view contrib/hgfixes/fix_bytesmod.py @ 20040:ed80cecdfc57

test-filecache.py: make setbeforeget test clearer

'0' and 'None' as outputs tripped me up. Make the distinction between values
set externally and values computed by calling the decorated function clearer.

"""Fixer that changes bytes % whatever to a function that actually formats
it."""

from lib2to3 import fixer_base
from lib2to3.fixer_util import is_tuple, Call, Comma, Name, touch_import

# XXX: Implementing a blacklist in 2to3 turned out to be more troublesome than
# blacklisting some modules inside the fixers. So, this is what I came with.

blacklist = ['mercurial/demandimport.py',
             'mercurial/py3kcompat.py',
             'mercurial/i18n.py',
            ]

def isnumberremainder(formatstr, data):
    try:
        if data.value.isdigit():
            return True
    except AttributeError:
        return False

class FixBytesmod(fixer_base.BaseFix):
    # XXX: There's one case (I suppose) I can't handle: when a remainder
    # operation like foo % bar is performed, I can't really know what the
    # contents of foo and bar are. I believe the best approach is to "correct"
    # the to-be-converted code and let bytesformatter handle that case in
    # runtime.
    PATTERN = '''
              term< formatstr=STRING '%' data=STRING > |
              term< formatstr=STRING '%' data=atom > |
              term< formatstr=NAME '%' data=any > |
              term< formatstr=any '%' data=any >
              '''

    def transform(self, node, results):
        if self.filename in blacklist:
            return
        elif self.filename == 'mercurial/util.py':
            touch_import('.', 'py3kcompat', node=node)

        formatstr = results['formatstr'].clone()
        data = results['data'].clone()
        formatstr.prefix = '' # remove spaces from start

        if isnumberremainder(formatstr, data):
            return

        # We have two possibilities:
        # 1- An identifier or name is passed, it is going to be a leaf, thus, we
        #    just need to copy its value as an argument to the formatter;
        # 2- A tuple is explicitly passed. In this case, we're gonna explode it
        # to pass to the formatter
        # TODO: Check for normal strings. They don't need to be translated

        if is_tuple(data):
            args = [formatstr, Comma().clone()] + \
                   [c.clone() for c in data.children[:]]
        else:
            args = [formatstr, Comma().clone(), data]

        call = Call(Name('bytesformatter', prefix=' '), args)
        return call