### async_read

The `async_read` function is a composed asynchronous operation that reads a certain amount of data from a stream before completion.

Start an asynchronous operation to read a certain amount of data from a stream.

    template<
        typename AsyncReadStream,
        typename MutableBufferSequence,
        typename ReadToken = default_completion_token_t<        typename AsyncReadStream::executor_type>>
    DEDUCED async_read(
        AsyncReadStream & s,
        const MutableBufferSequence & buffers,
        ReadToken && token = default_completion_token_t< typename AsyncReadStream::executor_type >(),
        constraint_t< is_mutable_buffer_sequence< MutableBufferSequence >::value >  = 0,
        constraint_t< !is_completion_condition< ReadToken >::value >  = 0);
      » more...

    template<
        typename AsyncReadStream,
        typename MutableBufferSequence,
        typename CompletionCondition,
        typename ReadToken = default_completion_token_t<        typename AsyncReadStream::executor_type>>
    DEDUCED async_read(
        AsyncReadStream & s,
        const MutableBufferSequence & buffers,
        CompletionCondition completion_condition,
        ReadToken && token = default_completion_token_t< typename AsyncReadStream::executor_type >(),
        constraint_t< is_mutable_buffer_sequence< MutableBufferSequence >::value >  = 0,
        constraint_t< is_completion_condition< CompletionCondition >::value >  = 0);
      » more...

    template<
        typename AsyncReadStream,
        typename DynamicBuffer_v1,
        typename ReadToken = default_completion_token_t<        typename AsyncReadStream::executor_type>>
    DEDUCED async_read(
        AsyncReadStream & s,
        DynamicBuffer_v1 && buffers,
        ReadToken && token = default_completion_token_t< typename AsyncReadStream::executor_type >(),
        constraint_t< is_dynamic_buffer_v1< decay_t< DynamicBuffer_v1 > >::value >  = 0,
        constraint_t< !is_dynamic_buffer_v2< decay_t< DynamicBuffer_v1 > >::value >  = 0,
        constraint_t< !is_completion_condition< ReadToken >::value >  = 0);
      » more...

    template<
        typename AsyncReadStream,
        typename DynamicBuffer_v1,
        typename CompletionCondition,
        typename ReadToken = default_completion_token_t<        typename AsyncReadStream::executor_type>>
    DEDUCED async_read(
        AsyncReadStream & s,
        DynamicBuffer_v1 && buffers,
        CompletionCondition completion_condition,
        ReadToken && token = default_completion_token_t< typename AsyncReadStream::executor_type >(),
        constraint_t< is_dynamic_buffer_v1< decay_t< DynamicBuffer_v1 > >::value >  = 0,
        constraint_t< !is_dynamic_buffer_v2< decay_t< DynamicBuffer_v1 > >::value >  = 0,
        constraint_t< is_completion_condition< CompletionCondition >::value >  = 0);
      » more...

    template<
        typename AsyncReadStream,
        typename Allocator,
        typename ReadToken = default_completion_token_t<        typename AsyncReadStream::executor_type>>
    DEDUCED async_read(
        AsyncReadStream & s,
        basic_streambuf< Allocator > & b,
        ReadToken && token = default_completion_token_t< typename AsyncReadStream::executor_type >(),
        constraint_t< !is_completion_condition< ReadToken >::value >  = 0);
      » more...

    template<
        typename AsyncReadStream,
        typename Allocator,
        typename CompletionCondition,
        typename ReadToken = default_completion_token_t<        typename AsyncReadStream::executor_type>>
    DEDUCED async_read(
        AsyncReadStream & s,
        basic_streambuf< Allocator > & b,
        CompletionCondition completion_condition,
        ReadToken && token = default_completion_token_t< typename AsyncReadStream::executor_type >(),
        constraint_t< is_completion_condition< CompletionCondition >::value >  = 0);
      » more...

    template<
        typename AsyncReadStream,
        typename DynamicBuffer_v2,
        typename ReadToken = default_completion_token_t<        typename AsyncReadStream::executor_type>>
    DEDUCED async_read(
        AsyncReadStream & s,
        DynamicBuffer_v2 buffers,
        ReadToken && token = default_completion_token_t< typename AsyncReadStream::executor_type >(),
        constraint_t< is_dynamic_buffer_v2< DynamicBuffer_v2 >::value >  = 0,
        constraint_t< !is_completion_condition< ReadToken >::value >  = 0);
      » more...

    template<
        typename AsyncReadStream,
        typename DynamicBuffer_v2,
        typename CompletionCondition,
        typename ReadToken = default_completion_token_t<        typename AsyncReadStream::executor_type>>
    DEDUCED async_read(
        AsyncReadStream & s,
        DynamicBuffer_v2 buffers,
        CompletionCondition completion_condition,
        ReadToken && token = default_completion_token_t< typename AsyncReadStream::executor_type >(),
        constraint_t< is_dynamic_buffer_v2< DynamicBuffer_v2 >::value >  = 0,
        constraint_t< is_completion_condition< CompletionCondition >::value >  = 0);
      » more...

##### Requirements

Header: `asio/read.hpp`

Convenience header: `asio.hpp`