# Module Bigbuffer

    module Bigbuffer: sig .. end

Extensible string buffers based on Bigstrings.

This module implements string buffers that automatically expand as necessary. It provides accumulative concatenation of strings in quasi-linear time (instead of quadratic time when strings are concatenated pairwise).

This implementation uses Bigstrings instead of strings. This removes the 16MB limit on buffer size, and improves I/O-performance when reading/writing from/to channels.

    type t

The abstract type of buffers.

    val create : int -> t

`create n` returns a fresh buffer, initially empty. The `n` parameter is the initial size of the internal string that holds the buffer contents. That string is automatically reallocated when more than `n` characters are stored in the buffer, but shrinks back to `n` characters when `reset` is called. For best performance, `n` should be of the same order of magnitude as the number of characters that are expected to be stored in the buffer (for instance, 80 for a buffer that holds one output line). Nothing bad will happen if the buffer grows beyond that limit, however. In doubt, take `n = 16` for instance.

    val contents : t -> string

Return a copy of the current contents of the buffer. The buffer itself is unchanged.

    val big_contents : t -> Bigstring.t

Return a copy of the current contents of the buffer as a bigstring. The buffer itself is unchanged.

    val volatile_contents : t -> Bigstring.t

Return the actual underlying bigstring used by this bigbuffer. No copying is involved. To be safe, use and finish with the returned value before calling any other function in this module on the same `Bigbuffer.t`.

    include Blit.S_distinct

`blit ~src ~src_pos ~dst ~dst_pos ~len` copies `len` characters from the current contents of the buffer `src`, starting at offset `src_pos` to string `dst`, starting at character `dst_pos`.

Raise `Invalid_argument` if `src_pos` and `len` do not designate a valid substring of `src`, or if `dst_pos` and `len` do not designate a valid substring of `dst`.

    val nth : t -> int -> char

get the (zero-based) n-th character of the buffer. Raise `Invalid_argument` if index out of bounds

    val length : t -> int

Return the number of characters currently contained in the buffer.

    val clear : t -> unit

Empty the buffer.

    val reset : t -> unit

Empty the buffer and deallocate the internal string holding the buffer contents, replacing it with the initial internal string of length `n` that was allocated by `Bigbuffer.create` `n`. For long-lived buffers that may have grown a lot, `reset` allows faster reclamation of the space used by the buffer.

    val add_char : t -> char -> unit

`add_char b c` appends the character `c` at the end of the buffer `b`.

    val add_string : t -> string -> unit

`add_string b s` appends the string `s` at the end of the buffer `b`.

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

`add_substring b s ofs len` takes `len` characters from offset `ofs` in string `s` and appends them at the end of the buffer `b`.

    val add_substitute : t -> (string -> string) -> string -> unit

`add_substitute b f s` appends the string pattern `s` at the end of the buffer `b` with substitution. The substitution process looks for variables into the pattern and substitutes each variable name by its value, as obtained by applying the mapping `f` to the variable name. Inside the string pattern, a variable name immediately follows a non-escaped `$` character and is one of the following:

- a non empty sequence of alphanumeric or `_` characters,
- an arbitrary sequence of characters enclosed by a pair of matching parentheses or curly brackets. An escaped `$` character is a `$` that immediately follows a backslash character; it then stands for a plain `$`. Raise `Not_found` if the closing character of a parenthesized variable cannot be found.

    val add_buffer : t -> t -> unit

`add_buffer b1 b2` appends the current contents of buffer `b2` at the end of buffer `b1`. `b2` is not modified.
NOTE: additions

    module Format: sig .. end

    module Printf: sig .. end

For Core.Std.Bigbuffer, not for users!