fix a bug when the buffer ends in a backslash

zsh-no-ps2

@@ -1,35 +1,43 @@
 #!/usr/bin/env zsh
 
-builtin emulate -L zsh
+setopt local_options no_err_return no_err_exit
 
-builtin local -r func=zsh-no-ps2-test
-
-if (( ${+functions[$func]} )); then
-  builtin unfunction -- $func
-fi
+# Succeeds if $1 is a well-formed command.
+() {
+  # If it ends with an odd number of backslashes, it's malformed.
+  () {
+    builtin emulate -L zsh -o extended_glob
+    [[ $1 == (|*[^\\])(\\\\)#\\ ]]
+  } "$1" && builtin return 1
 
-if functions[$func]=$PREBUFFER$BUFFER 2>/dev/null &&
-   (( ${+functions[$func]} )); then
-  builtin unfunction -- $func
+  if [[ -v functions[-zsh-no-ps2-test] ]]; then
+    builtin unfunction -- -zsh-no-ps2-test
+  fi
+  functions[-zsh-no-ps2-test]="$1" 2>/dev/null              || builtin return 1
+  [[ -v functions[-zsh-no-ps2-test] ]]                      || builtin return 1
+  builtin unfunction -- -zsh-no-ps2-test
   # This suffix allows us to detect two tricky cases: "for x" and "<<END".
   # Each of these on their own is a valid function body but neither can
   # be executed as a command in interactive shell.
-  if functions[$func]=$PREBUFFER$BUFFER$'\ndo\ndone' 2>/dev/null &&
-     (( ${+functions[$func]} )) ; then
-     builtin unfunction -- $func
-  else
-    builtin local w
-    builtin zstyle -s :zsh-no-ps2: accept-line w || w=accept-line
-    if [[ -n $w ]]; then
-      builtin zle -- $w
-    fi
-    builtin return
-  fi
-fi
+  functions[-zsh-no-ps2-test]="$1"$'\ndo\ndone' 2>/dev/null || builtin return 0
+  [[ -v functions[-zsh-no-ps2-test] ]]                      || builtin return 0
+  builtin unfunction -- -zsh-no-ps2-test
+  builtin return 1
+} "$PREBUFFER$BUFFER"
 
-() {
+if (( $? )); then
   # We do it this way instead of the plain LBUFFER+=$'\n' in order
-  # to make this plugin work with zsh-autosuggestions.
-  local -h KEYS=$'\n'
+  # to make this plugin work with zsh-autosuggestions. Unfortunately, this
+  # means that binding zsh-no-ps2 to anything other than Enter won't work.
+  # This can be fixed: we just need to define our own widget that does
+  # LBUFFER+=$'\n' and invoke it here.
+  #
+  # TODO: do what the above says.
   builtin zle self-insert-unmeta
-}
+else
+  builtin local w
+  builtin zstyle -s :zsh-no-ps2: accept-line w || w=accept-line
+  if [[ -n $w ]]; then
+    builtin zle -- "$w"
+  fi
+fi