cpython/Lib/sre_compile.py

#
# Secret Labs' Regular Expression Engine
# $Id$
#
# convert template to internal format
#
# Copyright (c) 1997-2000 by Secret Labs AB.  All rights reserved.
#
# This code can only be used for 1.6 alpha testing.  All other use
# require explicit permission from Secret Labs AB.
#
# Portions of this engine have been developed in cooperation with
# CNRI.  Hewlett-Packard provided funding for 1.6 integration and
# other compatibility work.
#

# FIXME: <fl> formalize (objectify?) and document the compiler code
# format, so that other frontends can use this compiler

import array, string, sys

import _sre

from sre_constants import *

# find an array type code that matches the engine's code size
for WORDSIZE in "BHil":
    if len(array.array(WORDSIZE, [0]).tostring()) == _sre.getcodesize():
	break
else:
    raise RuntimeError, "cannot find a useable array type"

# FIXME: <fl> should move some optimizations from the parser to here!

class Code:
    def __init__(self):
	self.data = []
    def __len__(self):
	return len(self.data)
    def __getitem__(self, index):
	return self.data[index]
    def __setitem__(self, index, code):
	self.data[index] = code
    def append(self, code):
	self.data.append(code)
    def todata(self):
	# print self.data
	return array.array(WORDSIZE, self.data).tostring()

def _lower(literal):
    # return _sre._lower(literal) # FIXME
    return string.lower(literal)

def _compile(code, pattern, flags):
    append = code.append
    for op, av in pattern:
	if op is ANY:
	    if "s" in flags:
		append(CODES[op]) # any character at all!
	    else:
		append(CODES[NOT_LITERAL])
		append(10)
	elif op in (SUCCESS, FAILURE):
	    append(CODES[op])
	elif op is AT:
	    append(CODES[op])
	    append(POSITIONS[av])
	elif op is BRANCH:
	    append(CODES[op])
	    tail = []
	    for av in av[1]:
		skip = len(code); append(0)
		_compile(code, av, flags)
		append(CODES[JUMP])
		tail.append(len(code)); append(0)
		code[skip] = len(code) - skip
	    append(0) # end of branch
	    for tail in tail:
		code[tail] = len(code) - tail
	elif op is CALL:
	    append(CODES[op])
	    skip = len(code); append(0)
	    _compile(code, av, flags)
	    append(CODES[SUCCESS])
	    code[skip] = len(code) - skip
	elif op is CATEGORY: # not used by current parser
	    append(CODES[op])
	    append(CATEGORIES[av])
	elif op is GROUP:
	    if "i" in flags:
		append(CODES[MAP_IGNORE[op]])
	    else:
		append(CODES[op])
	    append(av)
	elif op is IN:
	    if "i" in flags:
		append(CODES[MAP_IGNORE[op]])
		def fixup(literal):
		    return ord(_lower(literal))
	    else:
		append(CODES[op])
		fixup = ord
	    skip = len(code); append(0)
	    for op, av in av:
		append(CODES[op])
		if op is NEGATE:
		    pass
		elif op is LITERAL:
		    append(fixup(av))
		elif op is RANGE:
		    append(fixup(av[0]))
		    append(fixup(av[1]))
		elif op is CATEGORY:
		    append(CATEGORIES[av])
		else:
		    raise ValueError, "unsupported set operator"
	    append(CODES[FAILURE])
	    code[skip] = len(code) - skip
	elif op in (LITERAL, NOT_LITERAL):
	    if "i" in flags:
		append(CODES[MAP_IGNORE[op]])
		append(ord(_lower(av)))
	    else:
		append(CODES[op])
		append(ord(av))
	elif op is MARK:
	    append(CODES[op])
	    append(av)
 	elif op in (REPEAT, MIN_REPEAT, MAX_REPEAT):
	    lo, hi = av[2].getwidth()
 	    if lo == 0:
 		raise SyntaxError, "cannot repeat zero-width items"
	    if lo == hi == 1 and op is MAX_REPEAT:
		append(CODES[MAX_REPEAT_ONE])
		skip = len(code); append(0)
		append(av[0])
		append(av[1])
		_compile(code, av[2], flags)
		append(CODES[SUCCESS])
		code[skip] = len(code) - skip
	    else:
		append(CODES[op])
		skip = len(code); append(0)
		append(av[0])
		append(av[1])
		_compile(code, av[2], flags)
		if op is MIN_REPEAT:
		    append(CODES[MIN_UNTIL])
		else:
		    # FIXME: MAX_REPEAT PROBABLY DOESN'T WORK (?)
		    append(CODES[MAX_UNTIL])
		code[skip] = len(code) - skip
	elif op is SUBPATTERN:
## 	    group = av[0]
## 	    if group:
## 		append(CODES[MARK])
## 		append((group-1)*2)
	    _compile(code, av[1], flags)
## 	    if group:
## 		append(CODES[MARK])
## 		append((group-1)*2+1)
	else:
	    raise ValueError, ("unsupported operand type", op)

def compile(p, flags=()):
    # convert pattern list to internal format
    if type(p) is type(""):
	import sre_parse
	pattern = p
	p = sre_parse.parse(p)
    else:
	pattern = None
    # print p.getwidth()
    # print p
    code = Code()
    _compile(code, p.data, p.pattern.flags)
    code.append(CODES[SUCCESS])
    # print list(code.data)
    data = code.todata()
    if 0: # debugging
	print
	print "-" * 68
	import sre_disasm
	sre_disasm.disasm(data)
	print "-" * 68
    # print len(data), p.pattern.groups, len(p.pattern.groupdict)
    return _sre.compile(pattern, data, p.pattern.groups-1, p.pattern.groupdict)