/usr/include/cpprest/containerstream.h is in libcpprest-dev 2.10.2-6.
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* Copyright (C) Microsoft. All rights reserved.
* Licensed under the MIT license. See LICENSE.txt file in the project root for full license information.
*
* =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
*
* This file defines a basic STL-container-based stream buffer. Reading from the buffer will not remove any data
* from it and seeking is thus supported.
*
* For the latest on this and related APIs, please see: https://github.com/Microsoft/cpprestsdk
*
* =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
****/
#pragma once
#include <vector>
#include <queue>
#include <algorithm>
#include <iterator>
#include "pplx/pplxtasks.h"
#include "cpprest/astreambuf.h"
#include "cpprest/streams.h"
namespace Concurrency { namespace streams {
// Forward declarations
template<typename _CollectionType> class container_buffer;
namespace details {
/// <summary>
/// The basic_container_buffer class serves as a memory-based steam buffer that supports writing or reading
/// sequences of characters.
/// The class itself should not be used in application code, it is used by the stream definitions farther down in the header file.
/// </summary>
/// <remarks> When closed, neither writing nor reading is supported any longer. <c>basic_container_buffer</c> does not support simultaneous use of the buffer
/// for reading and writing.</remarks>
template<typename _CollectionType>
class basic_container_buffer : public streams::details::streambuf_state_manager<typename _CollectionType::value_type>
{
public:
typedef typename _CollectionType::value_type _CharType;
typedef typename basic_streambuf<_CharType>::traits traits;
typedef typename basic_streambuf<_CharType>::int_type int_type;
typedef typename basic_streambuf<_CharType>::pos_type pos_type;
typedef typename basic_streambuf<_CharType>::off_type off_type;
/// <summary>
/// Returns the underlying data container
/// </summary>
_CollectionType& collection()
{
return m_data;
}
/// <summary>
/// Destructor
/// </summary>
virtual ~basic_container_buffer()
{
// Invoke the synchronous versions since we need to
// purge the request queue before deleting the buffer
this->_close_read();
this->_close_write();
}
protected:
/// <summary>
/// can_seek is used to determine whether a stream buffer supports seeking.
/// </summary>
virtual bool can_seek() const { return this->is_open(); }
/// <summary>
/// <c>has_size<c/> is used to determine whether a stream buffer supports size().
/// </summary>
virtual bool has_size() const { return this->is_open(); }
/// <summary>
/// Gets the size of the stream, if known. Calls to <c>has_size</c> will determine whether
/// the result of <c>size</c> can be relied on.
/// </summary>
virtual utility::size64_t size() const
{
return utility::size64_t(m_data.size());
}
/// <summary>
/// Get the stream buffer size, if one has been set.
/// </summary>
/// <param name="direction">The direction of buffering (in or out)</param>
/// <remarks>An implementation that does not support buffering will always return '0'.</remarks>
virtual size_t buffer_size(std::ios_base::openmode = std::ios_base::in) const
{
return 0;
}
/// <summary>
/// Sets the stream buffer implementation to buffer or not buffer.
/// </summary>
/// <param name="size">The size to use for internal buffering, 0 if no buffering should be done.</param>
/// <param name="direction">The direction of buffering (in or out)</param>
/// <remarks>An implementation that does not support buffering will silently ignore calls to this function and it will not have any effect on what is returned by subsequent calls to <see cref="::buffer_size method" />.</remarks>
virtual void set_buffer_size(size_t , std::ios_base::openmode = std::ios_base::in)
{
return;
}
/// <summary>
/// For any input stream, <c>in_avail</c> returns the number of characters that are immediately available
/// to be consumed without blocking. May be used in conjunction with <cref="::sbumpc method"/> to read data without
/// incurring the overhead of using tasks.
/// </summary>
virtual size_t in_avail() const
{
// See the comment in seek around the restriction that we do not allow read head to
// seek beyond the current write_end.
