asio::read_until

The read_until function is a composed operation that reads data into a dynamic buffer sequence, or into a streambuf, until it contains a delimiter, matches a regular expression, or a function object indicates a match. More...

Functions
template<typename SyncReadStream , typename DynamicBuffer_v1 >
std::size_t	asio::read_until (SyncReadStream &s, ASIO_MOVE_ARG(DynamicBuffer_v1) buffers, char delim, typename enable_if< is_dynamic_buffer_v1< typename decay< DynamicBuffer_v1 >::type >::value &&!is_dynamic_buffer_v2< typename decay< DynamicBuffer_v1 >::type >::value >::type *=0)
	Read data into a dynamic buffer sequence until it contains a specified delimiter. More...
template<typename SyncReadStream , typename DynamicBuffer_v1 >
std::size_t	asio::read_until (SyncReadStream &s, ASIO_MOVE_ARG(DynamicBuffer_v1) buffers, char delim, asio::error_code &ec, typename enable_if< is_dynamic_buffer_v1< typename decay< DynamicBuffer_v1 >::type >::value &&!is_dynamic_buffer_v2< typename decay< DynamicBuffer_v1 >::type >::value >::type *=0)
	Read data into a dynamic buffer sequence until it contains a specified delimiter. More...
template<typename SyncReadStream , typename DynamicBuffer_v1 >
std::size_t	asio::read_until (SyncReadStream &s, ASIO_MOVE_ARG(DynamicBuffer_v1) buffers, ASIO_STRING_VIEW_PARAM delim, typename enable_if< is_dynamic_buffer_v1< typename decay< DynamicBuffer_v1 >::type >::value &&!is_dynamic_buffer_v2< typename decay< DynamicBuffer_v1 >::type >::value >::type *=0)
	Read data into a dynamic buffer sequence until it contains a specified delimiter. More...
template<typename SyncReadStream , typename DynamicBuffer_v1 >
std::size_t	asio::read_until (SyncReadStream &s, ASIO_MOVE_ARG(DynamicBuffer_v1) buffers, ASIO_STRING_VIEW_PARAM delim, asio::error_code &ec, typename enable_if< is_dynamic_buffer_v1< typename decay< DynamicBuffer_v1 >::type >::value &&!is_dynamic_buffer_v2< typename decay< DynamicBuffer_v1 >::type >::value >::type *=0)
	Read data into a dynamic buffer sequence until it contains a specified delimiter. More...
template<typename SyncReadStream , typename DynamicBuffer_v1 , typename MatchCondition >
std::size_t	asio::read_until (SyncReadStream &s, ASIO_MOVE_ARG(DynamicBuffer_v1) buffers, MatchCondition match_condition, typename enable_if< is_match_condition< MatchCondition >::value &&is_dynamic_buffer_v1< typename decay< DynamicBuffer_v1 >::type >::value &&!is_dynamic_buffer_v2< typename decay< DynamicBuffer_v1 >::type >::value >::type *=0)
	Read data into a dynamic buffer sequence until a function object indicates a match. More...
template<typename SyncReadStream , typename DynamicBuffer_v1 , typename MatchCondition >
std::size_t	asio::read_until (SyncReadStream &s, ASIO_MOVE_ARG(DynamicBuffer_v1) buffers, MatchCondition match_condition, asio::error_code &ec, typename enable_if< is_match_condition< MatchCondition >::value &&is_dynamic_buffer_v1< typename decay< DynamicBuffer_v1 >::type >::value &&!is_dynamic_buffer_v2< typename decay< DynamicBuffer_v1 >::type >::value >::type *=0)
	Read data into a dynamic buffer sequence until a function object indicates a match. More...
template<typename SyncReadStream , typename Allocator >
std::size_t	asio::read_until (SyncReadStream &s, asio::basic_streambuf< Allocator > &b, char delim)
	Read data into a streambuf until it contains a specified delimiter. More...
template<typename SyncReadStream , typename Allocator >
std::size_t	asio::read_until (SyncReadStream &s, asio::basic_streambuf< Allocator > &b, char delim, asio::error_code &ec)
	Read data into a streambuf until it contains a specified delimiter. More...
template<typename SyncReadStream , typename Allocator >
std::size_t	asio::read_until (SyncReadStream &s, asio::basic_streambuf< Allocator > &b, ASIO_STRING_VIEW_PARAM delim)
	Read data into a streambuf until it contains a specified delimiter. More...
template<typename SyncReadStream , typename Allocator >
std::size_t	asio::read_until (SyncReadStream &s, asio::basic_streambuf< Allocator > &b, ASIO_STRING_VIEW_PARAM delim, asio::error_code &ec)
	Read data into a streambuf until it contains a specified delimiter. More...
template<typename SyncReadStream , typename Allocator , typename MatchCondition >
std::size_t	asio::read_until (SyncReadStream &s, asio::basic_streambuf< Allocator > &b, MatchCondition match_condition, typename enable_if< is_match_condition< MatchCondition >::value >::type *=0)
	Read data into a streambuf until a function object indicates a match. More...
template<typename SyncReadStream , typename Allocator , typename MatchCondition >
std::size_t	asio::read_until (SyncReadStream &s, asio::basic_streambuf< Allocator > &b, MatchCondition match_condition, asio::error_code &ec, typename enable_if< is_match_condition< MatchCondition >::value >::type *=0)
	Read data into a streambuf until a function object indicates a match. More...
template<typename SyncReadStream , typename DynamicBuffer_v2 >
std::size_t	asio::read_until (SyncReadStream &s, DynamicBuffer_v2 buffers, char delim, typename enable_if< is_dynamic_buffer_v2< DynamicBuffer_v2 >::value >::type *=0)
	Read data into a dynamic buffer sequence until it contains a specified delimiter. More...
template<typename SyncReadStream , typename DynamicBuffer_v2 >
std::size_t	asio::read_until (SyncReadStream &s, DynamicBuffer_v2 buffers, char delim, asio::error_code &ec, typename enable_if< is_dynamic_buffer_v2< DynamicBuffer_v2 >::value >::type *=0)
	Read data into a dynamic buffer sequence until it contains a specified delimiter. More...
template<typename SyncReadStream , typename DynamicBuffer_v2 >
std::size_t	asio::read_until (SyncReadStream &s, DynamicBuffer_v2 buffers, ASIO_STRING_VIEW_PARAM delim, typename enable_if< is_dynamic_buffer_v2< DynamicBuffer_v2 >::value >::type *=0)
	Read data into a dynamic buffer sequence until it contains a specified delimiter. More...
template<typename SyncReadStream , typename DynamicBuffer_v2 >
std::size_t	asio::read_until (SyncReadStream &s, DynamicBuffer_v2 buffers, ASIO_STRING_VIEW_PARAM delim, asio::error_code &ec, typename enable_if< is_dynamic_buffer_v2< DynamicBuffer_v2 >::value >::type *=0)
	Read data into a dynamic buffer sequence until it contains a specified delimiter. More...
template<typename SyncReadStream , typename DynamicBuffer_v2 , typename MatchCondition >
std::size_t	asio::read_until (SyncReadStream &s, DynamicBuffer_v2 buffers, MatchCondition match_condition, typename enable_if< is_match_condition< MatchCondition >::value &&is_dynamic_buffer_v2< DynamicBuffer_v2 >::value >::type *=0)
	Read data into a dynamic buffer sequence until a function object indicates a match. More...
template<typename SyncReadStream , typename DynamicBuffer_v2 , typename MatchCondition >
std::size_t	asio::read_until (SyncReadStream &s, DynamicBuffer_v2 buffers, MatchCondition match_condition, asio::error_code &ec, typename enable_if< is_match_condition< MatchCondition >::value &&is_dynamic_buffer_v2< DynamicBuffer_v2 >::value >::type *=0)
	Read data into a dynamic buffer sequence until a function object indicates a match. More...

