Modules/Strings/public/Strings.hpp

#pragma once

#include "PoolAllocator.hpp"
#include "StringLogic.hpp"

namespace tp {

	// Static data
	extern ModuleManifest gModuleStrings;

	template<typename tChar> class StringTemplate;

	// Hidden slave class
	template<typename tChar = int1>
	class StringData {
		friend StringTemplate<tChar>;
		typedef StringLogic<tChar> Logic;

	private:
		uint2 mIsConst; // source is non-modifiable
		uint2 mEditedIdx; // editor id
		uint4 mReferenceCount; // number of users of this
		tChar* mBuff; // actual string data

		StringData() {
			mBuff = (tChar*) "*";
			mReferenceCount = 0;
			mIsConst = true;
			mEditedIdx = 0;
		}

		StringData(const tChar* aBuff, bool aIsConst) {
			MODULE_SANITY_CHECK(gModuleStrings)
			DEBUG_ASSERT(aBuff)
			mBuff = (tChar*) aBuff;
			mReferenceCount = 0;
			mIsConst = aIsConst;
			mEditedIdx = 0;
		}

		explicit StringData(const tChar* aBuff) {
			MODULE_SANITY_CHECK(gModuleStrings)
			DEBUG_ASSERT(aBuff)
			auto const len = Logic::calcLength(aBuff);
			resize(len);
			memCopy(mBuff, aBuff, len);
			mReferenceCount = 0;
			mIsConst = false;
			mEditedIdx = 0;
		}

		[[nodiscard]] tChar* getBuffer() {
			return mBuff;
		}

		~StringData() {
			if (!mIsConst) delete[] mBuff;
		}

		void resize(ualni size) {
			DEBUG_ASSERT(mReferenceCount == 1 && !mIsConst)
			delete[] mBuff;
			mBuff = new tChar[size + 1];
			mBuff[size] = Logic::getEndChar();
		}
	};

	template<typename tChar = int1>
	class StringTemplate {
	public:
		typedef StringLogic<tChar> Logic;
		typedef StringData<tChar> Data;
		typedef typename Logic::Index Index;

		enum { STRINGS_POOL_SIZE = 1024, };
		static PoolAlloc<StringData<tChar>, STRINGS_POOL_SIZE>* sStringPool;
		static Data sNullString;

	private:
		Data* mData;

	public: //  Main Interface
		// Creates null string reference
		StringTemplate() {
			mData = &sNullString;
			incReference(mData);
		}

		// References existing string data
		StringTemplate(const StringTemplate& in) {
			mData = in.mData;
			incReference(mData);
		}

		// Creates new string data from raw data pointer.
		// Does not own string buffer - string buffer will not be freed. Initializes as const memory.
		explicit StringTemplate(const tChar* raw) {
			mData = new (sStringPool->allocate(0)) StringData(raw, true);
			incReference(mData);
		}

		// Copies raw data and claims ownership over it
		explicit StringTemplate(tChar* raw) {
			mData = new (sStringPool->allocate(0)) StringData(raw);
			incReference(mData);
		}

		~StringTemplate() {
			decReference(mData);
		}

	private:
		static void incReference(Data* dp) {
			dp->mReferenceCount++;
		}

		void decReference(Data* dp) {
			dp->mReferenceCount--;
			if (!dp->mReferenceCount) {
				sStringPool->deallocate(mData);
				mData->~StringData();
			}
		}

	public: // Access
		// used to read data
		[[nodiscard]] const tChar* read() const {
			return mData->mBuff;
		}

		// used to write data
		// output will be null if in TextEditing mode
		[[nodiscard]] tChar* write() {
			makeModifiable();
			return mData->getBuffer();
		}

		// output will be null if in TextEditing mode
		tChar* resize(uint1 size) {
			if (!mData->getEditor()) mData->resize(size);
			return mData->getBuffer();
		}

	public:
		void makeModifiable() {
			// We have no rights to modify if someone references that memory too
			// So we need to create new copy of StringData
			if (mData->mReferenceCount > 1) {
				mData = new (sStringPool->allocate(0)) StringData(mData->mBuff);
				incReference(mData);
				return;
			}

			// Also if initial raw data was marked as const - create copy of raw data
			// Note - raw data will be lost at this point if no other record of such is stored
			if (mData->mIsConst) {
				mData = new (sStringPool->allocate(0)) StringData(mData->mBuff);
				incReference(mData);
			}
		}

	public: // Syntax sugars
		Index size() const {
			return Logic::calcLength(read());
		}

		void calcLineOffsets(Buffer<Index>& aOut) const {
			Logic::calcLineOffsets(read(), size(), aOut);
		}

		StringTemplate& operator=(const tChar* in) {
			this->~StringTemplate();
			new (this) StringTemplate(in);
			return *this;
		}

		StringTemplate& operator=(const StringTemplate& in) {
			if (&in == this) return *this;
			~StringTemplate();
			new (this) StringTemplate(in);
			return *this;
		}
	};

	template<typename tChar>
	PoolAlloc<StringData<tChar>, StringTemplate<tChar>::STRINGS_POOL_SIZE>* StringTemplate<tChar>::sStringPool;

	template<typename tChar>
	StringData<tChar> StringTemplate<tChar>::sNullString;

	using String = StringTemplate<int1>;
}