Feature: Option to handle empty filter results

README.md

@@ -135,6 +135,7 @@ print(o.find_first(d))  # Output: "value"
 
 #### Avaible methodes:
 - `CsonPath(path)`: create a new csonpath object.
+- `CsonPath(path, return_empty_array)`: Create a new csonpath object and return an empty list instead of None (like jsonpath-ng).
 - `OBJ.find_first(self, json)`: take a json, return first found occurrence.
 - `OBJ.find_all(self, json)`: take a json, return all found occurrence in a list.
 - `OBJ.remove(self, json)`: take a json, remove all found occurrence from it.

csonpath.h

@@ -111,6 +111,7 @@ struct csonpath {
     int regex_cnt;
     regex_t *regexs;
 #endif
+		int return_empty_array;
 };
 
 struct csonpath_child_info {
@@ -204,6 +205,9 @@ static inline int csonpath_init(struct csonpath cjp[static 1],
     if (!cjp->path || !cjp->inst_lst) {
 	return -ENOMEM;
     }
+
+	cjp->return_empty_array = 0;
+
     return 0;
 }
 
@@ -845,15 +849,14 @@ need_reloop_in = 0;
 #define CSONPATH_DO_FILTER_FIND CSONPATH_DO_FIND_ALL
 
 #define CSONPATH_DO_FIND_ALL_OUT		\
-    if (!nb_res) {				\
+	if (!cjp->return_empty_array && !nb_res) {				\
 	return CSONPATH_NONE_FOUND_RET;		\
     }						\
     return ret_ar;
 
 #define CSONPATH_DO_EXTRA_ARGS_IN , ret_ar
 #define CSONPATH_DO_EXTRA_DECLATION , CSONPATH_FIND_ALL_RET ret_ar
 
-
 #include "csonpath_do.h"
 
 /* Delete */

csonpath_do.h

@@ -382,7 +382,7 @@ static CSONPATH_DO_RET_TYPE csonpath_do_(struct csonpath cjp[static 1],
 
     CSONPATH_DO_POST_OPERATION;
 
-    return ret;
+	return ret;
 }
 
 #ifndef CSONPATH_NO_UNDEF

csonpath_python.c

@@ -1,4 +1,5 @@
 #include <Python.h>
+#include <stdio.h>
 
 #define CSONPATH_JSON PyObject *
 
@@ -207,42 +208,64 @@ typedef struct {
 
 
 static PyObject *PyCsonPath_new(PyTypeObject *subtype, PyObject* args,
-				PyObject* dont_care)
+				PyObject* kwargs)
 {
-  PyCsonPathObject *self = (PyCsonPathObject *)subtype->tp_alloc(subtype, 0);
-  const char *s;
-
-  if (!self)
-    BAD_ARG();
-
-  if (!PyArg_ParseTuple(args, "s", &s))
-    BAD_ARG();
-
-  struct csonpath *ret = malloc(sizeof *ret);
-  if (!self)
-    return PyErr_NoMemory();
-
-  if (csonpath_init(ret, s) < 0)
-    return PyErr_NoMemory();
-
-  if (csonpath_compile(ret) < 0) {
-    char *error = ret->compile_error;
-    PyErr_Format(PyExc_ValueError, "compilation fail %s", error ? error : "(unknow error)");
-    csonpath_destroy(ret);
-    return NULL;
-  }
-  self->cp = ret;
-
-  return (PyObject *)self;
+	static char *kwlist[] = {"path", "return_empty_array", NULL};
+	PyCsonPathObject *self = (PyCsonPathObject *)subtype->tp_alloc(subtype, 0);
+	const char *s;
+	int return_empty_array = 0;
+	struct csonpath *ret = NULL;
+	PyObject *py_ret = NULL;
+
+	if (!self)
+		BAD_ARG();
+
+	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s|p", kwlist,
+					 &s, &return_empty_array)) {
+		goto error;
+					 }
+
+	ret = malloc(sizeof *ret);
+	if (!ret) {
+		PyErr_NoMemory();
+		goto error;
+	}
+
+	if (csonpath_init(ret, s) < 0) {
+		py_ret = PyErr_NoMemory();
+		goto error_free_ret;
+	}
+
+	ret->return_empty_array = return_empty_array;
+
+	if (csonpath_compile(ret) < 0) {
+		char *err_str = ret->compile_error;
+		PyErr_Format(PyExc_ValueError, "compilation fail %s",
+				 err_str ? err_str : "(unknow error)");
+		goto error_destroy_ret;
+	}
+
+	self->cp = ret;
+	return (PyObject *)self;
+
+	error_destroy_ret:
+		csonpath_destroy(ret);
+	error_free_ret:
+		free(ret);
+	error:
+		Py_DECREF(self);
+	return py_ret;
 }
 
 static PyObject *find_all(PyCsonPathObject *self, PyObject* args)
 {
     PyObject *json;
 
     if (!PyArg_ParseTuple(args, "O", &json))
-	BAD_ARG();
+        BAD_ARG();
+
     PyObject *ret = csonpath_find_all(self->cp, json);
+
     return ret;
 }
 
