parsing.c

// Read Evaluate Print Loop....
#include "mpc.h"
#include <readline/history.h>
#include <readline/readline.h>
#include <stdio.h>
#include <stdlib.h>
int
main ()
{
  /* Create Some Parsers */
  mpc_parser_t *Number = mpc_new ("number");
  mpc_parser_t *Operator = mpc_new ("operator");
  mpc_parser_t *Expr = mpc_new ("expr");
  mpc_parser_t *Lispy = mpc_new ("lispy");

  /* Define them with the following Language */
  mpca_lang (MPCA_LANG_DEFAULT,
             "                                                     \
      number   : /-?[0-9]+/ ;                             \
      operator : '+' | '-' | '*' | '/' ;                  \
      expr     : <number> | '(' <operator> <expr>+ ')' ;  \
      lispy    : /^/ <operator> <expr>+ /$/ ;             \
    ",
             Number, Operator, Expr, Lispy);
  /*char input[2048];*/
  puts ("Lisp Version 1.0.0.1");
  puts ("Press Ctrl-c to exit\n");
  while (1)
    {
      char *input = readline ("Lispy>");
      add_history (input);
      /*printf ("Am i really a %s\n", input);*/
      /* Attempt to Parse the user Input */
      mpc_result_t r;
      if (mpc_parse ("<stdin>", input, Lispy, &r))
        {
          /* On Success Print the AST */
          mpc_ast_print (r.output);
          mpc_ast_delete (r.output);
        }
      else
        {
          /* Otherwise Print the Error */
          mpc_err_print (r.error);
          mpc_err_delete (r.error);
        }
      free (input);
    }
  /* Undefine and Delete our Parsers */
  mpc_cleanup (4, Number, Operator, Expr, Lispy);
  return 0;
}