/***

* Copyright (C) Microsoft. All rights reserved.

* Licensed under the MIT license. See LICENSE.txt file in the project root for full license information.

*

* =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+

*

* Asynchronous I/O: stream buffer. This is an extension to the PPL concurrency features and therefore

* lives in the Concurrency namespace.

*

* For the latest on this and related APIs, please see: https://github.com/Microsoft/cpprestsdk

*

* =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

****/

#pragma once

#include <ios>

#include <memory>

#include <cstring>

#include <math.h>

#include "pplx/pplxtasks.h"

#include "cpprest/details/basic_types.h"

#include "cpprest/asyncrt_utils.h"

namespace Concurrency

{

namespace details

{

template<class F, class T = bool>

pplx::task<T> _do_while(F func)

{

pplx::task<T> first = func();

return first.then([=](bool guard) -> pplx::task<T> {

if (guard)

return Concurrency::details::_do_while<F,T>(func);

else

return first;

});

}

}

/// Library for asynchronous streams.

namespace streams

{

/// <summary>

/// Extending the standard char_traits type with one that adds values and types

/// that are unique to "C++ REST SDK" streams.

/// </summary>

/// <typeparam name="_CharType">

/// The data type of the basic element of the stream.

/// </typeparam>

template<typename _CharType>

struct char_traits : std::char_traits<_CharType>

{

/// <summary>

/// Some synchronous functions will return this value if the operation

/// requires an asynchronous call in a given situation.

/// </summary>

/// <returns>An <c>int_type</c> value which implies that an asynchronous call is required.</returns>

static typename std::char_traits<_CharType>::int_type requires_async() { return std::char_traits<_CharType>::eof()-1; }

};

#if !defined(_WIN32)

template<>

struct char_traits<unsigned char> : private std::char_traits<char>

{

public:

typedef unsigned char char_type;

using std::char_traits<char>::eof;

using std::char_traits<char>::int_type;

using std::char_traits<char>::off_type;

using std::char_traits<char>::pos_type;

static size_t length(const unsigned char* str)

{

return std::char_traits<char>::length(reinterpret_cast<const char*>(str));

}

static void assign(unsigned char& left, const unsigned char& right) { left = right; }

static unsigned char* assign(unsigned char* left, size_t n, unsigned char value)

{

return reinterpret_cast<unsigned char*>(std::char_traits<char>::assign(reinterpret_cast<char*>(left), n, static_cast<char>(value)));

}

static unsigned char* copy(unsigned char* left, const unsigned char* right, size_t n)

{

return reinterpret_cast<unsigned char*>(std::char_traits<char>::copy(reinterpret_cast<char*>(left), reinterpret_cast<const char*>(right), n));

}

static unsigned char* move(unsigned char* left, const unsigned char* right, size_t n)

{

return reinterpret_cast<unsigned char*>(std::char_traits<char>::move(reinterpret_cast<char*>(left), reinterpret_cast<const char*>(right), n));

}

static int_type requires_async() { return eof() - 1; }

};

#endif

namespace details {

/// <summary>

/// Stream buffer base class.

/// </summary>

template<typename _CharType>

class basic_streambuf

{

public:

typedef _CharType char_type;

typedef ::concurrency::streams::char_traits<_CharType> traits;

typedef typename traits::int_type int_type;

typedef typename traits::pos_type pos_type;

typedef typename traits::off_type off_type;

/// <summary>

/// Virtual constructor for stream buffers.

/// </summary>

virtual ~basic_streambuf() { }

/// <summary>

/// <c>can_read</c> is used to determine whether a stream buffer will support read operations (get).

/// </summary>

virtual bool can_read() const = 0;

/// <summary>

/// <c>can_write</c> is used to determine whether a stream buffer will support write operations (put).

/// </summary>

virtual bool can_write() const = 0;

/// <summary>

/// <c>can_seek<c/> is used to determine whether a stream buffer supports seeking.

/// </summary>

virtual bool can_seek() const = 0;

/// <summary>

/// <c>has_size<c/> is used to determine whether a stream buffer supports size().