Detailed Description

The read_until function is a composed operation that reads data into a dynamic buffer sequence, or into a streambuf, until it contains a delimiter, matches a regular expression, or a function object indicates a match.

Function Documentation

read_until() [1/18]

template<typename SyncReadStream , typename DynamicBuffer_v1 >

std::size_t asio::read_until ( SyncReadStream &  s, ASIO_MOVE_ARG(DynamicBuffer_v1)  buffers, char  delim, typename enable_if< is_dynamic_buffer_v1< typename decay< DynamicBuffer_v1 >::type >::value &&!is_dynamic_buffer_v2< typename decay< DynamicBuffer_v1 >::type >::value >::type *  = 0  )

inline

Read data into a dynamic buffer sequence until it contains a specified delimiter.

This function is used to read data into the specified dynamic buffer sequence until the dynamic buffer sequence's get area contains the specified delimiter. The call will block until one of the following conditions is true:

• The get area of the dynamic buffer sequence contains the specified delimiter.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the dynamic buffer sequence's get area already contains the delimiter, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
buffers	The dynamic buffer sequence into which the data will be read.
delim	The delimiter character.

Returns

The number of bytes in the dynamic buffer sequence's get area up to and including the delimiter.

Exceptions

asio::system_error

Thrown on failure.

Note

After a successful read_until operation, the dynamic buffer sequence may contain additional data beyond the delimiter. An application will typically leave that data in the dynamic buffer sequence for a subsequent read_until operation to examine.

Example

To read data into a std::string until a newline is encountered:

 std::string data;
std::size_t n = asio::read_until(s,
    asio::dynamic_buffer(data), '\n');
std::string line = data.substr(0, n);
data.erase(0, n); 

After the read_until operation completes successfully, the string data contains the delimiter:

{ 'a', 'b', ..., 'c', '\n', 'd', 'e', ... } 

The call to substr then extracts the data up to and including the delimiter, so that the string line contains:

{ 'a', 'b', ..., 'c', '\n' } 

After the call to erase, the remaining data is left in the buffer b as follows:

{ 'd', 'e', ... } 

This data may be the start of a new line, to be extracted by a subsequent read_until operation.

read_until() [2/18]

template<typename SyncReadStream , typename DynamicBuffer_v1 >

std::size_t asio::read_until	(	SyncReadStream &	s,
		ASIO_MOVE_ARG(DynamicBuffer_v1)	buffers,
		char	delim,
		asio::error_code &	ec,
		typename enable_if< is_dynamic_buffer_v1< typename decay< DynamicBuffer_v1 >::type >::value &&!is_dynamic_buffer_v2< typename decay< DynamicBuffer_v1 >::type >::value >::type *	= 0
	)

Read data into a dynamic buffer sequence until it contains a specified delimiter.

