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 lexbuf and the beginning of the line); pos_cnum is the offset of the position (number of
       characters between the beginning of the lexbuf and the position).  The difference  between  pos_cnum  and
       pos_bol  is  the character offset within the line (i.e. the column number, assuming each character is one
       column wide).

       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.

OCamldoc                                           2016-05-05                                         Lexing(3o)