/// </summary>

virtual bool has_size() const = 0;

/// <summary>

/// <c>is_eof</c> is used to determine whether a read head has reached the end of the buffer.

/// </summary>

virtual bool is_eof() const = 0;

/// <summary>

/// Gets the stream buffer size, if one has been set.

/// </summary>

/// <param name="direction">The direction of buffering (in or out)</param>

/// <returns>The size of the internal buffer (for the given direction).</returns>

/// <remarks>An implementation that does not support buffering will always return 0.</remarks>

virtual size_t buffer_size(std::ios_base::openmode direction = std::ios_base::in) const = 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 size, std::ios_base::openmode direction = std::ios_base::in) = 0;

/// <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 = 0;

/// <summary>

/// Checks if the stream buffer is open.

/// </summary>

/// <remarks>No separation is made between open for reading and open for writing.</remarks>

virtual bool is_open() const = 0;

/// <summary>

/// Closes the stream buffer, preventing further read or write operations.

/// </summary>

/// <param name="mode">The I/O mode (in or out) to close for.</param>

virtual pplx::task<void> close(std::ios_base::openmode mode = (std::ios_base::in | std::ios_base::out)) = 0;

/// <summary>

/// Closes the stream buffer with an exception.

/// </summary>

/// <param name="mode">The I/O mode (in or out) to close for.</param>

/// <param name="eptr">Pointer to the exception.</param>

virtual pplx::task<void> close(std::ios_base::openmode mode, std::exception_ptr eptr) = 0;

/// <summary>

/// Writes a single character to the stream.

/// </summary>

/// <param name="ch">The character to write</param>

/// <returns>A <c>task</c> that holds the value of the character. This value is EOF if the write operation fails.</returns>

virtual pplx::task<int_type> putc(_CharType ch) = 0;

/// <summary>

/// Writes a number of characters to the stream.

/// </summary>

/// <param name="ptr">A pointer to the block of data to be written.</param>

/// <param name="count">The number of characters to write.</param>

/// <returns>A <c>task</c> that holds the number of characters actually written, either 'count' or 0.</returns>

virtual pplx::task<size_t> putn(const _CharType *ptr, size_t count) = 0;

/// <summary>

/// Writes a number of characters to the stream. Note: callers must make sure the data to be written is valid until

/// the returned task completes.

/// </summary>

/// <param name="ptr">A pointer to the block of data to be written.</param>

/// <param name="count">The number of characters to write.</param>

/// <returns>A <c>task</c> that holds the number of characters actually written, either 'count' or 0.</returns>

virtual pplx::task<size_t> putn_nocopy(const _CharType *ptr, size_t count) = 0;

/// <summary>

/// Reads a single character from the stream and advances the read position.

/// </summary>

/// <returns>A <c>task</c> that holds the value of the character. This value is EOF if the read fails.</returns>

virtual pplx::task<int_type> bumpc() = 0;

/// <summary>

/// Reads a single character from the stream and advances the read position.

/// </summary>

/// <returns>The value of the character. <c>-1</c> if the read fails. <c>-2</c> if an asynchronous read is required</returns>

/// <remarks>This is a synchronous operation, but is guaranteed to never block.</remarks>

virtual int_type sbumpc() = 0;

/// <summary>

/// Reads a single character from the stream without advancing the read position.

/// </summary>

/// <returns>A <c>task</c> that holds the value of the byte. This value is EOF if the read fails.</returns>

virtual pplx::task<int_type> getc() = 0;

/// <summary>

/// Reads a single character from the stream without advancing the read position.

/// </summary>

/// <returns>The value of the character. EOF if the read fails. <see cref="::requires_async method" /> if an asynchronous read is required</returns>

/// <remarks>This is a synchronous operation, but is guaranteed to never block.</remarks>

virtual int_type sgetc() = 0;

/// <summary>

/// Advances the read position, then returns the next character without advancing again.

/// </summary>

/// <returns>A <c>task</c> that holds the value of the character. This value is EOF if the read fails.</returns>

virtual pplx::task<int_type> nextc() = 0;

/// <summary>

/// Retreats the read position, then returns the current character without advancing.

