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).
The abstract type of buffers.
val create :
int -> t
create n returns a fresh buffer, initially empty.
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.
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 nth :
t -> int -> char
get the n-th character of the buffer. Raise
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
n that was allocated by
For long-lived buffers that may have grown a lot,
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
val add_string :
t -> string -> unit
add_string b s appends the string
s at the end of the buffer
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
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:
$character is a
$that immediately follows a backslash character; it then stands for a plain
Not_foundif 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
at the end of buffer
b2 is not modified.
val add_channel :
t -> Stdlib.in_channel -> int -> unit
add_channel b ic n reads exactly
n character from the
ic and stores them at the end of buffer
End_of_file if the channel contains fewer than
val output_buffer :
Stdlib.out_channel -> t -> unit
output_buffer oc b writes the current contents of buffer
on the output channel