1Buffer(3)                          OCamldoc                          Buffer(3)
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NAME

6       Buffer - Extensible buffers.
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Module

9       Module   Buffer
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Documentation

12       Module Buffer
13        : sig end
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15
16       Extensible buffers.
17
18       This  module implements buffers that automatically expand as necessary.
19       It provides accumulative concatenation of strings in quasi-linear  time
20       (instead of quadratic time when strings are concatenated pairwise).
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24
25
26       type t
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28
29       The abstract type of buffers.
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33       val create : int -> t
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35
36       create  n  returns a fresh buffer, initially empty.  The n parameter is
37       the initial size of the internal byte sequence that  holds  the  buffer
38       contents.  That  byte  sequence  is automatically reallocated when more
39       than n characters are stored in the buffer, but shrinks back to n char‐
40       acters  when reset is called.  For best performance, n should be of the
41       same order of magnitude as the number of characters that  are  expected
42       to  be  stored  in the buffer (for instance, 80 for a buffer that holds
43       one output line).  Nothing bad will happen if the buffer  grows  beyond
44       that  limit,  however. In doubt, take n = 16 for instance.  If n is not
45       between 1 and Sys.max_string_length , it will be clipped to that inter‐
46       val.
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48
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50       val contents : t -> string
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52       Return a copy of the current contents of the buffer.  The buffer itself
53       is unchanged.
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57       val to_bytes : t -> bytes
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59       Return a copy of the current contents of the buffer.  The buffer itself
60       is unchanged.
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63       Since 4.02
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67       val sub : t -> int -> int -> string
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70       Buffer.sub  b off len returns a copy of len bytes from the current con‐
71       tents of the buffer b , starting at offset off .
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73       Raise Invalid_argument if srcoff and len do not designate a valid range
74       of b .
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78       val blit : t -> int -> bytes -> int -> int -> unit
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81       Buffer.blit  src  srcoff  dst dstoff len copies len characters from the
82       current contents of the buffer src , starting at offset srcoff to dst ,
83       starting at character dstoff .
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85       Raise Invalid_argument if srcoff and len do not designate a valid range
86       of src , or if dstoff and len do not designate a valid range of dst .
87
88
89       Since 3.11.2
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93       val nth : t -> int -> char
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95       Get the n-th character of the buffer. Raise Invalid_argument  if  index
96       out of bounds
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100       val length : t -> int
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102       Return the number of characters currently contained in the buffer.
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106       val clear : t -> unit
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108       Empty the buffer.
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112       val reset : t -> unit
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114       Empty  the buffer and deallocate the internal byte sequence holding the
115       buffer contents, replacing it with the initial internal  byte  sequence
116       of  length  n  that  was allocated by Buffer.create n .  For long-lived
117       buffers that may have grown a lot, reset allows faster  reclamation  of
118       the space used by the buffer.
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122       val add_char : t -> char -> unit
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125       add_char b c appends the character c at the end of buffer b .
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129       val add_string : t -> string -> unit
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132       add_string b s appends the string s at the end of buffer b .
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136       val add_bytes : t -> bytes -> unit
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139       add_bytes b s appends the byte sequence s at the end of buffer b .
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141
142       Since 4.02
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146       val add_substring : t -> string -> int -> int -> unit
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149       add_substring  b  s  ofs  len  takes  len characters from offset ofs in
150       string s and appends them at the end of buffer b .
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154       val add_subbytes : t -> bytes -> int -> int -> unit
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156
157       add_subbytes b s ofs len takes len characters from offset ofs  in  byte
158       sequence s and appends them at the end of buffer b .
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160
161       Since 4.02
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164
165       val add_substitute : t -> (string -> string) -> string -> unit
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168       add_substitute  b f s appends the string pattern s at the end of buffer
169       b with substitution.  The substitution process looks for variables into
170       the  pattern  and  substitutes  each  variable  name  by  its value, as
171       obtained by applying the mapping f to the  variable  name.  Inside  the
172       string  pattern,  a  variable  name immediately follows a non-escaped $
173       character and is one of the following:
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175       -a non empty sequence of alphanumeric or _ characters,
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177       -an arbitrary sequence of characters enclosed by  a  pair  of  matching
178       parentheses  or  curly  brackets.   An  escaped $ character is a $ that
179       immediately follows a backslash character; it then stands for a plain $
180       .  Raise Not_found if the closing character of a parenthesized variable
181       cannot be found.
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186       val add_buffer : t -> t -> unit
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188
189       add_buffer b1 b2 appends the current contents of buffer b2 at  the  end
190       of buffer b1 .  b2 is not modified.
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194       val add_channel : t -> Pervasives.in_channel -> int -> unit
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197       add_channel b ic n reads at most n characters from the input channel ic
198       and stores them at the end of buffer b  .   Raise  End_of_file  if  the
199       channel  contains fewer than n characters. In this case, the characters
200       are still added to the buffer, so as to avoid loss of data.
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204       val output_buffer : Pervasives.out_channel -> t -> unit
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206
207       output_buffer oc b writes the current contents of buffer b on the  out‐
208       put channel oc .
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212       val truncate : t -> int -> unit
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215       truncate b len truncates the length of b to len Note: the internal byte
216       sequence is not shortened.  Raise Invalid_argument if len < 0 or len  >
217       length b .
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219
220       Since 4.05.0
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2262018-04-14                          source:                          Buffer(3)