feat: add skipkeys to dumps

src/pycJSON_encode.c

@@ -26,8 +26,11 @@ typedef struct printbuffer {
     size_t offset;
     size_t depth; /* current nesting depth (for formatted printing) */
     internal_hooks hooks;
-    bool format; /* is this print a formatted print */
     bool using_heap;
+
+    /* args to print */
+    bool format; /* is this print a formatted print */
+    bool skipkeys;
 } printbuffer;
 
 // forward declaration
@@ -409,6 +412,16 @@ static bool print_object(PyObject *item, printbuffer *const output_buffer) {
             }
             Py_DECREF(str);
         } else {
+            if(output_buffer->skipkeys) {
+                Py_DECREF(next_element);
+                next_element = PyIter_Next(iter);
+                if(next_element == NULL && *(output_buffer->buffer + output_buffer->offset - 1) == ',') {
+                    output_buffer->offset--;
+                }
+                output_pointer = (output_buffer->buffer + output_buffer->offset);
+                length = 0;
+                goto SKIP_PRINT;
+            }
             PyErr_SetString(PyExc_TypeError, "TypeError: Key must be str, None, bool or number");
             return false;
         }
@@ -445,6 +458,7 @@ static bool print_object(PyObject *item, printbuffer *const output_buffer) {
             *output_pointer++ = ',';
         }
 
+        SKIP_PRINT:
         if (output_buffer->format) {
             *output_pointer++ = '\n';
         }
@@ -524,10 +538,10 @@ PyObject *pycJSON_Encode(PyObject *self, PyObject *args, PyObject *kwargs) {
 
     unsigned char stack_buffer[CJSON_PRINTBUFFER_MAX_STACK_SIZE];
 
-    static const char *kwlist[] = {"obj", "format", NULL};
+    static const char *kwlist[] = {"obj", "format", "skipkeys", NULL};
     PyObject *arg;
     buffer->format = false;
-    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O|p", (char **) kwlist, &arg, &buffer->format)) {
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O|pp", (char **) kwlist, &arg, &buffer->format, &buffer->skipkeys)) {
         if (!PyErr_Occurred()) PyErr_SetString(PyExc_TypeError, "Failed to parse arguments");
         return NULL;
     }

test/encode_test.py

@@ -33,6 +33,29 @@ class A:
         #         with self.assertRaises(MemoryError):
         #             cjson.dumps(case)
 
+    def test_skipkeys(self):
+        import cjson
+        import json
+
+        class A:
+            pass
+
+        test_cases = [
+            {"a": 1, 2: 3},
+            {"a": "b", A(): 1},
+            {A(): 1, "a": "b"},
+            {"e": 2, A(): 1, "a": "b"},
+        ]
+
+        for case in test_cases:
+            result_json = json.dumps(case, indent=None, separators=(",", ":"), ensure_ascii=False, skipkeys=True)
+            result_loadback_json = json.loads(result_json)
+
+            with self.subTest(msg=f'encoding_test(case={case})'):
+                result_cjson = cjson.dumps(case, skipkeys=True)
+                result_loadback_cjson = json.loads(result_cjson)
+                self._check_obj_same(result_loadback_json, result_loadback_cjson)
+
     def test_encode(self):
         import collections
         import json