Add 'transform' action to conditionally perform a series of actions

'transform' action runs an external command that prints a series of
actions to perform.

  # Disallow selecting an empty line
  echo -e "1. Hello\n2. Goodbye\n\n3. Exit" |
    fzf --reverse --header 'Select one' \
        --bind 'enter:transform:[[ -n {} ]] && echo accept || echo "change-header:Invalid selection"'

  # Move cursor past the empty line
  echo -e "1. Hello\n2. Goodbye\n\n3. Exit" |
    fzf --reverse --header 'Select one' \
        --bind 'enter:transform:[[ -n {} ]] && echo accept || echo "change-header:Invalid selection"' \
        --bind 'focus:transform:[[ -n {} ]] && exit; [[ {fzf:action} =~ up$ ]] && echo up || echo down'

Close #3368
Close #2980

src/terminal.go

@@ -52,11 +52,12 @@ var offsetComponentRegex *regexp.Regexp
 var offsetTrimCharsRegex *regexp.Regexp
 var activeTempFiles []string
 var passThroughRegex *regexp.Regexp
+var actionTypeRegex *regexp.Regexp
 
 const clearCode string = "\x1b[2J"
 
 func init() {
-	placeholder = regexp.MustCompile(`\\?(?:{[+sf]*[0-9,-.]*}|{q}|{\+?f?nf?})`)
+	placeholder = regexp.MustCompile(`\\?(?:{[+sf]*[0-9,-.]*}|{q}|{fzf:(?:query|action)}|{\+?f?nf?})`)
 	whiteSuffix = regexp.MustCompile(`\s*$`)
 	offsetComponentRegex = regexp.MustCompile(`([+-][0-9]+)|(-?/[1-9][0-9]*)`)
 	offsetTrimCharsRegex = regexp.MustCompile(`[^0-9/+-]`)
@@ -285,6 +286,7 @@ type Terminal struct {
 	tui                tui.Renderer
 	executing          *util.AtomicBool
 	termSize           tui.TermSize
+	lastAction         actionType
 }
 
 type selectedItem struct {
@@ -332,12 +334,15 @@ type action struct {
 	a string
 }
 
+//go:generate stringer -type=actionType
 type actionType int
 
 const (
 	actIgnore actionType = iota
+	actStart
+	actClick
 	actInvalid
-	actRune
+	actChar
 	actMouse
 	actBeginningOfLine
 	actAbort
@@ -346,7 +351,7 @@ const (
 	actAcceptOrPrintQuery
 	actBackwardChar
 	actBackwardDeleteChar
-	actBackwardDeleteCharEOF
+	actBackwardDeleteCharEof
 	actBackwardWord
 	actCancel
 	actChangeBorderLabel
@@ -359,7 +364,7 @@ const (
 	actClearSelection
 	actClose
 	actDeleteChar
-	actDeleteCharEOF
+	actDeleteCharEof
 	actEndOfLine
 	actForwardChar
 	actForwardWord
@@ -400,6 +405,7 @@ const (
 	actHidePreview
 	actTogglePreview
 	actTogglePreviewWrap
+	actTransform
 	actTransformBorderLabel
 	actTransformHeader
 	actTransformPreviewLabel
@@ -441,13 +447,15 @@ const (
 
 func processExecution(action actionType) bool {
 	switch action {
-	case actTransformBorderLabel,
+	case actTransform,
+		actTransformBorderLabel,
 		actTransformHeader,
 		actTransformPreviewLabel,
 		actTransformPrompt,
 		actTransformQuery,
 		actPreview,
 		actChangePreview,
+		actRefreshPreview,
 		actExecute,
 		actExecuteSilent,
 		actExecuteMulti,
@@ -514,7 +522,7 @@ func defaultKeymap() map[tui.Event][]*action {
 	add(tui.CtrlG, actAbort)
 	add(tui.CtrlQ, actAbort)
 	add(tui.ESC, actAbort)
-	add(tui.CtrlD, actDeleteCharEOF)
+	add(tui.CtrlD, actDeleteCharEof)
 	add(tui.CtrlE, actEndOfLine)
 	add(tui.CtrlF, actForwardChar)
 	add(tui.CtrlH, actBackwardDeleteChar)
@@ -556,7 +564,7 @@ func defaultKeymap() map[tui.Event][]*action {
 	add(tui.SDown, actPreviewDown)
 
 	add(tui.Mouse, actMouse)
-	add(tui.LeftClick, actIgnore)
+	add(tui.LeftClick, actClick)
 	add(tui.RightClick, actToggle)
 	add(tui.SLeftClick, actToggle)
 	add(tui.SRightClick, actToggle)
@@ -740,7 +748,8 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 		eventChan:          make(chan tui.Event, 3), // load / zero|one | GetChar
 		tui:                renderer,
 		initFunc:           func() { renderer.Init() },
-		executing:          util.NewAtomicBool(false)}
+		executing:          util.NewAtomicBool(false),
+		lastAction:         actStart}
 	t.prompt, t.promptLen = t.parsePrompt(opts.Prompt)
 	t.pointer, t.pointerLen = t.processTabs([]rune(opts.Pointer), 0)
 	t.marker, t.markerLen = t.processTabs([]rune(opts.Marker), 0)
@@ -2344,6 +2353,10 @@ func parsePlaceholder(match string) (bool, string, placeholderFlags) {
 		return true, match[1:], flags
 	}
 
