contrib/python-hook-examples.py

templater: convert resources to a table of callables for future extension

I'm going to add a full templating support to the annotate command. As the
annotate is a filectx-oriented command, we'll  need a way to look up a ctx
from a bounded fctx only when necessary.

This is the minimal change to support that. I'm thinking of defining a proper
interface to look up template resources to fix other issues, but that isn't
ready yet.

(Changes from V1: just updated tests and patch descriptions.)

'''
Examples of useful python hooks for Mercurial.
'''
from __future__ import absolute_import
from mercurial import (
    patch,
    util,
)

def diffstat(ui, repo, **kwargs):
    '''Example usage:

    [hooks]
    commit.diffstat = python:/path/to/this/file.py:diffstat
    changegroup.diffstat = python:/path/to/this/file.py:diffstat
    '''
    if kwargs.get('parent2'):
        return
    node = kwargs['node']
    first = repo[node].p1().node()
    if 'url' in kwargs:
        last = repo['tip'].node()
    else:
        last = node
    diff = patch.diff(repo, first, last)
    ui.write(patch.diffstat(util.iterlines(diff)))