This function is used to read data into the specified dynamic buffer sequence until the dynamic buffer sequence's get area contains the specified delimiter. The call will block until one of the following conditions is true:

• The get area of the dynamic buffer sequence contains the specified delimiter.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the dynamic buffer sequence's get area already contains the delimiter, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
buffers	The dynamic buffer sequence into which the data will be read.
delim	The delimiter character.
ec	Set to indicate what error occurred, if any.

Returns

The number of bytes in the dynamic buffer sequence's get area up to and including the delimiter. Returns 0 if an error occurred.

Note

After a successful read_until operation, the dynamic buffer sequence may contain additional data beyond the delimiter. An application will typically leave that data in the dynamic buffer sequence for a subsequent read_until operation to examine.

read_until() [3/18]

template<typename SyncReadStream , typename DynamicBuffer_v1 >

std::size_t asio::read_until ( SyncReadStream &  s, ASIO_MOVE_ARG(DynamicBuffer_v1)  buffers, ASIO_STRING_VIEW_PARAM  delim, typename enable_if< is_dynamic_buffer_v1< typename decay< DynamicBuffer_v1 >::type >::value &&!is_dynamic_buffer_v2< typename decay< DynamicBuffer_v1 >::type >::value >::type *  = 0  )

inline

Read data into a dynamic buffer sequence until it contains a specified delimiter.

This function is used to read data into the specified dynamic buffer sequence until the dynamic buffer sequence's get area contains the specified delimiter. The call will block until one of the following conditions is true:

• The get area of the dynamic buffer sequence contains the specified delimiter.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the dynamic buffer sequence's get area already contains the delimiter, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
buffers	The dynamic buffer sequence into which the data will be read.
delim	The delimiter string.

Returns

The number of bytes in the dynamic buffer sequence's get area up to and including the delimiter.

Note

After a successful read_until operation, the dynamic buffer sequence may contain additional data beyond the delimiter. An application will typically leave that data in the dynamic buffer sequence for a subsequent read_until operation to examine.

Example

To read data into a std::string until a CR-LF sequence is encountered:

 std::string data;
std::size_t n = asio::read_until(s,
    asio::dynamic_buffer(data), "\r\n");
std::string line = data.substr(0, n);
data.erase(0, n); 

After the read_until operation completes successfully, the string data contains the delimiter:

{ 'a', 'b', ..., 'c', '\r', '\n', 'd', 'e', ... } 

The call to substr then extracts the data up to and including the delimiter, so that the string line contains:

{ 'a', 'b', ..., 'c', '\r', '\n' } 

After the call to erase, the remaining data is left in the buffer b as follows:

{ 'd', 'e', ... } 

This data may be the start of a new line, to be extracted by a subsequent read_until operation.

read_until() [4/18]

template<typename SyncReadStream , typename DynamicBuffer_v1 >

std::size_t asio::read_until	(	SyncReadStream &	s,
		ASIO_MOVE_ARG(DynamicBuffer_v1)	buffers,
		ASIO_STRING_VIEW_PARAM	delim,
		asio::error_code &	ec,
		typename enable_if< is_dynamic_buffer_v1< typename decay< DynamicBuffer_v1 >::type >::value &&!is_dynamic_buffer_v2< typename decay< DynamicBuffer_v1 >::type >::value >::type *	= 0
	)

Read data into a dynamic buffer sequence until it contains a specified delimiter.

This function is used to read data into the specified dynamic buffer sequence until the dynamic buffer sequence's get area contains the specified delimiter. The call will block until one of the following conditions is true:

• The get area of the dynamic buffer sequence contains the specified delimiter.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the dynamic buffer sequence's get area already contains the delimiter, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
buffers	The dynamic buffer sequence into which the data will be read.
delim	The delimiter string.
ec	Set to indicate what error occurred, if any.

Returns

The number of bytes in the dynamic buffer sequence's get area up to and including the delimiter. Returns 0 if an error occurred.

Note

After a successful read_until operation, the dynamic buffer sequence may contain additional data beyond the delimiter. An application will typically leave that data in the dynamic buffer sequence for a subsequent read_until operation to examine.

read_until() [5/18]

template<typename SyncReadStream , typename DynamicBuffer_v1 , typename MatchCondition >

std::size_t asio::read_until ( SyncReadStream &  s, ASIO_MOVE_ARG(DynamicBuffer_v1)  buffers, MatchCondition  match_condition, typename enable_if< is_match_condition< MatchCondition >::value &&is_dynamic_buffer_v1< typename decay< DynamicBuffer_v1 >::type >::value &&!is_dynamic_buffer_v2< typename decay< DynamicBuffer_v1 >::type >::value >::type *  = 0  )

inline

Read data into a dynamic buffer sequence until a function object indicates a match.

