Add zsh completion function for Meson

Deprecated Meson syntax is not supported.
There are features not yet implemented, like completing
build targets and build options; more on this in the comments.

data/_meson

@@ -0,0 +1,189 @@
+#compdef meson mesonconf=meson-configure mesontest=meson-test mesonintrospect=meson-introspect
+
+# vim:ts=2 sw=2
+
+local curcontext="$curcontext" state line
+local -i ret
+
+local __meson_backends="(ninja xcode ${(j. .)${:-vs{,2010,2015,2017}}})"
+local __meson_build_types="(plain debug debugoptimized minsize release)"
+local __meson_wrap_modes="(WrapMode.{default,nofallback,nodownload})"
+
+local -a meson_commands=(
+'setup:set up a build directory'
+'configure:configure a project'
+'test:run tests'
+'introspect:query project properties'
+'wrap:manage source dependencies'
+)
+
+(( $+functions[__meson_is_build_dir] )) || __meson_is_build_dir() {
+  local mpd="${1:-$PWD}/meson-private"
+  [[ -f "$mpd/build.dat" && -f "$mpd/coredata.dat" ]]
+  return $?
+}
+
+# TODO: implement build option completion
+(( $+functions[__meson_build_options] )) || __meson_build_options() {}
+# TODO: implement target name completion
+(( $+functions[__meson_targets] )) || __meson_targets() {}
+# `meson introspect` currently can provide that information in JSON.
+# We can:
+# 1) pipe its output to python3 -m json.tool | grep "$alovelyregex" | cut <...>
+# 2) teach mintro.py to use a different output format
+#    (or perhaps just to select the fields printed)
+
+(( $+functions[__meson_test_names] )) || __meson_test_names() {
+  local rtests
+  if rtests="$(_call_program meson meson test ${opt_args[-C]:+-C "$opt_args[-C]"} --list)";
+  then
+    local -a tests=(${(@f)rtests})
+    _describe -t "tests" "Meson tests" tests
+  else
+    _message -r "current working directory is not a build directory"
+    _message -r 'use -C $build_dir or cd $build_dir'
+  fi
+}
+
+(( $+functions[_meson_commands] )) || _meson_commands() {
+    _describe -t commands "Meson subcommands" meson_commands
+}
+
+(( $+functions[_meson-setup] )) || _meson-setup() {
+  local firstd secondd
+  if [[ -f "meson.build" ]]; then
+    # if there's no second argument on the command line
+    # cwd will implicitly be substituted:
+    # - as the source directory if it has a file with the name "meson.build";
+    # - as the build directory otherwise
+    # more info in mesonbuild/mesonmain.py
+    firstd="build"
+    secondd="source"
+  else
+    firstd="source"
+    secondd="build"
+  fi
+
+  _arguments \
+  '*-D-[set the value of a build option]:build option:__meson_build_options' \
+  '--prefix=[installation prefix]: :_directories' \
+  '--libdir=[library directory]: :_directories' \
+  '--libexecdir=[library executable directory]: :_directories' \
+  '--bindir=[executable directory]: :_directories' \
+  '--sbindir=[system executable directory]: :_directories' \
+  '--includedir=[header file directory]: :_directories' \
+  '--datadir=[data file directory]: :_directories' \
+  '--mandir=[manual page directory]: :_directories' \
+  '--infodir=[info page directory]: :_directories' \
+  '--localedir=[locale data directory]: :_directories' \
+  '--sysconfdir=[system configuration directory]: :_directories' \
+  '--localstatedir=[local state data directory]: :_directories' \
+  '--sharedstatedir=[arch-independent data directory]: :_directories' \
+  '--backend=[backend to use]:Meson backend:'"$__meson_backends" \
+  '--buildtype=[build type to use]:Meson build type:'"$__meson_build_types" \
+  '--strip[strip targets on install]' \
+  '--unity=[unity builds on/off]:whether to do unity builds:(on off subprojects)' \
+  '--werror[treat warnings as errors]' \
