NAME¶
Buffer - Extensible string buffers.
Module¶
Module Buffer
Documentation¶
Module
Buffer
:
sig end
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 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. 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 sub :
t -> int -> int -> string
Buffer.sub b off len returns (a copy of) the substring of 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.
val blit :
t -> int -> string -> 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 string
dst , starting at character
dstoff .
Raise
Invalid_argument if
srcoff and
len do not designate a
valid substring of
src , or if
dstoff and
len do not
designate a valid substring 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 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 :
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.
val 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.
val output_buffer :
Pervasives.out_channel -> t -> unit
output_buffer oc b writes the current contents of buffer
b on the
output channel
oc .