Module Buffer
: sigend
Extensible buffers.
This module implements buffers that automatically expand as necessary. It provides accumulative
concatenation of strings in linear time (instead of quadratic time when strings are concatenated
pairwise). For example:
letconcat_stringsss=letb=Buffer.create16inList.iter(Buffer.add_stringb)ss;Buffer.contentsbAlertunsynchronized_access. Unsynchronized accesses to buffers are a programming error.
Unsynchronized accesses
Unsynchronized accesses to a buffer may lead to an invalid buffer state. Thus, concurrent accesses to a
buffer must be synchronized (for instance with a Mutex.t ).
typet
The abstract type of buffers.
valcreate : int->tcreaten returns a fresh buffer, initially empty. The n parameter is the initial size of the internal
byte sequence that holds the buffer contents. That byte sequence 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.
valcontents : t->string
Return a copy of the current contents of the buffer. The buffer itself is unchanged.
valto_bytes : t->bytes
Return a copy of the current contents of the buffer. The buffer itself is unchanged.
Since 4.02
valsub : t->int->int->stringBuffer.subbofflen returns a copy of len bytes from the current contents of the buffer b , starting at
offset off .
RaisesInvalid_argument if off and len do not designate a valid range of b .
valblit : t->int->bytes->int->int->unitBuffer.blitsrcsrcoffdstdstofflen copies len characters from the current contents of the buffer src ,
starting at offset srcoff to dst , starting at character dstoff .
Since 3.11.2
RaisesInvalid_argument if srcoff and len do not designate a valid range of src , or if dstoff and len do
not designate a valid range of dst .
valnth : t->int->char
Get the n-th character of the buffer.
RaisesInvalid_argument if index out of bounds
vallength : t->int
Return the number of characters currently contained in the buffer.
valclear : t->unit
Empty the buffer.
valreset : t->unit
Empty the buffer and deallocate the internal byte sequence holding the buffer contents, replacing it with
the initial internal byte sequence of length n that was allocated by Buffer.createn . For long-lived
buffers that may have grown a lot, reset allows faster reclamation of the space used by the buffer.
valoutput_buffer : out_channel->t->unitoutput_bufferocb writes the current contents of buffer b on the output channel oc .
valtruncate : t->int->unittruncateblen truncates the length of b to len Note: the internal byte sequence is not shortened.
Since 4.05
RaisesInvalid_argument if len<0 or len>lengthb .
Appending
Note: all add_* operations can raise Failure if the internal byte sequence of the buffer would need to
grow beyond Sys.max_string_length .
valadd_char : t->char->unitadd_charbc appends the character c at the end of buffer b .
valadd_utf_8_uchar : t->Uchar.t->unitadd_utf_8_ucharbu appends the UTF-8 encoding of u at the end of buffer b .
Since 4.06
valadd_utf_16le_uchar : t->Uchar.t->unitadd_utf_16le_ucharbu appends the UTF-16LE encoding of u at the end of buffer b .
Since 4.06
valadd_utf_16be_uchar : t->Uchar.t->unitadd_utf_16be_ucharbu appends the UTF-16BE encoding of u at the end of buffer b .
Since 4.06
valadd_string : t->string->unitadd_stringbs appends the string s at the end of buffer b .
valadd_bytes : t->bytes->unitadd_bytesbs appends the byte sequence s at the end of buffer b .
Since 4.02
valadd_substring : t->string->int->int->unitadd_substringbsofslen takes len characters from offset ofs in string s and appends them at the end of
buffer b .
RaisesInvalid_argument if ofs and len do not designate a valid range of s .
valadd_subbytes : t->bytes->int->int->unitadd_subbytesbsofslen takes len characters from offset ofs in byte sequence s and appends them at the
end of buffer b .
