Patchwork [1,of,2] patch: enable diff.tab markup for the color extension

# HG changeset patch
# User Jordi Gutiérrez Hermoso <jordigh@octave.org>
# Date 1408562150 14400
#      Wed Aug 20 15:15:50 2014 -0400
# Node ID b58e6a9a966a2ae349db1af92943d2bc8898aa06
# Parent  de783f2403c498ef1e20121acf178b32ec27199c
patch: enable diff.tab markup for the color extension

The following patch splits up changed lines along tabs (using
re.findall), and gives them a "diff.tab" label. This can be used by
the color extension for colorising tabs, like it does right now with
trailing whitespace.

On 08/20/2014 12:24 PM, Jordi Gutiérrez Hermoso wrote:
> # HG changeset patch
> # User Jordi Gutiérrez Hermoso <jordigh@octave.org>
> # Date 1408562150 14400
> #      Wed Aug 20 15:15:50 2014 -0400
> # Node ID b58e6a9a966a2ae349db1af92943d2bc8898aa06
> # Parent  de783f2403c498ef1e20121acf178b32ec27199c
> patch: enable diff.tab markup for the color extension
>
> The following patch splits up changed lines along tabs (using
> re.findall), and gives them a "diff.tab" label. This can be used by
> the color extension for colorising tabs, like it does right now with
> trailing whitespace.
>
> diff --git a/mercurial/patch.py b/mercurial/patch.py
> --- a/mercurial/patch.py
> +++ b/mercurial/patch.py
> @@ -18,6 +18,7 @@ from node import hex, short
>   import base85, mdiff, scmutil, util, diffhelpers, copies, encoding, error
>
>   gitre = re.compile('diff --git a/(.*) b/(.*)')
> +tabsplitter = re.compile(r'(\t+|[^\t]+)')
>
>   class PatchError(Exception):
>       pass
> @@ -1669,15 +1670,26 @@ def difflabel(func, *args, **kw):
>                   if line and line[0] not in ' +-@\\':
>                       head = True
>               stripline = line
> +            showtabs = False
>               if not head and line and line[0] in '+-':
> -                # highlight trailing whitespace, but only in changed lines
> +                # highlight tabs and trailing whitespace, but only in
> +                # changed lines
>                   stripline = line.rstrip()
> +                showtabs = True

consider something more generic than "showtabs" like "diff line" or 
"touched line"

> +
>               prefixes = textprefixes
>               if head:
>                   prefixes = headprefixes
>               for prefix, label in prefixes:
>                   if stripline.startswith(prefix):
> -                    yield (stripline, label)
> +                    if showtabs:
> +                        for token in tabsplitter.findall(stripline):
> +                            if token == '\t':
> +                                yield (token, 'diff.tab')

you regexp match multiple tab. you conditional does not.

Not super fan of the regexp approach but I've not good idea for now. I 
wonder what is the performance of it.

> +                            else:
> +                                yield (token, label)
> +                    else:
> +                        yield (stripline, label)
>                       break
>               else:
>                   yield (line, '')

This patch want a test to convince people it actually works.