[waiting for #1359] feat(_comp_compgen): support -P prefix with adjusted cur

bash_completion

@@ -439,6 +439,7 @@ _comp_split()
 # @var[in] $?
 # @var[in] _var
 # @var[in] _append
+# @var[in] _upvars
 # @return original $?
 _comp_compgen__error_fallback()
 {
@@ -449,6 +450,10 @@ _comp_compgen__error_fallback()
     else
         eval -- "$_var=()"
     fi
+    if ((${#_upvars[@]})); then
+        _comp_unlocal "${_upvars[@]}"
+        _upvars=()
+    fi
     return "$_status"
 }
 
@@ -478,6 +483,13 @@ _comp_compgen__error_fallback()
 #           is ${cur-}.
 #   -R      The same as -c ''.  Use raw outputs without filtering.
 #   -C dir  Evaluate compgen/generator in the specified directory.
+#   -P pref Prepend the prefix to the generated completions.  Unlike `compgen
+#           -P prefix`, this prefix is subject to filtering by `cur`.  When a
+#           non-empty prefix is specified, first `cur` is tested whether it is
+#           consistent with the prefix.  Then, `cur` is reduced for the part
+#           excluding the prefix, and the normal completion generation is
+#           performed.  Finally, the prefix is prepended to generated
+#           completions.
 # @var[in,opt] cur  Used as the default value of a prefix to filter the
 #   completions.
 #
@@ -562,6 +574,7 @@ _comp_compgen()
     local _var=
     local _cur=${_comp_compgen__cur-${cur-}}
     local _dir=""
+    local _prefix=""
     local _ifs=$' \t\n' _has_ifs=""
     local _icmd="" _xcmd=""
     local -a _upvars=()
@@ -572,7 +585,7 @@ _comp_compgen()
         shopt -u nocasematch
     fi
     local OPTIND=1 OPTARG="" OPTERR=0 _opt
-    while getopts ':av:U:Rc:C:lF:i:x:' _opt "$@"; do
+    while getopts ':av:U:Rc:C:P:lF:i:x:' _opt "$@"; do
         case $_opt in
             a) _append=set ;;
             v)
@@ -601,6 +614,7 @@ _comp_compgen()
                 fi
                 _dir=$OPTARG
                 ;;
+            P) _prefix=$OPTARG ;;
             l) _has_ifs=set _ifs=$'\n' ;;
             F) _has_ifs=set _ifs=$OPTARG ;;
             [ix])
@@ -636,6 +650,19 @@ _comp_compgen()
         [[ $_append ]] || _append=${_comp_compgen__append-}
     fi
 
+    local _prefix_fail=""
+    if [[ $_prefix ]]; then
+        if [[ $_cur == "$_prefix"* ]]; then
+            _cur=${_cur#"$_prefix"}
+        elif [[ $_prefix == "$_cur"* ]]; then
+            _cur=""
+        else
+            # No completions are generated because the current word does not match
+            # the prefix.
+            _prefix_fail=set
+        fi
+    fi
+
     if [[ $1 != -* ]]; then
         # usage: _comp_compgen [options] NAME args
         if [[ $_has_ifs ]]; then
@@ -657,6 +684,11 @@ _comp_compgen()
         fi
         shift
 
+        if [[ $_prefix_fail ]]; then
+            _comp_compgen__error_fallback
+            return 1
+        fi
+
         _comp_compgen__call_generator "$@"
     else
         # usage: _comp_compgen [options] -- [compgen_options]
@@ -680,6 +712,11 @@ _comp_compgen()
             return 2
         fi
 
+        if [[ $_prefix_fail ]]; then
+            _comp_compgen__error_fallback
+            return 1
+        fi
+
         _comp_compgen__call_builtin "$@"
     fi
 }
@@ -694,8 +731,6 @@ _comp_compgen()
 # @var[in] _var
 _comp_compgen__call_generator()
 {
-    ((${#_upvars[@]})) && _comp_unlocal "${_upvars[@]}"
-
     if [[ $_dir ]]; then
         local _original_pwd=$PWD
         local PWD=${PWD-} OLDPWD=${OLDPWD-}
@@ -708,14 +743,28 @@ _comp_compgen__call_generator()
             }
     fi
 
