zsh completion: move generation to runtime and improve

The completion function itself now parses --list-options on the first
tab press and caches the results. This does mean a slight delay on that
first tab press, but it will only do this if the argument being
completed looks like an option (i.e. starts with "-"), so there is never
a delay when just completing a file name. I've also put some effort into
making it reasonably fast; on my machine it's consistently under 100 ms,
more than half of which is mpv itself.

Installation of zsh completion is now done unconditionally because it's
nothing more than copying a file. If you really don't want it installed,
set zshdir to empty: `./waf configure --zshdir= ...`

Improvements in functionality compared to the old script:

 * Produces the right results for mpv binaries other than the one it was
   installed with (like a dev build for testing changes).

 * Does not require running mpv at build time, so it won't cause
   problems with cross compilation.

 * Handles aliases.

 * Slightly nicer handling of options that take comma-separated values
   and/or sub-options: A space is now inserted at the end instead of a
   comma, allowing you to immediately start typing the next argument,
   but typing a comma will still remove the automatically added space,
   and = and : will now do that too, so you can immediately add a
   sub-option.

 * More general/flexible handling of values for options that print their
   possible values with --option=help. The code as is could handle quite
   a few more options (*scale, demuxers, decoders, ...), but nobody
   wants to maintain that list here so we'll just stick with what the
   old completion script already did.

1 files changed, 2 insertions, 5 deletions

diff --git a/wscript_build.py b/wscript_build.py
index 50f8e641ea..301e8819e4 100644
--- a/wscript_build.py
+++ b/wscript_build.py
@@ -717,11 +717,8 @@ def build(ctx):
 
     if ctx.dependency_satisfied('cplayer'):
 
-        if ctx.dependency_satisfied('zsh-comp'):
-            ctx.zshcomp(target = "etc/_mpv", source = "TOOLS/zsh.pl")
-            ctx.install_files(
-                ctx.env.ZSHDIR,
-                ['etc/_mpv'])
+        if ctx.env.ZSHDIR:
+            ctx.install_as(ctx.env.ZSHDIR + '/_mpv', 'etc/_mpv.zsh')
 
         ctx.install_files(
             ctx.env.DATADIR + '/applications',