参考

{% collapse title=”parsing.c” %}

  1. #include "mpc.h"
  3. #ifdef _WIN32
  5. static char buffer[2048];
  7. char* readline(char* prompt) {
  8.   fputs(prompt, stdout);
  9.   fgets(buffer, 2048, stdin);
  10.   char* cpy = malloc(strlen(buffer)+1);
  11.   strcpy(cpy, buffer);
  12.   cpy[strlen(cpy)-1] = '\0';
  13.   return cpy;
  14. }
  16. void add_history(char* unused) {}
  18. #else
  19. #include <editline/readline.h>
  20. #include <editline/history.h>
  21. #endif
  23. int main(int argc, char** argv) {
  25.   /* Create Some Parsers */
  26.   mpc_parser_t* Number   = mpc_new("number");
  27.   mpc_parser_t* Operator = mpc_new("operator");
  28.   mpc_parser_t* Expr     = mpc_new("expr");
  29.   mpc_parser_t* Lispy    = mpc_new("lispy");
  31.   /* Define them with the following Language */
  32.   mpca_lang(MPCA_LANG_DEFAULT,
  33.     "                                                     \
  34.       number   : /-?[0-9]+/ ;                             \
  35.       operator : '+' | '-' | '*' | '/' ;                  \
  36.       expr     : <number> | '(' <operator> <expr>+ ')' ;  \
  37.       lispy    : /^/ <operator> <expr>+ /$/ ;             \
  38.     ",
  39.     Number, Operator, Expr, Lispy);
  41.   puts("Lispy Version 0.0.0.0.2");
  42.   puts("Press Ctrl+c to Exit\n");
  44.   while (1) {
  46.     char* input = readline("lispy> ");
  47.     add_history(input);
  49.     /* Attempt to parse the user input */
  50.     mpc_result_t r;
  51.     if (mpc_parse("<stdin>", input, Lispy, &r)) {
  52.       /* On success print and delete the AST */
  53.       mpc_ast_print(r.output);
  54.       mpc_ast_delete(r.output);
  55.     } else {
  56.       /* Otherwise print and delete the Error */
  57.       mpc_err_print(r.error);
  58.       mpc_err_delete(r.error);
  59.     }
  61.     free(input);
  62.   }
  64.   /* Undefine and delete our parsers */
  65.   mpc_cleanup(4, Number, Operator, Expr, Lispy);
  67.   return 0;
  68. }

{% endcollapse %}