[PATCH] Re: Editing the history in the shell

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

Another one from last May.

On Fri, May 22, 2020 at 3:24 PM Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx> wrote:
>
> The patch implements "zed -h" which loads the history into vared and
> arranges to replace the existing history with that before it exits.
> This does NOT solve Markus' complaint about the history numbers, they
> increase by the number of entries output by the editor. It makes no
> attempt to account for various history options, so those may change
> the final result if they affect "print -s".
>
> It also handles "zed -h filename" which loads that file and saves it
> back again rather than alter the current shell history.

On Tue, May 26, 2020 at 8:32 PM Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx> wrote:
>
> I think zed has a long-standing problem with SH_WORD_SPLIT and
> probably some other SH_ options?
>
> % setopt shwordsplit
> % zed "/tmp/one two"
> Where does this go?
> % cat "/tmp/one two"
> cat: '/tmp/one two': No such file or directory
> % cat /tmp/one
> Where does this go?
> %
>
> So ... how far do we go to make "zed" compatible with nonstandard
> options, and how do we approach doing it?  Try to use entirely
> portable syntax, or invoke "emulate -L", or something in between?
> Look at the handling of function names, too -- it creates the empty
> function definition with ${(q-)1} but makes no attempt to quote $1
> when calling "functions" or "autoload".

The attached patch both implements zed -h and fixes issues with
SH_WORD_SPLIT and NO_SHORT_LOOPS, but does not attempt a comprehensive
repair, so the "how far do we go?" question remains.  Completion is
updated per Oliver's advice in the "_arguments optspecs" thread
(starts at workers/45909, messages from Oliver seem to have been
doubled up in the archives) but could use a once-over.  Doc also
updated.

A minor head-scratcher for me (insufficient note-taking to return to
this a year later) is that at one time the code for zed -h was using
  var=( "${(@Oav)history:gs/\\/\\\\}" )
before invoking vared.  Now I can't figure out when or why I thought
that was necessary; I'm able to edit my existing 500 commands / 734
lines of history without seeing any garbled backslashes, using only
  var=( "${(@Oav)history}" )
as in the patch.  Can anyone jog my memory?  Do backslashes ever need
double-escaping?

diff --git a/Completion/Zsh/Command/_zed b/Completion/Zsh/Command/_zed
index 6b68fadf0..f84993d73 100644
--- a/Completion/Zsh/Command/_zed
+++ b/Completion/Zsh/Command/_zed
@@ -1,10 +1,16 @@
-#compdef zed fned
+#compdef zed fned histed
 
 case $service in
 (fned) _arguments -S : ':shell function:_functions';;
+(histed) _arguments -S : \
+	'1:history file:_files' \
+	'2:history size: ';;
 (zed) _arguments -S : \
-	'(- 2):file:_files' \
-	'(1):shell function:_functions' \
-	'(1)-x+[specify spaces to use for indentation in function expansion]:spaces' \
-	'(1)-f[edit function]';;
+        '(-h 1 3 4)-f[edit function]' \
+        '(-h 1 3 4)-x+[specify spaces to use for indentation in function expansion]:spaces' \
+        '(-f -x 1 2)-h[edit history]' \
+        '(- 2 3 4)1:file:_files' \
+        '(3 4)2:shell function:_functions' \
+        '3:history file:_files -g "*(D)"' \
+        '4:history size';;
 esac
diff --git a/Doc/Zsh/contrib.yo b/Doc/Zsh/contrib.yo
index 8bf1a208e..0f2d0664d 100644
--- a/Doc/Zsh/contrib.yo
+++ b/Doc/Zsh/contrib.yo
@@ -4295,6 +4295,12 @@ Same as tt(zed -f).  This function does not appear in the zsh
 distribution, but can be created by linking tt(zed) to the name tt(fned)
 in some directory in your tt(fpath).
 )
+findex(histed)
+item(tt(histed) [ [ var(name) ] var(size) ])(
+Same as tt(zed -h).  This function does not appear in the zsh
+distribution, but can be created by linking tt(zed) to the name tt(histed)
+in some directory in your tt(fpath).
+)
 findex(is-at-least)
 item(tt(is-at-least) var(needed) [ var(present) ])(
 Perform a greater-than-or-equal-to comparison of two strings having the
@@ -4504,6 +4510,7 @@ tt(zargs) with the tt(-)tt(-help) option.
 )
 findex(zed)
 xitem(tt(zed) [ tt(-f) [ tt(-x) var(num) ] ] var(name))
+xitem(tt(zed) [ tt(-h) [ var(name) ] var(size) ])
 item(tt(zed -b))(
 This function uses the ZLE editor to edit a file or function.
 
@@ -4518,7 +4525,14 @@ the given number of spaces; `tt(-x 2)' is consistent with the layout
 of functions distributed with the shell.
 
 Without tt(-f), var(name) is the path name of the file to edit, which need
-not exist; it is created on write, if necessary.
+not exist; it is created on write, if necessary.  With tt(-h), the file is
+presumed to contain history events.
+
+When no file name is provided for tt(-h) the current shell history is edited
+in place.  The history is renumbered when zed exits successfully.
+
+When editing history, multi-line events must have a trailing backslash on
+every line before the last.
 
