mercurial/help/filesets.txt

convert: don't drop commits that are empty in the source when using --filemap

I ran into this when using `hg lfconvert --to-normal` (which uses the filemap
class internally), and saw that commits with nothing but a branch change were
dropped.  We could put in an option that only lfconvert uses internally.  But
silently dropping anything other than a commit where all changes were excluded
seems unintended.  For example, there's a message in mercurial_sink.putcommit()
if it drops an empty commit.  (And the reason that isn't kicking in here is
because lfconvert isn't passing --filemap, so the self.filemapmode conditional
there is always False.)

The naive change of `return not files` broke test-convert-filemap.t, so this is
a little more elaborate than needed for converting from largefiles.

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. Pattern prefixes such as
``path:`` may be specified without quoting.

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'...'``.

See also :hg:`help patterns`.

Operators
=========

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.

Predicates
==========

The following predicates are supported:

.. predicatesmarker

Examples
========

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 files "set:grep(magic) and not binary()"

- Find C files in a non-standard encoding::

    hg files "set:**.c and not encoding('UTF-8')"

- Revert copies of large binary files::

    hg revert "set:copied() and binary() and size('>1M')"

- Revert files that were added to the working directory::

    hg revert "set:revs('wdir()', added())"

- Remove files listed in foo.lst that contain the letter a or b::

    hg remove "set: listfile:foo.lst and (**a* or **b*)"