New templater features: if/ifeq, join, sub, date, fill

[Matt Mackall]

I rewrote the templater a while back to allow the addition of a bunch of
new features, but got stalled on working around a quirk in the
command-line implementation of lists. Now I've worked around that issue
and added a bunch of new features.

First is the ability to specify templates for lists on the commandline
without creating a style file. For instance:

$ hg log -r 0 --template "files:\n{files % '  {file}\n'}"
files:
  PKG-INFO
  README
  hg
  mercurial/__init__.py
  mercurial/byterange.py
  mercurial/fancyopts.py
  mercurial/hg.py
  mercurial/mdiff.py
  mercurial/revlog.py
  mercurial/transaction.py
  notes.txt
  setup.py
  tkmerge

We also have a join function, which is nice for lists:

$ hg log -r 0 --template "files: {join(files, ', ')}\n"
files: PKG-INFO, README, hg, mercurial/__init__.py,
mercurial/byterange.py, mercurial/fancyopts.py, mercurial/hg.py,
mercurial/mdiff.py, mercurial/revlog.py, mercurial/transaction.py,
notes.txt, setup.py, tkmerge

There's also a sub function, which supports regular expressions:

$ hg log -r 0 --template 'files: {sub("/", r"\\", files)}\n'
files: PKG-INFO README hg mercurial\__init__.py mercurial\byterange.py
mercurial\fancyopts.py mercurial\hg.py mercurial\mdiff.py mercurial
\revlog.py mercurial\transaction.py notes.txt setup.py tkmerge

We can now do some basic conditionals using if(test, then, else) or
ifeq(test, match, then, else):

$ hg log -r 0 --template '{ifeq(branch, "default", "on the main branch",
"on branch {branch}")}\n'
on the main branch

Lastly, I've parameterized a couple of the existing filters:

$ hg log -r 0 --template '{date(date, "%Y")}\n'
2005

$ hg log -r 0 --template '{fill(desc, "30")}'
Add back links from file
revisions to changeset
revisions Add simple
transaction support Add hg
verify Improve caching in
revlog Fix a bunch of bugs
Self-hosting now that the
metadata is close to finalized


-- 
Mathematics is the supreme nostalgia of our time.