module Buffer:Extensible string buffers.sig
..end
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
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
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 nth : t -> int -> char
Invalid_argument
if
index out of boundsval length : t -> int
val clear : t -> unit
val reset : t -> unit
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:_
characters,$
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
.