Add negation of relative existence queries

jsonpath_ng/ext/filter.py

@@ -96,6 +96,9 @@ def __init__(self, target, op, value):
     def find(self, datum):
         datum = self.target.find(DatumInContext.wrap(datum))
 
+        if self.op == "!":
+            # Negated relative query existence test
+            return not datum
         if not datum:
             return []
         if self.op is None:

jsonpath_ng/ext/parser.py

@@ -23,7 +23,7 @@
 
 class ExtendedJsonPathLexer(lexer.JsonPathLexer):
     """Custom LALR-lexer for JsonPath"""
-    literals = lexer.JsonPathLexer.literals + ['?', '@', '+', '*', '/', '-']
+    literals = lexer.JsonPathLexer.literals + ['?', '@', '+', '*', '/', '-', '!']
     tokens = (['BOOL'] +
               parser.JsonPathLexer.tokens +
               ['FILTER_OP', 'SORT_DIRECTION', 'FLOAT'])
@@ -120,6 +120,10 @@ def p_expression(self, p):
             __, left, op, right = p
         p[0] = _filter.Expression(left, op, right)
 
+    def p_expression_not(self, p):
+        "expression : '!' jsonpath"
+        p[0] = _filter.Expression(p[2], p[1], None)
+
     def p_expressions_expression(self, p):
         "expressions : expression"
         p[0] = [p[1]]

tests/test_jsonpath_rw_ext.py

@@ -110,6 +110,12 @@
         [{"cow": "moo"}],
         id="filter_eq3",
     ),
+    pytest.param(
+        'objects[?cow!="moo"]',
+        {"objects": [{"cow": "moo"}, {"cow": "neigh"}]},
+        [{"cow": "neigh"}],
+        id="filter_ne",
+    ),
     pytest.param(
         "objects[?cow>5]",
         {"objects": [{"cow": 8}, {"cow": 7}, {"cow": 5}, {"cow": "neigh"}]},
@@ -448,6 +454,46 @@
         ["green"],
         id="boolean-filter-string-true-string-literal",
     ),
+    pytest.param(
+        '$[?!@..["type"]]',
+        [
+            {
+                "name": "foo",
+                "data": [{"value": "bar"}]
+            },
+            {
+                "name": "foo",
+                "data": [{"value": "bar", "type": "foo"}]
+            }
+        ],
+        [
+            {
+                "name": "foo",
+                "data": [{"value": "bar"}]
+            }
+        ],
+        id="negated_relative_query_existence"
+    ),
+    pytest.param(
+        '$[?!data[*].type]',
+        [
+            {
+                "name": "foo",
+                "data": [{"value": "bar"}]
+            },
+            {
+                "name": "foo",
+                "data": [{"value": "bar", "type": "foo"}]
+            }
+        ],
+        [
+            {
+                "name": "foo",
+                "data": [{"value": "bar"}]
+            }
+        ],
+        id="negated_relative_query_existence_implicit_this"
+    ),
 )