1 files changed, 138 insertions, 0 deletions
diff --git a/src/Bindings/BlockTypePalette.h b/src/Bindings/BlockTypePalette.h
new file mode 100644
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+++ b/src/Bindings/BlockTypePalette.h
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+#pragma once
+
+#include <utility>
+#include "BlockState.h"
+
+
+
+
+
+/** Holds a palette that maps between block type + state and numbers.
+Used primarily by PalettedBlockArea to map from stringular block representation to numeric,
+and by protocols to map from stringular block representation to protocol-numeric.
+The object itself provides no thread safety, users of this class need to handle locking, if required.
+Note that the palette itself doesn't support erasing;
+to erase, create a new instance and re-add only the wanted items.
+
+Internally, the object uses two synced maps, one for each translation direction.
+
+The palette can be loaded from a string (file). The loader supports either the blocks.json file exported by
+the vanilla server itself (https://wiki.vg/Data_Generators), or a processed text file generated by
+our tool $/Tools/BlockTypePaletteGenerator/, or a hand-written text file describing the upgrade from
+1.12 BlockType + BlockMeta to 1.13 string representations.
+The text file is a TSV (tab-separated values), which basically means the data is generally structured as
+<value1><tab><value2><tab><value3><tab>...<valueN><eol>, where eol is the platform's CR / CRLF / LF lineend.
+The file starts with a single value on the first line, "BlockTypePalette" or "UpgradeBlockTypePalette", which
+is used to detect the file format. The following lines are "headers", simple <key><tab><value><eol> entries
+that contain the metadata about the file. "FileVersion" is a compulsory key, "CommonPrefix" is supported, others
+are ignored.
+The headers are followed by an empty line (that signalizes the end of headers) and then the actual data.
+For regular BlockTypePalette TSV file of version 1, the data is in the format:
+<index><tab><blockTypeName><tab><state1Name><tab><state1Value><tab><state2Name> ... <eol>
+For the UpgradeBlockTypePalette TSV file of version 1, the data is in the format:
+<blockType><tab><blockMeta><tab><blockTypeName><tab><state1Name><tab><state1Value><tab><state2Name> ... <eol>
+If a CommonPrefix header is present, its value is pre-pended to each blockTypeName loaded (thus allowing
+the file to be overall smaller). */
+class BlockTypePalette
+{
+public:
+
+	/** Exception that is thrown if requiesting an index not present in the palette. */
+	class NoSuchIndexException:
+		public std::runtime_error
+	{
+		using Super = std::runtime_error;
+
+	public:
+		NoSuchIndexException(UInt32 aIndex):
+			Super(Printf("No such palette index: %u", aIndex))
+		{
+		}
+	};
+
+
+	/** Exception that is thrown when loading the palette fails hard (bad format). */
+	class LoadFailedException:
+		public std::runtime_error
+	{
+		using Super = std::runtime_error;
+
+	public:
+		LoadFailedException(const AString & aReason):
+			Super(aReason)
+		{
+		}
+	};
+
+
+
+	/** Create a new empty instance. */
+	BlockTypePalette();
+
+	/** Returns the index of the specified block type name and state.
+	If the combination is not found, it is added to the palette and the new index is returned. */
+	UInt32 index(const AString & aBlockTypeName, const BlockState & aBlockState);
+
+	/** Returns the <index, true> of the specified block type name and state, if it exists.
+	If the combination is not found, returns <undefined, false>. */
+	std::pair<UInt32, bool> maybeIndex(const AString & aBlockTypeName, const BlockState & aBlockState) const;
+
+	/** Returns the total number of entries in the palette. */
+	UInt32 count() const;
+
+	/** Returns the blockspec represented by the specified palette index.
+	If the index is not valid, throws a NoSuchIndexException. */
+	const std::pair<AString, BlockState> & entry(UInt32 aIndex) const;
+
+	/** Returns an index-transform map from aFrom to this (this.entry(idx) == aFrom.entry(res[idx])).
+	Entries from aFrom that are not present in this are added.
+	Used when pasting two areas, to transform the src palette to dst palette. */
+	std::map<UInt32, UInt32> createTransformMapAddMissing(const BlockTypePalette & aFrom);
+
+	/** Returns an index-transform map from aFrom to this (this.entry(idx) == aFrom.entry(res[idx])).
+	Entries from aFrom that are not present in this are assigned the fallback index.
+	Used for protocol block type mapping. */
+	std::map<UInt32, UInt32> createTransformMapWithFallback(const BlockTypePalette & aFrom, UInt32 aFallbackIndex) const;
+
+	/** Loads the palette from the string representation.
+	Throws a LoadFailedException if the loading fails hard (bad string format);
+	but still a part of the data may already be loaded at that point.
+	If the string specifies duplicate entries (either to already existing entries, or to itself),
+	the duplicates replace the current values silently (this allows us to chain multiple files as "overrides".
+	Auto-detects the string format (json / tsv, normal / upgrade palette) and calls the appropriate load function. */
+	void loadFromString(const AString & aString);
+
+
+protected:
+
+	/** The mapping from numeric to stringular representation.
+	mNumberToBlock[index] = {"blockTypeName", blockState}. */
+	std::map<UInt32, std::pair<AString, BlockState>> mNumberToBlock;
+
+	/** The mapping from stringular to numeric representation.
+	mStringToNumber["blockTypeName"][blockState] = index. */
+	std::unordered_map<AString, std::map<BlockState, UInt32>> mBlockToNumber;
+
+	/** The maximum index ever used in the maps.
+	Used when adding new entries through the index() call. */
+	UInt32 mMaxIndex;
+
+
+	/** Loads the palette from the JSON representation, https://wiki.vg/Data_Generators
+	Throws a LoadFailedException if the loading fails hard (bad string format);
+	but still a part of the data may already be loaded at that point.
+	See also: loadFromString(). */
+	void loadFromJsonString(const AString & aJsonPalette);
+
+	/** Loads the palette from the regular or upgrade TSV representation.
+	aIsUpgrade specifies whether the format is an upgrade TSV (true) or a regular one (false)
+	Throws a LoadFailedException if the loading fails hard (bad string format);
+	but still a part of the data may already be loaded at that point.
+	See also: loadFromString(). */
+	void loadFromTsv(const AString & aTsvPalette, bool aIsUpgrade);
+
+	/** Adds a mapping between the numeric and stringular representation into both maps,
+	updates the mMaxIndex, if appropriate.
+	Silently overwrites any previous mapping for the ID, if present, but keeps the old string->id mapping. */
+	void addMapping(UInt32 aID, const AString & aBlockTypeName, const BlockState & aBlockState);
+};