This function is used to read data into the specified dynamic buffer sequence until a user-defined match condition function object, when applied to the data contained in the dynamic buffer sequence, indicates a successful match. The call will block until one of the following conditions is true:

• The match condition function object returns a std::pair where the second element evaluates to true.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the match condition function object already indicates a match, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
buffers	A dynamic buffer sequence into which the data will be read.
match_condition	The function object to be called to determine whether a match exists. The signature of the function object must be: pair<iterator, bool> match_condition(iterator begin, iterator end); where iterator represents the type: buffers_iterator<typename DynamicBuffer_v1::const_buffers_type> The iterator parameters begin and end define the range of bytes to be scanned to determine whether there is a match. The first member of the return value is an iterator marking one-past-the-end of the bytes that have been consumed by the match function. This iterator is used to calculate the begin parameter for any subsequent invocation of the match condition. The second member of the return value is true if a match has been found, false otherwise.

Returns

The number of bytes in the dynamic_buffer's get area that have been fully consumed by the match function.

Exceptions

asio::system_error

Thrown on failure.

Note

After a successful read_until operation, the dynamic buffer sequence may contain additional data beyond that which matched the function object. An application will typically leave that data in the dynamic buffer sequence for a subsequent read_until operation to examine.

The default implementation of the is_match_condition type trait evaluates to true for function pointers and function objects with a result_type typedef. It must be specialised for other user-defined function objects.

Examples

To read data into a dynamic buffer sequence until whitespace is encountered:

 typedef asio::buffers_iterator<
    asio::const_buffers_1> iterator;

std::pair<iterator, bool>
match_whitespace(iterator begin, iterator end)
{
  iterator i = begin;
  while (i != end)
    if (std::isspace(*i++))
      return std::make_pair(i, true);
  return std::make_pair(i, false);
}
...
std::string data;
asio::read_until(s, data, match_whitespace);

To read data into a std::string until a matching character is found:

 class match_char
{
public:
  explicit match_char(char c) : c_(c) {}

  template <typename Iterator>
  std::pair<Iterator, bool> operator()(
      Iterator begin, Iterator end) const
  {
    Iterator i = begin;
    while (i != end)
      if (c_ == *i++)
        return std::make_pair(i, true);
    return std::make_pair(i, false);
  }

private:
  char c_;
};

namespace asio {
  template <> struct is_match_condition<match_char>
    : public boost::true_type {};
} // namespace asio
...
std::string data;
asio::read_until(s, data, match_char('a'));

read_until() [6/18]

template<typename SyncReadStream , typename DynamicBuffer_v1 , typename MatchCondition >

std::size_t asio::read_until	(	SyncReadStream &	s,
		ASIO_MOVE_ARG(DynamicBuffer_v1)	buffers,
		MatchCondition	match_condition,
		asio::error_code &	ec,
		typename enable_if< is_match_condition< MatchCondition >::value &&is_dynamic_buffer_v1< typename decay< DynamicBuffer_v1 >::type >::value &&!is_dynamic_buffer_v2< typename decay< DynamicBuffer_v1 >::type >::value >::type *	= 0
	)

Read data into a dynamic buffer sequence until a function object indicates a match.

This function is used to read data into the specified dynamic buffer sequence until a user-defined match condition function object, when applied to the data contained in the dynamic buffer sequence, indicates a successful match. The call will block until one of the following conditions is true:

• The match condition function object returns a std::pair where the second element evaluates to true.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the match condition function object already indicates a match, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
buffers	A dynamic buffer sequence into which the data will be read.
match_condition	The function object to be called to determine whether a match exists. The signature of the function object must be: pair<iterator, bool> match_condition(iterator begin, iterator end); where iterator represents the type: buffers_iterator<DynamicBuffer_v1::const_buffers_type> The iterator parameters begin and end define the range of bytes to be scanned to determine whether there is a match. The first member of the return value is an iterator marking one-past-the-end of the bytes that have been consumed by the match function. This iterator is used to calculate the begin parameter for any subsequent invocation of the match condition. The second member of the return value is true if a match has been found, false otherwise.
ec	Set to indicate what error occurred, if any.

Returns

The number of bytes in the dynamic buffer sequence's get area that have been fully consumed by the match function. Returns 0 if an error occurred.

Note

After a successful read_until operation, the dynamic buffer sequence may contain additional data beyond that which matched the function object. An application will typically leave that data in the dynamic buffer sequence for a subsequent read_until operation to examine.

The default implementation of the is_match_condition type trait evaluates to true for function pointers and function objects with a result_type typedef. It must be specialised for other user-defined function objects.

read_until() [7/18]

template<typename SyncReadStream , typename Allocator >

std::size_t asio::read_until ( SyncReadStream &  s, asio::basic_streambuf< Allocator > &  b, char  delim  )

inline

Read data into a streambuf until it contains a specified delimiter.

