lexer.mll

{
open Lexing
open Parser

exception SyntaxError of string

let next_line lexbuf =
  let pos = lexbuf.lex_curr_p in
  lexbuf.lex_curr_p <-
    { pos with pos_bol = lexbuf.lex_curr_pos;
               pos_lnum = pos.pos_lnum + 1
    }
}

let digit = ['0'-'9']
let frac = '.' digit*
let exp = ['e' 'E'] ['-' '+']? digit+

let int = '-'? digit digit*
let float = digit* frac? exp?

let white = [' ' '\t']+
let newline = '\r' | '\n' | "\r\n"
let space = white | newline

let letter = ['a'-'z' 'A'-'Z']
let special = '_' | '-' | '*'
let symbol = (letter | special)+

rule read =
  parse
  | white	{ read lexbuf }
  | newline	{ next_line lexbuf; read lexbuf }
  | int		{ INT (int_of_string (Lexing.lexeme lexbuf)) }
  | float	{ FLOAT (float_of_string (Lexing.lexeme lexbuf)) }
  | symbol	{ SYMBOL (Lexing.lexeme lexbuf) }
  | '"'		{ read_string (Buffer.create 0) lexbuf }
  | '('		{ LEFT_PAR }
  | ')'		{ RIGHT_PAR }
  | _ { raise (SyntaxError ("Unexpected char: " ^ Lexing.lexeme lexbuf)) }
  | eof	        { EOF }
and read_string buf =
  parse
  | '"'		{ STRING (Buffer.contents buf) }
  | '\\' '/'  { Buffer.add_char buf '/'; read_string buf lexbuf }
  | '\\' '\\' { Buffer.add_char buf '\\'; read_string buf lexbuf }
  | '\\' 'b'  { Buffer.add_char buf '\b'; read_string buf lexbuf }
  | '\\' 'n'  { Buffer.add_char buf '\n'; read_string buf lexbuf }
  | '\\' 'r'  { Buffer.add_char buf '\r'; read_string buf lexbuf }
  | '\\' 't'  { Buffer.add_char buf '\t'; read_string buf lexbuf }
  | [^ '"' '\\']+
              { Buffer.add_string buf (Lexing.lexeme lexbuf);
	        read_string buf lexbuf }
  | _ 	      { raise (SyntaxError ("Illegal string character: " ^ Lexing.lexeme lexbuf)) }
  | eof       { raise (SyntaxError ("String is not terminated")) }