Add json_object_foreach_safe

Fixes #230.

3 files changed, 39 insertions, 0 deletions

diff --git a/doc/apiref.rst b/doc/apiref.rst
index 7cd2483..fce1cb2 100644
--- a/doc/apiref.rst
+++ b/doc/apiref.rst
@@ -676,6 +676,10 @@ in an object.
 
    The items are not returned in any particular order.
 
+   **Note:** It's not safe to call ``json_object_del(object, key)``
+   during iteration. If you need to, use
+   :func:`json_object_foreach_safe` instead.
+
    This macro expands to an ordinary ``for`` statement upon
    preprocessing, so its performance is equivalent to that of
    hand-written iteration code using the object iteration protocol
@@ -686,6 +690,15 @@ in an object.
    .. versionadded:: 2.3
 
 
+.. function:: json_object_foreach_safe(object, tmp, key, value)
+
+   Like :func:`json_object_foreach()`, but it's safe to call
+   ``json_object_del(object, key)`` during iteration. You need to pass
+   an extra ``void *`` parameter ``tmp`` that is used for temporary storage.
+
+   .. versionadded:: 2.8
+
+
 The following functions implement an iteration protocol for objects,
 allowing to iterate through all key-value pairs in an object. The
 items are not returned in any particular order, as this would require
diff --git a/src/jansson.h b/src/jansson.h
index b980e8c..6f7fd07 100644
--- a/src/jansson.h
+++ b/src/jansson.h
@@ -152,6 +152,13 @@ int json_object_iter_set_new(json_t *object, void *iter, json_t *value);
         key && (value = json_object_iter_value(json_object_key_to_iter(key))); \
         key = json_object_iter_key(json_object_iter_next(object, json_object_key_to_iter(key))))
 
+#define json_object_foreach_safe(object, n, key, value)     \
+    for(key = json_object_iter_key(json_object_iter(object)), \
+            n = json_object_iter_next(object, json_object_key_to_iter(key)); \
+        key && (value = json_object_iter_value(json_object_key_to_iter(key))); \
+        key = json_object_iter_key(n), \
+            n = json_object_iter_next(object, json_object_key_to_iter(key)))
+
 #define json_array_foreach(array, index, value) \
 	for(index = 0; \
 		index < json_array_size(array) && (value = json_array_get(array, index)); \
diff --git a/test/suites/api/test_object.c b/test/suites/api/test_object.c
index c7acb40..01cc8fd 100644
--- a/test/suites/api/test_object.c
+++ b/test/suites/api/test_object.c
@@ -545,6 +545,24 @@ static void test_object_foreach()
     json_decref(object2);
 }
 
+static void test_object_foreach_safe()
+{
+    const char *key;
+    void *tmp;
+    json_t *object, *value;
+
+    object = json_pack("{sisisi}", "foo", 1, "bar", 2, "baz", 3);
+
+    json_object_foreach_safe(object, tmp, key, value) {
+        json_object_del(object, key);
+    }
+
+    if(json_object_size(object) != 0)
+        fail("json_object_foreach_safe failed to iterate all key-value pairs");
+
+    json_decref(object);
+}
+
 static void run_tests()
 {
     test_misc();
@@ -557,4 +575,5 @@ static void run_tests()
     test_iterators();
     test_preserve_order();
     test_object_foreach();
+    test_object_foreach_safe();
 }