This function is used to read data into the specified streambuf until the streambuf's get area contains the specified delimiter. The call will block until one of the following conditions is true:

• The get area of the streambuf contains the specified delimiter.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the streambuf's get area already contains the delimiter, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
b	A streambuf object into which the data will be read.
delim	The delimiter character.

Returns

The number of bytes in the streambuf's get area up to and including the delimiter.

Exceptions

asio::system_error

Thrown on failure.

Note

After a successful read_until operation, the streambuf may contain additional data beyond the delimiter. An application will typically leave that data in the streambuf for a subsequent read_until operation to examine.

Example

To read data into a streambuf until a newline is encountered:

 asio::streambuf b;
asio::read_until(s, b, '\n');
std::istream is(&b);
std::string line;
std::getline(is, line); 

After the read_until operation completes successfully, the buffer b contains the delimiter:

{ 'a', 'b', ..., 'c', '\n', 'd', 'e', ... } 

The call to std::getline then extracts the data up to and including the newline (which is discarded), so that the string line contains:

{ 'a', 'b', ..., 'c' } 

The remaining data is left in the buffer b as follows:

{ 'd', 'e', ... } 

This data may be the start of a new line, to be extracted by a subsequent read_until operation.

read_until() [8/18]

template<typename SyncReadStream , typename Allocator >

std::size_t asio::read_until ( SyncReadStream &  s, asio::basic_streambuf< Allocator > &  b, char  delim, asio::error_code &  ec  )

inline

Read data into a streambuf until it contains a specified delimiter.

This function is used to read data into the specified streambuf until the streambuf's get area contains the specified delimiter. The call will block until one of the following conditions is true:

• The get area of the streambuf contains the specified delimiter.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the streambuf's get area already contains the delimiter, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
b	A streambuf object into which the data will be read.
delim	The delimiter character.
ec	Set to indicate what error occurred, if any.

Returns

The number of bytes in the streambuf's get area up to and including the delimiter. Returns 0 if an error occurred.

Note

After a successful read_until operation, the streambuf may contain additional data beyond the delimiter. An application will typically leave that data in the streambuf for a subsequent read_until operation to examine.

read_until() [9/18]

template<typename SyncReadStream , typename Allocator >

std::size_t asio::read_until ( SyncReadStream &  s, asio::basic_streambuf< Allocator > &  b, ASIO_STRING_VIEW_PARAM  delim  )

inline

Read data into a streambuf until it contains a specified delimiter.

This function is used to read data into the specified streambuf until the streambuf's get area contains the specified delimiter. The call will block until one of the following conditions is true:

• The get area of the streambuf contains the specified delimiter.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the streambuf's get area already contains the delimiter, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
b	A streambuf object into which the data will be read.
delim	The delimiter string.

Returns

The number of bytes in the streambuf's get area up to and including the delimiter.

Exceptions

asio::system_error

Thrown on failure.

Note

After a successful read_until operation, the streambuf may contain additional data beyond the delimiter. An application will typically leave that data in the streambuf for a subsequent read_until operation to examine.

Example

To read data into a streambuf until a newline is encountered:

 asio::streambuf b;
asio::read_until(s, b, "\r\n");
std::istream is(&b);
std::string line;
std::getline(is, line); 

After the read_until operation completes successfully, the buffer b contains the delimiter:

{ 'a', 'b', ..., 'c', '\r', '\n', 'd', 'e', ... } 

The call to std::getline then extracts the data up to and including the newline (which is discarded), so that the string line contains:

{ 'a', 'b', ..., 'c', '\r' } 

The remaining data is left in the buffer b as follows:

{ 'd', 'e', ... } 

This data may be the start of a new line, to be extracted by a subsequent read_until operation.

read_until() [10/18]

template<typename SyncReadStream , typename Allocator >

std::size_t asio::read_until ( SyncReadStream &  s, asio::basic_streambuf< Allocator > &  b, ASIO_STRING_VIEW_PARAM  delim, asio::error_code &  ec  )

inline

Read data into a streambuf until it contains a specified delimiter.

This function is used to read data into the specified streambuf until the streambuf's get area contains the specified delimiter. The call will block until one of the following conditions is true:

• The get area of the streambuf contains the specified delimiter.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the streambuf's get area already contains the delimiter, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
b	A streambuf object into which the data will be read.
delim	The delimiter string.
ec	Set to indicate what error occurred, if any.

Returns

The number of bytes in the streambuf's get area up to and including the delimiter. Returns 0 if an error occurred.

Note

After a successful read_until operation, the streambuf may contain additional data beyond the delimiter. An application will typically leave that data in the streambuf for a subsequent read_until operation to examine.

read_until() [11/18]

template<typename SyncReadStream , typename Allocator , typename MatchCondition >

std::size_t asio::read_until ( SyncReadStream &  s, asio::basic_streambuf< Allocator > &  b, MatchCondition  match_condition, typename enable_if< is_match_condition< MatchCondition >::value >::type *  = 0  )

inline

Read data into a streambuf until a function object indicates a match.

