Implemented '$' root-node token.

Author: springcomp

jmespath/parser.py

@@ -27,6 +27,7 @@
 """
 import random
 
+
 from jmespath import lexer
 from jmespath.compat import with_repr_method
 from jmespath import ast
@@ -509,9 +510,8 @@ def __init__(self, expression, parsed):
         self.parsed = parsed
 
     def search(self, value, options=None):
-        interpreter = visitor.ScopedInterpreter(options)
-        result = interpreter.visit(self.parsed, value)
-        return result
+        evaluator = visitor.ScopedInterpreter(options)
+        return evaluator.evaluate(self.parsed, value)
 
     def _render_dot_file(self):
         """Render the parsed AST as a dot file.
@@ -526,6 +526,3 @@ def _render_dot_file(self):
         renderer = visitor.GraphvizVisitor()
         contents = renderer.visit(self.parsed)
         return contents
-
-    def __repr__(self):
-        return repr(self.parsed)

jmespath/visitor.py

@@ -2,6 +2,7 @@
 
 from jmespath import functions
 from jmespath.compat import string_type
+from jmespath.compat import with_str_method
 from numbers import Number
 
 
@@ -172,6 +173,11 @@ def visit_comparator(self, node, value):
     def visit_current(self, node, value):
         return value
 
+    def visit_root(self, *args, **kwargs):
+        if 'scopes' in kwargs:
+            return kwargs['scopes'].getValue('$')
+        return None
+
     def visit_expref(self, node, value):
         return _Expression(node['children'][0], self, value)
 
@@ -340,6 +346,7 @@ def _visit(self, node, current):
             self._visit(child, child_name)
 
 
+@with_str_method
 class Scopes:
     def __init__(self):
         self._scopes = []
@@ -357,15 +364,22 @@ def getValue(self, identifier):
                 return scope[identifier]
         return None
 
+    def __str__(self):
+        return '{}'.format(self._scopes)
+
 
 class ScopedInterpreter(TreeInterpreter):
     def __init__(self, options = None):
         super().__init__(options)
         self._scopes = Scopes()
 
+    def evaluate(self, ast, root_scope):
+        self._scopes.pushScope({'$': root_scope})
+        return self.visit(ast, root_scope)
+
     def visit(self, node, *args, **kwargs):
-        node_type = node['type']
-        if (node_type in ['field', 'function_expression']):
+        scoped_types = ['field', 'function_expression', 'root']
+        if (node['type'] in scoped_types):
             kwargs.update({'scopes': self._scopes})
         else:
             if 'scopes' in kwargs:

tests/compliance/lexical_scoping.json

@@ -166,5 +166,40 @@
 				"result": "fourth"
 			}
 		]
+	},
+	{
+		"given": {
+			"first_choice": "WA",
+			"states": [
+				{
+					"name": "WA",
+					"cities": [
+						"Seattle",
+						"Bellevue",
+						"Olympia"
+					]
+				},
+				{
+					"name": "CA",
+					"cities": [
+						"Los Angeles",
+						"San Francisco"
+					]
+				},
+				{
+					"name": "NY",
+					"cities": [
+						"New York City",
+						"Albany"
+					]
+				}
+			]
+		},
+		"cases": [
+			{
+				"expression": "states[?name==$.first_choice].cities[]",
+				"result": ["Seattle", "Bellevue", "Olympia"]
+			}
+		]
 	}
 ]