_ASSERTE(m_current_position <= m_data.size());
msl::safeint3::SafeInt<size_t> readhead(m_current_position);
msl::safeint3::SafeInt<size_t> writeend(m_data.size());
return (size_t)(writeend - readhead);
}
virtual pplx::task<bool> _sync()
{
return pplx::task_from_result(true);
}
virtual pplx::task<int_type> _putc(_CharType ch)
{
int_type retVal = (this->write(&ch, 1) == 1) ? static_cast<int_type>(ch) : traits::eof();
return pplx::task_from_result<int_type>(retVal);
}
virtual pplx::task<size_t> _putn(const _CharType *ptr, size_t count)
{
return pplx::task_from_result<size_t>(this->write(ptr, count));
}
/// <summary>
/// Allocates a contiguous memory block and returns it.
/// </summary>
/// <param name="count">The number of characters to allocate.</param>
/// <returns>A pointer to a block to write to, null if the stream buffer implementation does not support alloc/commit.</returns>
_CharType* _alloc(size_t count)
{
if (!this->can_write()) return nullptr;
// Allocate space
resize_for_write(m_current_position+count);
// Let the caller copy the data
return (_CharType*)&m_data[m_current_position];
}
/// <summary>
/// Submits a block already allocated by the stream buffer.
/// </summary>
/// <param name="count">The number of characters to be committed.</param>
void _commit(size_t actual )
{
// Update the write position and satisfy any pending reads
update_current_position(m_current_position+actual);
}
/// <summary>
/// Gets a pointer to the next already allocated contiguous block of data.
/// </summary>
/// <param name="ptr">A reference to a pointer variable that will hold the address of the block on success.</param>
/// <param name="count">The number of contiguous characters available at the address in 'ptr.'</param>
/// <returns><c>true</c> if the operation succeeded, <c>false</c> otherwise.</returns>
/// <remarks>
/// A return of false does not necessarily indicate that a subsequent read operation would fail, only that
/// there is no block to return immediately or that the stream buffer does not support the operation.
/// The stream buffer may not de-allocate the block until <see cref="::release method" /> is called.
/// If the end of the stream is reached, the function will return <c>true</c>, a null pointer, and a count of zero;
/// a subsequent read will not succeed.
/// </remarks>
virtual bool acquire(_Out_ _CharType*& ptr, _Out_ size_t& count)
{
ptr = nullptr;
count = 0;
if (!this->can_read()) return false;
count = in_avail();
if (count > 0)
{
ptr = (_CharType*)&m_data[m_current_position];
return true;
}
else
{
// Can only be open for read OR write, not both. If there is no data then
// we have reached the end of the stream so indicate such with true.
return true;
}
}
/// <summary>
/// Releases a block of data acquired using <see cref="::acquire method"/>. This frees the stream buffer to de-allocate the
/// memory, if it so desires. Move the read position ahead by the count.
/// </summary>
/// <param name="ptr">A pointer to the block of data to be released.</param>
/// <param name="count">The number of characters that were read.</param>
virtual void release(_Out_writes_opt_ (count) _CharType *ptr, _In_ size_t count)
{
if (ptr != nullptr)
update_current_position(m_current_position + count);
}
virtual pplx::task<size_t> _getn(_Out_writes_ (count) _CharType *ptr, _In_ size_t count)
{
return pplx::task_from_result(this->read(ptr, count));
}
size_t _sgetn(_Out_writes_ (count) _CharType *ptr, _In_ size_t count)
{
return this->read(ptr, count);
}
virtual size_t _scopy(_Out_writes_ (count) _CharType *ptr, _In_ size_t count)
{
return this->read(ptr, count, false);
}
virtual pplx::task<int_type> _bumpc()
{
return pplx::task_from_result(this->read_byte(true));
}
virtual int_type _sbumpc()
{
return this->read_byte(true);
}
virtual pplx::task<int_type> _getc()
{
return pplx::task_from_result(this->read_byte(false));
}
int_type _sgetc()
{
return this->read_byte(false);
}
virtual pplx::task<int_type> _nextc()
{
this->read_byte(true);
return pplx::task_from_result(this->read_byte(false));
}
virtual pplx::task<int_type> _ungetc()
{
auto pos = seekoff(-1, std::ios_base::cur, std::ios_base::in);
if ( pos == (pos_type)traits::eof())
return pplx::task_from_result(traits::eof());
return this->getc();
}
/// <summary>
/// Gets the current read or write position in the stream.
