SF.net SVN: matplotlib: [3744] trunk/matplotlib/lib/matplotlib

[<md...@us...>]

Revision: 3744
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=3744&view=rev
Author:   mdboom
Date:     2007-08-28 12:17:21 -0700 (Tue, 28 Aug 2007)

Log Message:
-----------
Use regular expressions to do dedenting.  This is ~15X faster than the
old implementation.  dedent accounted for around 30% of the time spent
in "import pylab", so was probably worthy of optimization, even if this
regex approach is less clear.  The results are identical to the old
implementation, with the exception of a single docstring (in
backend_bases.py) that needed to be fixed.

Modified Paths:
--------------
    trunk/matplotlib/lib/matplotlib/backend_bases.py
    trunk/matplotlib/lib/matplotlib/cbook.py

Modified: trunk/matplotlib/lib/matplotlib/backend_bases.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/backend_bases.py	2007-08-28 12:27:56 UTC (rev 3743)
+++ trunk/matplotlib/lib/matplotlib/backend_bases.py	2007-08-28 19:17:21 UTC (rev 3744)
@@ -1100,7 +1100,7 @@
         return newCanvas
 
     def mpl_connect(self, s, func):
-        """\
+        """
         Connect event with string s to func.  The signature of func is
 
           def func(event)

Modified: trunk/matplotlib/lib/matplotlib/cbook.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/cbook.py	2007-08-28 12:27:56 UTC (rev 3743)
+++ trunk/matplotlib/lib/matplotlib/cbook.py	2007-08-28 19:17:21 UTC (rev 3744)
@@ -533,6 +533,12 @@
         ret += pad + ' '.join(line) + '\n'
     return ret
 
+# A regular expression used to determine the amount of space to
+# remove.  It looks for the first sequence of spaces immediately
+# following the first newline, or at the beginning of the string.
+_find_dedent_regex = re.compile("(?:(?:\n\r?)|^)( *)\S")
+# A cache to hold the regexs that actually remove the indent.
+_dedent_regex = {}
 def dedent(s):
     """
     Remove excess indentation from docstrings.
@@ -546,24 +552,34 @@
 
     It is also faster in most cases.
     """
+    # This implementation has a somewhat obtuse use of regular
+    # expressions.  However, this function accounted for almost 30% of
+    # matplotlib startup time, so it is worthy of optimization at all
+    # costs.
+    
     if not s:      # includes case of s is None
         return ''
-    lines = s.splitlines(False)
-    ii = 0
-    while lines[ii].strip() == '':
-        ii += 1
-    lines = lines[ii:]
-    nshift = len(lines[0]) - len(lines[0].lstrip())
-    # Don't use first line in case of """blah...
-    if ii == 0 and len(lines) > 1:
-        nshift = len(lines[1]) - len(lines[1].lstrip())
-    for i, line in enumerate(lines):
-        nwhite = len(line) - len(line.lstrip())
-        lines[i] = line[min(nshift, nwhite):]
-    return '\n'.join(lines)
 
+    match = _find_dedent_regex.match(s)
+    if match is None:
+        return s
 
+    # This is the number of spaces to remove from the left-hand side.
+    nshift = match.end(1) - match.start(1)
+    if nshift == 0:
+        return s
 
+    # Get a regex that will remove *up to* nshift spaces from the
+    # beginning of each line.  If it isn't in the cache, generate it.
+    unindent = _dedent_regex.get(nshift, None)
+    if unindent = None
+        unindent = re.compile("\n\r?" + " ?" * nshift)
+        _dedent_regex[nshift] = unindent
+        
+    result = unindent.sub("\n", s).strip()
+    return result
+
+
 def listFiles(root, patterns='*', recurse=1, return_folders=0):
     """
     Recursively list files


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