package ppxlib

The abstract type of buffers.

create n 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.

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

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

• since 4.02

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.

Buffer.blit src srcoff dst dstoff len copies len characters from the current contents of the buffer src, starting at offset srcoff to dst, starting at character dstoff.

Raise Invalid_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.

• since 3.11.2

Get the n-th character of the buffer. Raise Invalid_argument if index out of bounds

Return the number of characters currently contained in the buffer.

Empty the buffer.

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.create n. For long-lived buffers that may have grown a lot, reset allows faster reclamation of the space used by the buffer.

add_char b c appends the character c at the end of buffer b.

add_utf_8_uchar b u appends the UTF-8 encoding of u at the end of buffer b.

• since 4.06.0

add_utf_16le_uchar b u appends the UTF-16LE encoding of u at the end of buffer b.

• since 4.06.0

add_utf_16be_uchar b u appends the UTF-16BE encoding of u at the end of buffer b.

• since 4.06.0

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

add_bytes b s appends the byte sequence s at the end of buffer b.

• since 4.02

add_substring b s ofs len takes len characters from offset ofs in string s and appends them at the end of buffer b.

add_subbytes b s ofs len takes len characters from offset ofs in byte sequence s and appends them at the end of buffer b.

• since 4.02

add_substitute b f s appends the string pattern s at the end of 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 $. Raise Not_found if the closing character of a parenthesized variable cannot be found.

add_buffer b1 b2 appends the current contents of buffer b2 at the end of buffer b1. b2 is not modified.

add_channel b ic n reads at most n characters 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. In this case, the characters are still added to the buffer, so as to avoid loss of data.

output_buffer oc b writes the current contents of buffer b on the output channel oc.

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

• since 4.05.0