refactor(cd): factorize generator for CDPATH

To apply the adjustment of suffixing "/" only to the completions
generated based on CDPATH, we isolate the CDPATH completion code in a
separate generator.  This is needed because we want to generate
cdable_vars completions into COMPREPLY, but we do not want to apply
sufixing to the cdable_vars completions.

Author: akinomyoga

completions/cd

@@ -1,56 +1,60 @@
 # cd(1) completion                                         -*- shell-script -*-
 
-# This meta-cd function observes the CDPATH variable, so that `cd`
-# additionally completes on directories under those specified in CDPATH.
-_comp_cmd_cd()
+# This generator function observes the CDPATH variable, to additionally
+# complete directories under those specified in CDPATH.
+_comp_cmd_cd__compgen_cdpath()
 {
-    local cur prev words cword comp_args
-    _comp_initialize -- "$@" || return
-
-    if [[ $cur == -* ]]; then
-        _comp_compgen_help -c help "$1"
-        compopt +o nospace
-        return
-    fi
+    local _p
 
-    local i j k
-
-    compopt -o filenames
-
-    # Use standard dir completion if no CDPATH or parameter starts with /,
+    # Generate CDPATH completions when the parameter does not start with /,
     # ./ or ../
-    if [[ ! ${CDPATH-} || $cur == ?(.)?(.)/* ]]; then
-        _comp_compgen_filedir -d
-        return
-    fi
+    [[ ! ${CDPATH-} || $cur == ?(.)?(.)/* ]] && return 1
+
+    local _mark_dirs="" _mark_symdirs=""
+    _comp_readline_variable_on mark-directories && _mark_dirs=set
+    _comp_readline_variable_on mark-symlinked-directories && _mark_symdirs=set
 
-    local mark_dirs="" mark_symdirs=""
-    _comp_readline_variable_on mark-directories && mark_dirs=set
-    _comp_readline_variable_on mark-symlinked-directories && mark_symdirs=set
+    local -a _cdpaths=()
 
     # we have a CDPATH, so loop on its contents
-    local paths dirs
+    local paths dirs _d
     _comp_split -F : paths "$CDPATH"
-    for i in "${paths[@]}"; do
+    for _p in "${paths[@]}"; do
         # create an array of matched subdirs
-        k=${#COMPREPLY[@]}
-        _comp_compgen -v dirs -c "$i/$cur" -- -d
-        for j in "${dirs[@]}"; do
-            if [[ ($mark_symdirs && -L $j || $mark_dirs && ! -L $j) && ! -d ${j#"$i/"} ]]; then
-                j+="/"
+        _comp_compgen -v dirs -c "$_p/$cur" -- -d
+        for _d in "${dirs[@]}"; do
+            if [[ ($_mark_symdirs && -L $_d || $_mark_dirs && ! -L $_d) && ! -d ${_d#"$_p/"} ]]; then
+                _d+="/"
             fi
-            COMPREPLY[k++]=${j#"$i/"}
+            _cdpaths+=("${_d#"$_p/"}")
         done
     done
+    _comp_unlocal paths dirs
 
-    _comp_compgen -a filedir -d
-
-    if ((${#COMPREPLY[@]} == 1)); then
-        i=${COMPREPLY[0]}
-        if [[ $i == "$cur" && $i != */ ]]; then
-            COMPREPLY[0]="${i}/"
+    if ((${#_cdpaths[@]} == 1)); then
+        _p=${_cdpaths[0]}
+        if [[ $_p == "$cur" && $_p != */ ]]; then
+            _cdpaths[0]=$_p/
         fi
     fi
+
+    _comp_compgen_set "${_cdpaths[@]}"
+}
+
+_comp_cmd_cd()
+{
+    local cur prev words cword comp_args
+    _comp_initialize -- "$@" || return
+
+    if [[ $cur == -* ]]; then
+        _comp_compgen_help -c help "$1"
+        compopt +o nospace
+        return
+    fi
+
+    compopt -o filenames
+    _comp_cmd_cd__compgen_cdpath
+    _comp_compgen -a filedir -d
 }
 if shopt -q cdable_vars; then
     complete -v -F _comp_cmd_cd -o nospace cd pushd