- added lookbehind support (?<=pattern), (?<!pattern).

  the pattern must have a fixed width.

- got rid of array-module dependencies; the match pro-
  gram is now stored inside the pattern object, rather
  than in an extra string buffer.

- cleaned up a various of potential leaks, api abuses,
  and other minors in the engine module.

- use mal's new isalnum macro, rather than my own work-
  around.

- untabified test_sre.py.  seems like I removed a couple
  of trailing spaces in the process...

3 files changed, 51 insertions, 40 deletions

diff --git a/Lib/sre_compile.py b/Lib/sre_compile.py
index 36986eb..701b267 100644
--- a/Lib/sre_compile.py
+++ b/Lib/sre_compile.py
@@ -10,18 +10,10 @@
 # other compatibility work.
 #
 
-import array
 import _sre
 
 from sre_constants import *
 
-# find an array type code that matches the engine's code size
-for WORDSIZE in "Hil":
-    if len(array.array(WORDSIZE, [0]).tostring()) == _sre.getcodesize():
-        break
-else:
-    raise RuntimeError, "cannot find a useable array type"
-
 MAXCODE = 65535
 
 def _charset(charset, fixup):
@@ -170,7 +162,20 @@ def _compile(code, pattern, flags):
                 emit((group-1)*2+1)
         elif op in (SUCCESS, FAILURE):
             emit(OPCODES[op])
-        elif op in (ASSERT, ASSERT_NOT, CALL):
+        elif op in (ASSERT, ASSERT_NOT):
+            emit(OPCODES[op])
+            skip = len(code); emit(0)
+            if av[0] >= 0:
+                emit(0) # look ahead
+            else:
+                lo, hi = av[1].getwidth()
+                if lo != hi:
+                    raise error, "look-behind requires fixed-width pattern"
+                emit(lo) # look behind
+            _compile(code, av[1], flags)
+            emit(OPCODES[SUCCESS])
+            code[skip] = len(code) - skip
+        elif op is CALL:
             emit(OPCODES[op])
             skip = len(code); emit(0)
             _compile(code, av, flags)
@@ -305,7 +310,7 @@ def compile(p, flags=0):
         indexgroup[i] = k
 
     return _sre.compile(
-        pattern, flags,
-        array.array(WORDSIZE, code).tostring(),
-        p.pattern.groups-1, groupindex, indexgroup
+        pattern, flags, code,
+        p.pattern.groups-1,
+        groupindex, indexgroup
         )
diff --git a/Lib/sre_parse.py b/Lib/sre_parse.py
index d78737f..07ab782 100644
--- a/Lib/sre_parse.py
+++ b/Lib/sre_parse.py
@@ -482,9 +482,15 @@ def _parse(source, state):
                         if source.next is None or source.next == ")":
                             break
                         source.get()
-                elif source.next in ("=", "!"):
+                elif source.next in ("=", "!", "<"):
                     # lookahead assertions
                     char = source.get()
+                    dir = 1
+                    if char == "<":
+                        if source.next not in ("=", "!"):
+                            raise error, "syntax error"
+                        dir = -1 # lookbehind
+                        char = source.get()
                     b = []
                     while 1:
                         p = _parse(source, state)
@@ -493,9 +499,9 @@ def _parse(source, state):
                                 b.append(p)
                                 p = _branch(state, b)
                             if char == "=":
-                                subpattern.append((ASSERT, p))
+                                subpattern.append((ASSERT, (dir, p)))
                             else:
-                                subpattern.append((ASSERT_NOT, p))
+                                subpattern.append((ASSERT_NOT, (dir, p)))
                             break
                         elif source.match("|"):
                             b.append(p)
diff --git a/Lib/test/test_sre.py b/Lib/test/test_sre.py
index dc42ed1..a22c51a 100644
--- a/Lib/test/test_sre.py
+++ b/Lib/test/test_sre.py
@@ -35,20 +35,20 @@ if verbose:
 
 try:
     assert sre.sub("(?i)b+", "x", "bbbb BBBB") == 'x x'
-    
+
     def bump_num(matchobj):
         int_value = int(matchobj.group(0))
         return str(int_value + 1)
 
     assert sre.sub(r'\d+', bump_num, '08.2 -2 23x99y') == '9.3 -3 24x100y'
     assert sre.sub(r'\d+', bump_num, '08.2 -2 23x99y', 3) == '9.3 -3 23x99y'
-    
+
     assert sre.sub('.', lambda m: r"\n", 'x') == '\\n'
     assert sre.sub('.', r"\n", 'x') == '\n'
 
     s = r"\1\1"
     assert sre.sub('(.)', s, 'x') == 'xx'
-    assert sre.sub('(.)', sre.escape(s), 'x') == s 
+    assert sre.sub('(.)', sre.escape(s), 'x') == s
     assert sre.sub('(.)', lambda m: s, 'x') == s
 
     assert sre.sub('(?P<a>x)', '\g<a>\g<a>', 'xx') == 'xxxx'
@@ -144,7 +144,7 @@ except AssertionError:
 