+    ((${#_upvars[@]})) && _comp_unlocal "${_upvars[@]}"
+
     local _comp_compgen__append=$_append
     local _comp_compgen__var=$_var
     local _comp_compgen__cur=$_cur cur=$_cur
+    if [[ $_prefix ]]; then
+        local -a tmp=()
+        local _comp_compgen__var=tmp
+        local _comp_compgen__append=""
+    fi
     # Note: we use $1 as a part of a function name, and we use $2... as
     # arguments to the function if any.
     # shellcheck disable=SC2145
     "${_generator[@]}" "$@"
     local _status=$?
+    if [[ $_prefix ]]; then
+        local _i
+        for _i in "${!tmp[@]}"; do
+            tmp[_i]=$_prefix${tmp[_i]}
+        done
+        _comp_compgen -RU tmp ${_append:+-a} -v "$_var" -- -W '"${tmp[@]}"'
+    fi
 
     # Go back to the original directory.
     # Note: Failure of this line results in the change of the current
@@ -770,6 +819,13 @@ if ((BASH_VERSINFO[0] > 5 || BASH_VERSINFO[0] == 5 && BASH_VERSINFO[1] >= 3)); t
 
         ((${#_upvars[@]})) && _comp_unlocal "${_upvars[@]}"
         ((${#_result[@]})) || return
+
+        if [[ $_prefix ]]; then
+            local _i
+            for _i in "${!_result[@]}"; do
+                _result[_i]=$_prefix${_result[_i]}
+            done
+        fi
         if [[ $_append ]]; then
             eval -- "$_var+=(\"\${_result[@]}\")"
         else
@@ -794,7 +850,13 @@ else
         }
 
         ((${#_upvars[@]})) && _comp_unlocal "${_upvars[@]}"
-        _comp_split -l ${_append:+-a} "$_var" "$_result"
+
+        if [[ $_prefix ]]; then
+            _comp_split -l ${_append:+-a} "$_var" \
+                "$(IFS=$'\n' compgen -W '$_result' -P "$_prefix")"
+        else
+            _comp_split -l ${_append:+-a} "$_var" "$_result"
+        fi
     }
 fi
 
@@ -1352,10 +1414,12 @@ _comp_delimited()
     # `show-all-if-ambiguous` on, but even that has cases where it fails
     # and the last separator including everything before it is lost.
     # https://github.com/scop/bash-completion/pull/913#issuecomment-1490140309
-    local i
-    for i in "${!COMPREPLY[@]}"; do
-        COMPREPLY[i]="$prefix${COMPREPLY[i]}"
-    done
+    if [[ $prefix ]]; then
+        local i
+        for i in "${!COMPREPLY[@]}"; do
+            COMPREPLY[i]="$prefix${COMPREPLY[i]}"
+        done
+    fi
 
     [[ $delimiter != : ]] || _comp_ltrim_colon_completions "$cur"
 }
@@ -1850,7 +1914,7 @@ _comp_compgen_tilde()
 {
     if [[ ${cur-} == \~* && $cur != */* ]]; then
         # Try generate ~username completions
-        if _comp_compgen -c "${cur#\~}" -- -P '~' -u; then
+        if _comp_compgen -P '~' -- -u; then
             # 2>/dev/null for direct invocation, e.g. in the
             # _comp_compgen_tilde unit test
             compopt -o filenames 2>/dev/null

completions/7z

@@ -15,20 +15,17 @@ _comp_cmd_7z()
 