@@ -251,8 +274,10 @@ static PyObject *find_first(PyCsonPathObject *self, PyObject* args)
     PyObject *json;
 
     if (!PyArg_ParseTuple(args, "O", &json))
-	BAD_ARG();
+        BAD_ARG();
+
     PyObject *ret = csonpath_find_first(self->cp, json);
+
     Py_INCREF(ret);
     return ret;
 }

tests/json-c/filter.c

@@ -60,6 +60,16 @@ int main(void)
   ret = csonpath_find_first(&p, jobj);
   assert(ret);
 
+  assert(csonpath_set_path(&p, "$.array[?a==9999]") == 0);
+  p.return_empty_array = 0;
+  ret = csonpath_find_first(&p, jobj);
+  assert(ret == NULL);
+
+  p.return_empty_array = 1;
+  ret = csonpath_find_first(&p, jobj);
+  assert(ret == NULL);
+  p.return_empty_array = 0;
+
   csonpath_set_path(&p, "$.array[?(@[\"a\"]==\"la\")]");
   ret = csonpath_find_first(&p, jobj);
   assert(ret);
@@ -138,6 +148,18 @@ int main(void)
   assert(!csonpath_set_path(&p, "$.ha[?(@[\"i\"][\"h\"] =~ \"gan\")][\"i\"][\"h\"]"));
   assert(csonpath_find_first(&p, jobj));
 
+  assert(!csonpath_set_path(&p, "$.ha[?i.h=~\"no_match_xyz\"]"));
+  p.return_empty_array = 1;
+  ret = csonpath_find_all(&p, jobj);
+  assert(ret != NULL);
+  assert(json_object_is_type(ret, json_type_array));
+  assert(json_object_array_length(ret) == 0);
+  json_object_put(ret);
+  p.return_empty_array = 0;
+  ret = csonpath_find_all(&p, jobj);
+  assert(ret == NULL);
+  json_object_put(ret);
+
   json_object_put(jobj);
 
   csonpath_destroy(&p);

tests/python/test_filter.py

@@ -49,6 +49,23 @@ def test_simple_filter():
 
     assert ret == ["Leodagan"], dict
 
+    dict = {"ha": [{"h": {"h1": "Leodagan"}}, {"h": "George"}]}
+    cp = csonpath.CsonPath('$.ha[?h.h1 =~ "Assim"].h.h1')
+    ret = cp.find_all(dict)
+
+    assert ret is None
+
+    dict = {"ha": [{"h": {"h1": "Leodagan"}}, {"h": "George"}]}
+    cp = csonpath.CsonPath('$.ha[?h.h1 =~ "Assim"].h.h1', return_empty_array=True)
+    ret = cp.find_all(dict)
+
+    assert ret == []
+
+    cp = csonpath.CsonPath('$.ha[?h.h1 =~ "Assim"].h.h1', True)
+    ret = cp.find_all(dict)
+
+    assert ret == []
+
 
 def test_multiple_filters():
     # cf. https://github.com/h2non/jsonpath-ng?tab=readme-ov-file#extensions, last example of filter
@@ -66,3 +83,13 @@ def test_multiple_filters():
     cp = csonpath.CsonPath('$.knights[?laterality = "left" & sub.a = 10].sub')
     ret = cp.find_first(dict)
     assert ret == {"a": 10}
+
+    cp = csonpath.CsonPath('$.knights[?(@.name == "Assim")].laterality')
+    ret = cp.find_first(dict)
+
+    assert ret is None
+
+    cp = csonpath.CsonPath('$.knights[?(@.name == "Assim")].laterality', return_empty_array=True)
+    ret = cp.find_first(dict)
+
+    assert ret is None

tests/python/test_needrefacto.py

@@ -20,6 +20,11 @@ def test_torefacto():
 
     assert r is None
 
+    o = csonpath.CsonPath("$.C", True)
+    r = o.find_first(d)
+
+    assert r is None
+
     o = csonpath.CsonPath("$[*]")
     r = o.find_all(d)