From c9fb4913a6f62deb95d8367ea100efee595a86b9 Mon Sep 17 00:00:00 2001
From: Igor Dejanovic <igor.dejanovic@gmail.com>
Date: Mon, 17 Feb 2014 01:14:42 +0100
Subject: [PATCH] refs #2 Support for referencing child node as attributes on
NonTerminal
This works for rules that are referenced from the rule which created
NonTerminal.
---
arpeggio/__init__.py | 23 +++++++++++++++++++++++
tests/test_rulename_lookup.py | 33 +++++++++++++++++++++++++++++++++
2 files changed, 56 insertions(+)
create mode 100644 tests/test_rulename_lookup.py
diff --git a/arpeggio/__init__.py b/arpeggio/__init__.py
index 267bd58..1319e88 100644
--- a/arpeggio/__init__.py
+++ b/arpeggio/__init__.py
@@ -615,6 +615,9 @@ class NonTerminal(ParseTreeNode):
super(NonTerminal, self).__init__(type, position, error)
self.nodes = flatten([nodes])
+ # Child nodes cache. Used for lookup by rule name.
+ self._child_cache = {}
+
@property
def desc(self):
return self.name
@@ -628,6 +631,26 @@ class NonTerminal(ParseTreeNode):
def __repr__(self):
return "[ %s ]" % ", ".join([repr(x) for x in self.nodes])
+ def __getattr__(self, item):
+ """
+ Find a child (non)terminal by the rule name.
+
+ Args:
+ item(str): The name of the child node.
+ """
+ # First check the cache
+ if item in self._child_cache:
+ return self._child_cache[item]
+
+ # If not found in the cache find it and store it in the
+ # cache for later.
+ for n in self.nodes:
+ if n.type == item:
+ self._child_cache[item] = n
+ return n
+
+ raise AttributeError
+
# ----------------------------------------------------
# Semantic Actions
diff --git a/tests/test_rulename_lookup.py b/tests/test_rulename_lookup.py
new file mode 100644
index 0000000..2fec9d0
--- /dev/null
+++ b/tests/test_rulename_lookup.py
@@ -0,0 +1,33 @@
+# -*- coding: utf-8 -*-
+#######################################################################
+# Name: test_peg_parser
+# Purpose: Test for parser constructed using PEG textual grammars.
+# Author: Igor R. Dejanović <igor DOT dejanovic AT gmail DOT com>
+# Copyright: (c) 2014 Igor R. Dejanović <igor DOT dejanovic AT gmail DOT com>
+# License: MIT License
+#######################################################################
+
+from unittest import TestCase
+
+# Grammar
+from arpeggio import ParserPython, ZeroOrMore
+
+
+def foo(): return "a", bar, "b", baz
+def bar(): return "c"
+def baz(): return "d"
+
+
+
+class TestPEGParser(TestCase):
+
+ def test_lookup_single(self):
+
+ parser = ParserPython(foo)
+
+ result = parser.parse("a c b d")
+
+ self.assertTrue(hasattr(result, "bar"))
+ self.assertTrue(hasattr(result, "baz"))
+ self.assertTrue(not hasattr(result, "unexisting"))
+
--
2.18.0