# Structure Lexing

Identifier index | Structure index
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    (* Lexing -- run-time library for lexers generated by mosmllex             *)
    (* Closely based on the library for camllex.  Copyright 1993 INRIA, France *)

    local open Obj in

    type lexbuf

    val createLexerString : string -> lexbuf
    val createLexer       : (CharArray.array -> int -> int) -> lexbuf

    val getLexeme         : lexbuf -> string
    val getLexemeChar     : lexbuf -> int -> char
    val getLexemeStart    : lexbuf -> int
    val getLexemeEnd      : lexbuf -> int

    (* For internal use in generated lexers: *)

    val dummyAction       : lexbuf -> obj
    val backtrack         : lexbuf -> 'a
    prim_val getNextChar  : lexbuf -> char = 1 "get_next_char"

    prim_val getLexBuffer     : lexbuf -> string           = 1 "field1"
    prim_val getLexAbsPos     : lexbuf -> int              = 1 "field2"
    prim_val getLexStartPos   : lexbuf -> int              = 1 "field3"
    prim_val getLexCurrPos    : lexbuf -> int              = 1 "field4"
    prim_val getLexLastPos    : lexbuf -> int              = 1 "field5"
    prim_val getLexLastAction : lexbuf -> (lexbuf -> obj)  = 1 "field6"

    prim_val setLexAbsPos     : lexbuf -> int -> unit             = 2 "setfield2"
    prim_val setLexStartPos   : lexbuf -> int -> unit             = 2 "setfield3"
    prim_val setLexCurrPos    : lexbuf -> int -> unit             = 2 "setfield4"
    prim_val setLexLastPos    : lexbuf -> int -> unit             = 2 "setfield5"
    prim_val setLexLastAction : lexbuf -> (lexbuf -> obj) -> unit = 2 "setfield6"
    end

    (*
       These functions are for use in mosmllex-generated lexers.  For
       further information, see the Moscow ML Owner's Manual.  For
       examples, see mosml/examples/lexyacc and mosml/examples/calc.

       [lexbuf] is the type of lexer buffers.  A lexer buffer is the
       argument passed to the scanning functions defined by the
       mosmllex-generated scanners.  The lexer buffer holds the current
       state of the scanner, plus a function to refill the buffer from the
       input.

       [createLexerString s] returns a lexer buffer which reads from the
       given string s. Reading starts from the first character in the
       string.  An end-of-input condition is generated when the end of the
       string is reached.

       [createLexer f] returns a lexer buffer that will use the given
       function f for reading additional input.  When the lexer needs more
       characters, it will call the given function as (f carr n), where
       carr is a character array, and n is an integer.  The function
       should put at most characters or in carr, starting at character
       number 0, and return the number of characters actually stored.  A
       return value of 0 means end of input.

       A lexer definition (input to mosmllex) consists of fragments of
       this form

          parse
              lhs1   { rhs1 }
            | lhs2   { rhs2 }
            | lhs3   { rhs3 }
            | ...

       where the lhs are regular expressions matching some string of
       characters, and the rhs are corresponding semantic actions, written
       in ML.  The following functions can be used in the semantic actions:

       [getLexeme lexbuf] returns the string matched by the left-hand side
       regular expression.

       [getLexemeChar lexbuf i] returns character number i in the matched
       string.

       [getLexemeStart lexbuf] returns the start position of the matched
       string (in the input stream).  The first character in the stream
       has position 0.

       [getLexemeEnd lexbuf] returns the end position, plus one, of the
       matched string (in the input stream).  The first character in the
       stream has position 0.
    *)

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Moscow ML 2.00