package batteries

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package batteries
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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).

  • author Pierre Weis (Base module)
  • author Xavier Leroy (Base module)
  • author David Teller
  • author Dawid Toton
type t = Buffer.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 to_bytes : t -> Bytes.t

Return a copy of the current contents of the buffer. The buffer itself is unchanged.

  • since 2.3.0
val sub : t -> int -> int -> string

Buffer.sub b off len returns a copy of len bytes from the current contents of the buffer b, starting at offset off.

Raise Invalid_argument if srcoff and len do not designate a valid range of b.

val blit : t -> int -> Bytes.t -> 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.

  • raises 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.

  • raises 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_bytes : t -> Bytes.t -> unit

add_bytes b s appends the string s at the end of the buffer b.

  • since 2.3.0
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_subbytes : t -> Bytes.t -> int -> int -> unit

add_subbytes 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 2.3.0
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 $.
  • raises 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_input : t -> BatInnerIO.input -> int -> unit

add_input b ic n reads exactly n character from the input ic and stores them at the end of buffer b.

  • raises End_of_file

    if the channel contains fewer than n characters.

val add_channel : t -> BatInnerIO.input -> int -> unit

@obsolete replaced by add_input

val output_buffer : t -> string BatInnerIO.output

output_buffer b creates an output channel that writes to that buffer, and when closed, returns the contents of the buffer.

val truncate : t -> int -> unit

truncate b len truncates the length of b to len Note: the internal byte sequence is not shortened. Raises Invalid_argument if len < 0 or len > length b.

  • since 2.7.0 and OCaml 4.05.0
Boilerplate code
val enum : t -> char BatEnum.t

Returns an enumeration of the characters of a buffer.

Contents of the enumeration is unspecified if the buffer is modified after the enumeration is returned.

val of_enum : char BatEnum.t -> t

Creates a buffer from a character enumeration.

val print : 'a BatInnerIO.output -> t -> unit