view contrib/hgfixes/fix_bytesmod.py @ 26362:3bfc473f4d33

gitweb, monoblue: fix vertical align of spans in .sourcelines

Empty lines in file view could produce an inexplicable margin before the next
line (most noticeable in browsers on webkit/blink engine). That was making
empty lines seem taller than the rest.

Instead of using default vertical align, let's set it to 'top'.

This issue is actually present in paper, and only recently got into gitweb
(2239626369f5) and monoblue (119202d4d7a4). There's a bit more to it in paper,
so that will be dealt with in a future patch.

Recipe to see live: preferably using a webkit/blink browser, such as chromium,
browse a file with empty lines, e.g. https://selenic.com/hg/file/3.5/README#l8
Selecting a block of text that includes empty lines will reveal white "breaks"
in the selection. Highlighted line (#l8) also shows such a break below itself.

"""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):
        for bfn in blacklist:
            if self.filename.endswith(bfn):
                return
        if not self.filename.endswith('mercurial/py3kcompat.py'):
            touch_import('mercurial', '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