Module Buffer

module Buffer: sig .. end

Extensible buffers.

This module implements 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).

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 byte sequence that holds the buffer contents. That byte sequence 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. If n is not between 1 and Sys.max_string_length, it will be clipped to that interval.

val contents : t -> string

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

val to_bytes : t -> bytes

Return a copy of the current contents of the buffer. The buffer itself is unchanged.
Since 4.02

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

Buffer.sub b off len returns a copy of len bytes from the current contents of the buffer b, starting at offset off.

Raise Invalid_argument if srcoff and len do not designate a valid range of b.

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

Buffer.blit src srcoff dst dstoff len copies len characters from the current contents of the buffer src, starting at offset srcoff to dst, starting at character dstoff.

Raise Invalid_argument if srcoff and len do not designate a valid range of src, or if dstoff and len do not designate a valid range of dst.
Since 3.11.2

val nth : t -> int -> char

Get the 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 byte sequence holding the buffer contents, replacing it with the initial internal byte sequence of length n that was allocated by Buffer.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 buffer b.

val add_string : t -> string -> unit

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

val add_bytes : t -> bytes -> unit

add_bytes b s appends the byte sequence s at the end of buffer b.
Since 4.02

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 buffer b.

val add_subbytes : t -> bytes -> int -> int -> unit

add_subbytes b s ofs len takes len characters from offset ofs in byte sequence s and appends them at the end of buffer b.
Since 4.02

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

add_substitute b f s appends the string pattern s at the end of 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.

val add_channel : t -> in_channel -> int -> unit

add_channel b ic n reads at most n characters from the input channel ic and stores them at the end of buffer b. Raise End_of_file if the channel contains fewer than n characters. In this case, the characters are still added to the buffer, so as to avoid loss of data.

val output_buffer : out_channel -> t -> unit

output_buffer oc b writes the current contents of buffer b on the output channel oc.

The present documentation is copyright Institut National de Recherche en Informatique et en Automatique (INRIA). A complete version can be obtained from this page.