From 6825c18df9edd1e69d26ead3f9542983a4b16a1a Mon Sep 17 00:00:00 2001
From: Erik Moqvist <erik.moqvist@gmail.com>
Date: Sun, 22 Jul 2018 08:59:01 +0200
Subject: [PATCH] Various new functionality.

---
 tests/test_textparser.py | 15 +++++++++++++
 textparser.py            | 47 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/tests/test_textparser.py b/tests/test_textparser.py
index 9aee9bb..64903d3 100644
--- a/tests/test_textparser.py
+++ b/tests/test_textparser.py
@@ -3,6 +3,7 @@
 import textparser
 from textparser import Grammar
 from textparser import Sequence
+from textparser import DelimitedList
 from textparser import Token
 
 
@@ -34,6 +35,20 @@ def test_sequence_mismatch(self):
 
         self.assertEqual(str(cm.exception), '')
 
+    def test_delimited_list(self):
+        grammar = Grammar(DelimitedList('WORD'))
+
+        datas = [
+            ([], []),
+            ([('WORD', 'foo')], ['foo']),
+            ([('WORD', 'foo'), (',', ','), ('WORD', 'bar')], ['foo', 'bar'])
+        ]
+
+        for tokens, expected_tree in datas:
+            tokens = tokenize(tokens + [('__EOF__', '')])
+            tree = grammar.parse(tokens)
+            self.assertEqual(tree, expected_tree)
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/textparser.py b/textparser.py
index a1316fa..0aeface 100644
--- a/textparser.py
+++ b/textparser.py
@@ -14,6 +14,34 @@ class Error(Exception):
     pass
 
 
+def markup_line(string, offset):
+    begin = string.rfind('\n', 0, offset)
+    begin += 1
+
+    end = string.find('\n', offset)
+
+    if end == -1:
+        end = len(string)
+
+    return string[begin:offset] + '>>!<<' + string[offset:end]
+
+
+class TokenizerError(Error):
+
+    def __init__(self, line, column, offset, string):
+        message = 'Invalid syntax at line {}, column {}: "{}"'.format(
+            line,
+            column,
+            markup_line(string, offset))
+        super().__init__(message)
+
+
+def create_token_re(spec):
+    return '|'.join([
+        '(?P<{}>{})'.format(name, regex) for name, regex in spec
+    ])
+
+
 class _Tokens(object):
 
     def __init__(self, tokens):
@@ -220,7 +248,10 @@ def match(self, tokens):
             mo = _match_item(self._element, tokens)
 
             if mo is None:
-                return None
+                if len(matched) == 0:
+                    return []
+                else:
+                    return None
 
             matched.append(mo)
 
@@ -240,6 +271,20 @@ def match(self, tokens):
         return self._element.match(tokens)
 
 
+class Forward(object):
+
+    def __init__(self):
+        self._inner = None
+
+    def __ilshift__(self, other):
+        self._inner = other
+
+        return self
+
+    def match(self, tokens):
+        return self._inner.match(tokens)
+
+
 class Grammar(object):
     """Creates a tree of given tokens.