Generate templates from text.

xtemplate.py

def xtemplate(toks, str):
    '''
    A function that generates templates from given tokens and
    strings. We are using this to generate email templates:
    >>> sep = [(',', ','), ('-', '-'), ('_', '_')]
    >>> ini = [('$fini', 'a'), ('$lini', 'z')]
    >>> name = [('$fname', 'ali'), ('$lname', 'zaidi')]
    >>> toks = sep + ini + name
    >>> xtemplate(toks, 'ali.zaidi')
    '$fname.$lname'
    >>> xtemplate(toks, 'ali-zaidi')
    '$fname-$lname'
    >>> xtemplate(toks, 'ali-')
    '$fname-'
    >>> xtemplate(toks, 'zaidi')
    '$lname'
    >>> xtemplate(toks, 'a.zaidi')
    '$fini.$lname'
    >>> xtemplate(toks, 'a.z')
    '$fini.$lini'
    >>> xtemplate(toks, 'az')
    '$fini$lini'
    >>> xtemplate(toks, 'cake')
    'c$finike'
    '''
    if toks == [] or str == '':
        return str
    toks = toks[:]
    key, val = toks.pop()
    residue = [xtemplate(toks, r) for r in str.split(val)]
    return key.join(residue)