/// </summary>
/// <param name="direction">The I/O direction to seek (see remarks)</param>
/// <returns>The current position. EOF if the operation fails.</returns>
/// <remarks>Some streams may have separate write and read cursors.
/// For such streams, the direction parameter defines whether to move the read or the write cursor.</remarks>
virtual pos_type getpos(std::ios_base::openmode mode) const
{
if ( ((mode & std::ios_base::in) && !this->can_read()) ||
((mode & std::ios_base::out) && !this->can_write()))
return static_cast<pos_type>(traits::eof());
return static_cast<pos_type>(m_current_position);
}
/// <summary>
/// Seeks to the given position.
/// </summary>
/// <param name="pos">The offset from the beginning of the stream.</param>
/// <param name="direction">The I/O direction to seek (see remarks).</param>
/// <returns>The position. EOF if the operation fails.</returns>
/// <remarks>Some streams may have separate write and read cursors. For such streams, the direction parameter defines whether to move the read or the write cursor.</remarks>
virtual pos_type seekpos(pos_type position, std::ios_base::openmode mode)
{
pos_type beg(0);
// In order to support relative seeking from the end position we need to fix an end position.
// Technically, there is no end for the stream buffer as new writes would just expand the buffer.
// For now, we assume that the current write_end is the end of the buffer. We use this artificial
// end to restrict the read head from seeking beyond what is available.
pos_type end(m_data.size());
if (position >= beg)
{
auto pos = static_cast<size_t>(position);
// Read head
if ((mode & std::ios_base::in) && this->can_read())
{
if (position <= end)
{
// We do not allow reads to seek beyond the end or before the start position.
update_current_position(pos);
return static_cast<pos_type>(m_current_position);
}
}
// Write head
if ((mode & std::ios_base::out) && this->can_write())
{
// Allocate space
resize_for_write(pos);
// Nothing to really copy
// Update write head and satisfy read requests if any
update_current_position(pos);
return static_cast<pos_type>(m_current_position);
}
}
return static_cast<pos_type>(traits::eof());
}
/// <summary>
/// Seeks to a position given by a relative offset.
/// </summary>
/// <param name="offset">The relative position to seek to</param>
/// <param name="way">The starting point (beginning, end, current) for the seek.</param>
/// <param name="mode">The I/O direction to seek (see remarks)</param>
/// <returns>The position. EOF if the operation fails.</returns>
/// <remarks>Some streams may have separate write and read cursors.
/// For such streams, the mode parameter defines whether to move the read or the write cursor.</remarks>
virtual pos_type seekoff(off_type offset, std::ios_base::seekdir way, std::ios_base::openmode mode)
{
pos_type beg = 0;
pos_type cur = static_cast<pos_type>(m_current_position);
pos_type end = static_cast<pos_type>(m_data.size());
switch ( way )
{
case std::ios_base::beg:
return seekpos(beg + offset, mode);
case std::ios_base::cur:
return seekpos(cur + offset, mode);
case std::ios_base::end:
return seekpos(end + offset, mode);
default:
return static_cast<pos_type>(traits::eof());
}
}
private:
template<typename _CollectionType1> friend class streams::container_buffer;
/// <summary>
/// Constructor
/// </summary>
basic_container_buffer(std::ios_base::openmode mode)
: streambuf_state_manager<typename _CollectionType::value_type>(mode),
m_current_position(0)
{
validate_mode(mode);
}
/// <summary>
/// Constructor
/// </summary>
basic_container_buffer(_CollectionType data, std::ios_base::openmode mode)
: streambuf_state_manager<typename _CollectionType::value_type>(mode),
m_data(std::move(data)),
m_current_position((mode & std::ios_base::in) ? 0 : m_data.size())
{
validate_mode(mode);
}
static void validate_mode(std::ios_base::openmode mode)
{
// Disallow simultaneous use of the stream buffer for writing and reading.
