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   1 #include <string.h>
   2 #include "config.h"
   3
   4 /**
   5  * json - Parse and generate JSON (JavaScript Object Notation)
   6  *
   7  * This is a library for encoding and decoding JSON that strives to be
   8  * easy to learn, use, and incorporate into an application.
   9  *
  10  * JSON (JavaScript Object Notation) facilitates passing data among different
  11  * programming languages, particularly JavaScript.  It looks like this:
  12  *
  13  *     [
  14  *         {
  15  *             "id":           1,
  16  *             "firstname":    "John",
  17  *             "lastname":     "Smith",
  18  *             "email":        "john@example.com",
  19  *             "likes_pizza":  false
  20  *         },
  21  *         {
  22  *             "id":           2,
  23  *             "firstname":    "Linda",
  24  *             "lastname":     "Jones",
  25  *             "email":        null,
  26  *             "likes_pizza":  true
  27  *         }
  28  *     ]
  29  *
  30  * Example:
  31  *      #include <ccan/json/json.h>
  32  *      #include <math.h>
  33  *      #include <stdio.h>
  34  *      #include <stdlib.h>
  35  *
  36  *      static int find_number(JsonNode *object, const char *name, double *out)
  37  *      {
  38  *              JsonNode *node = json_find_member(object, name);
  39  *              if (node && node->tag == JSON_NUMBER) {
  40  *                      *out = node->number_;
  41  *                      return 1;
  42  *              }
  43  *              return 0;
  44  *      }
  45  *
  46  *      static void solve_pythagorean(JsonNode *triple)
  47  *      {
  48  *              double a = 0, b = 0, c = 0;
  49  *              int a_given, b_given, c_given;
  50  *
  51  *              if (triple->tag != JSON_OBJECT) {
  52  *                      fprintf(stderr, "Error: Expected a JSON object.\n");
  53  *                      exit(EXIT_FAILURE);
  54  *              }
  55  *
  56  *              a_given = find_number(triple, "a", &a);
  57  *              b_given = find_number(triple, "b", &b);
  58  *              c_given = find_number(triple, "c", &c);
  59  *
  60  *              if (a_given + b_given + c_given != 2) {
  61  *                      fprintf(stderr, "Error: I need two sides to compute the length of the third.\n");
  62  *                      exit(EXIT_FAILURE);
  63  *              }
  64  *
  65  *              if (a_given && b_given) {
  66  *                      c = sqrt(a*a + b*b);
  67  *                      json_append_member(triple, "c", json_mknumber(c));
  68  *              } else if (a_given && c_given) {
  69  *                      b = sqrt(c*c - a*a);
  70  *                      json_append_member(triple, "b", json_mknumber(b));
  71  *              } else if (b_given && c_given) {
  72  *                      a = sqrt(c*c - b*b);
  73  *                      json_append_member(triple, "a", json_mknumber(a));
  74  *              }
  75  *      }
  76  *
  77  *      int main(void)
  78  *      {
  79  *              JsonNode *triples = json_mkarray();
  80  *
  81  *              json_append_element(triples, json_decode("{\"a\": 3, \"b\": 4}"));
  82  *              json_append_element(triples, json_decode("{\"a\": 5, \"c\": 13}"));
  83  *              json_append_element(triples, json_decode("{\"b\": 24, \"c\": 25}"));
  84  *
  85  *              JsonNode *triple;
  86  *              json_foreach(triple, triples)
  87  *                      solve_pythagorean(triple);
  88  *
  89  *              char *tmp = json_stringify(triples, "\t");
  90  *              puts(tmp);
  91  *              free(tmp);
  92  *
  93  *              json_delete(triples);
  94  *              return 0;
  95  *      }
  96  *
  97  * Author: Joey Adams
  98  * Version: 0.1
  99  * License: MIT
 100  */
 101 int main(int argc, char *argv[])
 102 {
 103         /* Expect exactly one argument */
 104         if (argc != 2)
 105                 return 1;
 106
 107         if (strcmp(argv[1], "depends") == 0) {
 108                 /* Nothing */
 109                 return 0;
 110         }
 111
 112         if (strcmp(argv[1], "libs") == 0) {
 113                 printf("m\n"); /* Needed for sqrt() used in example code above. */
 114                 return 0;
 115         }
 116
 117         return 1;
 118 }