The fundamentals...

[Fredrik Lundh]

"mspiggie at my-deja.com" wrote:
> I have been trying to find a way to use replace() to perform more than
> one replacement within a given file.  For instance, suppose I needed to
> replace ". " with "\n", but also need to replace "!" with "exclamation"
> and "?" with "question".  I have tried several approaches to this, but
> none of my neophyte ideas have produced satisfying results.

here's one way to do it:

http://www.deja.com/=dnc/getdoc.xp?AN=672888429

import re, string

class MultiReplace:
    def __init__(self, repl_dict):
        # "compile" replacement dictionary

        # assume char to char mapping
        charmap = map(chr, range(256))
        for k, v in repl_dict.items():
            if len(k) != 1 or len(v) != 1:
                self.charmap = None
                break # cannot use translate
            charmap[ord(k)] = v
        else:
            self.charmap = string.join(charmap, "")
            return

        # string to string mapping; use a regular expression
        keys = repl_dict.keys()
        keys.sort() # lexical order
        pattern = string.join(map(re.escape, keys), "|")
        self.pattern = re.compile(pattern)
        self.dict = repl_dict

    def replace(self, str):
        # apply replacement dictionary to string
        if self.charmap:
            return string.translate(str, self.charmap)
        def repl(match, get=self.dict.get):
            item = match.group(0)
            return get(item, item)
        return self.pattern.sub(repl, str)

r = MultiReplace({"spam": "eggs", "spam": "eggs"})
print r.replace("spam&eggs")

r = MultiReplace({"a": "b", "b": "a"})
print r.replace("keaba")

r = MultiReplace({". ": "\n", "!": "exclamation", "?": "question"})
print repr(r.replace("look. an albatross !"))

Cheers /F

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