Merge pull request #329 from npmccallum/embed

Add JSON_EMBED encoding flag

doc/apiref.rst

@@ -940,6 +940,13 @@ can be ORed together to obtain *flags*.
 
    .. versionadded:: 2.7
 
+``JSON_EMBED``
+   If this flag is used, the opening and closing characters of the top-level
+   array ('[', ']') or object ('{', '}') are omitted during encoding. This
+   flag is useful when concatenating multiple arrays or objects into a stream.
+
+   .. versionadded:: 2.10
+
 These functions output UTF-8:
 
 .. function:: char *json_dumps(const json_t *json, size_t flags)

src/dump.c

@@ -199,6 +199,10 @@ static int compare_keys(const void *key1, const void *key2)
 static int do_dump(const json_t *json, size_t flags, int depth,
                    json_dump_callback_t dump, void *data)
 {
+    int embed = flags & JSON_EMBED;
+
+    flags &= ~JSON_EMBED;
+
     if(!json)
         return -1;
 
@@ -258,11 +262,11 @@ static int do_dump(const json_t *json, size_t flags, int depth,
 
             n = json_array_size(json);
 
-            if(dump("[", 1, data))
+            if(!embed && dump("[", 1, data))
                 goto array_error;
             if(n == 0) {
                 array->visited = 0;
-                return dump("]", 1, data);
+                return embed ? 0 : dump("]", 1, data);
             }
             if(dump_indent(flags, depth + 1, 0, dump, data))
                 goto array_error;
@@ -286,7 +290,7 @@ static int do_dump(const json_t *json, size_t flags, int depth,
             }
 
             array->visited = 0;
-            return dump("]", 1, data);
+            return embed ? 0 : dump("]", 1, data);
 
         array_error:
             array->visited = 0;
@@ -317,11 +321,11 @@ static int do_dump(const json_t *json, size_t flags, int depth,
 
             iter = json_object_iter((json_t *)json);
 
-            if(dump("{", 1, data))
+            if(!embed && dump("{", 1, data))
                 goto object_error;
             if(!iter) {
                 object->visited = 0;
-                return dump("}", 1, data);
+                return embed ? 0 : dump("}", 1, data);
             }
             if(dump_indent(flags, depth + 1, 0, dump, data))
                 goto object_error;
@@ -417,7 +421,7 @@ static int do_dump(const json_t *json, size_t flags, int depth,
             }
 
             object->visited = 0;
-            return dump("}", 1, data);
+            return embed ? 0 : dump("}", 1, data);
 
         object_error:
             object->visited = 0;

src/jansson.h

@@ -289,6 +289,7 @@ json_t *json_load_callback(json_load_callback_t callback, void *data, size_t fla
 #define JSON_ENCODE_ANY         0x200
 #define JSON_ESCAPE_SLASH       0x400
 #define JSON_REAL_PRECISION(n)  (((n) & 0x1F) << 11)
+#define JSON_EMBED              0x10000
 
 typedef int (*json_dump_callback_t)(const char *buffer, size_t size, void *data);
 

test/suites/api/test_dump.c

@@ -278,6 +278,39 @@ static void dumpfd()
 #endif
 }
 
+static void embed()
+{
+    static const char *plains[] = {
+        "{\"bar\":[],\"foo\":{}}",
+        "[[],{}]",
+        "{}",
+        "[]",
+        NULL
+    };
+
+    size_t i;
+
+    for(i = 0; plains[i]; i++) {
+        const char *plain = plains[i];
+        json_t *parse = NULL;
+        char *embed = NULL;
+        size_t psize = 0;
+        size_t esize = 0;
+
+        psize = strlen(plain) - 2;
+        embed = calloc(1, psize);
+        parse = json_loads(plain, 0, NULL);
+        esize = json_dumpb(parse, embed, psize,
+                           JSON_COMPACT | JSON_SORT_KEYS | JSON_EMBED);
+        json_decref(parse);
+        if(esize != psize)
+            fail("json_dumpb(JSON_EMBED) returned an invalid size");
+        if(strncmp(plain + 1, embed, esize) != 0)
+            fail("json_dumps(JSON_EMBED) returned an invalid value");
+        free(embed);
+    }
+}
+
 static void run_tests()
 {
     encode_null();
@@ -289,4 +322,5 @@ static void run_tests()
     dump_file();
     dumpb();
     dumpfd();
+    embed();
 }