Add docs

docs/manual/config/index.rst

@@ -58,6 +58,7 @@ mix!)
     mouse
     screens
     hooks
+    match
 
 In addition to the above variables, there are several other boolean
 configuration variables that control specific aspects of Qtile's behavior:

docs/manual/config/match.rst

@@ -0,0 +1,85 @@
+.. _match:
+
+================
+Matching windows
+================
+
+Qtile's config provides a number of situations where the behaviour depends
+on whether the relevant window matches some specified criteria.
+
+These situations include:
+
+  - Defining which windows should be floated by default
+  - Assigning windows to specific groups
+  - Assigning window to a master section of a layout
+
+In each instance, the criteria are defined via a ``Match`` object. The properties
+of the object will be compared to a :class:`~libqtile.base.Window` to determine if
+its properties *match*. It can match by title, wm_class, role, wm_type,
+wm_instance_class, net_wm_pid, or wid. Additionally, a function may be
+passed, which takes in the :class:`~libqtile.base.Window` to be compared
+against and returns a boolean.
+
+A basic rule would therefore look something like:
+
+.. code::  python
+
+    Match(wm_class="mpv")
+
+This would match against any window whose class was ``mpv``.
+
+Where a string is provided as an argument then the value must match exactly. More
+flexibility can be achieved by using regular expressions. For example:
+
+.. code::  python
+
+    import re
+
+    Match(wm_class=re.compile(r"mpv"))
+
+This would still match a window whose class was ``mpv`` but it would also match
+any class starting with ``mpv`` e.g. ``mpvideo``.
+
+.. note::
+
+    When providing a regular expression, qtile applies the ``.match`` method.
+    This matches from the start of the string so, if you want to match any substring,
+    you will need to adapt the regular expression accordingly e.g.
+
+    .. code::  python
+
+        import re
+
+        Match(wm_class=re.compile(r".*mpv"))
+
+    This would match any string containing ``mpv``
+
+Creating advanced rules
+=======================
+
+While the ``func`` parameter allows users to create more complex matches, this requires
+a knowledge of qtile's internal objects. An alternative is to combine Match objects using
+logical operators ``&`` (and), ``|`` (or), ``~`` (not) and ``^`` (xor).
+
+For example, to create rule that matches all windows with a fixed aspect ratio except for
+mpv windows, you would provide the following:
+
+.. code::  python
+
+    Match(func=lambda c: c.has_fixed_ratio()) & ~Match(wm_class="mpv")
+
+It is also possible to use wrappers for ``Match`` objects if you do not want to use the
+operators. The following wrappers are available:
+
+  - ``MatchAll(Match(...), ...)`` equivalent to "and" test. All matches must match.
+  - ``MatchAny(Match(...), ...)`` equivalent to "or" test. At least one match must match.
+  - ``MatchOnlyOne(Match(...), Match(...))`` equivalent to "xor". Only one match must match.
+  - ``InvertMatch(Match(...))`` equivalent to "not". Inverts the result of the match.
+
+So, to recreate the above rule using the wrappers, you would write the following:
+
+.. code::  python
+
+    from libqtile.config import InvertMatch, Match, MatchAll
+
+    MatchAll(Match(func=lambda c: c.has_fixed_ratio()), InvertMatch(Match(wm_class="mpv")))