The type of lexer buffers. A lexer buffer is the argument passed
to the scanning functions defined by the generated scanners.
The lexer buffer holds the current state of the scanner, plus
a function to refill the buffer from the input.
Create a lexer buffer which reads from
the given string. Reading starts from the first character in
the string. An end-of-input condition is generated when the
end of the string is reached.
valfrom_function : (string -> int -> int) -> lexbuf
Create a lexer buffer with the given function as its reading method.
When the scanner needs more characters, it will call the given
function, giving it a character string s and a character
count n. The function should put n characters or less in s,
starting at character number 0, and return the number of characters
provided. A return value of 0 means end of input.
Functions for lexer semantic actions
The following functions can be called from the semantic actions
of lexer definitions (the ML code enclosed in braces that
computes the value returned by lexing functions). They give
access to the character string matched by the regular expression
associated with the semantic action. These functions must be
applied to the argument lexbuf, which, in the code generated by
ocamllex, is bound to the lexer buffer passed to the parsing