+	if strings.HasPrefix(match, "{fzf:") {
+		return false, match, flags
+	}
+
 	skipChars := 1
 	for _, char := range match[1:] {
 		switch char {
@@ -2408,7 +2421,7 @@ func cleanTemporaryFiles() {
 
 func (t *Terminal) replacePlaceholder(template string, forcePlus bool, input string, list []*Item) string {
 	return replacePlaceholder(
-		template, t.ansi, t.delimiter, t.printsep, forcePlus, input, list)
+		template, t.ansi, t.delimiter, t.printsep, forcePlus, input, list, t.lastAction)
 }
 
 func (t *Terminal) evaluateScrollOffset() int {
@@ -2446,7 +2459,7 @@ func (t *Terminal) evaluateScrollOffset() int {
 	return util.Max(0, base)
 }
 
-func replacePlaceholder(template string, stripAnsi bool, delimiter Delimiter, printsep string, forcePlus bool, query string, allItems []*Item) string {
+func replacePlaceholder(template string, stripAnsi bool, delimiter Delimiter, printsep string, forcePlus bool, query string, allItems []*Item, lastAction actionType) string {
 	current := allItems[:1]
 	selected := allItems[1:]
 	if current[0] == nil {
@@ -2467,7 +2480,16 @@ func replacePlaceholder(template string, stripAnsi bool, delimiter Delimiter, pr
 		switch {
 		case escaped:
 			return match
-		case match == "{q}":
+		case match == "{fzf:action}":
+			name := ""
+			for i, r := range lastAction.String()[3:] {
+				if i > 0 && r >= 'A' && r <= 'Z' {
+					name += "-"
+				}
+				name += string(r)
+			}
+			return strings.ToLower(name)
+		case match == "{q}" || match == "{fzf:query}":
 			return quoteEntry(query)
 		case match == "{}":
 			replace = func(item *Item) string {
@@ -3207,7 +3229,7 @@ func (t *Terminal) Loop() {
 		}
 		doAction = func(a *action) bool {
 			switch a.t {
-			case actIgnore:
+			case actIgnore, actStart, actClick:
 			case actResponse:
 				t.serverOutputChan <- t.dumpStatus(parseGetParams(a.a))
 			case actBecome:
@@ -3354,6 +3376,10 @@ func (t *Terminal) Loop() {
 					t.previewLabel, t.previewLabelLen = t.ansiLabelPrinter(a.a, &tui.ColPreviewLabel, false)
 					req(reqRedrawPreviewLabel)
 				}
+			case actTransform:
+				body := t.executeCommand(a.a, false, true, true, false)
+				actions := parseSingleActionList(strings.Trim(body, "\r\n"), func(message string) {})
+				t.serverInputChan <- actions
 			case actTransformBorderLabel:
 				if t.border != nil {
 					label := t.executeCommand(a.a, false, true, true, true)
@@ -3384,7 +3410,7 @@ func (t *Terminal) Loop() {
 				req(reqQuit)
 			case actDeleteChar:
 				t.delChar()
-			case actDeleteCharEOF:
+			case actDeleteCharEof:
 				if !t.delChar() && t.cx == 0 {
 					req(reqQuit)
 				}
@@ -3398,7 +3424,7 @@ func (t *Terminal) Loop() {
 					t.input = []rune{}
 					t.cx = 0
 				}
-			case actBackwardDeleteCharEOF:
+			case actBackwardDeleteCharEof:
 				if len(t.input) == 0 {
 					req(reqQuit)
 				} else if t.cx > 0 {
@@ -3617,7 +3643,7 @@ func (t *Terminal) Loop() {
 					t.yanked = copySlice(t.input[t.cx:])
 					t.input = t.input[:t.cx]
 				}
-			case actRune:
+			case actChar:
 				prefix := copySlice(t.input[:t.cx])
 				t.input = append(append(prefix, event.Char), t.input[t.cx:]...)
 				t.cx++
@@ -3895,6 +3921,10 @@ func (t *Terminal) Loop() {
 					}
 				}
 			}
+
+			if !processExecution(a.t) {
+				t.lastAction = a.t
+			}
 			return true
 		}
 
@@ -3908,7 +3938,7 @@ func (t *Terminal) Loop() {
 				actions = t.keymap[event.Comparable()]
 			}
 			if len(actions) == 0 && event.Type == tui.Rune {
-				doAction(&action{t: actRune})
+				doAction(&action{t: actChar})
 			} else if !doActions(actions) {
 				continue
 			}