     case $cur in
         -ao*)
-            _comp_compgen -c "${cur:3}" -- -P"${cur:0:3}" -W 'a s t u'
+            _comp_compgen -P "-ao" -- -W 'a s t u'
             return
             ;;
         -?(a)[ix]*)
-            local opt
-            if [[ $cur == -a[ix]* ]]; then
-                opt=${cur:0:3} cur=${cur:3}
-            else
-                opt=${cur:0:2} cur=${cur:2}
-            fi
             if [[ $cur != *[@\!]* ]]; then
-                _comp_compgen -- -P"$opt" -W '@ ! r@ r-@ r0@ r! r-! r0!'
-            elif [[ $cur == ?(r@(-|0|))@* ]]; then
-                _comp_compgen -c "${cur#*@}" -- -P"${opt}${cur%%@*}@" -f
+                [[ $cur =~ ^-a?[ix] ]]
+                local prefix=${BASH_REMATCH-}
+                _comp_compgen -P "$prefix" -- -W '@ ! r@ r-@ r0@ r! r-! r0!'
+            elif [[ $cur =~ ^-a?[ix](r|r-|r0)?@ ]]; then
+                local prefix=${BASH_REMATCH-}
+                _comp_compgen -P "$prefix" -- -f
                 compopt -o filenames
             fi
             return
@@ -43,31 +40,30 @@ _comp_cmd_7z()
             ;;
         -o* | -w?*)
             compopt -o filenames
-            _comp_compgen -c "${cur:2}" -- -d -P"${cur:0:2}" -S/
+            _comp_compgen -P "${cur:0:2}" -- -d -S/
             compopt -o nospace
             return
             ;;
         -r?*)
-            _comp_compgen -c "${cur:2}" -- -P"${cur:0:2}" -W '- 0'
+            _comp_compgen -P "-r" -- -W '- 0'
             return
             ;;
         -scs*)
-            _comp_compgen -c "${cur:4}" -- -P"${cur:0:4}" -W 'UTF-8 WIN DOS'
+            _comp_compgen -P "-scs" -- -W 'UTF-8 WIN DOS'
             return
             ;;
         -ssc?*)
-            _comp_compgen -c "${cur:4}" -- -P"${cur:0:4}" -W '-'
+            _comp_compgen -P "-ssc" -- -W '-'
             return
             ;;
         -t*)
             if [[ $mode == w ]]; then
-                _comp_compgen -c "${cur:2}" -- -P"${cur:0:2}" -W '7z bzip2 gzip
-                    swfc tar wim xz zip'
+                _comp_compgen -P "-t" -- -W '7z bzip2 gzip swfc tar wim xz zip'
             else
-                _comp_compgen -c "${cur:2}" -- -P"${cur:0:2}" -W '7z apm arj
-                    bzip2 cab chm cpio cramfs deb dmg elf fat flv gzip hfs iso
-                    lzh lzma lzma86 macho mbr mslz mub nsis ntfs pe ppmd rar
-                    rpm squashfs swf swfc tar udf vhd wim xar xz z zip'
+                _comp_compgen -P "-t" -- -W '7z apm arj bzip2 cab chm cpio
+                    cramfs deb dmg elf fat flv gzip hfs iso lzh lzma lzma86
+                    macho mbr mslz mub nsis ntfs pe ppmd rar rpm squashfs swf
+                    swfc tar udf vhd wim xar xz z zip'
             fi
             return
             ;;

completions/_mount

@@ -44,7 +44,7 @@ _comp_cmd_mount()
         host=${cur#//}
         host=${host%%/*}
         if [[ $host ]]; then
-            _comp_compgen -c "${cur#//"$host"}" split -P "//$host" -- "$(
+            _comp_compgen -P "//$host" split -- "$(
                 smbclient -d 0 -NL "$host" 2>/dev/null |
                     command sed -ne '/^[[:blank:]]*Sharename/,/^$/p' |
                     command sed -ne '3,$s|^[^A-Za-z]*\([^[:blank:]]*\).*$|/\1|p'