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

10 files changed, 255 insertions, 52 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index fec32d97..bb986dee 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,22 @@ CHANGELOG
 
 0.45.0
 ------
+- Added `transform` action to conditionally perform a series of actions
+  ```sh
+  # 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'
+  ```
+- Added placeholder expressions
+    - `{fzf:action}` - the name of the last action performed
+    - `{fzf:query}` - synonym for `{q}`
 - Added support for negative height
   ```sh
   # Terminal height minus 1, so you can still see the command line
diff --git a/Makefile b/Makefile
index a55c6bdb..32164a6e 100644
--- a/Makefile
+++ b/Makefile
@@ -89,6 +89,9 @@ bench:
 
 install: bin/fzf
 
+generate:
+	PATH=$(PATH):$(GOPATH)/bin $(GO) generate ./...
+
 build:
 	goreleaser build --rm-dist --snapshot --skip-post-hooks
 
@@ -181,4 +184,4 @@ update:
 	$(GO) get -u
 	$(GO) mod tidy
 
-.PHONY: all build release test bench install clean docker docker-test update
+.PHONY: all generate build release test bench install clean docker docker-test update
diff --git a/go.mod b/go.mod
index 31f9b0b0..ca3ebb98 100644
--- a/go.mod
+++ b/go.mod
@@ -14,8 +14,10 @@ require (
 require (
 	github.com/gdamore/encoding v1.0.0 // indirect
 	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
-	golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4 // indirect
+	golang.org/x/mod v0.14.0 // indirect
+	golang.org/x/sync v0.5.0 // indirect
 	golang.org/x/text v0.5.0 // indirect
+	golang.org/x/tools v0.16.1 // indirect
 )
 
 go 1.17
diff --git a/go.sum b/go.sum
index 3270c091..d9bb109f 100644
--- a/go.sum
+++ b/go.sum
@@ -19,6 +19,8 @@ github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5t
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
+golang.org/x/mod v0.14.0 h1:dGoOF9QVLYng8IHTm7BAyWqCqSheQ5pYWGhzW00YJr0=
+golang.org/x/mod v0.14.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
@@ -26,6 +28,8 @@ golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20220601150217-0de741cfad7f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4 h1:uVc8UZUe6tr40fFVnUP5Oj+veunVezqYl9z7DYw9xzw=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.5.0 h1:60k92dhOjHxJkrqnwsfl8KuaHbn/5dl0lUPUklKo3qE=
+golang.org/x/sync v0.5.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
@@ -46,4 +50,6 @@ golang.org/x/text v0.5.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
+golang.org/x/tools v0.16.1 h1:TLyB3WofjdOEepBHAU20JdNC1Zbg87elYofWYAY5oZA=
+golang.org/x/tools v0.16.1/go.mod h1:kYVVN6I1mBNoB1OX+noeBjbRk4IUEPa7JJ+TJMEooJ0=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
diff --git a/man/man1/fzf.1 b/man/man1/fzf.1
index c4fe788c..20e7e17d 100644
--- a/man/man1/fzf.1
+++ b/man/man1/fzf.1
@@ -574,10 +574,6 @@ e.g.
 When using a field index expression, leading and trailing whitespace is stripped
 from the replacement string. To preserve the whitespace, use the \fBs\fR flag.
 
-Also, \fB{q}\fR is replaced to the current query string, and \fB{n}\fR is
-replaced to zero-based ordinal index of the line. Use \fB{+n}\fR if you want
-all index numbers when multiple lines are selected.
-
 A placeholder expression with \fBf\fR flag is replaced to the path of
 a temporary file that holds the evaluated list. This is useful when you
 multi-select a large number of items and the length of the evaluated string may
@@ -589,6 +585,15 @@ e.g.
      seq 100000 | fzf --multi --bind ctrl-a:select-all \\
                       --preview "awk '{sum+=\\$1} END {print sum}' {+f}"\fR
 
+Also,
+
+* \fB{q}\fR (or \fB{fzf:query}\fR) is replaced to the current query string
+.br
+* \fB{n}\fR is replaced to the zero-based ordinal index of the current item.
