JoltPhysics/Jolt/Core/StreamIn.h

// Jolt Physics Library (https://github.com/jrouwe/JoltPhysics)
// SPDX-FileCopyrightText: 2021 Jorrit Rouwe
// SPDX-License-Identifier: MIT

#pragma once

#include <Jolt/Core/NonCopyable.h>

JPH_NAMESPACE_BEGIN

/// Simple binary input stream
class JPH_EXPORT StreamIn : public NonCopyable
{
public:
	/// Virtual destructor
	virtual				~StreamIn() = default;

	/// Read a string of bytes from the binary stream
	virtual void		ReadBytes(void *outData, size_t inNumBytes) = 0;

	/// Returns true when an attempt has been made to read past the end of the file.
	/// Note that this follows the convention of std::basic_ios::eof which only returns true when an attempt is made to read past the end, not when the read pointer is at the end.
	virtual bool		IsEOF() const = 0;

	/// Returns true if there was an IO failure
	virtual bool		IsFailed() const = 0;

	/// Read a primitive (e.g. float, int, etc.) from the binary stream
	template <class T, std::enable_if_t<std::is_trivially_copyable_v<T>, bool> = true>
	void				Read(T &outT)
	{
		ReadBytes(&outT, sizeof(outT));
	}

	/// Read a vector of primitives from the binary stream
	template <class T, class A, std::enable_if_t<std::is_trivially_copyable_v<T>, bool> = true>
	void				Read(Array<T, A> &outT)
	{
		uint32 len = uint32(outT.size()); // Initialize to previous array size, this is used for validation in the StateRecorder class
		Read(len);
		if (!IsEOF() && !IsFailed())
		{
			outT.resize(len);
			if constexpr (std::is_same_v<T, Vec3> || std::is_same_v<T, DVec3> || std::is_same_v<T, DMat44>)
			{
				// These types have unused components that we don't want to read
				for (typename Array<T, A>::size_type i = 0; i < len; ++i)
					Read(outT[i]);
			}
			else
			{
				// Read all elements at once
				ReadBytes(outT.data(), len * sizeof(T));
			}
		}
		else
			outT.clear();
	}

	/// Read a string from the binary stream (reads the number of characters and then the characters)
	template <class Type, class Traits, class Allocator>
	void				Read(std::basic_string<Type, Traits, Allocator> &outString)
	{
		uint32 len = 0;
		Read(len);
		if (!IsEOF() && !IsFailed())
		{
			outString.resize(len);
			ReadBytes(outString.data(), len * sizeof(Type));
		}
		else
			outString.clear();
	}

	/// Read a vector of primitives from the binary stream using a custom function to read the elements
	template <class T, class A, typename F>
	void				Read(Array<T, A> &outT, const F &inReadElement)
	{
		uint32 len = uint32(outT.size()); // Initialize to previous array size, this is used for validation in the StateRecorder class
		Read(len);
		if (!IsEOF() && !IsFailed())
		{
			outT.resize(len);
			for (typename Array<T, A>::size_type i = 0; i < len; ++i)
				inReadElement(*this, outT[i]);
		}
		else
			outT.clear();
	}

	/// Read a Vec3 (don't read W)
	void				Read(Vec3 &outVec)
	{
		ReadBytes(&outVec, 3 * sizeof(float));
		outVec = Vec3::sFixW(outVec.mValue);
	}

	/// Read a DVec3 (don't read W)
	void				Read(DVec3 &outVec)
	{
		ReadBytes(&outVec, 3 * sizeof(double));
		outVec = DVec3::sFixW(outVec.mValue);
	}

	/// Read a DMat44 (don't read W component of translation)
	void				Read(DMat44 &outVec)
	{
		Vec4 x, y, z;
		Read(x);
		Read(y);
		Read(z);

		DVec3 t;
		Read(t);

		outVec = DMat44(x, y, z, t);
	}
};

JPH_NAMESPACE_END