/// </summary>

/// <returns>A <c>task</c> that holds the value of the character. This value is EOF if the read fails, <c>requires_async</c> if an asynchronous read is required</returns>

virtual pplx::task<int_type> ungetc() = 0;

/// <summary>

/// Reads up to a given number of characters from the stream.

/// </summary>

/// <param name="ptr">The address of the target memory area.</param>

/// <param name="count">The maximum number of characters to read.</param>

/// <returns>A <c>task</c> that holds the number of characters read. This value is O if the end of the stream is reached.</returns>

virtual pplx::task<size_t> getn(_Out_writes_(count) _CharType *ptr, _In_ size_t count) = 0;

/// <summary>

/// Copies up to a given number of characters from the stream, synchronously.

/// </summary>

/// <param name="ptr">The address of the target memory area.</param>

/// <param name="count">The maximum number of characters to read.</param>

/// <returns>The number of characters copied. O if the end of the stream is reached or an asynchronous read is required.</returns>

/// <remarks>This is a synchronous operation, but is guaranteed to never block.</remarks>

virtual size_t scopy(_Out_writes_(count) _CharType *ptr, _In_ size_t count) = 0;

/// <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 direction) const = 0;

/// <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 = 0;

/// <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 pos, std::ios_base::openmode direction) = 0;

/// <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) = 0;

/// <summary>

/// For output streams, flush any internally buffered data to the underlying medium.

/// </summary>

/// <returns>A <c>task</c> that returns <c>true</c> if the sync succeeds, <c>false</c> if not.</returns>

virtual pplx::task<void> sync() = 0;

//

// Efficient read and write.

//

// The following routines are intended to be used for more efficient, copy-free, reading and

// writing of data from/to the stream. Rather than having the caller provide a buffer into which

// data is written or from which it is read, the stream buffer provides a pointer directly to the

// internal data blocks that it is using. Since not all stream buffers use internal data structures

// to copy data, the functions may not be supported by all. An application that wishes to use this

// functionality should therefore first try them and check for failure to support. If there is

// such failure, the application should fall back on the copying interfaces (putn / getn)

//

/// <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>

virtual _CharType* alloc(_In_ size_t count) = 0;

/// <summary>

/// Submits a block already allocated by the stream buffer.

/// </summary>

/// <param name="count">The number of characters to be committed.</param>

virtual void commit(_In_ size_t count) = 0;

/// <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) = 0;

/// <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_(count) _CharType *ptr, _In_ size_t count) = 0;

/// <summary>

/// Retrieves the stream buffer exception_ptr if it has been set.

/// </summary>

/// <returns>Pointer to the exception, if it has been set; otherwise, <c>nullptr</c> will be returned</returns>

virtual std::exception_ptr exception() const = 0;

};

template<typename _CharType>

class streambuf_state_manager : public basic_streambuf<_CharType>, public std::enable_shared_from_this<streambuf_state_manager<_CharType>>

{

public:

typedef typename details::basic_streambuf<_CharType>::traits traits;

typedef typename details::basic_streambuf<_CharType>::int_type int_type;

typedef typename details::basic_streambuf<_CharType>::pos_type pos_type;

typedef typename details::basic_streambuf<_CharType>::off_type off_type;

/// <summary>

/// <c>can_read</c> is used to determine whether a stream buffer will support read operations (get).

/// </summary>

virtual bool can_read() const

{

return m_stream_can_read;

}

/// <summary>

/// <c>can_write</c> is used to determine whether a stream buffer will support write operations (put).

/// </summary>

virtual bool can_write() const

{

return m_stream_can_write;

}

/// <summary>

/// Checks if the stream buffer is open.

/// </summary>

/// <remarks>No separation is made between open for reading and open for writing.</remarks>

virtual bool is_open() const

{

return can_read() || can_write();

}

/// <summary>

/// Closes the stream buffer, preventing further read or write operations.

