Support for skipws and ws params for Sequence.

arpeggio/__init__.py

@@ -280,10 +280,25 @@ class Sequence(ParsingExpression):
     """
     Will match sequence of parser expressions in exact order they are defined.
     """
+
+    def __init__(self, *elements, **kwargs):
+        super(Sequence, self).__init__(*elements, **kwargs)
+        self.ws = kwargs.pop('ws', None)
+        self.skipws = kwargs.pop('skipws', None)
+
     def _parse(self, parser):
         results = []
         c_pos = parser.position
         seq_len = len(self.nodes)
+
+        if self.ws is not None:
+            old_ws = parser.ws
+            parser.ws = self.ws
+
+        if self.skipws is not None:
+            old_skipws = parser.skipws
+            parser.skipws = self.skipws
+
         try:
             for e in self.nodes:
                 result = None
@@ -307,6 +322,12 @@ class Sequence(ParsingExpression):
             self._nm_change_rule(m, parser)
             raise
 
+        finally:
+            if self.ws is not None:
+                parser.ws = old_ws
+            if self.skipws is not None:
+                parser.skipws = old_skipws
+
         return results
 
 
@@ -1504,7 +1525,8 @@ class ParserPython(Parser):
             elif isinstance(expression, Match):
                 retval = expression
 
-            elif isinstance(expression, Repetition) or \
+            elif isinstance(expression, Sequence) or \
+                    isinstance(expression, Repetition) or \
                     isinstance(expression, SyntaxPredicate) or \
                     isinstance(expression, Decorator):
                 retval = expression

tests/unit/test_sequence_params.py

+# -*- coding: utf-8 -*-
+#######################################################################
+# Name: test_sequence_params
+# Purpose: Test Sequence expression parameters.
+# 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 __future__ import unicode_literals
+import pytest
+from arpeggio import ParserPython, NoMatch, Sequence
+from arpeggio import RegExMatch as _
+
+
+def test_skipws():
+    """
+    skipws may be defined per Sequence.
+    """
+
+    def grammar():     return Sequence("one", "two", "three"), "four"
+
+    parser = ParserPython(grammar)
+
+    # By default, skipws is True and whitespaces will be skipped.
+    parser.parse("one two   three  four")
+
+
+    def grammar():     return Sequence("one", "two", "three",
+                                       skipws=False), "four"
+
+    parser = ParserPython(grammar)
+
+    # If we disable skipws for sequence only then whitespace
+    # skipping should not be done inside sequence.
+    with pytest.raises(NoMatch):
+        parser.parse("one two   three  four")
+
+    # But it will be done outside of it
+    parser.parse("onetwothree  four")
+
+
+def test_ws():
+    """
+    ws can be changed per Sequence.
+    """
+
+    def grammar():     return Sequence("one", "two", "three"), "four"
+
+    parser = ParserPython(grammar)
+
+    # By default, ws consists of space, tab and newline
+    # So this should parse.
+    parser.parse("""one
+            two   three  four""")
+
+
+    def grammar():     return Sequence("one", "two", "three",
+                                       ws=' '), "four"
+
+    parser = ParserPython(grammar)
+
+    # If we change ws per sequence and set it to space only
+    # given input will raise exception
+    with pytest.raises(NoMatch):
+        parser.parse("""one
+                two   three  four""")
+
+    # But ws will be default outside of sequence
+    parser.parse("""one two  three
+        four""")