Support fixed size arrays in json_scanf format

README.md

@@ -62,6 +62,25 @@ Scans the JSON string `str`, performing scanf-like conversions according to `fmt
 Returns the number of elements successfully scanned & converted.
 Negative number means scan error.
 
+Example - parse fixed size array of objects:
+
+```c
+  // str has the following JSON string (notice keys are out of order):
+  // { "a": 123, "d": true, "b": [1, 2], "c": "hi",
+  //   "e": [ {"k": 123}, {"k": 345} ] }
+  // This example shows how to iterate over fixed size array, and parse each object.
+
+  int a = 0, b1 = 0, b2 = 0, d = 0, k1 = 0, k2 = 0;
+  char *c = NULL;
+  void *my_data = NULL;
+  json_scanf(str, strlen(str), "{ a:%d, b:[%B, %B], c:%Q, d:%B, e:[{k: %d},{k: %d}]}",
+             &a, &b1, &b2, &c, &d, &k1, &k2);
+  }
+
+  // Free string allocated by %Q format specifier
+  free(c)
+```
+
 Example - scan arbitrary JSON string:
 
 ```c

frozen.c

@@ -1079,6 +1079,22 @@ int json_vscanf(const char *s, int len, const char *fmt, va_list ap) {
     } else if (fmt[i] == '}') {
       if ((p = strrchr(path, '.')) != NULL) *p = '\0';
       i++;
+    } else if (fmt[i] == '[') {
+      strcat(path, "[0]");
+      i++;
+    } else if (fmt[i] == ',' && path[strlen(path)-1] == ']' ) {
+      int idx;
+      p = strrchr(path, '[');
+      if(p != NULL){
+          path[strlen(path)-1] = '\0';
+          *p = '\0';
+          idx = atoi(p+1);
+          snprintf(p, sizeof(path)-(p - path), "[%d]", idx+1);
+      }
+      i++;
+    } else if (fmt[i] == ']') {
+      if ((p = strrchr(path, '[')) != NULL) *p = '\0';
+      i++;
     } else if (fmt[i] == '%') {
       info.target = va_arg(ap, void *);
       info.type = fmt[i + 1];
@@ -1099,8 +1115,6 @@ int json_vscanf(const char *s, int len, const char *fmt, va_list ap) {
           memcpy(fmtbuf, fmt + i, conv_len);
           fmtbuf[conv_len] = '\0';
           i += conv_len;
-          if (fmt[i] != '}')
-            i += strspn(fmt + i, delims);
           break;
         }
       }

unit_test.c

@@ -501,12 +501,12 @@ static void scan_array(const char *str, int len, void *user_data) {
 
 static const char *test_scanf(void) {
   char buf[100] = "";
-  int a = 0, b = 0;
+  int a = 0, b = 0, e = 0, f = 0, g = 0;
   char *d = NULL;
   const char *str =
       "{ a: 1234, b : true, \"c\": {x: [17, 78, -20]}, d: \"hi%20there\" }";
 
-  ASSERT(json_scanf(str, strlen(str), "{a: %d, b: %B, c: [%M], d: %Q}", &a, &b,
+  ASSERT(json_scanf(str, strlen(str), "{a: %d, b: %B, c: %M, d: %Q}", &a, &b,
                     &scan_array, buf, &d) == 4);
   ASSERT(a == 1234);
   ASSERT(b == 1);
@@ -515,6 +515,18 @@ static const char *test_scanf(void) {
   ASSERT(strcmp(d, "hi%20there") == 0);
   free(d);
 
+  ASSERT(json_scanf(str, strlen(str), "{a: %d, b: %B, c:{ x: [%d, %d, %d]}, d: %Q}", &a, &b,
+                    &e, &f, &g, &d) == 6);
+  ASSERT(a == 1234);
+  ASSERT(b == 1);
+  ASSERT(e == 17);
+  ASSERT(f == 78);
+  ASSERT(g == -20);
+  ASSERT(d != NULL);
+  ASSERT(strcmp(d, "hi%20there") == 0);
+  free(d);
+
+
   {
       const char* str = "{a:{b:4},c:5}";
       int b = 0, c=0;