Add JSON_REAL_PRECISION

Fixes #178.

src/dump.c

@@ -22,6 +22,9 @@
 #define MAX_INTEGER_STR_LENGTH  100
 #define MAX_REAL_STR_LENGTH     100
 
+#define FLAGS_TO_INDENT(f)      ((f) & 0x1F)
+#define FLAGS_TO_PRECISION(f)   (((f) >> 11) & 0x1F)
+
 struct object_key {
     size_t serial;
     const char *key;
@@ -45,9 +48,9 @@ static const char whitespace[] = "                                ";
 
 static int dump_indent(size_t flags, int depth, int space, json_dump_callback_t dump, void *data)
 {
-    if(JSON_INDENT(flags) > 0)
+    if(FLAGS_TO_INDENT(flags) > 0)
     {
-        int i, ws_count = JSON_INDENT(flags);
+        int i, ws_count = FLAGS_TO_INDENT(flags);
 
         if(dump("\n", 1, data))
             return -1;
@@ -208,7 +211,8 @@ static int do_dump(const json_t *json, size_t flags, int depth,
             int size;
             double value = json_real_value(json);
 
-            size = jsonp_dtostr(buffer, MAX_REAL_STR_LENGTH, value);
+            size = jsonp_dtostr(buffer, MAX_REAL_STR_LENGTH, value,
+                                FLAGS_TO_PRECISION(flags));
             if(size < 0)
                 return -1;
 

src/jansson.h

@@ -259,13 +259,14 @@ json_t *json_load_callback(json_load_callback_t callback, void *data, size_t fla
 
 /* encoding */
 
-#define JSON_INDENT(n)      (n & 0x1F)
-#define JSON_COMPACT        0x20
-#define JSON_ENSURE_ASCII   0x40
-#define JSON_SORT_KEYS      0x80
-#define JSON_PRESERVE_ORDER 0x100
-#define JSON_ENCODE_ANY     0x200
-#define JSON_ESCAPE_SLASH   0x400
+#define JSON_INDENT(n)          ((n) & 0x1F)
+#define JSON_COMPACT            0x20
+#define JSON_ENSURE_ASCII       0x40
+#define JSON_SORT_KEYS          0x80
+#define JSON_PRESERVE_ORDER     0x100
+#define JSON_ENCODE_ANY         0x200
+#define JSON_ESCAPE_SLASH       0x400
+#define JSON_REAL_PRECISION(n)  (((n) & 0x1F) << 11)
 
 typedef int (*json_dump_callback_t)(const char *buffer, size_t size, void *data);
 

src/jansson_private.h

@@ -81,7 +81,7 @@ void jsonp_error_vset(json_error_t *error, int line, int column,
 
 /* Locale independent string<->double conversions */
 int jsonp_strtod(strbuffer_t *strbuffer, double *out);
-int jsonp_dtostr(char *buffer, size_t size, double value);
+int jsonp_dtostr(char *buffer, size_t size, double value, int prec);
 
 /* Wrappers for custom memory functions */
 void* jsonp_malloc(size_t size);

src/strconv.c

@@ -78,13 +78,16 @@ int jsonp_strtod(strbuffer_t *strbuffer, double *out)
     return 0;
 }
 
-int jsonp_dtostr(char *buffer, size_t size, double value)
+int jsonp_dtostr(char *buffer, size_t size, double value, int precision)
 {
     int ret;
     char *start, *end;
     size_t length;
 
-    ret = snprintf(buffer, size, "%.17g", value);
+    if (precision == 0)
+        precision = 17;
+
+    ret = snprintf(buffer, size, "%.*g", precision, value);
     if(ret < 0)
         return -1;