+  '--layout=[build directory layout]:build directory layout:(flat mirror)' \
+  '--default-library=[default library type]:default library type:(shared static)' \
+  '--warnlevel=[compiler warning level]:compiler warning level:warning level:(1 2 3)' \
+  '--stdsplit=[split stdout and stderr in test logs]' \
+  '--errorlogs=[prints the logs from failing tests]' \
+  '--cross-file=[cross-compilation environment description]:cross file:_files' \
+  '--wrap-mode=[special wrap mode]:wrap mode:'"$__meson_wrap_modes" \
+  ":$firstd directory:_directories" \
+  "::$secondd directory:_directories" \
+  #
+}
+
+(( $+functions[_meson-configure] )) || _meson-configure() {
+  local curcontext="$curcontext"
+  # TODO: implement 'mesonconf @file'
+  local -a specs=(
+  '--clearcache[clear cached state]'
+  '*-D-[set the value of a build option]:build option:__meson_build_options'
+  '::build directory:_directories'
+  )
+
+  _arguments \
+    '(: -)'{'--help','-h'}'[show a help message and quit]' \
+    "${(@)specs}"
+}
+
+(( $+functions[_meson-test] )) || _meson-test() {
+  local curcontext="$curcontext"
+
+  # TODO: complete test suites
+  local -a specs=(
+  '(--quiet -q)'{'--quiet','-q'}'[produce less output to the terminal]'
+  '(--verbose -v)'{'--verbose','-v'}'[do not redirect stdout and stderr]'
+  '(--timeout-multiplier -t)'{'--timeout-multiplier','-t'}'[a multiplier for test timeouts]:Python floating-point number: '
+  '-C[directory to cd into]: :_directories'
+  '--repeat[number of times to run the tests]:number of times to repeat: '
+  '--no-rebuild[do not rebuild before running tests]'
+  '--gdb[run tests under gdb]'
+  '--list[list available tests]'
+  '(--wrapper --wrap)'{'--wrapper=','--wrap='}'[wrapper to run tests with]:wrapper program:_path_commands'
+  '(--no-suite)--suite[only run tests from this suite]:test suite: '
+  '(--suite)--no-suite[do not run tests from this suite]:test suite: '
+  '--no-stdsplit[do not split stderr and stdout in logs]'
+  '--print-errorlogs[print logs for failing tests]'
+  '--benchmark[run benchmarks instead of tests]'
+  '--logbase[base name for log file]:filename: '
+  '--num-processes[how many threads to use]:number of processes: '
+  '--setup[which test setup to use]:test setup: '
+  '--test-args[arguments to pass to the tests]: : '
+  '*:Meson tests:__meson_test_names'
+  )
+
+  _arguments \
+    '(: -)'{'--help','-h'}'[show a help message and quit]' \
+    "${(@)specs}"
+}
+
+(( $+functions[_meson-introspect] )) || _meson-introspect() {
+  local curcontext="$curcontext"
+  local -a specs=(
+  '--targets[list top level targets]'
+  '--installed[list all installed files and directories]'
+  '--target-files[list source files for a given target]:target:__meson_targets'
+  '--buildsystem-files[list files that belong to the build system]'
+  '--buildoptions[list all build options]'
+  '--tests[list all unit tests]'
+  '--benchmarks[list all benchmarks]'
+  '--dependencies[list external dependencies]'
+  '--projectinfo[show project information]'
+  '::build directory:_directories'
+  )
+_arguments \
+  '(: -)'{'--help','-h'}'[show a help message and quit]' \
+  "${(@)specs}"
+}
+
+(( $+functions[_meson-wrap] )) || _meson-wrap() {
+  # TODO
+}
+
+if [[ $service != meson ]]; then
+  _call_function ret _$service
+  return ret
+fi
+
+_arguments -C -R \
+  '(: -)'{'--help','-h'}'[show a help message and quit]' \
+  '(: -)'{'--version','-v'}'[show version information and quit]' \
+  '(-): :_meson_commands' \
+  '*:: :->post-command' \
+#
+ret=$?
+
+[[ $ret = 300 ]] && case "$state" in
+  post-command)
+    service="meson-$words[1]"
+    curcontext=${curcontext%:*:*}:$service:
+    _call_function ret _$service
+    ;;
+esac
+
+return ret
+