Rewrite of the target resolution internals to be simpler and more

consistent but with much less duplication, but keeping the same internal
API. Also adds more readable aliases for some of the special tokens used
in targets (eg "{start}" instead of "^"). Some behaviours may have
changed, for example prefix matches now happen before fnmatch.

tmux.1

@@ -358,8 +358,9 @@ argument with one of
 or
 .Ar target-pane .
 These specify the client, session, window or pane which a command should affect.
+.Pp
 .Ar target-client
-is the name of the
+should be the name of the
 .Xr pty 4
 file to which the client is connected, for example either of
 .Pa /dev/ttyp1
@@ -367,27 +368,35 @@ or
 .Pa ttyp1
 for the client attached to
 .Pa /dev/ttyp1 .
-If no client is specified, the current client is chosen, if possible, or an
-error is reported.
+If no client is specified,
+.Nm
+attempts to work out the client currently in use; if that fails, an error is
+reported.
 Clients may be listed with the
 .Ic list-clients
 command.
 .Pp
 .Ar target-session
-is the session id prefixed with a $, the name of a session (as listed by the
+is tried as, in order:
+.Bl -enum -offset Ds
+.It
+A session ID prefixed with a $.
+.It
+An exact name of a session (as listed by the
 .Ic list-sessions
-command), or the name of a client with the same syntax as
-.Ar target-client ,
-in which case the session attached to the client is used.
-When looking for the session name,
-.Nm
-initially searches for an exact match; if none is found, the session names
-are checked for any for which
-.Ar target-session
-is a prefix or for which it matches as an
+command).
+.It
+The start of a session name, for example
+.Ql mysess
+would match a session named
+.Ql mysession .
+.It
+An
 .Xr fnmatch 3
-pattern.
-If a single match is found, it is used as the target session; multiple matches
+pattern which is matched against the session name.
+.El
+.Pp
+If a single session is found, it is used as the target session; multiple matches
 produce an error.
 If a session is omitted, the current session is used if available; if no
 current session is available, the most recently used is chosen.
@@ -400,12 +409,29 @@ follows the same rules as for
 .Ar target-session ,
 and
 .Em window
-is looked for in order: as a window index, for example mysession:1;
-as a window ID, such as @1;
-as an exact window name, such as mysession:mywindow; then as an
+is looked for in order as:
+.Bl -enum -offset Ds
+.It
+A special token, listed below.
+.It
+A window index, for example
+.Ql mysession:1
+is window 1 in session
+.Ql mysession .
+.It
+A window ID, such as @1.
+.It
+An exact window name, such as
+.Ql mysession:mywindow .
+.It
+The start of a window name, such as
+.Ql mysession:mywin .
+.It
+As an
 .Xr fnmatch 3
-pattern or the start of a window name, such as mysession:mywin* or
-mysession:mywin.
+pattern matched against the window name.
+.El
+.Pp
 An empty window name specifies the next unused index if appropriate (for
 example the
 .Ic new-window
@@ -415,53 +441,50 @@ commands)
 otherwise the current window in
 .Em session
 is chosen.
-The special character
-.Ql \&!
-uses the last (previously current) window,
-.Ql ^
-selects the highest numbered window,
-.Ql $
-selects the lowest numbered window, and
-.Ql +
-and
-.Ql -
-select the next window or the previous window by number.
-When the argument does not contain a colon,
-.Nm
-first attempts to parse it as window; if that fails, an attempt is made to
-match a session.
+.Pp
+The following special tokens are available to indicate particular windows. Each
+has a single-character alternative form.
+.Bl -column "XXXXXXXXXX" "X"
+.It Sy "Token" Ta Sy "" Ta Sy "Meaning"
