Bash completion for subcommand flags (#87)

Signed-off-by: Mabel Zhang <[email protected]>

CMakeLists.txt

@@ -223,3 +223,4 @@ endif(build_errors)
 include(CTest)
 
 add_subdirectory(src)
+add_subdirectory(etc)

etc/CMakeLists.txt

@@ -0,0 +1,18 @@
+# Tack version onto and install the bash completion scripts
+
+# Install script to source all bash completion scripts, of all library versions.
+configure_file(
+  "gz.completion"
+    "${CMAKE_CURRENT_BINARY_DIR}/gz${PROJECT_MAJOR_VERSION}.completion" @ONLY)
+install(FILES
+    ${CMAKE_CURRENT_BINARY_DIR}/gz${PROJECT_MAJOR_VERSION}.completion
+  DESTINATION
+    ${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_DATAROOTDIR}/gz)
+
+configure_file(
+  "ign.bash_completion.sh"
+    "${CMAKE_CURRENT_BINARY_DIR}/ign${PROJECT_MAJOR_VERSION}.bash_completion.sh" @ONLY)
+install(FILES
+    ${CMAKE_CURRENT_BINARY_DIR}/ign${PROJECT_MAJOR_VERSION}.bash_completion.sh
+  DESTINATION
+    ${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_DATAROOTDIR}/gz/gz${PROJECT_MAJOR_VERSION}.completion.d)

etc/gz.completion

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+#
+# Copyright (C) 2022 Open Source Robotics Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# Source scripts from different libraries for subcommand bash completions
+
+# Directory of current script
+SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null && pwd )"
+
+# Source the bash completion script for each subcommand
+# Files with greater version numbers will be sourced after files with lesser
+# version numbers, which means functions from newer versions will overwrite
+# those from older versions.
+for f in $SCRIPT_DIR/gz*.completion.d/*.bash_completion.sh ; do
+  source $f
+done

etc/ign.bash_completion.sh

@@ -1,31 +1,66 @@
+#!/usr/bin/env bash
+#
+# Copyright (C) 2022 Open Source Robotics Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
 # ign bash completion
 
 function _ign
 {
   local prev cur cmd opts
   local ign="$1"
-  COMPREPLY=()
   cur="$2"
   prev="$3"
 
-  # searching for the command
+  # Return value
+  COMPREPLY=()
+
+  # Look for the first command that is not an option (-*)
+  # COMP_WORDS: array of words in current command line COMP_LINE
+  # COMP_CWORD: index of word containing current cursur location
+  # COMP_LINE: line entered so far
   for ((i=1; $i<=$COMP_CWORD; i++)); do
     if [[ ${COMP_WORDS[i]} != -* ]]; then
       cmd="${COMP_WORDS[i]}"
       break
     fi
   done
 
+  # On a word after top-level command ign. It may be an option (-*)
   if [[ "$cur" == -* ]] || [[ "$prev" != "ign" ]]; then
 
+    # Subcommand is help
     if [[ "$cmd" == "help" ]]; then
       opts=$(ign --commands)
+
+    # Subcommand is a library name or an option (-*)
     else
-      COMPREPLY=($(compgen -f  -- "${COMP_WORDS[${COMP_CWORD}]}" ))
-      complete -o filenames -o nospace -F "_ign" "ign"
+      # Complete subcommands
+      # If subcommand completion function exists (defined by corresponding
+      # library), call it.
+      func="_gz_$cmd"
+      if [[ "$(type -t $func)" == 'function' ]]; then
+        $func
+      else
+        # Use bash default auto-complete
+        COMPREPLY=($(compgen -o default -- "${COMP_WORDS[COMP_CWORD]}"))
+      fi
       return
     fi
 
+  # on first word, top-level command (ign)
   else
     opts="$(ign --commands) help"
   fi