Lisp bison grammar.

lisp.y

/*
* lisp-grammar.y - Lisp Grammar
*
* Copyright (C) 2007 Ragner Magalhaes 
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License only.
*/


%{
#define YYSTYPE double
%}


%token NUMBER SYMBOL STRING SHARP_QUOTE
%start input

%%

input : /* empty */
  | input line
  ;

line : '\n' 
  | s_exp '\n' { printf( "%g\n", $1 ); }
  ;

s_exp : atom
  | list
  ;

atom : NUMBER
  | SYMBOL
  | STRING
  ;

list : '(' ')'
  | '(' s_exp_list ')'
  | '(' s_exp_list '.' s_exp ')'
  | '\'' s_exp
  | SHARP_QUOTE s_exp
  ;

s_exp_list : s_exp
  | s_exp_list s_exp
  ;

%%

#include 
#include 

main()
{
  yyparse();
}

yyerror( char * str )
{
  printf( "lisp: PUUUUUU %s\n", str );
}

int yylex( void )
{
  int ic;
  
  while (ic = getchar(), ic == ' ' || ic == '\t') { ; }
  if (ic == EOF)
    return 0;
  else if (isalpha(ic))
    return STRING;
  else if ( isdigit( ic ) )
    return NUMBER;
  else if ( ic == '\'')
    return SHARP_QUOTE;
  else switch (ic) {
    case '+':
    case '-':
    case '*':
    case '/':
      return SYMBOL;
  }
  return ic;
}