Since 4.02
RaisesInvalid_argument if ofs and len do not designate a valid range of s .
valadd_substitute : t->(string->string)->string->unitadd_substitutebfs appends the string pattern s at the end of buffer b with substitution. The
substitution process looks for variable references in the pattern and substitutes each variable reference
with its value, as obtained by applying the mapping f to the variable name. Inside the string pattern, a
variable reference is a non-escaped $ immediately followed by a variable name, which 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; the two characters together
stand for a plain $ .
valadd_buffer : t->t->unitadd_bufferb1b2 appends the current contents of buffer b2 at the end of buffer b1 . b2 is not modified.
valadd_channel : t->in_channel->int->unitadd_channelbicn reads at most n characters from the input channel ic and stores them at the end of
buffer b .
RaisesEnd_of_file if the channel contains fewer than n characters. In this case, the characters are
still added to the buffer, so as to avoid loss of data.
RaisesInvalid_argument if len<0 or len>Sys.max_string_length .
BuffersandSequencesvalto_seq : t->charSeq.t
Iterate on the buffer, in increasing order.
The behavior is not specified if the buffer is modified during iteration.
Since 4.07
valto_seqi : t->(int*char)Seq.t
Iterate on the buffer, in increasing order, yielding indices along chars.
The behavior is not specified if the buffer is modified during iteration.
Since 4.07
valadd_seq : t->charSeq.t->unit
Add chars to the buffer
Since 4.07
valof_seq : charSeq.t->t
Create a buffer from the generator
Since 4.07
Binaryencodingofintegers
The functions in this section append binary encodings of integers to buffers.
Little-endian (resp. big-endian) encoding means that least (resp. most) significant bytes are stored
first. Big-endian is also known as network byte order. Native-endian encoding is either little-endian
or big-endian depending on Sys.big_endian .
32-bit and 64-bit integers are represented by the int32 and int64 types, which can be interpreted either
as signed or unsigned numbers.
8-bit and 16-bit integers are represented by the int type, which has more bits than the binary encoding.
Functions that encode these values truncate their inputs to their least significant bytes.
valadd_uint8 : t->int->unitadd_uint8bi appends a binary unsigned 8-bit integer i to b .
Since 4.08
valadd_int8 : t->int->unitadd_int8bi appends a binary signed 8-bit integer i to b .
Since 4.08
valadd_uint16_ne : t->int->unitadd_uint16_nebi appends a binary native-endian unsigned 16-bit integer i to b .
Since 4.08
valadd_uint16_be : t->int->unitadd_uint16_bebi appends a binary big-endian unsigned 16-bit integer i to b .
Since 4.08
valadd_uint16_le : t->int->unitadd_uint16_lebi appends a binary little-endian unsigned 16-bit integer i to b .
Since 4.08
valadd_int16_ne : t->int->unitadd_int16_nebi appends a binary native-endian signed 16-bit integer i to b .
Since 4.08
valadd_int16_be : t->int->unitadd_int16_bebi appends a binary big-endian signed 16-bit integer i to b .
Since 4.08
valadd_int16_le : t->int->unitadd_int16_lebi appends a binary little-endian signed 16-bit integer i to b .
Since 4.08
valadd_int32_ne : t->int32->unitadd_int32_nebi appends a binary native-endian 32-bit integer i to b .
Since 4.08
valadd_int32_be : t->int32->unitadd_int32_bebi appends a binary big-endian 32-bit integer i to b .
Since 4.08
valadd_int32_le : t->int32->unitadd_int32_lebi appends a binary little-endian 32-bit integer i to b .
Since 4.08
valadd_int64_ne : t->int64->unitadd_int64_nebi appends a binary native-endian 64-bit integer i to b .
Since 4.08
valadd_int64_be : t->int64->unitadd_int64_bebi appends a binary big-endian 64-bit integer i to b .
Since 4.08
valadd_int64_le : t->int64->unitadd_int64_nebi appends a binary little-endian 64-bit integer i to b .
Since 4.08
OCamldoc 2025-06-12 Buffer(3o)
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