 if verbose:
     print 'Running tests on sre.split'
-    
+
 try:
     assert sre.split(":", ":a:b::c") == ['', 'a', 'b', '', 'c']
     assert sre.split(":*", ":a:b::c") == ['', 'a', 'b', 'c']
@@ -164,7 +164,7 @@ try:
     assert sre.split(':', 'a:b:c:d', 2) == ['a', 'b', 'c:d']
 
     assert sre.split("(:)", ":a:b::c", 2) == ['', ':', 'a', ':', 'b::c']
-    assert sre.split("(:*)", ":a:b::c", 2) == ['', ':', 'a', ':', 'b::c']    
+    assert sre.split("(:*)", ":a:b::c", 2) == ['', ':', 'a', ':', 'b::c']
 except AssertionError:
     raise TestFailed, "qualified sre.split"
 
@@ -186,29 +186,29 @@ if verbose:
 
 try:
     # No groups at all
-    m = sre.match('a', 'a') ; assert m.groups() == ()    
+    m = sre.match('a', 'a') ; assert m.groups() == ()
     # A single group
-    m = sre.match('(a)', 'a') ; assert m.groups() == ('a',)      
+    m = sre.match('(a)', 'a') ; assert m.groups() == ('a',)
 
     pat = sre.compile('((a)|(b))(c)?')
-    assert pat.match('a').groups() == ('a', 'a', None, None)    
-    assert pat.match('b').groups() == ('b', None, 'b', None)    
-    assert pat.match('ac').groups() == ('a', 'a', None, 'c')    
-    assert pat.match('bc').groups() == ('b', None, 'b', 'c')    
-    assert pat.match('bc').groups("") == ('b', "", 'b', 'c')    
+    assert pat.match('a').groups() == ('a', 'a', None, None)
+    assert pat.match('b').groups() == ('b', None, 'b', None)
+    assert pat.match('ac').groups() == ('a', 'a', None, 'c')
+    assert pat.match('bc').groups() == ('b', None, 'b', 'c')
+    assert pat.match('bc').groups("") == ('b', "", 'b', 'c')
 except AssertionError:
     raise TestFailed, "match .groups() method"
 
 try:
     # A single group
-    m = sre.match('(a)', 'a') 
-    assert m.group(0) == 'a' ; assert m.group(0) == 'a' 
+    m = sre.match('(a)', 'a')
+    assert m.group(0) == 'a' ; assert m.group(0) == 'a'
     assert m.group(1) == 'a' ; assert m.group(1, 1) == ('a', 'a')
 
     pat = sre.compile('(?:(?P<a1>a)|(?P<b2>b))(?P<c3>c)?')
-    assert pat.match('a').group(1, 2, 3) == ('a', None, None)   
-    assert pat.match('b').group('a1', 'b2', 'c3') == (None, 'b', None)  
-    assert pat.match('ac').group(1, 'b2', 3) == ('a', None, 'c')        
+    assert pat.match('a').group(1, 2, 3) == ('a', None, None)
+    assert pat.match('b').group('a1', 'b2', 'c3') == (None, 'b', None)
+    assert pat.match('ac').group(1, 'b2', 3) == ('a', None, 'c')
 except AssertionError:
     raise TestFailed, "match .group() method"
 
@@ -252,10 +252,10 @@ try:
     assert sre.I == sre.IGNORECASE
     assert sre.L == sre.LOCALE
     assert sre.M == sre.MULTILINE
-    assert sre.S == sre.DOTALL 
-    assert sre.X == sre.VERBOSE 
-    assert sre.T == sre.TEMPLATE 
-    assert sre.U == sre.UNICODE 
+    assert sre.S == sre.DOTALL
+    assert sre.X == sre.VERBOSE
+    assert sre.T == sre.TEMPLATE
+    assert sre.U == sre.UNICODE
 except AssertionError:
     raise TestFailed, 're module constants'
 
@@ -272,7 +272,7 @@ if verbose:
 else:
     # To save time, only run the first and last 10 tests
     #tests = tests[:10] + tests[-10:]
-    pass 
+    pass
 
 for t in tests:
     sys.stdout.flush()
@@ -280,7 +280,7 @@ for t in tests:
     if len(t)==5:
         pattern, s, outcome, repl, expected = t
     elif len(t)==3:
-        pattern, s, outcome = t 
+        pattern, s, outcome = t
     else:
         raise ValueError, ('Test tuples should have 3 or 5 fields',t)
 
@@ -288,7 +288,7 @@ for t in tests:
         obj=sre.compile(pattern)
     except sre.error:
         if outcome==SYNTAX_ERROR: pass  # Expected a syntax error
-        else: 
+        else:
             print '=== Syntax error:', t
     except KeyboardInterrupt: raise KeyboardInterrupt
     except:
@@ -356,7 +356,7 @@ for t in tests:
             # of the match and see if it still succeeds.  \B will
             # break (because it won't match at the end or start of a
             # string), so we'll ignore patterns that feature it.
-            
+
             if pattern[:2]!='\\B' and pattern[-2:]!='\\B':
                 obj=sre.compile(pattern)
                 result=obj.search(s, result.start(0), result.end(0)+1)