/// </summary>

/// <param name="mode">The I/O mode (in or out) to close for.</param>

virtual pplx::task<void> close(std::ios_base::openmode mode = std::ios_base::in | std::ios_base::out)

{

pplx::task<void> closeOp = pplx::task_from_result();

if (mode & std::ios_base::in && can_read()) {

closeOp = _close_read();

}

// After the flush_internal task completed, "this" object may have been destroyed,

// accessing the members is invalid, use shared_from_this to avoid access violation exception.

auto this_ptr = std::static_pointer_cast<streambuf_state_manager>(this->shared_from_this());

if (mode & std::ios_base::out && can_write()) {

if (closeOp.is_done())

closeOp = closeOp && _close_write().then([this_ptr]{}); // passing down exceptions from closeOp

else

closeOp = closeOp.then([this_ptr] { return this_ptr->_close_write().then([this_ptr]{}); });

}

return closeOp;

}

/// <summary>

/// Closes the stream buffer with an exception.

/// </summary>

/// <param name="mode">The I/O mode (in or out) to close for.</param>

/// <param name="eptr">Pointer to the exception.</param>

virtual pplx::task<void> close(std::ios_base::openmode mode, std::exception_ptr eptr)

{

if (m_currentException == nullptr)

m_currentException = eptr;

return close(mode);

}

/// <summary>

/// <c>is_eof</c> is used to determine whether a read head has reached the end of the buffer.

/// </summary>

virtual bool is_eof() const

{

return m_stream_read_eof;

}

/// <summary>

/// Writes a single character to the stream.

/// </summary>

/// <param name="ch">The character to write</param>

/// <returns>The value of the character. EOF if the write operation fails</returns>

virtual pplx::task<int_type> putc(_CharType ch)

{

if (!can_write())

return create_exception_checked_value_task<int_type>(traits::eof());

return create_exception_checked_task<int_type>(_putc(ch), [](int_type) {

return false; // no EOF for write

});

}

/// <summary>

/// Writes a number of characters to the stream.

/// </summary>

/// <param name="ptr">A pointer to the block of data to be written.</param>

/// <param name="count">The number of characters to write.</param>

/// <returns>The number of characters actually written, either 'count' or 0.</returns>

CASABLANCA_DEPRECATED("This API in some cases performs a copy. It is deprecated and will be removed in a future release. Use putn_nocopy instead.")

virtual pplx::task<size_t> putn(const _CharType *ptr, size_t count)

{

if (!can_write())

return create_exception_checked_value_task<size_t>(0);

if (count == 0)

return pplx::task_from_result<size_t>(0);

return create_exception_checked_task<size_t>(_putn(ptr, count, true), [](size_t) {

return false; // no EOF for write

});

}

/// <summary>

/// Writes a number of characters to the stream. Note: callers must make sure the data to be written is valid until

/// the returned task completes.

/// </summary>

/// <param name="ptr">A pointer to the block of data to be written.</param>

/// <param name="count">The number of characters to write.</param>

/// <returns>A <c>task</c> that holds the number of characters actually written, either 'count' or 0.</returns>

virtual pplx::task<size_t> putn_nocopy(const _CharType *ptr, size_t count)

{

if (!can_write())

return create_exception_checked_value_task<size_t>(0);

if (count == 0)

return pplx::task_from_result<size_t>(0);

return create_exception_checked_task<size_t>(_putn(ptr, count), [](size_t) {

return false; // no EOF for write

});

}

/// <summary>

/// Reads a single character from the stream and advances the read position.

/// </summary>

/// <returns>The value of the character. EOF if the read fails.</returns>

virtual pplx::task<int_type> bumpc()

{

if (!can_read())

return create_exception_checked_value_task<int_type>(streambuf_state_manager<_CharType>::traits::eof());

return create_exception_checked_task<int_type>(_bumpc(), [](int_type val) {

return val == streambuf_state_manager<_CharType>::traits::eof();

});

}

/// <summary>

/// Reads a single character from the stream and advances the read position.

/// </summary>

/// <returns>The value of the character. <c>-1</c> if the read fails. <c>-2</c> if an asynchronous read is required</returns>

/// <remarks>This is a synchronous operation, but is guaranteed to never block.</remarks>

virtual int_type sbumpc()

{

if ( !(m_currentException == nullptr) )

std::rethrow_exception(m_currentException);

if (!can_read())

return traits::eof();

return check_sync_read_eof(_sbumpc());

}

/// <summary>

/// Reads a single character from the stream without advancing the read position.