 While editing, the function sets the main keymap to tt(zed) and the
 vi command keymap to tt(zed-vicmd).  These will be copied from the existing
@@ -4543,7 +4557,11 @@ of the return key), or can be bound to a key in either of the tt(zed) or
 tt(zed-vicmd) keymaps after `tt(zed -b)' has been run.  When the widget is
 called, it prompts for a new name for the file being edited.  When zed
 exits the file will be written under that name and the original file will
-be left alone.  The widget has no effect with `tt(zed -f)'.
+be left alone.  The widget has no effect with `tt(zed -f)'.  When editing
+the current history with `tt(zed -h)', the history is first updated and
+then the file is written, but the global setting of tt(HISTFILE) is not
+altered.
+
 
 While tt(zed-set-file-name) is running, zed uses the keymap
 tt(zed-normal-keymap), which is linked from the main keymap in effect
diff --git a/Functions/Misc/zed b/Functions/Misc/zed
index 9eb4b2d93..7d0d590db 100644
--- a/Functions/Misc/zed
+++ b/Functions/Misc/zed
@@ -5,16 +5,18 @@
 # Edit small files with the command line editor.
 # Use ^X^W to save (or ZZ in vicmd mode), ^C to abort.
 # Option -f: edit shell functions.  (Also if called as fned.)
+# Option -h: edit shell history.  (Also if called as histed.)
 
 setopt localoptions noksharrays
 
 local var opts zed_file_name
 # We do not want timeout while we are editing a file
-integer TMOUT=0 okargs=1 fun bind
+integer TMOUT=0 okargs=1 fun hist bind
 local -a expand
 
-zparseopts -D -A opts f b x:
+zparseopts -D -A opts f h b x:
 fun=$+opts[-f]
+hist=$+opts[-h]
 bind=$+opts[-b]
 if [[ $opts[-x] == <-> ]]; then
   expand=(-x $opts[-x])
@@ -24,23 +26,28 @@ elif (( $+opts[-x] )); then
 fi
 
 [[ $0 = fned ]] && fun=1
+[[ $0 = histed ]] && hist=1
+(( hist && $# <= 2 )) && okargs=$#
 (( bind )) && okargs=0
 
-if (( $# != okargs )); then
+if (( $# != okargs || bind + fun + hist > 1 )); then
     echo 'Usage:
 zed filename
 zed -f [ -x N ] function
+zed -h [ filename [ size ] ]
 zed -b' >&2
     return 1
 fi
 
 local curcontext=zed:::
 
-# Matching used in zstyle -m: hide result from caller.
-# Variables not used directly here.
-local -a match mbegin mend
-zstyle -m ":completion:zed:*" insert-tab '*' ||
-    zstyle ":completion:zed:*" insert-tab yes
+() {
+    # Matching used in zstyle -m: hide result from caller.
+    # Variables not used directly here.
+    local -a match mbegin mend
+    zstyle -m ":completion:zed:*" insert-tab '*' ||
+	zstyle ":completion:zed:*" insert-tab yes
+}
 
 zmodload zsh/terminfo 2>/dev/null
 
@@ -124,22 +131,51 @@ fi
 setopt localoptions nobanghist
 
 if ((fun)) then
-  var="$(functions $expand -- $1)"
+  var="$(functions $expand -- "$1")"
   # If function is undefined but autoloadable, load it
   if [[ $var = *\#\ undefined* ]] then
-    var="$(autoload +X $1; functions -- $1)"
+    var="$(autoload +X "$1"; functions -- "$1")"
   elif [[ -z $var ]] then
     var="${(q-)1} () {
 }"
   fi
   vared -M zed -m zed-vicmd -i __zed_init var && eval function "$var"
+elif ((hist)) then
+  if [[ -n $1 ]]; then
+    { fc -p -a "$1" ${2:-$({ wc -l <"$1" } 2>/dev/null)} || return }
+    let HISTSIZE++  
+    print -s ""		# Work around fc -p limitation
+  fi
+  # When editing the current shell history, the "zed -h" command is not
+  # itself included because the current event is not added to the ring
+  # until the next prompt is printed.  This means "zed -h" is prepended
+  # to the result of the edit, because of the way "print -s" is defined.
+  var=( "${(@Oav)history}" )
+  IFS=$'\n' vared -M zed -m zed-vicmd -i __zed_init var
+  if (( ? )); then
+    [[ -n $1 ]] && unset HISTFILE
+  else
+    local HISTSIZE=0 savehist=$#var
+    fc -R /dev/null	# Remove entries other than those added here
+    HISTSIZE=$savehist	# Resets on function exit because local
+    [[ -n $1 ]] && SAVEHIST=$savehist	# Resets via foregoing fc -a
+    for (( hist=1; hist <= savehist; hist++ ))
+    do print -rs -- "$var[hist]"
+    done
+    if [[ -n $zed_file_name ]]; then
+      fc -W "$zed_file_name"
+      [[ -n $1 ]] && unset HISTFILE
+    fi
+    # Note prepend effect when global HISTSIZE greater than $savehist.
+    # This does not affect file editing.
+  fi
 else
-  zed_file_name=$1
-  [[ -f $1 ]] && var="$(<$1)"
+  zed_file_name="$1"
+  [[ -f $1 ]] && var="$(<"$1")"
   while vared -M zed -m zed-vicmd -i __zed_init var
   do
     {
-      print -r -- "$var" >| $zed_file_name
+      print -r -- "$var" >| "$zed_file_name"
     } always {
       (( TRY_BLOCK_ERROR = 0 ))
     } && break