and improve the speed of the if/elif/else blocks.

Backported to 2.3.

* pre-build a single identity function for the fixup function
* pre-build membership tests in dictionaries instead of in-line tuples
* assign len() to a local variable
* assign append() methods to a local variable
* use xrange() instead of range()
* replace "x<<1" with "x+x"

Use isinstance() instead of comparing types directly, to enable
subclasses of str and unicode to be used as patterns.
Blessed by /F.

A small fix for bug #545855 and Greg Chapman's
addition of op code SRE_OP_MIN_REPEAT_ONE for
eliminating recursion on simple uses of pattern '*?' on a
long string.

    The problem is in sre_compile.py: the call to
    _compile_charset near the end of _compile_info forgets to
    pass in the flags, so that the info charset is not compiled
    with re.U. (The info charset is used when searching to find
    the first character at which a match could start; it is not
    generated for patterns beginning with a repeat like '\w{1}'.)

Will backport to 2.2

+ test_quopri.py relied on significant trailing spaces.  Fixed.
+ test_dircache.py (still) doesn't work on Windows (directory mtime on
  Windows doesn't work like it does on Unix).

speedups for certain unicode character ranges.

- take locale into account for word boundary anchors (#410271)
- restored 2.0's *? behaviour (#233283, #408936 and others)
- speed up re.sub/re.subn

- removed __all__ cruft from internal modules (sorry, skip)
- don't assume ASCII for string escapes (sorry, per)

also modified check_all function to suppress all warnings since they aren't
relevant to what this test is doing (allows quiet checking of regsub, for
instance)

uppercase strings also when the IGNORECASE flag is set (bug #128899)

(also added test cases for recently fixed bugs to the regression suite
-- or in other words, check in re_tests.py too...)

by compiler/engine mismatches

-- added some more docstrings
-- fixed typo in scanner class (#125531)
-- the multiline flag (?m) should't affect the \Z operator (#127259)
-- fixed non-greedy backtracking bug (#123769, #127259)
-- added sre.DEBUG flag (currently dumps the parsed pattern structure)
-- fixed a couple of glitches in groupdict (the #126587 memory leak
   had already been fixed by AMK)

   (this should fix Sjoerd's xmllib problem)
-- added skip field to INFO header
-- changed compiler to generate charset INFO header
-- changed trace messages to support post-mortem analysis

-- added REPEAT_ONE operator
-- added ANY_ALL operator (used to represent "(?s).")

-- fixed literal check in branch operator
   (this broke test_tokenize, as reported by Mark Favas)
-- added REPEAT_ONE operator (still not enabled, though)
-- added some debugging stuff (maxlevel)

-- reverted REPEAT operator to use "repeat context" strategy
   (from 0.8.X), but done right this time.
-- got rid of backtracking stack; use nested SRE_MATCH calls
   instead (should probably put it back again in 0.9.9 ;-)
-- properly reset state in scanner mode
-- don't use aggressive inlining by default

 + added "regs" attribute
 + fixed "pos" and "endpos" attributes
 + reset "lastindex" and "lastgroup" in scanner methods
 + removed (?P#id) syntax; the "lastindex" and "lastgroup"
   attributes are now always set
 + removed string module dependencies in sre_parse
 + better debugging support in sre_parse
 + various tweaks to build under 1.5.2

- reorganized some code to get rid of -Wall and -W4
  warnings

- fixed default argument handling for sub/subn/split
  methods (reported by Peter Schneider-Kamp).

- changed "group" operator to "groupref"

  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...

  "lastgroup" is the name of the last matched capturing group,
  "lastindex" is the index of the same group.  if no group was
  matched, both attributes are set to None.

  the (?P#) feature will be removed in the next relase.

  used by the code generator)

- changed max repeat value in engine (to match earlier array fix)

- added experimental "which part matched?" mechanism to sre; see
  http://hem.passagen.se/eff/2000_07_01_bot-archive.htm#416954
  or python-dev for details.

   speedup for some tests, including the python tokenizer.

-- added support for an optional charset anchor to the engine
   (currently unused by the code generator).

-- removed workaround for array module bug.

-- changed 1.6 to 2.0 in the file headers

-- fixed ISALNUM macro for the unicode locale.  this
   solution isn't perfect, but the best I can do with
   Python's current unicode database.