Mercurial supports a functional language for selecting a set of
revisions.

The language supports a number of predicates which are joined by infix
operators. Parenthesis can be used for grouping.

Identifiers such as branch names 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.

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``
  Changesets not in x. Short form is ``! x``.

These are the supported infix operators:

``x::y``
  A DAG range, meaning all changesets that are descendants of x and
  ancestors of y, including x and y themselves. If the first endpoint
  is left out, this is equivalent to ``ancestors(y)``, if the second
  is left out it is equivalent to ``descendants(x)``.

  An alternative syntax is ``x..y``.

``x:y``
  All changesets with revision numbers between x and y, both
  inclusive. Either endpoint can be left out, they default to 0 and
  tip.

``x and y``
  The intersection of changesets in x and y. Short form is ``x & y``.

``x or y``
  The union of changesets in x and y. There are two alternative short
  forms: ``x | y`` and ``x + y``.

``x - y``
  Changesets in x but not in y.

The following predicates are supported:

``adds(pattern)``
  Changesets that add a file matching pattern.

``all()``
  All changesets, the same as ``0:tip``.

``ancestor(single, single)``
  Greatest common ancestor of the two changesets.

``ancestors(set)``
  Changesets that are ancestors of a changeset in set.

``author(string)``
  Alias for ``user(string)``.

``branch(set)``
  All changesets belonging to the branches of changesets in set.

``children(set)``
  Child changesets of changesets in set.

``closed()``
  Changeset is closed.

``contains(pattern)``
  Revision contains pattern.

``date(interval)``
  Changesets within the interval, see :hg:`help dates`.

``descendants(set)``
  Changesets which are descendants of changesets in set.

``file(pattern)``
  Changesets affecting files matched by pattern.

``follow()``
  An alias for ``::.`` (ancestors of the working copy's first parent).

``grep(regex)``
  Like ``keyword(string)`` but accepts a regex. Use ``grep(r'...')``
  to ensure special escape characters are handled correctly.

``head()``
  Changeset is a named branch head.

``heads(set)``
  Members of set with no children in set.

``keyword(string)``
  Search commit message, user name, and names of changed files for
  string.

``limit(set, n)``
  First n members of set.

``max(set)``
  Changeset with highest revision number in set.

``min(set)``
  Changeset with lowest revision number in set.

``merge()``
  Changeset is a merge changeset.

``modifies(pattern)``
  Changesets modifying files matched by pattern.

``outgoing([path])``
  Changesets not found in the specified destination repository, or the
  default push location.

``p1(set)``
  First parent of changesets in set.

``p2(set)``
  Second parent of changesets in set.

``parents(set)``
  The set of all parents for all changesets in set.

``present(set)``
  An empty set, if any revision in set isn't found; otherwise,
  all revisions in set.

``removes(pattern)``
  Changesets which remove files matching pattern.

``reverse(set)``
  Reverse order of set.

``roots(set)``
  Changesets with no parent changeset in set.

``sort(set[, [-]key...])``
  Sort set by keys. The default sort order is ascending, specify a key
  as ``-key`` to sort in descending order.

  The keys can be:

  - ``rev`` for the revision number,
  - ``branch`` for the branch name,
  - ``desc`` for the commit message (description),
  - ``user`` for user name (``author`` can be used as an alias),
  - ``date`` for the commit date

``tag(name)``
  The specified tag by name, or all tagged revisions if no name is given.

``user(string)``
  User name is string.

Command line equivalents for :hg:`log`::

  -f    ->  ::.
  -d x  ->  date(x)
  -k x  ->  keyword(x)
  -m    ->  merge()
  -u x  ->  user(x)
  -b x  ->  branch(x)
  -P x  ->  !::x
  -l x  ->  limit(expr, x)

Some sample queries:

- Changesets on the default branch::

    hg log -r 'branch(default)'

- Changesets on the default branch since tag 1.5 (excluding merges)::

    hg log -r 'branch(default) and 1.5:: and not merge()'

- Open branch heads::

    hg log -r 'head() and not closed()'

- Changesets between tags 1.3 and 1.5 mentioning "bug" that affect
  ``hgext/*``::

    hg log -r '1.3::1.5 and keyword(bug) and file("hgext/*")'

- Changesets in committed May 2008, sorted by user::

    hg log -r 'sort(date("May 2008"), user)'

- Changesets mentioning "bug" or "issue" that are not in a tagged
  release::

    hg log -r '(keyword(bug) or keyword(issue)) and not ancestors(tagged())'