/// </summary>

/// <returns>The value of the byte. EOF if the read fails.</returns>

virtual pplx::task<int_type> getc()

{

if (!can_read())

return create_exception_checked_value_task<int_type>(traits::eof());

return create_exception_checked_task<int_type>(_getc(), [](int_type val) {

return val == streambuf_state_manager<_CharType>::traits::eof();

});

}

/// <summary>

/// Reads a single character from the stream without advancing the read position.

/// </summary>

/// <returns>The value of the character. EOF if the read fails. <see cref="::requires_async method" /> if an asynchronous read is required</returns>

/// <remarks>This is a synchronous operation, but is guaranteed to never block.</remarks>

virtual int_type sgetc()

{

if ( !(m_currentException == nullptr) )

std::rethrow_exception(m_currentException);

if (!can_read())

return traits::eof();

return check_sync_read_eof(_sgetc());

}

/// <summary>

/// Advances the read position, then returns the next character without advancing again.

/// </summary>

/// <returns>The value of the character. EOF if the read fails.</returns>

virtual pplx::task<int_type> nextc()

{

if (!can_read())

return create_exception_checked_value_task<int_type>(traits::eof());

return create_exception_checked_task<int_type>(_nextc(), [](int_type val) {

return val == streambuf_state_manager<_CharType>::traits::eof();

});

}

/// <summary>

/// Retreats the read position, then returns the current character without advancing.

/// </summary>

/// <returns>The value of the character. EOF if the read fails. <see cref="::requires_async method" /> if an asynchronous read is required</returns>

virtual pplx::task<int_type> ungetc()

{

if (!can_read())

return create_exception_checked_value_task<int_type>(traits::eof());

return create_exception_checked_task<int_type>(_ungetc(), [](int_type) {

return false;

});

}

/// <summary>

/// Reads up to a given number of characters from the stream.

/// </summary>

/// <param name="ptr">The address of the target memory area.</param>

/// <param name="count">The maximum number of characters to read.</param>

/// <returns>The number of characters read. O if the end of the stream is reached.</returns>

virtual pplx::task<size_t> getn(_Out_writes_(count) _CharType *ptr, _In_ size_t count)

{

if (!can_read())

return create_exception_checked_value_task<size_t>(0);

if (count == 0)

return pplx::task_from_result<size_t>(0);

return create_exception_checked_task<size_t>(_getn(ptr, count), [](size_t val) {

return val == 0;

});

}

/// <summary>

/// Copies up to a given number of characters from the stream, synchronously.

/// </summary>

/// <param name="ptr">The address of the target memory area.</param>

/// <param name="count">The maximum number of characters to read.</param>

/// <returns>The number of characters copied. O if the end of the stream is reached or an asynchronous read is required.</returns>

/// <remarks>This is a synchronous operation, but is guaranteed to never block.</remarks>

virtual size_t scopy(_Out_writes_(count) _CharType *ptr, _In_ size_t count)

{

if ( !(m_currentException == nullptr) )

std::rethrow_exception(m_currentException);

if (!can_read())

return 0;

return _scopy(ptr, count);

}

/// <summary>

/// For output streams, flush any internally buffered data to the underlying medium.

/// </summary>

/// <returns><c>true</c> if the flush succeeds, <c>false</c> if not</returns>

virtual pplx::task<void> sync()

{

if (!can_write())

{

if (m_currentException == nullptr)

return pplx::task_from_result();

else

return pplx::task_from_exception<void>(m_currentException);

}

return create_exception_checked_task<bool>(_sync(), [](bool) {

return false;

}).then([](bool){});

}

/// <summary>

/// Retrieves the stream buffer exception_ptr if it has been set.

/// </summary>

/// <returns>Pointer to the exception, if it has been set; otherwise, <c>nullptr</c> will be returned.</returns>

virtual std::exception_ptr exception() const

{

return m_currentException;

}

/// <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>

/// <remarks>This is intended as an advanced API to be used only when it is important to avoid extra copies.</remarks>

_CharType* alloc(size_t count)

{

if (m_alloced)

throw std::logic_error("The buffer is already allocated, this maybe caused by overlap of stream read or write");

_CharType* alloc_result = _alloc(count);

if (alloc_result)

m_alloced = true;

return alloc_result;

}

/// <summary>

/// Submits a block already allocated by the stream buffer.

