From 8609d13ac8b561ee8b3ed58cc58ec38d710b5fe5 Mon Sep 17 00:00:00 2001
From: Igor Dejanovic <igor.dejanovic@gmail.com>
Date: Sun, 10 Aug 2014 22:58:01 +0200
Subject: [PATCH] Change the way non-terminals are created in the parse method
---
arpeggio/__init__.py | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/arpeggio/__init__.py b/arpeggio/__init__.py
index ac277d8..df37b93 100644
--- a/arpeggio/__init__.py
+++ b/arpeggio/__init__.py
@@ -245,17 +245,18 @@ class ParsingExpression(object):
if parser.debug:
print("<< Leaving rule {}".format(self.name))
- # Create terminal or non-terminal if result is not
- # already a Terminal.
+ # For root rules flatten non-terminal/list
if self.root and result and not isinstance(result, Terminal):
- if parser.reduce_tree:
- if isinstance(result, list):
- result = flatten(result)
- if len(result) == 1:
- result = result[0]
- else:
- result = NonTerminal(self, c_pos, result)
- else:
+ if not isinstance(result, NonTerminal):
+ result = flatten(result)
+
+ # Tree reduction will eliminate Non-terminal with single child.
+ if parser.reduce_tree and len(result) == 1:
+ result = result[0]
+
+ # If the result is not parse tree node it must be a plain list
+ # so create a new NonTerminal.
+ if not isinstance(result, ParseTreeNode):
result = NonTerminal(self, c_pos, result)
# Result caching for use by memoization.
--
2.18.0