feat: add support for build-presets

When running `cmake --build --preset=*` the preset would not complete.
Additionally fix `cmake --build --preset=* --target=*` target completion
too, by looking for the first CMakeCache.txt in five levels of
directories.

src/_cmake

@@ -144,6 +144,29 @@ _cmake_generator_options() {
   fi
 }
 
+# ----------------------
+# _cmake_build_presets
+# ----------------------
+(( $+functions[_cmake_build_presets] )) ||
+_cmake_build_presets() {
+  local list_presets=(${(f)"$(cmake --list-presets=build 2>/dev/null |
+    sed -n -e 's,^[[:space:]]*"\([^"]*\)"[[:space:]]*-[[:space:]]*\(.*\),\1:\2,p' \
+           -e 's,^[[:space:]]*"\([^"]*\)"[[:space:]]*$,\1,p')"})
+
+  _describe 'build presets' list_presets
+}
+
+# --------------------------
+# _cmake_preset_build_dir
+#
+# Finds the build directory by locating the nearest CMakeCache.txt.
+# --------------------------
+(( $+functions[_cmake_preset_build_dir] )) ||
+_cmake_preset_build_dir() {
+  find . -maxdepth 5 -name CMakeCache.txt -print -quit | xargs -I{} dirname {}
+}
+
+
 # --------------
 # _cmake_presets
 # --------------
@@ -194,6 +217,8 @@ _cmake_on_build() {
     '--config[For multi-configuration tools]'
     '--parallel[maximum number of build processes]'
     '--use-stderr'
+    '--preset[Specify a build preset]:preset:_cmake_build_presets'
+    '--list-presets[List available build presets]'
   )
   local -a undescribed_build_extras
   local i=1
@@ -226,23 +251,41 @@ _cmake_on_build() {
     if [[ $words[(($i - 1))] == --target ]]; then continue ; fi
     if [[ $words[(($i - 1))] == --config ]]; then continue ; fi
     if [[ $words[(($i - 1))] == --parallel ]] ; then continue ; fi
+    if [[ $words[(($i - 1))] == --preset ]] ; then continue ; fi
     out_of_build=true
   done
 
   if (( $dash_dash_position > 0 )) ; then
-    _cmake_generator_options $words[(($build_at + 1))] $dash_dash_position && return 0
+    local _build_first=$words[(($build_at + 1))]
+    [[ $_build_first != --* ]] && _cmake_generator_options $_build_first $dash_dash_position && return 0
   fi
 
-  if [[ "$in_build" == false || "$difference" -eq 1 ]] ; then
+  if [[ "$in_build" == false ]] ; then
-    # either there is no --build or completing the directory after --build
+    # no --build seen, complete normally
     _arguments -s \
       - build_opts \
       "$cmake_build_options[@]" \
       - build_cmds \
       "$cmake_suggest_build[@]" && return 0
+  elif [[ "$difference" -eq 1 ]] ; then
+    # completing first arg after --build: dir, --preset, or --list-presets
+    _alternative \
+      ':current directory:(.)' \
+      'directory::_directories' \
+      'preset-flags:flag:((--preset\:"Specify a build preset" --list-presets\:"List available build presets"))' && return 0
+  elif [[ $words[(($CURRENT - 1))] == --preset ]] ; then
+    # after --build --preset, complete build presets
+    _cmake_build_presets && return 0
   elif [[ $words[(($CURRENT - 1))] == --target ]] ; then
-    # after --build <dir> --target, suggest targets
+    # after --build <dir|--preset name> --target, suggest targets
-    _cmake_targets $words[(($build_at + 1))] && return 0
+    local _tgt_first=$words[(($build_at + 1))]
+    if [[ $_tgt_first == --preset ]]; then
+      local _tgt_dir=$(_cmake_preset_build_dir "$words[(($build_at + 2))]")
+      [[ -n "$_tgt_dir" ]] && _cmake_targets "$_tgt_dir"
+    elif [[ $_tgt_first != --* ]]; then
+      _cmake_targets "$_tgt_first"
+    fi
+    return 0
   elif [[ $words[(($CURRENT - 1))] == --config ]] ; then
     # after --build <dir> --config, no idea
     return 0