if ((mode & std::ios_base::in) && (mode & std::ios_base::out))
throw std::invalid_argument("this combination of modes on container stream not supported");
}
/// <summary>
/// Determine if the request can be satisfied.
/// </summary>
bool can_satisfy(size_t)
{
// We can always satisfy a read, at least partially, unless the
// read position is at the very end of the buffer.
return (in_avail() > 0);
}
/// <summary>
/// Reads a byte from the stream and returns it as int_type.
/// Note: This routine shall only be called if can_satisfy() returned true.
/// </summary>
int_type read_byte(bool advance = true)
{
_CharType value;
auto read_size = this->read(&value, 1, advance);
return read_size == 1 ? static_cast<int_type>(value) : traits::eof();
}
/// <summary>
/// Reads up to count characters into ptr and returns the count of characters copied.
/// The return value (actual characters copied) could be <= count.
/// Note: This routine shall only be called if can_satisfy() returned true.
/// </summary>
size_t read(_Out_writes_ (count) _CharType *ptr, _In_ size_t count, bool advance = true)
{
if (!can_satisfy(count))
return 0;
msl::safeint3::SafeInt<size_t> request_size(count);
msl::safeint3::SafeInt<size_t> read_size = request_size.Min(in_avail());
size_t newPos = m_current_position + read_size;
auto readBegin = std::begin(m_data) + m_current_position;
auto readEnd = std::begin(m_data) + newPos;
#ifdef _WIN32
// Avoid warning C4996: Use checked iterators under SECURE_SCL
std::copy(readBegin, readEnd, stdext::checked_array_iterator<_CharType *>(ptr, count));
#else
std::copy(readBegin, readEnd, ptr);
#endif // _WIN32
if (advance)
{
update_current_position(newPos);
}
return (size_t) read_size;
}
/// <summary>
/// Write count characters from the ptr into the stream buffer
/// </summary>
size_t write(const _CharType *ptr, size_t count)
{
if (!this->can_write() || (count == 0)) return 0;
auto newSize = m_current_position + count;
// Allocate space
resize_for_write(newSize);
// Copy the data
std::copy(ptr, ptr + count, std::begin(m_data) + m_current_position);
// Update write head and satisfy pending reads if any
update_current_position(newSize);
return count;
}
/// <summary>
/// Resize the underlying container to match the new write head
/// </summary>
void resize_for_write(size_t newPos)
{
// Resize the container if required
if (newPos > m_data.size())
{
m_data.resize(newPos);
}
}
/// <summary>
/// Updates the write head to the new position
/// </summary>
void update_current_position(size_t newPos)
{
// The new write head
m_current_position = newPos;
_ASSERTE(m_current_position <= m_data.size());
}
// The actual data store
_CollectionType m_data;
// Read/write head
size_t m_current_position;
};
} // namespace details
/// <summary>
/// The basic_container_buffer class serves as a memory-based steam buffer that supports writing or reading
/// sequences of characters. Note that it cannot be used as a consumer producer buffer.
/// </summary>
/// <typeparam name="_CollectionType">
/// The type of the container.
/// </typeparam>
/// <remarks>
/// This is a reference-counted version of <c>basic_container_buffer</c>.
