Experimental speedup patch by Tim Peters (please test!):

It wasn't hard to speed pyclbr by a factor of 3, and I'll attach an
experimental patch for that (experimental because barely tested).  Uncomment
the new "String" stuff and it will deal with strings correctly (pyclbr
currently ignores the possibility), but that slows it down a lot.  Still
faster in the end than current pyclbr, but-- frankly --I'd rather have the
dramatic speedup!

Lib/pyclbr.py

@@ -30,7 +30,9 @@ shouldn't happen often.
 
 BUGS
 Continuation lines are not dealt with at all and strings may confuse
-the hell out of the parser, but it usually works.''' # ' <-- bow to font lock
+the hell out of the parser, but it usually works.
+Nested classes are not recognized.
+Nested defs may be mistaken for class methods.''' # ' <-- bow to font lock
 
 import os
 import sys
@@ -38,16 +40,70 @@ import imp
 import re
 import string
 
-id = '[A-Za-z_][A-Za-z0-9_]*'	# match identifier
-blank_line = re.compile('^[ \t]*($|#)')
-is_class = re.compile('^class[ \t]+(?P<id>'+id+')[ \t]*(?P<sup>\([^)]*\))?[ \t]*:')
-is_method = re.compile('^[ \t]+def[ \t]+(?P<id>'+id+')[ \t]*\(')
-is_import = re.compile('^import[ \t]*(?P<imp>[^#;]+)')
-is_from = re.compile('^from[ \t]+(?P<module>'+id+'([ \t]*\\.[ \t]*'+id+')*)[ \t]+import[ \t]+(?P<imp>[^#;]+)')
-dedent = re.compile('^[^ \t]')
-indent = re.compile('^[^ \t]*')
+_getnext = re.compile(r"""
+## String slows it down by more than a factor of 2 (not because the
+## string regexp is slow, but because there are often a lot of strings,
+## which means the regexp has to get called that many more times).
+##    (?P<String>
+##	" [^"\\\n]* (?: \\. [^"\\\n]* )* "
+##
+##    |   ' [^'\\\n]* (?: \\. [^'\\\n]* )* '
+##
+##    |  \""" [^"\\]* (?:
+##			(?: \\. | "(?!"") )
+##			[^"\\]*
+##		    )*
+##       \"""
+##
+##    |   ''' [^'\\]* (?:
+##			(?: \\. | '(?!'') )
+##			[^'\\]*
+##		    )*
+##	'''
+##    )
+##
+##|   (?P<Method>
+    (?P<Method>
+	# dicey trick:  assume a def not at top level is a method
+	^ [ \t]+ def [ \t]+
+	(?P<MethodName> [a-zA-Z_] \w* )
+	[ \t]* \(
+    )
 
-_modules = {}				# cache of modules we've seen
+|   (?P<Class>
+	# lightly questionable:  assume only top-level classes count
+	^ class [ \t]+
+	(?P<ClassName> [a-zA-Z_] \w* )
+	[ \t]*
+	(?P<ClassSupers> \( [^)\n]* \) )?
+	[ \t]* :
+    )
+
+|   (?P<Import>
+	^ import [ \t]+
+	(?P<ImportList> [^#;\n]+ )
+    )
+
+|   (?P<ImportFrom>
+	^ from [ \t]+
+	(?P<ImportFromPath>
+	    [a-zA-Z_] \w*
+	    (?:
+		[ \t]* \. [ \t]* [a-zA-Z_] \w*
+	    )*
+	)
+	[ \t]+
+	import [ \t]+
+	(?P<ImportFromList> [^#;\n]+ )
+    )
+
+|   (?P<AtTopLevel>
+	# cheap trick: anything other than ws in first column
+	^ \S
+    )
+""", re.VERBOSE | re.DOTALL | re.MULTILINE).search
+
+_modules = {}                           # cache of modules we've seen
 