/// </summary>

/// <param name="count">The number of characters to be committed.</param>

/// <remarks>This is intended as an advanced API to be used only when it is important to avoid extra copies.</remarks>

void commit(size_t count)

{

if (!m_alloced)

throw std::logic_error("The buffer needs to allocate first");

_commit(count);

m_alloced = false;

}

public:

virtual bool can_seek() const = 0;

virtual bool has_size() const = 0;

virtual utility::size64_t size() const { return 0; }

virtual size_t buffer_size(std::ios_base::openmode direction = std::ios_base::in) const = 0;

virtual void set_buffer_size(size_t size, std::ios_base::openmode direction = std::ios_base::in) = 0;

virtual size_t in_avail() const = 0;

virtual pos_type getpos(std::ios_base::openmode direction) const = 0;

virtual pos_type seekpos(pos_type pos, std::ios_base::openmode direction) = 0;

virtual pos_type seekoff(off_type offset, std::ios_base::seekdir way, std::ios_base::openmode mode) = 0;

virtual bool acquire(_Out_writes_(count) _CharType*& ptr, _In_ size_t& count) = 0;

virtual void release(_Out_writes_(count) _CharType *ptr, _In_ size_t count) = 0;

protected:

virtual pplx::task<int_type> _putc(_CharType ch) = 0;

// This API is only needed for file streams and until we remove the deprecated stream buffer putn overload.

virtual pplx::task<size_t> _putn(const _CharType *ptr, size_t count, bool)

{

// Default to no copy, only the file streams API overloads and performs a copy.

return _putn(ptr, count);

}

virtual pplx::task<size_t> _putn(const _CharType *ptr, size_t count) = 0;

virtual pplx::task<int_type> _bumpc() = 0;

virtual int_type _sbumpc() = 0;

virtual pplx::task<int_type> _getc() = 0;

virtual int_type _sgetc() = 0;

virtual pplx::task<int_type> _nextc() = 0;

virtual pplx::task<int_type> _ungetc() = 0;

virtual pplx::task<size_t> _getn(_Out_writes_(count) _CharType *ptr, _In_ size_t count) = 0;

virtual size_t _scopy(_Out_writes_(count) _CharType *ptr, _In_ size_t count) = 0;

virtual pplx::task<bool> _sync() = 0;

virtual _CharType* _alloc(size_t count) = 0;

virtual void _commit(size_t count) = 0;

/// <summary>

/// The real read head close operation, implementation should override it if there is any resource to be released.

/// </summary>

virtual pplx::task<void> _close_read()

{

m_stream_can_read = false;

return pplx::task_from_result();

}

/// <summary>

/// The real write head close operation, implementation should override it if there is any resource to be released.

/// </summary>

virtual pplx::task<void> _close_write()

{

m_stream_can_write = false;

return pplx::task_from_result();

}

protected:

streambuf_state_manager(std::ios_base::openmode mode)

{

m_stream_can_read = (mode & std::ios_base::in) != 0;

m_stream_can_write = (mode & std::ios_base::out) != 0;

m_stream_read_eof = false;

m_alloced = false;

}

std::exception_ptr m_currentException;

// The in/out mode for the buffer

bool m_stream_can_read, m_stream_can_write, m_stream_read_eof, m_alloced;

private:

template<typename _CharType1>

pplx::task<_CharType1> create_exception_checked_value_task(const _CharType1 &val) const

{

if (this->exception() == nullptr)

return pplx::task_from_result<_CharType1>(static_cast<_CharType1>(val));

else

return pplx::task_from_exception<_CharType1>(this->exception());

}

// Set exception and eof states for async read

template<typename _CharType1>

pplx::task<_CharType1> create_exception_checked_task(pplx::task<_CharType1> result, std::function<bool(_CharType1)> eof_test, std::ios_base::openmode mode = std::ios_base::in | std::ios_base::out)

