match: introduce boolean prefix() method
tl;dr: This is another step towards a (previously unstated) goal of
eliminating match.files() in conditions.
There are four types of matchers:
* always: Matches everything, checked with always(), files() is empty
* exact: Matches exact set of files, checked with isexact(), files()
contains the files to match
* patterns: Matches more complex patterns, checked with anypats(),
files() contains roots of the matched patterns
* prefix: Matches simple 'path:' patterns as prefixes ('foo' matches
both 'foo' and 'foo/bar'), no single method to check, files()
contains the prefixes to match
For completeness, it would be nice to have a method for checking for
the "prefix" type of matcher as well, so let's add that, making it
return True simply when none of the others do.
The larger goal here is to eliminate uses of match.files() in
conditions (i.e. bool(match.files())). The reason for this is that
there are scenarios when you would like to create a "prefix" matcher
that happens to match no files. One example is for 'hg files -I foo
bar'. The narrowmatcher also restricts the set of files given and it
would not surprise me if have bugs caused by that already. Note that
'if m.files() and not m.anypats()' and similar is sometimes used to
catch the "exact" and "prefix" cases above.
# A dummy extension that installs an hgweb command that throws an Exception.
from mercurial.hgweb import webcommands
def raiseerror(web, req, tmpl):
'''Dummy web command that raises an uncaught Exception.'''
# Simulate an error after partial response.
if 'partialresponse' in req.form:
req.respond(200, 'text/plain')
req.write('partial content\n')
raise AttributeError('I am an uncaught error!')
def extsetup(ui):
setattr(webcommands, 'raiseerror', raiseerror)
webcommands.__all__.append('raiseerror')