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NAME

       Lexing - The run-time library for lexers generated by ocamllex.

Module

       Module   Lexing

Documentation

       Module Lexing
        : sig end

       The run-time library for lexers generated by ocamllex .

       === Positions ===

       type position = {
        pos_fname : string ;
        pos_lnum : int ;
        pos_bol : int ;
        pos_cnum : int ;
        }

       A  value of type position describes a point in a source file.  pos_fname is the file name;
       pos_lnum is the line number; pos_bol is the offset of the beginning of the line (number of
       characters  between  the beginning of the file and the beginning of the line); pos_cnum is
       the offset of the position (number of characters between the beginning of the file and the
       position).

       See  the  documentation  of  type  lexbuf for information about how the lexing engine will
       manage positions.

       val dummy_pos : position

       A value of type position , guaranteed to be different from any valid position.

       === Lexer buffers ===

       type lexbuf = {
        refill_buff : lexbuf -> unit ;

       mutable lex_buffer : string ;

       mutable lex_buffer_len : int ;

       mutable lex_abs_pos : int ;

       mutable lex_start_pos : int ;

       mutable lex_curr_pos : int ;

       mutable lex_last_pos : int ;

       mutable lex_last_action : int ;

       mutable lex_eof_reached : bool ;

       mutable lex_mem : int array ;

       mutable lex_start_p : position ;

       mutable lex_curr_p : position ;
        }

       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.

       At each token, the lexing engine will copy lex_curr_p to lex_start_p  ,  then  change  the
       pos_cnum  field  of lex_curr_p by updating it with the number of characters read since the
       start of the lexbuf .  The other fields are left unchanged by the lexing engine.  In order
       to  keep  them  accurate, they must be initialised before the first use of the lexbuf, and
       updated by the relevant lexer actions (i.e. at each end of line -- see also new_line ).

       val from_channel : Pervasives.in_channel -> lexbuf

       Create a lexer buffer on the given input channel.  Lexing.from_channel  inchan  returns  a
       lexer buffer which reads from the input channel inchan , at the current reading position.

       val from_string : string -> lexbuf

       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.

       val from_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 function.
       ===

       val lexeme : lexbuf -> string

       Lexing.lexeme lexbuf returns the string matched by the regular expression.

       val lexeme_char : lexbuf -> int -> char

       Lexing.lexeme_char lexbuf i returns character number i in the matched string.

       val lexeme_start : lexbuf -> int

       Lexing.lexeme_start lexbuf returns the offset in the input stream of the  first  character
       of the matched string.  The first character of the stream has offset 0.

       val lexeme_end : lexbuf -> int

       Lexing.lexeme_end lexbuf returns the offset in the input stream of the character following
       the last character of the matched string. The first character of the stream has offset 0.

       val lexeme_start_p : lexbuf -> position

       Like lexeme_start , but return a complete position instead of an offset.

       val lexeme_end_p : lexbuf -> position

       Like lexeme_end , but return a complete position instead of an offset.

       val new_line : lexbuf -> unit

       Update the lex_curr_p field of the lexbuf to reflect the start of a  new  line.   You  can
       call  this  function  in  the  semantic  action  of  the rule that matches the end-of-line
       character.

       Since 3.11.0

       === Miscellaneous functions ===

       val flush_input : lexbuf -> unit

       Discard the contents of the buffer and reset the current position to 0.  The next  use  of
       the lexbuf will trigger a refill.