Reduce coupling in the unreal side

Source/Integration/AnimQueue.cpp

@@ -1,6 +1,7 @@
 
 #include "AnimQueue.h"
 #include "Common.h"
+#include "StreamBuffer.h"
 #include "UtilityLibrary.h"
 #include "GameFramework/Actor.h"
 #include "Components/MeshComponent.h"
@@ -10,6 +11,127 @@
 #include "Materials/MaterialInstanceDynamic.h"
 #include <iostream>
 
+
+////////////////////////////////////////////////////////////
+//
+// An animation step that doesn't actually store the step,
+// it just contains a pointer to the string.
+//
+////////////////////////////////////////////////////////////
+
+struct FlxAnimationStepView {
+	int64 Hash;
+	std::string_view Body;
+
+	FlxAnimationStepView() : Hash(0), Body("") {}
+	FlxAnimationStepView(int64 h, std::string_view b) : Hash(h), Body(b) {}
+};
+
+////////////////////////////////////////////////////////////
+//
+// FlxAnimationField
+//
+// A single field from an animation step: a variable name, a
+// persistent flag, a type, and value storage.
+// 
+// IMPORTANT: Stores a string_view, not a string, so the lifetime
+// of this field is only as long as the step you're parsing.
+//
+// Boolean values are stored in X as 1 or 0. Double values
+// are stored in X.
+//
+////////////////////////////////////////////////////////////
+
+struct FlxAnimationField {
+	std::string_view Name;
+	bool Persistent;
+	LuaValueType Type;
+	double X, Y, Z;
+	std::string_view S;
+};
+
+////////////////////////////////////////////////////////////
+//
+// FlxAnimationStepDecoder
+//
+// Stream reader for a single animation step. Reads one
+// FlxAnimationField at a time until EOF.
+//
+////////////////////////////////////////////////////////////
+
+class FlxAnimationStepDecoder {
+private:
+	FlxStreamBuffer Decoder;
+
+public:
+	// Initialize from an encoded step body.
+	//
+	FlxAnimationStepDecoder(std::string_view body) : Decoder(body) {}
+
+	// Return true if the parser has reached EOF.
+	//
+	bool AtEOF() { return Decoder.empty(); }
+
+	// Read one field.
+	//
+	FlxAnimationField ReadField();
+
+	// Convert an animation step to a debug string.
+	//
+	static FString DebugString(bool finished, int64 hash, std::string_view body);
+};
+
+////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////
+//
+// FlxAnimQueueDecoder
+//
+// Stream reader for animation queues.  Reads one
+// FlxAnimationStepView at a time until EOF.
+//
+////////////////////////////////////////////////////////////
+
+class FlxAnimQueueDecoder {
+private:
+	FlxStreamBuffer Decoder;
+
+	// Read from the header immediately on
+	// construction.
+	//
+	int SizeLimit;
+	int ActualSize;
+
+public:
+	// Initialize with an encoded animation queue.
+	//
+	FlxAnimQueueDecoder(std::string_view s);
+
+	// Get the size limit of the animation queue.
+	//
+	int GetSizeLimit() const { return SizeLimit; }
+
+	// Get the actual size of the animation queue.
+	//
+	int GetActualSize() const { return ActualSize; }
+
+	// Return true if the parser has reached EOF.
+	//
+	bool AtEOF() { return Decoder.empty(); }
+
+	// Read one animation step.
+	//
+	FlxAnimationStepView ReadStep();
+
+	// Peek at the hash of the next step.
+	//
+	int64 PeekHash();
+
+	// Convert an AnimQueue to an FString.
+	//
+	// static FString DebugString(std::string_view s);
+};
+
 FlxAnimationStep::FlxAnimationStep(int64 hash, std::string_view body) {
 	Finished = false;
 	Hash = hash;