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/*
* ChunkReader.h
* -------------
* Purpose: An extended FileReader to read Iff-like chunk-based file structures.
* Notes : (currently none)
* Authors: OpenMPT Devs
* The OpenMPT source code is released under the BSD license. Read LICENSE for more details.
*/
#pragma once
#include "BuildSettings.h"
#include "../common/FileReader.h"
#include <vector>
OPENMPT_NAMESPACE_BEGIN
class ChunkReader : public FileReader
{
public:
template <typename Tbyte> ChunkReader(mpt::span<Tbyte> bytedata) : FileReader(bytedata) { }
ChunkReader(const FileReader &other) : FileReader(other) { }
ChunkReader(FileReader &&other) : FileReader(std::move(other)) { }
template<typename T>
class Item
{
private:
T chunkHeader;
FileReader chunkData;
public:
Item(const T &header, FileReader &&data) : chunkHeader(header), chunkData(std::move(data)) { }
Item(const Item<T> &) = default;
Item(Item<T> &&) noexcept = default;
const T &GetHeader() const { return chunkHeader; }
const FileReader &GetData() const { return chunkData; }
};
template<typename T>
class ChunkList : public std::vector<Item<T>>
{
public:
typedef decltype(T().GetID()) id_type;
// Check if the list contains a given chunk.
bool ChunkExists(id_type id) const
{
return std::find_if(this->cbegin(), this->cend(), [&id](const Item<T> &item) { return item.GetHeader().GetID() == id; }) != this->cend();
}
// Retrieve the first chunk with a given ID.
FileReader GetChunk(id_type id) const
{
auto item = std::find_if(this->cbegin(), this->cend(), [&id](const Item<T> &item) { return item.GetHeader().GetID() == id; });
if(item != this->cend())
return item->GetData();
return FileReader();
}
// Retrieve all chunks with a given ID.
std::vector<FileReader> GetAllChunks(id_type id) const
{
std::vector<FileReader> result;
for(const auto &item : *this)
{
if(item.GetHeader().GetID() == id)
{
result.push_back(item.GetData());
}
}
return result;
}
};
// Read a single "T" chunk.
// T is required to have the methods GetID() and GetLength().
// GetLength() must return the chunk size in bytes, and GetID() the chunk ID.
template<typename T>
Item<T> GetNextChunk(off_t padding)
{
T chunkHeader;
off_t dataSize = 0;
if(Read(chunkHeader))
{
dataSize = chunkHeader.GetLength();
}
Item<T> resultItem(chunkHeader, ReadChunk(dataSize));
// Skip padding bytes
if(padding != 0 && dataSize % padding != 0)
{
Skip(padding - (dataSize % padding));
}
return resultItem;
}
// Read a series of "T" chunks until the end of file is reached.
// T is required to have the methods GetID() and GetLength().
// GetLength() must return the chunk size in bytes, and GetID() the chunk ID.
template<typename T>
ChunkList<T> ReadChunks(off_t padding)
{
ChunkList<T> result;
while(CanRead(sizeof(T)))
{
result.push_back(GetNextChunk<T>(padding));
}
return result;
}
// Read a series of "T" chunks until a given chunk ID is found.
// T is required to have the methods GetID() and GetLength().
// GetLength() must return the chunk size in bytes, and GetID() the chunk ID.
template<typename T>
ChunkList<T> ReadChunksUntil(off_t padding, decltype(T().GetID()) stopAtID)
{
ChunkList<T> result;
while(CanRead(sizeof(T)))
{
result.push_back(GetNextChunk<T>(padding));
if(result.back().GetHeader().GetID() == stopAtID)
{
break;
}
}
return result;
}
};
OPENMPT_NAMESPACE_END
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