context: add a no-op _prestatus method
This patch adds a private _prestatus method so that certain contexts, such as
workingctx, can add custom pre-processing to status.
Mercurial supports a functional language for selecting a set of
files.
Like other file patterns, this pattern type is indicated by a prefix,
'set:'. The language supports a number of predicates which are joined
by infix operators. Parenthesis can be used for grouping.
Identifiers such as filenames or patterns must be quoted with single
or double quotes if they contain characters outside of
``[.*{}[]?/\_a-zA-Z0-9\x80-\xff]`` or if they match one of the
predefined predicates. This generally applies to file patterns other
than globs and arguments for predicates.
Special characters can be used in quoted identifiers by escaping them,
e.g., ``\n`` is interpreted as a newline. To prevent them from being
interpreted, strings can be prefixed with ``r``, e.g. ``r'...'``.
There is a single prefix operator:
``not x``
Files not in x. Short form is ``! x``.
These are the supported infix operators:
``x and y``
The intersection of files in x and y. Short form is ``x & y``.
``x or y``
The union of files in x and y. There are two alternative short
forms: ``x | y`` and ``x + y``.
``x - y``
Files in x but not in y.
The following predicates are supported:
.. predicatesmarker
Some sample queries:
- Show status of files that appear to be binary in the working directory::
hg status -A "set:binary()"
- Forget files that are in .hgignore but are already tracked::
hg forget "set:hgignore() and not ignored()"
- Find text files that contain a string::
hg locate "set:grep(magic) and not binary()"
- Find C files in a non-standard encoding::
hg locate "set:**.c and not encoding('UTF-8')"
- Revert copies of large binary files::
hg revert "set:copied() and binary() and size('>1M')"
- Remove files listed in foo.lst that contain the letter a or b::
hg remove "set: 'listfile:foo.lst' and (**a* or **b*)"
See also :hg:`help patterns`.