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fileIO.h
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fileIO.h
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//
// Copyright 2016 Pixar
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
// names, trademarks, service marks, or product names of the Licensor
// and its affiliates, except as required to comply with Section 4(c) of
// the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the Apache License with the above modification is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the Apache License for the specific
// language governing permissions and limitations under the Apache License.
//
#ifndef PXR_USD_SDF_FILE_IO_H
#define PXR_USD_SDF_FILE_IO_H
#include "pxr/pxr.h"
#include "pxr/usd/ar/ar.h"
#include "pxr/usd/ar/writableAsset.h"
#include "pxr/base/tf/diagnosticLite.h"
#include <algorithm>
#include <cstring>
#include <memory>
#include <ostream>
#include <sstream>
PXR_NAMESPACE_OPEN_SCOPE
class SdfSpec;
// ArWritableAsset implementation that writes to a std::ostream.
class Sdf_StreamWritableAsset
: public ArWritableAsset
{
public:
explicit Sdf_StreamWritableAsset(std::ostream& out)
: _out(out)
{
}
virtual ~Sdf_StreamWritableAsset();
bool Close() override
{
_out.flush();
return true;
}
size_t Write(const void* buffer, size_t count, size_t offset) override
{
// The offset is ignored as we assume this object will only be
// used for sequential writes. This is a performance optimization,
// since calling tellp repeatedly can be expensive.
// if (_out.tellp() != static_cast<ssize_t>(offset)) {
// _out.seekp(offset);
// }
_out.write(static_cast<const char*>(buffer), count);
return count;
}
private:
std::ostream& _out;
};
// Helper class for writing out strings for the text file format.
class Sdf_TextOutput
{
public:
explicit Sdf_TextOutput(std::ostream& out)
: Sdf_TextOutput(std::make_shared<Sdf_StreamWritableAsset>(out))
{ }
explicit Sdf_TextOutput(std::shared_ptr<ArWritableAsset>&& asset)
: _asset(std::move(asset))
, _offset(0)
, _buffer(new char[BUFFER_SIZE])
, _bufferPos(0)
{ }
~Sdf_TextOutput()
{
if (_asset) {
Close();
}
}
Sdf_TextOutput(const Sdf_TextOutput&) = delete;
const Sdf_TextOutput& operator=(const Sdf_TextOutput&) = delete;
// Close the output, flushing contents to destination.
bool Close()
{
if (!_asset) {
return true;
}
const bool ok = _FlushBuffer() && _asset->Close();
_asset.reset();
return ok;
}
// Write given \p str to output.
bool Write(const std::string& str)
{
return _Write(str.c_str(), str.length());
}
// Write NUL-terminated character string \p str to output.
bool Write(const char* str)
{
return _Write(str, strlen(str));
}
private:
bool _Write(const char* str, size_t strLength)
{
// Much of the text format writing code writes small number of
// characters at a time. Buffer writes to batch writes into larger
// chunks.
while (strLength != 0) {
const size_t numAvail = BUFFER_SIZE - _bufferPos;
const size_t numToCopy = std::min(numAvail, strLength);
memcpy(_buffer.get() + _bufferPos, str, numToCopy);
_bufferPos += numToCopy;
str += numToCopy;
strLength -= numToCopy;
if (_bufferPos == BUFFER_SIZE) {
if (!_FlushBuffer()) {
return false;
}
}
}
return true;
}
bool _FlushBuffer()
{
if (_bufferPos == 0) {
return true;
}
const size_t nWritten = _asset->Write(
_buffer.get(), _bufferPos, _offset);
if (nWritten != _bufferPos) {
TF_RUNTIME_ERROR("Failed to write bytes");
return false;
}
_offset += nWritten;
_bufferPos = 0;
return true;
};
std::shared_ptr<ArWritableAsset> _asset;
size_t _offset;
const size_t BUFFER_SIZE = 4096;
std::unique_ptr<char[]> _buffer;
size_t _bufferPos;
};
// Helper class for writing out strings for the text file format
// into a single string.
class Sdf_StringOutput
: public Sdf_TextOutput
{
public:
explicit Sdf_StringOutput()
: Sdf_TextOutput(_str)
{
}
// Closes the output and returns the text output as a string.
std::string GetString()
{
Close();
return _str.str();
}
private:
std::stringstream _str;
};
// Write the provided \a spec to \a out indented \a indent levels.
bool Sdf_WriteToStream(const SdfSpec &spec, std::ostream& out, size_t indent);
PXR_NAMESPACE_CLOSE_SCOPE
#endif