{

auto thisPointer = this->shared_from_this();

auto func1 = [=](pplx::task<_CharType1> t1) -> pplx::task<_CharType1> {

try {

thisPointer->m_stream_read_eof = eof_test(t1.get());

} catch (...) {

thisPointer->close(mode, std::current_exception()).get();

return pplx::task_from_exception<_CharType1>(thisPointer->exception(), pplx::task_options());

}

if (thisPointer->m_stream_read_eof && !(thisPointer->exception() == nullptr))

return pplx::task_from_exception<_CharType1>(thisPointer->exception(), pplx::task_options());

return t1;

};

if ( result.is_done() )

{

// If the data is already available, we should avoid scheduling a continuation, so we do it inline.

return func1(result);

}

else

{

return result.then(func1);

}

}

// Set eof states for sync read

int_type check_sync_read_eof(int_type ch)

{

m_stream_read_eof = ch == traits::eof();

return ch;

}

};

} // namespace details

// Forward declarations

template<typename _CharType> class basic_istream;

template<typename _CharType> class basic_ostream;

/// <summary>

/// Reference-counted stream buffer.

/// </summary>

/// <typeparam name="_CharType">

/// The data type of the basic element of the <c>streambuf.</c>

/// </typeparam>

/// <typeparam name="_CharType2">

/// The data type of the basic element of the <c>streambuf.</c>

/// </typeparam>

template<typename _CharType>

class streambuf : public details::basic_streambuf<_CharType>

{

public:

typedef typename details::basic_streambuf<_CharType>::traits traits;

typedef typename details::basic_streambuf<_CharType>::int_type int_type;

typedef typename details::basic_streambuf<_CharType>::pos_type pos_type;

typedef typename details::basic_streambuf<_CharType>::off_type off_type;

typedef typename details::basic_streambuf<_CharType>::char_type char_type;

template <typename _CharType2> friend class streambuf;

/// <summary>

/// Constructor.

/// </summary>

/// <param name="ptr">A pointer to the concrete stream buffer implementation.</param>

streambuf(_In_ const std::shared_ptr<details::basic_streambuf<_CharType>> &ptr) : m_buffer(ptr) {}

/// <summary>

/// Default constructor.

/// </summary>

streambuf() { }

/// <summary>

/// Converter Constructor.

/// </summary>

/// <typeparam name="AlterCharType">

/// The data type of the basic element of the source <c>streambuf</c>.

/// </typeparam>

/// <param name="other">The source buffer to be converted.</param>

template <typename AlterCharType>

streambuf(const streambuf<AlterCharType> &other) :

m_buffer(std::static_pointer_cast<details::basic_streambuf<_CharType>>(std::static_pointer_cast<void>(other.m_buffer)))

{

static_assert(std::is_same<pos_type, typename details::basic_streambuf<AlterCharType>::pos_type>::value

&& std::is_same<off_type, typename details::basic_streambuf<AlterCharType>::off_type>::value

&& std::is_integral<_CharType>::value && std::is_integral<AlterCharType>::value

&& std::is_integral<int_type>::value && std::is_integral<typename details::basic_streambuf<AlterCharType>::int_type>::value

&& sizeof(_CharType) == sizeof(AlterCharType)

&& sizeof(int_type) == sizeof(typename details::basic_streambuf<AlterCharType>::int_type),

"incompatible stream character types");

}

/// <summary>

/// Constructs an input stream head for this stream buffer.

/// </summary>

/// <returns><c>basic_istream</c>.</returns>

concurrency::streams::basic_istream<_CharType> create_istream() const

{

if (!can_read()) throw std::runtime_error("stream buffer not set up for input of data");

return concurrency::streams::basic_istream<_CharType>(*this);

}

/// <summary>

/// Constructs an output stream for this stream buffer.

/// </summary>

/// <returns>basic_ostream</returns>

concurrency::streams::basic_ostream<_CharType> create_ostream() const

{

if (!can_write()) throw std::runtime_error("stream buffer not set up for output of data");

return concurrency::streams::basic_ostream<_CharType>(*this);

}

/// <summary>

/// Checks if the stream buffer has been initialized or not.

