* Convenience regular expression module.

regexps.py

@@ -0,0 +1,65 @@
+# -*- python -*-
+#
+# $Id: regexps.py,v 1.1 2010-10-06 16:37:42 wirawan Exp $
+#
+# Created: 20101006
+# Wirawan Purwanto
+#
+"""
+
+Various convenience regular expression tools.
+
+"""
+
+import re
+
+
+class regex(object):
+  """Single-state regex matcher.
+  For quick and dirty matching (single-use, disposable).
+  This is intended to make python scripts a bit more convenient to
+  use for regexp-intensive matches, just like perl.
+
+  Examples:
+
+      rx = regex(r'deltau = ([0-9.]+)')
+      rx2 = regex(r'deltau2 = ([0-9.]+)')
+      ...
+      for text in f:
+        if rx % text:  # equal to rx.search(text)
+          deltau = float(rx[1])
+        if rx2 ^ text: # equal to rx.match(text)
+          deltau2 = float(rx2[1])
+
+  Note that the regex object must appear as the *LEFT* operand of the
+  string being scanned.
+
+  """
+  def __init__(self, pat, flags=0):
+    self.rx = re.compile(pat, flags)
+
+  # The following names are the same as standard python re compiled object:
+  def match(self, s, flags=0):
+    self.m = self.rx.match(s, flags)
+    return self.m
+  def search(self, s, flags=0):
+    self.m = self.rx.search(s, flags)
+    return self.m
+
+  # Experimental: using operators instead of names
+  # No user-defined flags are possible in this case.
+  def __xor__(self, s):
+    """Match the string to the regex at the beginning."""
+    self.m = self.rx.match(s)
+    return self.m
+  def __mod__(self, s):
+    """Match the string to the regex at the any position.
+    Too bad python does not have ~= like perl, so we use the
+    quirky % or == here."""
+    self.m = self.rx.search(s)
+    return self.m
+  __eq__ = __mod__
+
+  def __getitem__(self, i):
+    """Returns the i-th group from the last match operation."""
+    return self.m.group(i)