This function is used to read data into the specified streambuf until a user-defined match condition function object, when applied to the data contained in the streambuf, indicates a successful match. The call will block until one of the following conditions is true:

• The match condition function object returns a std::pair where the second element evaluates to true.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the match condition function object already indicates a match, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
b	A streambuf object into which the data will be read.
match_condition	The function object to be called to determine whether a match exists. The signature of the function object must be: pair<iterator, bool> match_condition(iterator begin, iterator end); where iterator represents the type: buffers_iterator<basic_streambuf<Allocator>::const_buffers_type> The iterator parameters begin and end define the range of bytes to be scanned to determine whether there is a match. The first member of the return value is an iterator marking one-past-the-end of the bytes that have been consumed by the match function. This iterator is used to calculate the begin parameter for any subsequent invocation of the match condition. The second member of the return value is true if a match has been found, false otherwise.

Returns

The number of bytes in the streambuf's get area that have been fully consumed by the match function.

Exceptions

asio::system_error

Thrown on failure.

Note

After a successful read_until operation, the streambuf may contain additional data beyond that which matched the function object. An application will typically leave that data in the streambuf for a subsequent read_until operation to examine.

The default implementation of the is_match_condition type trait evaluates to true for function pointers and function objects with a result_type typedef. It must be specialised for other user-defined function objects.

Examples

To read data into a streambuf until whitespace is encountered:

 typedef asio::buffers_iterator<
    asio::streambuf::const_buffers_type> iterator;

std::pair<iterator, bool>
match_whitespace(iterator begin, iterator end)
{
  iterator i = begin;
  while (i != end)
    if (std::isspace(*i++))
      return std::make_pair(i, true);
  return std::make_pair(i, false);
}
...
asio::streambuf b;
asio::read_until(s, b, match_whitespace);

To read data into a streambuf until a matching character is found:

 class match_char
{
public:
  explicit match_char(char c) : c_(c) {}

  template <typename Iterator>
  std::pair<Iterator, bool> operator()(
      Iterator begin, Iterator end) const
  {
    Iterator i = begin;
    while (i != end)
      if (c_ == *i++)
        return std::make_pair(i, true);
    return std::make_pair(i, false);
  }

private:
  char c_;
};

namespace asio {
  template <> struct is_match_condition<match_char>
    : public boost::true_type {};
} // namespace asio
...
asio::streambuf b;
asio::read_until(s, b, match_char('a'));

read_until() [12/18]

template<typename SyncReadStream , typename Allocator , typename MatchCondition >

std::size_t asio::read_until ( SyncReadStream &  s, asio::basic_streambuf< Allocator > &  b, MatchCondition  match_condition, asio::error_code &  ec, typename enable_if< is_match_condition< MatchCondition >::value >::type *  = 0  )

inline

Read data into a streambuf until a function object indicates a match.

This function is used to read data into the specified streambuf until a user-defined match condition function object, when applied to the data contained in the streambuf, indicates a successful match. The call will block until one of the following conditions is true:

• The match condition function object returns a std::pair where the second element evaluates to true.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the match condition function object already indicates a match, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
b	A streambuf object into which the data will be read.
match_condition	The function object to be called to determine whether a match exists. The signature of the function object must be: pair<iterator, bool> match_condition(iterator begin, iterator end); where iterator represents the type: buffers_iterator<basic_streambuf<Allocator>::const_buffers_type> The iterator parameters begin and end define the range of bytes to be scanned to determine whether there is a match. The first member of the return value is an iterator marking one-past-the-end of the bytes that have been consumed by the match function. This iterator is used to calculate the begin parameter for any subsequent invocation of the match condition. The second member of the return value is true if a match has been found, false otherwise.
ec	Set to indicate what error occurred, if any.

Returns

The number of bytes in the streambuf's get area that have been fully consumed by the match function. Returns 0 if an error occurred.

Note

After a successful read_until operation, the streambuf may contain additional data beyond that which matched the function object. An application will typically leave that data in the streambuf for a subsequent read_until operation to examine.

The default implementation of the is_match_condition type trait evaluates to true for function pointers and function objects with a result_type typedef. It must be specialised for other user-defined function objects.

read_until() [13/18]

template<typename SyncReadStream , typename DynamicBuffer_v2 >

std::size_t asio::read_until ( SyncReadStream &  s, DynamicBuffer_v2  buffers, char  delim, typename enable_if< is_dynamic_buffer_v2< DynamicBuffer_v2 >::value >::type *  = 0  )

inline

Read data into a dynamic buffer sequence until it contains a specified delimiter.

This function is used to read data into the specified dynamic buffer sequence until the dynamic buffer sequence's get area contains the specified delimiter. The call will block until one of the following conditions is true:

• The get area of the dynamic buffer sequence contains the specified delimiter.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the dynamic buffer sequence's get area already contains the delimiter, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
buffers	The dynamic buffer sequence into which the data will be read.
delim	The delimiter character.

Returns

The number of bytes in the dynamic buffer sequence's get area up to and including the delimiter.

Exceptions

asio::system_error

Thrown on failure.

