Ocamlnet 4 Reference Manual : Netbuffer

# Module Netbuffer

    module Netbuffer: sig .. end

A Netbuffer.t is a buffer that can grow and shrink dynamically.

    type t

    val create : int -> t

Creates a netbuffer which allocates initially this number of bytes. The logical length is zero.

    val contents : t -> string

Returns the contents of the buffer as fresh string.

    val length : t -> int

Returns the logical length of the buffer

## Extracting strings

    val get : t -> int -> char

`get nb pos`: Get the character at `pos`

    val nth : t -> int -> char

Alias for `get`

    val sub : t -> int -> int -> string

`sub nb k n`: returns the n characters starting at position `n` from netbuffer `nb` as fresh string

    val blit_to_string : t -> int -> string -> int -> int -> unit

`blit_to_string nb srcpos dest destpos len`: Copies the `len` bytes at position `srcpos` from `nb` to the string `dest` at position `destpos`.

    val blit : t -> int -> string -> int -> int -> unit

Compatibility name for `blit_to_string`, now deprecated

## Appending strings

    val add_string : t -> string -> unit

`add_string nb s`: Adds a copy of the string `s` to the logical end of the netbuffer `nb`. If necessary, `nb` grows.

    val add_sub_string : t -> string -> int -> int -> unit

`add_sub_string nb s k n`: Adds the substring of `s` starting at position `k` with length `n` to the logical end of the netbuffer `nb`. If necessary, `nb` grows.

This is semantically the same as `add_string nb (String.sub s k n)`, but the extra copy is avoided.

    val add_substring : t -> string -> int -> int -> unit

Alias for add_sub_string

    val add_char : t -> char -> unit

`add_char nb c`: Adds a single char at the end of the buffer

    val add_char_2 : t -> char -> char -> unit

`add_char_2 nb c1 c2`: Adds two chars at the end of the buffer

    val add_char_4 : t -> char -> char -> char -> char -> unit

`add_char_4 nb c1 c2 c3 c4`: Adds four chars at the end of the buffer

    val add_inplace : ?len:int -> t -> (string -> int -> int -> int) -> int

`add_inplace nb f`: Calls the function `f` to add bytes to the netbuffer `nb`. The arguments of `f` are the buffer, the position in the buffer, and the maximum length. The function `f` must return the actual number of added bytes; this number is also returned by `add_inplace`.

Example: let n = add_inplace nb (Pervasives.input ch)

The argument `len` is the number of bytes to add (second argument of `f`). It defaults to the number of free bytes in the buffer after space for at least one byte has been allocated.

    val add_buffer : t -> t -> unit

`add_buffer nb1 nb2`: Adds the contents of `nb2` to the end of `nb1`

    val area_for_additions : ?len:int -> t -> string * int * int

    val advance : t -> int -> unit

These two functions work together, so that the effect of `add_inplace` can be obtained in two steps. First, the user calls

            let (s,pos,len) = area_for_additions nb

to get the area where to put new data of length `n`, with `n <= len`. After this the data is made valid by

            advance n

## Inserting strings

    val insert_string : t -> int -> string -> unit

`insert_string nb p s`: Inserts the value of string `s` at position `p` into the netbuffer `nb`

    val insert_sub_string : t -> int -> string -> int -> int -> unit

`insert_string nb p s k n`: Inserts a substring of string `s` at position `p` into the netbuffer `nb`. The substring is denoted by position `k` and has length `n`

    val insert_char : t -> int -> char -> unit

`insert_char nb p c`: Inserts character `c` at position `p` into the netbuffer `nb`

## Overwriting strings

    val set : t -> int -> char -> unit

`set nb pos c`: Sets the character at `pos` to `c`

    val put_string : t -> int -> string -> unit

`put_string nb pos s`: Copies the string `s` to the position `pos` of netbuffer `nb`

    val blit_from_string : string -> int -> t -> int -> int -> unit

`blit_from_string src srcpos dest destpos len`: Copies the `len` bytes at position `srcpos` from the string `src` to the netbuffer `dest` at position `destpos`.

It is possible to copy the string beyond the end of the buffer. The buffer is automatically enlarged in this case.

## Deleting

    val delete : t -> int -> int -> unit

`delete nb k n`: Deletes the `n` bytes at position `k` of netbuffer `nb` in-place.

The netbuffer does not shrink, however, i.e. the free space is not given back to the memory manager.

    val clear : t -> unit

Deletes all contents from the buffer. As `delete`, the netbuffer does not shrink.

    val reset : t -> unit

Empty the buffer, deallocate the internal string, and replace it with a new string of length `n` that was allocated by `Netbuffer.create` `n`.

    val try_shrinking : t -> unit

`try_shrinking nb`: If the length of the buffer is less than half of the allocated space, the netbuffer is reallocated in order to save memory.

## Searching

    val index_from : t -> int -> char -> int

`index_from nb k c`: Searches the character `c` in the netbuffer beginning at position `k`. If found, the position of the left-most occurence is returned. Otherwise, `Not_found` is raised.

## Memory

    val blit_to_memory : t -> int -> Netsys_mem.memory -> int -> int -> unit

`blit_to_memory nb srcpos dest destpos len`: Copies the `len` bytes at position `srcpos` from `nb` to the membuffer `dest` at position `destpos`.

    val add_sub_memory : t -> Netsys_mem.memory -> int -> int -> unit

Same as `add_sub_string`, but gets data from a memory buffer

## Miscelleneous

    val unsafe_buffer : t -> string

Warning! This is a low-level function! Returns the current string that internally holds the buffer. The byte positions 0 to length - 1 actually store the contents of the buffer. You can directly read and modify the buffer. Note that there is no protection if you read or write positions beyond the length of the buffer.

    val print_buffer : t -> unit

For the toploop