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.
let 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.
let contents: t => string;
Return a copy of the current contents of the buffer. The buffer itself is unchanged.
let to_bytes: t => bytes;
Return a copy of the current contents of the buffer. The buffer itself is unchanged.
Since 4.02
let sub: (t, int, int) => string;
Buffer.sub b off len returns (a copy of) the bytes from the current contents of the buffer b starting at offset off of length len bytes. May raise Invalid_argument if out of bounds request. The buffer itself is unaffected.
let 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

let nth: (t, int) => char;
get the n-th character of the buffer. Raise Invalid_argument if index out of bounds
let length: t => int;
Return the number of characters currently contained in the buffer.
let clear: t => unit;
Empty the buffer.
let 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.
let add_char: (t, char) => unit;
add_char b c appends the character c at the end of the buffer b.
let add_string: (t, string) => unit;
add_string b s appends the string s at the end of the buffer b.
let add_bytes: (t, bytes) => unit;
add_string b s appends the string s at the end of the buffer b.
Since 4.02
let 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.
let add_subbytes: (t, bytes, int, int) => unit;
add_substring b s ofs len takes len characters from offset ofs in byte sequence s and appends them at the end of the buffer b.
Since 4.02
let 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:
let 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.
let add_channel: (t, Pervasives.in_channel, int) => unit;
add_channel b ic n reads exactly n character 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.
let output_buffer: (Pervasives.out_channel, t) => unit;
output_buffer oc b writes the current contents of buffer b on the output channel oc.