/// </remarks>
template<typename _CollectionType>
class container_buffer : public streambuf<typename _CollectionType::value_type>
{
public:
typedef typename _CollectionType::value_type char_type;
/// <summary>
/// Creates a container_buffer given a collection, copying its data into the buffer.
/// </summary>
/// <param name="data">The collection that is the starting point for the buffer</param>
/// <param name="mode">The I/O mode that the buffer should use (in / out)</param>
container_buffer(_CollectionType data, std::ios_base::openmode mode = std::ios_base::in)
: streambuf<typename _CollectionType::value_type>(
std::shared_ptr<details::basic_container_buffer<_CollectionType>>(new streams::details::basic_container_buffer<_CollectionType>(std::move(data), mode)))
{
}
/// <summary>
/// Creates a container_buffer starting from an empty collection.
/// </summary>
/// <param name="mode">The I/O mode that the buffer should use (in / out)</param>
container_buffer(std::ios_base::openmode mode = std::ios_base::out)
: streambuf<typename _CollectionType::value_type>(
std::shared_ptr<details::basic_container_buffer<_CollectionType>>(new details::basic_container_buffer<_CollectionType>(mode)))
{
}
_CollectionType& collection() const
{
auto listBuf = static_cast<details::basic_container_buffer<_CollectionType> *>(this->get_base().get());
return listBuf->collection();
}
};
/// <summary>
/// A static class to allow users to create input and out streams based off STL
/// collections. The sole purpose of this class to avoid users from having to know
/// anything about stream buffers.
/// </summary>
/// <typeparam name="_CollectionType">The type of the STL collection.</typeparam>
template<typename _CollectionType>
class container_stream
{
public:
typedef typename _CollectionType::value_type char_type;
typedef container_buffer<_CollectionType> buffer_type;
/// <summary>
/// Creates an input stream given an STL container.
/// </summary>
/// </param name="data">STL container to back the input stream.</param>
/// <returns>An input stream.</returns>
static concurrency::streams::basic_istream<char_type> open_istream(_CollectionType data)
{
return concurrency::streams::basic_istream<char_type>(buffer_type(std::move(data), std::ios_base::in));
}
/// <summary>
/// Creates an output stream using an STL container as the storage.
/// </summary>
/// <returns>An output stream.</returns>
static concurrency::streams::basic_ostream<char_type> open_ostream()
{
return concurrency::streams::basic_ostream<char_type>(buffer_type(std::ios_base::out));
}
};
/// <summary>
/// The stringstream allows an input stream to be constructed from std::string or std::wstring
/// For output streams the underlying string container could be retrieved using <c>buf->collection().</c>
/// </summary>
typedef container_stream<std::basic_string<char>> stringstream;
typedef stringstream::buffer_type stringstreambuf;
typedef container_stream<utility::string_t> wstringstream;
typedef wstringstream::buffer_type wstringstreambuf;
/// <summary>
/// The <c>bytestream</c> is a static class that allows an input stream to be constructed from any STL container.
/// </summary>
class bytestream
{
public:
/// <summary>
/// Creates a single byte character input stream given an STL container.
/// </summary>
/// <typeparam name="_CollectionType">The type of the STL collection.</typeparam>
/// <param name="data">STL container to back the input stream.</param>
/// <returns>An single byte character input stream.</returns>
template<typename _CollectionType>
static concurrency::streams::istream open_istream(_CollectionType data)
{
return concurrency::streams::istream(streams::container_buffer<_CollectionType>(std::move(data), std::ios_base::in));
}
/// <summary>
/// Creates a single byte character output stream using an STL container as storage.
/// </summary>
/// <typeparam name="_CollectionType">The type of the STL collection.</typeparam>
/// <returns>A single byte character output stream.</returns>
template<typename _CollectionType>
static concurrency::streams::ostream open_ostream()
{
return concurrency::streams::ostream(streams::container_buffer<_CollectionType>());
}
};
}} // namespaces
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