/// </summary>

operator bool() const { return (bool)m_buffer; }

/// <summary>

/// Destructor

/// </summary>

virtual ~streambuf() { }

const std::shared_ptr<details::basic_streambuf<_CharType>> & get_base() const

{

if (!m_buffer)

{

throw std::invalid_argument("Invalid streambuf object");

}

return m_buffer;

}

/// <summary>

/// <c>can_read</c> is used to determine whether a stream buffer will support read operations (get).

/// </summary>

virtual bool can_read() const { return get_base()->can_read(); }

/// <summary>

/// <c>can_write</c> is used to determine whether a stream buffer will support write operations (put).

/// </summary>

virtual bool can_write() const { return get_base()->can_write(); }

/// <summary>

/// <c>can_seek</c> is used to determine whether a stream buffer supports seeking.

/// </summary>

/// <returns>True if seeking is supported, false otherwise.</returns>

virtual bool can_seek() const { return get_base()->can_seek(); }

/// <summary>

/// <c>has_size</c> is used to determine whether a stream buffer supports size().

/// </summary>

/// <returns>True if the <c>size</c> API is supported, false otherwise.</returns>

virtual bool has_size() const { return get_base()->has_size(); }

/// <summary>

/// Gets the total number of characters in the stream buffer, if known. Calls to <c>has_size</c> will determine whether

/// the result of <c>size</c> can be relied on.

/// </summary>

/// <returns>The total number of characters in the stream buffer.</returns>

virtual utility::size64_t size() const { return get_base()->size(); }

/// <summary>

/// Gets the stream buffer size, if one has been set.

/// </summary>

/// <param name="direction">The direction of buffering (in or out)</param>

/// <returns>The size of the internal buffer (for the given direction).</returns>

/// <remarks>An implementation that does not support buffering will always return 0.</remarks>

virtual size_t buffer_size(std::ios_base::openmode direction = std::ios_base::in) const { return get_base()->buffer_size(direction); }

/// <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 size, std::ios_base::openmode direction = std::ios_base::in) { get_base()->set_buffer_size(size,direction); }

/// <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>

/// <returns>Number of characters that are ready to read.</returns>

virtual size_t in_avail() const { return get_base()->in_avail(); }

/// <summary>

/// Checks if the stream buffer is open.

/// </summary>

/// <remarks>No separation is made between open for reading and open for writing.</remarks>

/// <returns>True if the stream buffer is open for reading or writing, false otherwise.</returns>

virtual bool is_open() const { return get_base()->is_open(); }

/// <summary>

/// <c>is_eof</c> is used to determine whether a read head has reached the end of the buffer.

/// </summary>

/// <returns>True if at the end of the buffer, false otherwise.</returns>

virtual bool is_eof() const { return get_base()->is_eof(); }

/// <summary>

/// Closes the stream buffer, preventing further read or write operations.

/// </summary>

/// <param name="mode">The I/O mode (in or out) to close for.</param>

virtual pplx::task<void> close(std::ios_base::openmode mode = (std::ios_base::in | std::ios_base::out))

{

// We preserve the check here to workaround a Dev10 compiler crash

auto buffer = get_base();

return buffer ? buffer->close(mode) : pplx::task_from_result();

}

/// <summary>

/// Closes the stream buffer with an exception.

/// </summary>

/// <param name="mode">The I/O mode (in or out) to close for.</param>

/// <param name="eptr">Pointer to the exception.</param>

virtual pplx::task<void> close(std::ios_base::openmode mode, std::exception_ptr eptr)

{

// We preserve the check here to workaround a Dev10 compiler crash

auto buffer = get_base();

return buffer ? buffer->close(mode, eptr) : pplx::task_from_result();

}

/// <summary>

/// Writes a single character to the stream.

/// </summary>

/// <param name="ch">The character to write</param>

/// <returns>The value of the character. EOF if the write operation fails</returns>

virtual pplx::task<int_type> putc(_CharType ch)

{

return get_base()->putc(ch);

}

/// <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>

virtual _CharType* alloc(size_t count)

{

return get_base()->alloc(count);

}

/// <summary>

/// Submits a block already allocated by the stream buffer.

/// </summary>