Note

After a successful read_until operation, the dynamic buffer sequence may contain additional data beyond the delimiter. An application will typically leave that data in the dynamic buffer sequence for a subsequent read_until operation to examine.

Example

To read data into a std::string until a newline is encountered:

 std::string data;
std::size_t n = asio::read_until(s,
    asio::dynamic_buffer(data), '\n');
std::string line = data.substr(0, n);
data.erase(0, n); 

After the read_until operation completes successfully, the string data contains the delimiter:

{ 'a', 'b', ..., 'c', '\n', 'd', 'e', ... } 

The call to substr then extracts the data up to and including the delimiter, so that the string line contains:

{ 'a', 'b', ..., 'c', '\n' } 

After the call to erase, the remaining data is left in the buffer b as follows:

{ 'd', 'e', ... } 

This data may be the start of a new line, to be extracted by a subsequent read_until operation.

read_until() [14/18]

template<typename SyncReadStream , typename DynamicBuffer_v2 >

std::size_t asio::read_until	(	SyncReadStream &	s,
		DynamicBuffer_v2	buffers,
		char	delim,
		asio::error_code &	ec,
		typename enable_if< is_dynamic_buffer_v2< DynamicBuffer_v2 >::value >::type *	= 0
	)

Read data into a dynamic buffer sequence until it contains a specified delimiter.

This function is used to read data into the specified dynamic buffer sequence until the dynamic buffer sequence's get area contains the specified delimiter. The call will block until one of the following conditions is true:

• The get area of the dynamic buffer sequence contains the specified delimiter.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the dynamic buffer sequence's get area already contains the delimiter, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
buffers	The dynamic buffer sequence into which the data will be read.
delim	The delimiter character.
ec	Set to indicate what error occurred, if any.

Returns

The number of bytes in the dynamic buffer sequence's get area up to and including the delimiter. Returns 0 if an error occurred.

Note

After a successful read_until operation, the dynamic buffer sequence may contain additional data beyond the delimiter. An application will typically leave that data in the dynamic buffer sequence for a subsequent read_until operation to examine.

read_until() [15/18]

template<typename SyncReadStream , typename DynamicBuffer_v2 >

std::size_t asio::read_until ( SyncReadStream &  s, DynamicBuffer_v2  buffers, ASIO_STRING_VIEW_PARAM  delim, typename enable_if< is_dynamic_buffer_v2< DynamicBuffer_v2 >::value >::type *  = 0  )

inline

Read data into a dynamic buffer sequence until it contains a specified delimiter.

This function is used to read data into the specified dynamic buffer sequence until the dynamic buffer sequence's get area contains the specified delimiter. The call will block until one of the following conditions is true:

• The get area of the dynamic buffer sequence contains the specified delimiter.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the dynamic buffer sequence's get area already contains the delimiter, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
buffers	The dynamic buffer sequence into which the data will be read.
delim	The delimiter string.

Returns

The number of bytes in the dynamic buffer sequence's get area up to and including the delimiter.

Note

After a successful read_until operation, the dynamic buffer sequence may contain additional data beyond the delimiter. An application will typically leave that data in the dynamic buffer sequence for a subsequent read_until operation to examine.

Example

To read data into a std::string until a CR-LF sequence is encountered:

 std::string data;
std::size_t n = asio::read_until(s,
    asio::dynamic_buffer(data), "\r\n");
std::string line = data.substr(0, n);
data.erase(0, n); 

After the read_until operation completes successfully, the string data contains the delimiter:

{ 'a', 'b', ..., 'c', '\r', '\n', 'd', 'e', ... } 

The call to substr then extracts the data up to and including the delimiter, so that the string line contains:

{ 'a', 'b', ..., 'c', '\r', '\n' } 

After the call to erase, the remaining data is left in the buffer b as follows:

{ 'd', 'e', ... } 

This data may be the start of a new line, to be extracted by a subsequent read_until operation.

read_until() [16/18]

template<typename SyncReadStream , typename DynamicBuffer_v2 >

std::size_t asio::read_until	(	SyncReadStream &	s,
		DynamicBuffer_v2	buffers,
		ASIO_STRING_VIEW_PARAM	delim,
		asio::error_code &	ec,
		typename enable_if< is_dynamic_buffer_v2< DynamicBuffer_v2 >::value >::type *	= 0
	)

Read data into a dynamic buffer sequence until it contains a specified delimiter.

This function is used to read data into the specified dynamic buffer sequence until the dynamic buffer sequence's get area contains the specified delimiter. The call will block until one of the following conditions is true:

• The get area of the dynamic buffer sequence contains the specified delimiter.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the dynamic buffer sequence's get area already contains the delimiter, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
buffers	The dynamic buffer sequence into which the data will be read.
delim	The delimiter string.
ec	Set to indicate what error occurred, if any.

Returns

The number of bytes in the dynamic buffer sequence's get area up to and including the delimiter. Returns 0 if an error occurred.