+  Use \fB{+n}\fR if you want all index numbers when multiple lines are selected.
+.br
+* \fB{fzf:action}\fR is replaced to to the name of the last action performed
+
 Note that you can escape a placeholder pattern by prepending a backslash.
 
 Preview window will be updated even when there is no match for the current
diff --git a/src/actiontype_string.go b/src/actiontype_string.go
new file mode 100644
index 00000000..90fa909a
--- /dev/null
+++ b/src/actiontype_string.go
@@ -0,0 +1,127 @@
+// Code generated by "stringer -type=actionType"; DO NOT EDIT.
+
+package fzf
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[actIgnore-0]
+	_ = x[actStart-1]
+	_ = x[actClick-2]
+	_ = x[actInvalid-3]
+	_ = x[actChar-4]
+	_ = x[actMouse-5]
+	_ = x[actBeginningOfLine-6]
+	_ = x[actAbort-7]
+	_ = x[actAccept-8]
+	_ = x[actAcceptNonEmpty-9]
+	_ = x[actAcceptOrPrintQuery-10]
+	_ = x[actBackwardChar-11]
+	_ = x[actBackwardDeleteChar-12]
+	_ = x[actBackwardDeleteCharEof-13]
+	_ = x[actBackwardWord-14]
+	_ = x[actCancel-15]
+	_ = x[actChangeBorderLabel-16]
+	_ = x[actChangeHeader-17]
+	_ = x[actChangePreviewLabel-18]
+	_ = x[actChangePrompt-19]
+	_ = x[actChangeQuery-20]
+	_ = x[actClearScreen-21]
+	_ = x[actClearQuery-22]
+	_ = x[actClearSelection-23]
+	_ = x[actClose-24]
+	_ = x[actDeleteChar-25]
+	_ = x[actDeleteCharEof-26]
+	_ = x[actEndOfLine-27]
+	_ = x[actForwardChar-28]
+	_ = x[actForwardWord-29]
+	_ = x[actKillLine-30]
+	_ = x[actKillWord-31]
+	_ = x[actUnixLineDiscard-32]
+	_ = x[actUnixWordRubout-33]
+	_ = x[actYank-34]
+	_ = x[actBackwardKillWord-35]
+	_ = x[actSelectAll-36]
+	_ = x[actDeselectAll-37]
+	_ = x[actToggle-38]
+	_ = x[actToggleSearch-39]
+	_ = x[actToggleAll-40]
+	_ = x[actToggleDown-41]
+	_ = x[actToggleUp-42]
+	_ = x[actToggleIn-43]
+	_ = x[actToggleOut-44]
+	_ = x[actToggleTrack-45]
+	_ = x[actToggleHeader-46]
+	_ = x[actTrack-47]
+	_ = x[actDown-48]
+	_ = x[actUp-49]
+	_ = x[actPageUp-50]
+	_ = x[actPageDown-51]
+	_ = x[actPosition-52]
+	_ = x[actHalfPageUp-53]
+	_ = x[actHalfPageDown-54]
+	_ = x[actOffsetUp-55]
+	_ = x[actOffsetDown-56]
+	_ = x[actJump-57]
+	_ = x[actJumpAccept-58]
+	_ = x[actPrintQuery-59]
+	_ = x[actRefreshPreview-60]
+	_ = x[actReplaceQuery-61]
+	_ = x[actToggleSort-62]
+	_ = x[actShowPreview-63]
+	_ = x[actHidePreview-64]
+	_ = x[actTogglePreview-65]
+	_ = x[actTogglePreviewWrap-66]
+	_ = x[actTransform-67]
+	_ = x[actTransformBorderLabel-68]
+	_ = x[actTransformHeader-69]
+	_ = x[actTransformPreviewLabel-70]
+	_ = x[actTransformPrompt-71]
+	_ = x[actTransformQuery-72]
+	_ = x[actPreview-73]
+	_ = x[actChangePreview-74]