 # each Python class is represented by an instance of this class
 class Class:
@@ -117,66 +173,49 @@ def readmodule(module, path=[], inpackage=0):
 	dict = {}
 	_modules[module] = dict
 	imports = []
-	lineno = 0
+	src = f.read()
+	f.close()
+
+	# To avoid having to stop the regexp at each newline, instead
+	# when we need a line number we simply string.count the number of
+	# newlines in the string since the last time we did this; i.e.,
+	#    lineno = lineno + \
+	#             string.count(src, '\n', last_lineno_pos, here)
+	#    last_lineno_pos = here
+	countnl = string.count
+	lineno, last_lineno_pos = 1, 0
+	i = 0
 	while 1:
-		line = f.readline()
-		if not line:
+		m = _getnext(src, i)
+		if not m:
 			break
-		lineno = lineno + 1	# count lines
-		line = line[:-1]	# remove line feed
-		if blank_line.match(line):
-			# ignore blank (and comment only) lines
-			continue
-## 		res = indent.match(line)
-## 		if res:
-## 			indentation = len(string.expandtabs(res.group(0), 8))
-		res = is_import.match(line)
-		if res:
-			# import module
-			for n in string.splitfields(res.group('imp'), ','):
-				n = string.strip(n)
-				try:
-					# recursively read the
-					# imported module
-					d = readmodule(n, path, inpackage)
-				except:
-					print 'module',n,'not found'
-					pass
-			continue
-		res = is_from.match(line)
-		if res:
-			# from module import stuff
-			mod = res.group('module')
-			names = string.splitfields(res.group('imp'), ',')
-			try:
-				# recursively read the imported module
-				d = readmodule(mod, path, inpackage)
-			except:
-				print 'module',mod,'not found'
-				continue
-			# add any classes that were defined in the
-			# imported module to our name space if they
-			# were mentioned in the list
-			for n in names:
-				n = string.strip(n)
-				if d.has_key(n):
-					dict[n] = d[n]
-				elif n == '*':
-					# only add a name if not
-					# already there (to mimic what
-					# Python does internally)
-					# also don't add names that
-					# start with _
-					for n in d.keys():
-						if n[0] != '_' and \
-						   not dict.has_key(n):
-							dict[n] = d[n]
-			continue
-		res = is_class.match(line)
-		if res:
+		start, i = m.span()
+
+		if m.start("AtTopLevel") >= 0:
+			# end of class definition
+			cur_class = None
+
+##		elif m.start("String") >= 0:
+##			pass
+
+		elif m.start("Method") >= 0:
+			# found a method definition
+			if cur_class:
+				# and we know the class it belongs to
+				meth_name = m.group("MethodName")
+				lineno = lineno + \
+					 countnl(src, '\n',
+						 last_lineno_pos, start)
+				last_lineno_pos = start
+				cur_class._addmethod(meth_name, lineno)
+
+		elif m.start("Class") >= 0:
 			# we found a class definition
-			class_name = res.group('id')
-			inherit = res.group('sup')
+			lineno = lineno + \
+				 countnl(src, '\n', last_lineno_pos, start)
+			last_lineno_pos = start
+			class_name = m.group("ClassName")
+			inherit = m.group("ClassSupers")
 			if inherit:
 				# the class inherits from other classes
 				inherit = string.strip(inherit[1:-1])
@@ -203,20 +242,48 @@ def readmodule(module, path=[], inpackage=0):
 					names.append(n)
 				inherit = names
 			# remember this class
-			cur_class = Class(module, class_name, inherit, file, lineno)
+			cur_class = Class(module, class_name, inherit,
+					  file, lineno)
 			dict[class_name] = cur_class
-			continue
-		res = is_method.match(line)
-		if res:
-			# found a method definition
-			if cur_class:
-				# and we know the class it belongs to
-				meth_name = res.group('id')
-				cur_class._addmethod(meth_name, lineno)
-			continue
-		if dedent.match(line):
-			# end of class definition
-			cur_class = None
-	f.close()
-	return dict
 
+		elif m.start("Import") >= 0:
+			# import module
+			for n in string.split(m.group("ImportList"), ','):
+				n = string.strip(n)
+				try:
+					# recursively read the imported module
+					d = readmodule(n, path, inpackage)
+				except:
+					print 'module', n, 'not found'
+
+		elif m.start("ImportFrom") >= 0:
+			# from module import stuff
+			mod = m.group("ImportFromPath")
+			names = string.split(m.group("ImportFromList"), ',')
+			try:
+				# recursively read the imported module
+				d = readmodule(mod, path, inpackage)
+			except:
+				print 'module', mod, 'not found'
+				continue
+			# add any classes that were defined in the
+			# imported module to our name space if they
+			# were mentioned in the list
+			for n in names:
+				n = string.strip(n)
+				if d.has_key(n):
+					dict[n] = d[n]
+				elif n == '*':
+					# only add a name if not
+					# already there (to mimic what
+					# Python does internally)
+					# also don't add names that
+					# start with _
+					for n in d.keys():
+						if n[0] != '_' and \
+						   not dict.has_key(n):
+							dict[n] = d[n]
+		else:
+			assert 0, "regexp _getnext found something unexpected"
+
+	return dict