users/15738: better cursor positioning in modify-current-argument

1 files changed, 34 insertions, 10 deletions

diff --git a/Functions/Zle/modify-current-argument b/Functions/Zle/modify-current-argument
index 92ca7bdab..92851d600 100644
--- a/Functions/Zle/modify-current-argument
+++ b/Functions/Zle/modify-current-argument
@@ -14,7 +14,7 @@
 setopt localoptions noksharrays multibyte
 
 local -a reply
-integer REPLY REPLY2
+integer REPLY REPLY2 fromend endoffset
 
 autoload -Uz split-shell-arguments
 split-shell-arguments
@@ -30,6 +30,13 @@ if (( REPLY & 1 )); then
   (( REPLY2 = ${#reply[REPLY]} + 1 ))
 fi
 
+# Work out offset from end of string
+(( fromend = $REPLY2 - ${#reply[REPLY]} - 1 ))
+if (( fromend >= -1 )); then
+  # Cursor is near the end of the word, we'll try to keep it there.
+  endoffset=1
+fi
+
 # Length of all characters before current.
 # Force use of character (not index) counting and join without IFS.
 integer wordoff="${(cj..)#reply[1,REPLY-1]}"
@@ -37,15 +44,32 @@ integer wordoff="${(cj..)#reply[1,REPLY-1]}"
 # Replacement for current word.  This could do anything to ${reply[REPLY]}.
 local ARG="${reply[REPLY]}" repl
 eval repl=\"$1\"
+
+if (( !endoffset )) && [[ ${repl[fromend,-1]} = ${ARG[fromend,-1]} ]]; then
+  # If the part of the string from here to the end hasn't changed,
+  # leave the cursor this distance from the end instead of the beginning.
+  endoffset=1
+fi
+
 # New line:  all words before and after current word, with
 # no additional spaces since we've already got the whitespace
 # and the replacement word in the middle.
-BUFFER="${(j..)reply[1,REPLY-1]}${repl}${(j..)reply[REPLY+1,-1]}"
-
-# Keep cursor at same position in replaced word.
-# Redundant here, but useful if $repl changes the length.
-# Limit to the next position after the end of the word.
-integer repmax=$(( ${#repl} + 1 ))
-# Remember CURSOR starts from offset 0 for some reason, so
-# subtract 1 from positions.
-(( CURSOR = wordoff + (REPLY2 > repmax ? repmax : REPLY2) - 1 ))
+local left="${(j..)reply[1,REPLY-1]}${repl}"
+local right="${(j..)reply[REPLY+1,-1]}"
+
+if [[ endoffset -ne 0 && ${#repl} -ne 0 ]]; then
+  # Place cursor relative to end.
+  LBUFFER="$left"
+  RBUFFER="$right"
+  (( CURSOR += fromend ))
+else
+  BUFFER="$left$right"
+
+  # Keep cursor at same position in replaced word.
+  # Redundant here, but useful if $repl changes the length.
+  # Limit to the next position after the end of the word.
+  integer repmax=$(( ${#repl} + 1 ))
+  # Remember CURSOR starts from offset 0 for some reason, so
+  # subtract 1 from positions.
+  (( CURSOR = wordoff + (REPLY2 > repmax ? repmax : REPLY2) - 1 ))
+fi