tests/test-gendoc-el.t

revsetlang: build optimized tree by helper function

This should make optimize() more readable, but it doubles the parsing cost.

  (original)
  $ python -m timeit -n10000 -s 'from mercurial import revsetlang as L' \
  'L.optimize(L.analyze(L.parse("::tip")))'
  10000 loops, best of 3: 18.1 usec per loop

  (this patch)
  $ python -m timeit -n10000 -s 'from mercurial import revsetlang as L' \
  'L._treecache.clear(); L.optimize(L.analyze(L.parse("::tip")))'
  10000 loops, best of 3: 48.4 usec per loop

30usec isn't dominant compared to the revset evaluation, but that is a cost.
That's why a parsed tree is cached, which can benefit in hgweb or chg server.

#require docutils gettext

  $ $TESTDIR/check-gendoc el
  checking for parse errors