+.It Li "{start}" Ta "^" Ta "The lowest-numbered window"
+.It Li "{end}" Ta "$" Ta "The highest-numbered window"
+.It Li "{last}" Ta "!" Ta "The last (previously current) window"
+.It Li "{next}" Ta "+" Ta "The next window by number"
+.It Li "{previous}" Ta "-" Ta "The previous window by number"
+.It Li "{mouse}" Ta "=" Ta "The window where the mouse event happened"
+.El
 .Pp
 .Ar target-pane
-takes a similar form to
+may be a
+pane ID or takes a similar form to
 .Ar target-window
-but with the optional addition of a period followed by a pane index, for
-example: mysession:mywindow.1.
+but with the optional addition of a period followed by a pane index or pane ID,
+for example:
+.Ql mysession:mywindow.1 .
 If the pane index is omitted, the currently active pane in the specified
 window is used.
-If neither a colon nor period appears,
-.Nm
-first attempts to use the argument as a pane index; if that fails, it is looked
-up as for
-.Ar target-window .
-A
-.Ql + ,
-.Ql -
-or
-.Ql \&!
-indicate the next, previous or last pane.
-One of the strings
-.Em top ,
-.Em bottom ,
-.Em left ,
-.Em right ,
-.Em top-left ,
-.Em top-right ,
-.Em bottom-left
-or
-.Em bottom-right
-may be used instead of a pane index.
+The following special tokens are available for the pane index:
+.Bl -column "XXXXXXXXXXXXXX" "X"
+.It Sy "Token" Ta Sy "" Ta Sy "Meaning"
+.It Li "{last}" Ta "!" Ta "The last (previously active) pane"
+.It Li "{next}" Ta "+" Ta "The next pane by number"
+.It Li "{previous}" Ta "-" Ta "The previous pane by number"
+.It Li "{top}" Ta "" Ta "The top pane"
+.It Li "{bottom}" Ta "" Ta "The bottom pane"
+.It Li "{left}" Ta "" Ta "The leftmost pane"
+.It Li "{right}" Ta "" Ta "The rightmost pane"
+.It Li "{top-left}" Ta "" Ta "The top-left pane"
+.It Li "{top-right}" Ta "" Ta "The top-right pane"
+.It Li "{bottom-left}" Ta "" Ta "The bottom-left pane"
+.It Li "{bottom-right}" Ta "" Ta "The bottom-right pane"
+.It Li "{up}" Ta "" Ta "The pane above the active pane"
+.It Li "{down}" Ta "" Ta "The pane below the active pane"
+.It Li "{left}" Ta "" Ta "The pane to the left of the active pane"
+.It Li "{right}" Ta "" Ta "The pane to the right of the active pane"
+.It Li "{mouse}" Ta "=" Ta "The pane where the mouse event happened"
+.El
 .Pp
-The special characters
+The tokens
 .Ql +
 and
 .Ql -
@@ -470,19 +493,34 @@ may be followed by an offset, for example:
 select-window -t:+2
 .Ed
 .Pp
-When dealing with a session that doesn't contain sequential window indexes,
-they will be correctly skipped.
-.Pp
+Sessions, window and panes are each numbered with a unique ID; session IDs are
+prefixed with a
+.Ql $ ,
+windows with a
+.Ql @ ,
+and panes with a
+.Ql % .
+These are unique and are unchanged for the life of the session, window or pane
+in the
 .Nm
-also gives each pane created in a server an identifier consisting of a
-.Ql %
-and a number, starting from zero.
-A pane's identifier is unique for the life of the
-.Nm
-server and is passed to the child process of the pane in the
+server.
+The pane ID is passed to the child process of the pane in the
 .Ev TMUX_PANE
 environment variable.
-It may be used alone to target a pane or the window containing it.
+IDs may be displayed using the
+.Ql session_id ,
+.Ql window_id ,
+or
+.Ql pane_id
+formats (see the
+.Sx FORMATS
+section) and the
+.Ic display-message ,
+.Ic list-sessions ,
+.Ic list-windows
+or
+.Ic list-panes
+commands.
 .Pp
 .Ar shell-command
 arguments are
@@ -3144,7 +3182,9 @@ The following mouse events are available:
 Each should be suffixed with a location, for example
 .Ql MouseDown1Status .
 .Pp
-The special character
+The special token
+.Ql {mouse}
+or
 .Ql =
 may be used as
 .Ar target-window