impls/c/step1_read_print.c

   1 #include <stdlib.h>
   2 #include <stdio.h>
   3 #include <string.h>
   4 #include <unistd.h>
   5
   6 #include "types.h"
   7 #include "readline.h"
   8 #include "reader.h"
   9
  10 // read
  11 MalVal *READ(char prompt[], char *str) {
  12     char *line;
  13     MalVal *ast;
  14     if (str) {
  15         line = str;
  16     } else {
  17         line = _readline(prompt);
  18         if (!line) {
  19             _error("EOF");
  20             return NULL;
  21         }
  22     }
  23     ast = read_str(line);
  24     if (!str) { MAL_GC_FREE(line); }
  25     return ast;
  26 }
  27
  28 // eval
  29 MalVal *EVAL(MalVal *ast, GHashTable *env) {
  30     if (!ast || mal_error) return NULL;
  31     return ast;
  32 }
  33
  34 // print
  35 char *PRINT(MalVal *exp) {
  36     if (mal_error) {
  37         return NULL;
  38     }
  39     return _pr_str(exp,1);
  40 }
  41
  42 // repl
  43
  44 // read and eval
  45 MalVal *RE(GHashTable *env, char *prompt, char *str) {
  46     MalVal *ast, *exp;
  47     ast = READ(prompt, str);
  48     if (!ast || mal_error) return NULL;
  49     exp = EVAL(ast, env);
  50     if (ast != exp) {
  51         malval_free(ast);    // Free input structure
  52     }
  53     return exp;
  54 }
  55
  56 int main()
  57 {
  58     MalVal *exp;
  59     char *output;
  60     char prompt[100];
  61
  62     MAL_GC_SETUP();
  63
  64     // Set the initial prompt
  65     snprintf(prompt, sizeof(prompt), "user> ");
  66
  67     // repl loop
  68     for(;;) {
  69         exp = RE(NULL, prompt, NULL);
  70         if (mal_error && strcmp("EOF", mal_error->val.string) == 0) {
  71             return 0;
  72         }
  73         output = PRINT(exp);
  74
  75         if (mal_error) {
  76             fprintf(stderr, "Error: %s\n", _pr_str(mal_error,1));
  77             malval_free(mal_error);
  78             mal_error = NULL;
  79         } else if (output) {
  80             puts(output);
  81             MAL_GC_FREE(output);        // Free output string
  82         }
  83
  84         //malval_free(exp);    // Free evaluated expression
  85     }
  86 }