = default;
+
+	/** Registers the specified block type.
+	If the block type already exists and the plugin is the same, updates the registration.
+	If the block type already exists and the plugin is different, throws an AlreadyRegisteredException. */
+	void registerBlockType(
+		const AString & aPluginName,
+		const AString & aBlockTypeName,
+		std::shared_ptr<cBlockHandler> aHandler,
+		const std::map<AString, AString> & aHints = std::map<AString, AString>(),
+		const std::map<AString, BlockInfo::HintCallback> & aHintCallbacks = std::map<AString, BlockInfo::HintCallback>()
+	);
+
+	/** Returns the registration information for the specified BlockTypeName.
+	Returns nullptr if BlockTypeName not found. */
+	std::shared_ptr<BlockInfo> blockInfo(const AString & aBlockTypeName);
+
+	/** Removes all registrations done by the specified plugin. */
+	void removeAllByPlugin(const AString & aPluginName);
+
+	/** Sets (adds or overwrites) a single Hint value for a BlockType.
+	Throws NotRegisteredException if the BlockTypeName is not registered. */
+	void setBlockTypeHint(
+		const AString & aBlockTypeName,
+		const AString & aHintKey,
+		const AString & aHintValue
+	);
+
+	/** Removes a previously registered single Hint value for a BlockType.
+	Throws NotRegisteredException if the BlockTypeName is not registered.
+	Silently ignored if the Hint hasn't been previously set. */
+	void removeBlockTypeHint(
+		const AString & aBlockTypeName,
+		const AString & aHintKey
+	);
+
+
+private:
+
+	/** The actual block type registry.
+	Maps the BlockTypeName to the BlockInfo instance. */
+	std::map<AString, std::shared_ptr<BlockInfo>> m_Registry;
+
+	/** The CS that protects m_Registry against multithreaded access. */
+	cCriticalSection m_CSRegistry;
+};
+
+
+
+
+
+/** The exception thrown from BlockTypeRegistry::registerBlockType() if the same block type is being registered from a different plugin. */
+class BlockTypeRegistry::AlreadyRegisteredException: public std::runtime_error
+{
+	using Super = std::runtime_error;
+
+public:
+
+	/** Creates a new instance of the exception that provides info on both the original registration and the newly attempted
+	registration that caused the failure. */
+	AlreadyRegisteredException(
+		const std::shared_ptr<BlockInfo> & aPreviousRegistration,
+		const std::shared_ptr<BlockInfo> & aNewRegistration
+	);
+
+	// Simple getters:
+	std::shared_ptr<BlockInfo> previousRegistration() const { return m_PreviousRegistration; }
+	std::shared_ptr<BlockInfo> newRegistration()      const { return m_NewRegistration; }
+
+
+private:
+
+	std::shared_ptr<BlockInfo> m_PreviousRegistration;
+	std::shared_ptr<BlockInfo> m_NewRegistration;
+
+
+	/** Returns the general exception message formatted by the two registrations.
+	The output is used when logging. */
+	static AString message(
+		const std::shared_ptr<BlockInfo> & aPreviousRegistration,
+		const std::shared_ptr<BlockInfo> & aNewRegistration
+	);
+};
+
+
+
+
+
+/** The exception thrown from BlockTypeRegistry::setBlockTypeHint() if the block type has not been registered before. */
+class BlockTypeRegistry::NotRegisteredException: public std::runtime_error
+{
+	using Super = std::runtime_error;
+
+public:
+
+	/** Creates a new instance of the exception that provides info on both the original registration and the newly attempted
+	registration that caused the failure. */
+	NotRegisteredException(
+		const AString & aBlockTypeName,
+		const AString & aHintKey,
+		const AString & aHintValue
+	);
+
+	// Simple getters:
+	const AString & blockTypeName() const { return m_BlockTypeName; }
+
+
+private:
+
+	const AString m_BlockTypeName;
+};