Feature: Suspend live grep and filter results

See README for explanation. Use <c-k> to switch to pattern search
  mode during live grep.

M  README.md
M  autoload/scope/fuzzy.vim
M  autoload/scope/popup.vim
M  doc/scope.txt

README.md

@@ -77,7 +77,6 @@ def File(findCmd: string = null_string, count: number = 10000, ignore: bool = tr
 ```
 
 > [!NOTE]
->
 > - To prevent *find* command from descending into `.git` directory, put `.git/` in the `~/.gitignore` or `~/.findignore` file.
 > - If `.gitignore` file contains `**` or `!` in the patterns, performance of *find* command may degrade. Use [fd](https://github.com/sharkdp/fd) if this becomes an issue.
 > - To **echo the command string** in Vim's command line, set the option `find_echo_cmd` to `true`. Default is `false`. Setting of options is discussed later.
@@ -95,6 +94,7 @@ nnoremap <your_key> <scriptcmd>fuzzy.Grep()<cr>
 > [!NOTE]
 > 1. To perform a second grep with the same keyword, there's no need to retype it. The prompt conveniently retains the previous grep string as virtual text. Simply input `<Right>` or `<PgDn>` to auto-fill and proceed, or overwrite it as needed. For smaller projects, you can efficiently execute repeated greps without relying on the quickfix list.
 > 2. Special characters can be entered into the prompt window directly without requiring backslash escaping.
+> 3. It is sometimes useful to suspend live grep and filter results returned by live grep. Type `<C-k>` to enter pattern search mode (case insensitive). For example, typing `^foo` will filter lines that begin with `foo`. Patterns are negated if the first character is `!`. To filter lines *not* containing `foo` or `bar` type `!foo|bar` into the prompt.
 
 Define your own grep command:
 
@@ -314,6 +314,7 @@ Mapping | Action
 `<C-Q>` | Send only filtered items to the quickfix list
 `<C-l>` | Send all unfiltered items to the location list (`:h location-list`)
 `<C-L>` | Send only filtered items to the location list
+`<C-k>` | Switch to pattern search of results during live grep
 
 Prompt window editor key mappings align with Vim's default mappings for command-line editing.
 

autoload/scope/fuzzy.vim

@@ -101,6 +101,7 @@ export def Grep(grepCmd: string = null_string, ignorecase: bool = true,
     var grep_throttle_len = max([0, options.grep_throttle_len])
     var grep_skip_len = max([0, options.grep_skip_len])
     var cmd: string
+    var select_mode = false  # grep mode or select mode
 
     def DoGrep(prompt: string, timer: number)
         # during pasting from clipboard to prompt window, spawning a new job for
@@ -162,6 +163,12 @@ export def Grep(grepCmd: string = null_string, ignorecase: bool = true,
 
     menu = popup.FilterMenu.new('Grep', [],
         (res, key) => {
+            if key == "\<C-k>"
+                select_mode = true
+                menu.SetPrompt(null_string)
+                menu.SetText(menu.items_dict)
+                return
+            endif
             if !util.Send2Qickfix(key, menu.items_dict, menu.filtered_items[0], cmd, null_function, true)
                 # let quicfix parse output of 'grep' for filename, line, column.
                 # it deals with ':' in filename and other corner cases.
@@ -178,6 +185,9 @@ export def Grep(grepCmd: string = null_string, ignorecase: bool = true,
             endif
         },
         (id, idp) => {
+            if select_mode
+                return
+            endif
             if cword != null_string
                 def SetPrompt(s: string, timer: number)
                     menu.SetPrompt(s)
@@ -204,8 +214,28 @@ export def Grep(grepCmd: string = null_string, ignorecase: bool = true,
         },
         (lst: list<dict<any>>, prompt: string): list<any> => {
             # This function is called everytime when user types something
-            timer_start(timer_delay, function(DoGrep, [prompt]))
-            return [[], [[]]]
+            if select_mode
+                if prompt->empty()
+                    return [lst, [lst]]
+                else
+                    # pattern match only (not fuzzy match)
+                    var filtered = []
+                    if prompt[0] == '!'
+                        filtered = lst->copy()->filter((_, v) => v.text !~ $'\v{prompt->slice(1)}')
+                    else
+                        for item in lst
+                            var pos = item.text->matchstrpos($'\c{prompt}')
+                            if pos[1] != -1
+                                filtered->add({text: item.text, props: [{col: pos[1] + 1, length: pos[2] - pos[1], type: 'ScopeMenuMatch'}]})
+                            endif
+                        endfor
+                    endif
+                    return [lst, [filtered]]
+                endif
+            else
+                timer_start(timer_delay, function(DoGrep, [prompt]))
+                return [[], [[]]]
+            endif
         },
         () => {
             if options.grep_echo_cmd

autoload/scope/popup.vim

@@ -295,6 +295,9 @@ export class FilterMenu
                                 this.prompt = this.prompt->slice(0, pos) .. key .. this.prompt->slice(pos)
                                 this.cursorpos = this.cursorpos + 1
                             endif
+                        elseif key == "\<C-k>"
+                            Callback(null_string, key)
+                            return true
                         endif
                         var GetFilteredItemsFn = GetFilteredItems == null_function ? this._GetFilteredItems : GetFilteredItems
                         [this.items_dict, this.filtered_items] = GetFilteredItemsFn(this.items_dict, this.prompt)
@@ -372,13 +375,7 @@ export class FilterMenu
                 })}
             })
         else
-            if itemsAny[0]->empty()
-                return []
-            else
-                return itemsAny[0]->mapnew((_, v) => {
-                    return {text: v.text}
-                })
-            endif
+            return itemsAny->empty() ? [] : itemsAny[0]
         endif
     enddef
 
@@ -389,7 +386,3 @@ export class FilterMenu
         matchaddpos('ScopeMenuCursor', [[1, bytepos]], 10, -1, {window: this.idp})
     enddef
 endclass
-
-# some chunks shamelessly ripped from habamax
-#   https://github.com/habamax/.vim/blob/master/autoload/popup.vim
-

doc/scope.txt

@@ -56,9 +56,15 @@ API ~
 	#                      Applicable only when 'findCmd' is omitted or set to 'null_string'.
 	def File(findCmd: string = null_string, count: number = 10000, ignore: bool = true)
 <
-To echo the command string in Vim's command line, set the option
-`find_echo_cmd` to `true`. Default is `false`. Setting of options is discussed
-later.
+> [!NOTE]
+> - To prevent 'find' command from descending into `.git` directory, put `.git/`
+>   in the `~/.gitignore` or `~/.findignore` file.
+> - If `.gitignore` file contains `**` or `!` in the patterns, performance of
+>   'find' command may degrade. Use fd (https://github.com/sharkdp/fd) if this
+>   becomes an issue.
+> - To echo the command string in Vim's command line, set the option
+>   `find_echo_cmd` to `true`. Default is `false`. Setting of options is
+>   discussed later.
 
 Live Grep ~
 
@@ -76,6 +82,11 @@ Live grep in the directory.
 >    repeated greps without relying on the quickfix list.
 > 2. Special characters can be entered into the prompt window directly without
 >    requiring backslash escaping.
+> 3. It is sometimes useful to suspend live grep and filter results returned
+>    by live grep. Type `<C-k>` to enter pattern search mode (case
+>    insensitive). For example, typing `^foo` will filter lines that begin
+>    with `foo`. Patterns are negated if the first character is `!`. To filter
+>    lines not containing `foo` or `bar` type `!foo|bar` into the prompt.
 
 Define your own grep command.
 >