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5.3  Module Buffer

Extensible string buffers.

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).

type (='a:level, #'b:level) t
The abstract type of buffers.

val create : 'a int -> ('a, 'b) 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. If n is not between 1 and Sys.max_string_length, it will be clipped to that interval.

val contents : ('a, 'b) t -> 'b string
               with 'a < 'b
Return a copy of the current contents of the buffer. The buffer itself is unchanged.

val length : ('a, 'b) t -> 'b int
             with 'a < 'b
Return the number of characters currently contained in the buffer.

val clear : ('a, 'a) t -{'a ||}-> unit
Empty the buffer.

val reset : ('a, 'a) t -{'a ||}-> 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 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 : ('a, 'a) t -> 'a char -{'a ||}-> unit
add_char b c appends the character c at the end of the buffer b.

val add_substring : ('a, 'a) t ->
                    'a string -> 'a int -> 'a int -{'a ||}-> 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_string : ('a, 'a) t -> 'a string -{'a ||}-> unit
add_string b s appends the string s at the end of the buffer b.

val add_buffer : ('a, 'a) t -> ('b, 'a) t -{'a ||}-> unit
                 with 'b < 'a
add_buffer b1 b2 appends the current contents of buffer b2 at the end of buffer b1. b2 is not modified.

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