Note

After a successful read_until operation, the dynamic buffer sequence may contain additional data beyond the delimiter. An application will typically leave that data in the dynamic buffer sequence for a subsequent read_until operation to examine.

read_until() [17/18]

template<typename SyncReadStream , typename DynamicBuffer_v2 , typename MatchCondition >

std::size_t asio::read_until ( SyncReadStream &  s, DynamicBuffer_v2  buffers, MatchCondition  match_condition, typename enable_if< is_match_condition< MatchCondition >::value &&is_dynamic_buffer_v2< DynamicBuffer_v2 >::value >::type *  = 0  )

inline

Read data into a dynamic buffer sequence until a function object indicates a match.

This function is used to read data into the specified dynamic buffer sequence until a user-defined match condition function object, when applied to the data contained in the dynamic buffer sequence, indicates a successful match. The call will block until one of the following conditions is true:

• The match condition function object returns a std::pair where the second element evaluates to true.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the match condition function object already indicates a match, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
buffers	A dynamic buffer sequence into which the data will be read.
match_condition	The function object to be called to determine whether a match exists. The signature of the function object must be: pair<iterator, bool> match_condition(iterator begin, iterator end); where iterator represents the type: buffers_iterator<typename DynamicBuffer_v2::const_buffers_type> The iterator parameters begin and end define the range of bytes to be scanned to determine whether there is a match. The first member of the return value is an iterator marking one-past-the-end of the bytes that have been consumed by the match function. This iterator is used to calculate the begin parameter for any subsequent invocation of the match condition. The second member of the return value is true if a match has been found, false otherwise.

Returns

The number of bytes in the dynamic_buffer's get area that have been fully consumed by the match function.

Exceptions

asio::system_error

Thrown on failure.

Note

After a successful read_until operation, the dynamic buffer sequence may contain additional data beyond that which matched the function object. An application will typically leave that data in the dynamic buffer sequence for a subsequent read_until operation to examine.

The default implementation of the is_match_condition type trait evaluates to true for function pointers and function objects with a result_type typedef. It must be specialised for other user-defined function objects.

Examples

To read data into a dynamic buffer sequence until whitespace is encountered:

 typedef asio::buffers_iterator<
    asio::const_buffers_1> iterator;

std::pair<iterator, bool>
match_whitespace(iterator begin, iterator end)
{
  iterator i = begin;
  while (i != end)
    if (std::isspace(*i++))
      return std::make_pair(i, true);
  return std::make_pair(i, false);
}
...
std::string data;
asio::read_until(s, data, match_whitespace);

To read data into a std::string until a matching character is found:

 class match_char
{
public:
  explicit match_char(char c) : c_(c) {}

  template <typename Iterator>
  std::pair<Iterator, bool> operator()(
      Iterator begin, Iterator end) const
  {
    Iterator i = begin;
    while (i != end)
      if (c_ == *i++)
        return std::make_pair(i, true);
    return std::make_pair(i, false);
  }

private:
  char c_;
};

namespace asio {
  template <> struct is_match_condition<match_char>
    : public boost::true_type {};
} // namespace asio
...
std::string data;
asio::read_until(s, data, match_char('a'));

read_until() [18/18]

template<typename SyncReadStream , typename DynamicBuffer_v2 , typename MatchCondition >

std::size_t asio::read_until	(	SyncReadStream &	s,
		DynamicBuffer_v2	buffers,
		MatchCondition	match_condition,
		asio::error_code &	ec,
		typename enable_if< is_match_condition< MatchCondition >::value &&is_dynamic_buffer_v2< DynamicBuffer_v2 >::value >::type *	= 0
	)

Read data into a dynamic buffer sequence until a function object indicates a match.

This function is used to read data into the specified dynamic buffer sequence until a user-defined match condition function object, when applied to the data contained in the dynamic buffer sequence, indicates a successful match. The call will block until one of the following conditions is true:

• The match condition function object returns a std::pair where the second element evaluates to true.

• An error occurred.

This operation is implemented in terms of zero or more calls to the stream's read_some function. If the match condition function object already indicates a match, the function returns immediately.

Parameters

s	The stream from which the data is to be read. The type must support the SyncReadStream concept.
buffers	A dynamic buffer sequence into which the data will be read.
match_condition	The function object to be called to determine whether a match exists. The signature of the function object must be: pair<iterator, bool> match_condition(iterator begin, iterator end); where iterator represents the type: buffers_iterator<DynamicBuffer_v2::const_buffers_type> The iterator parameters begin and end define the range of bytes to be scanned to determine whether there is a match. The first member of the return value is an iterator marking one-past-the-end of the bytes that have been consumed by the match function. This iterator is used to calculate the begin parameter for any subsequent invocation of the match condition. The second member of the return value is true if a match has been found, false otherwise.
ec	Set to indicate what error occurred, if any.

Returns

The number of bytes in the dynamic buffer sequence's get area that have been fully consumed by the match function. Returns 0 if an error occurred.

Note

After a successful read_until operation, the dynamic buffer sequence may contain additional data beyond that which matched the function object. An application will typically leave that data in the dynamic buffer sequence for a subsequent read_until operation to examine.

The default implementation of the is_match_condition type trait evaluates to true for function pointers and function objects with a result_type typedef. It must be specialised for other user-defined function objects.