+	_ = x[actChangePreviewWindow-75]
+	_ = x[actPreviewTop-76]
+	_ = x[actPreviewBottom-77]
+	_ = x[actPreviewUp-78]
+	_ = x[actPreviewDown-79]
+	_ = x[actPreviewPageUp-80]
+	_ = x[actPreviewPageDown-81]
+	_ = x[actPreviewHalfPageUp-82]
+	_ = x[actPreviewHalfPageDown-83]
+	_ = x[actPrevHistory-84]
+	_ = x[actPrevSelected-85]
+	_ = x[actPut-86]
+	_ = x[actNextHistory-87]
+	_ = x[actNextSelected-88]
+	_ = x[actExecute-89]
+	_ = x[actExecuteSilent-90]
+	_ = x[actExecuteMulti-91]
+	_ = x[actSigStop-92]
+	_ = x[actFirst-93]
+	_ = x[actLast-94]
+	_ = x[actReload-95]
+	_ = x[actReloadSync-96]
+	_ = x[actDisableSearch-97]
+	_ = x[actEnableSearch-98]
+	_ = x[actSelect-99]
+	_ = x[actDeselect-100]
+	_ = x[actUnbind-101]
+	_ = x[actRebind-102]
+	_ = x[actBecome-103]
+	_ = x[actResponse-104]
+}
+
+const _actionType_name = "actIgnoreactStartactClickactInvalidactCharactMouseactBeginningOfLineactAbortactAcceptactAcceptNonEmptyactAcceptOrPrintQueryactBackwardCharactBackwardDeleteCharactBackwardDeleteCharEofactBackwardWordactCancelactChangeBorderLabelactChangeHeaderactChangePreviewLabelactChangePromptactChangeQueryactClearScreenactClearQueryactClearSelectionactCloseactDeleteCharactDeleteCharEofactEndOfLineactForwardCharactForwardWordactKillLineactKillWordactUnixLineDiscardactUnixWordRuboutactYankactBackwardKillWordactSelectAllactDeselectAllactToggleactToggleSearchactToggleAllactToggleDownactToggleUpactToggleInactToggleOutactToggleTrackactToggleHeaderactTrackactDownactUpactPageUpactPageDownactPositionactHalfPageUpactHalfPageDownactOffsetUpactOffsetDownactJumpactJumpAcceptactPrintQueryactRefreshPreviewactReplaceQueryactToggleSortactShowPreviewactHidePreviewactTogglePreviewactTogglePreviewWrapactTransformactTransformBorderLabelactTransformHeaderactTransformPreviewLabelactTransformPromptactTransformQueryactPreviewactChangePreviewactChangePreviewWindowactPreviewTopactPreviewBottomactPreviewUpactPreviewDownactPreviewPageUpactPreviewPageDownactPreviewHalfPageUpactPreviewHalfPageDownactPrevHistoryactPrevSelectedactPutactNextHistoryactNextSelectedactExecuteactExecuteSilentactExecuteMultiactSigStopactFirstactLastactReloadactReloadSyncactDisableSearchactEnableSearchactSelectactDeselectactUnbindactRebindactBecomeactResponse"
+
+var _actionType_index = [...]uint16{0, 9, 17, 25, 35, 42, 50, 68, 76, 85, 102, 123, 138, 159, 183, 198, 207, 227, 242, 263, 278, 292, 306, 319, 336, 344, 357, 373, 385, 399, 413, 424, 435, 453, 470, 477, 496, 508, 522, 531, 546, 558, 571, 582, 593, 605, 619, 634, 642, 649, 654, 663, 674, 685, 698, 713, 724, 737, 744, 757, 770, 787, 802, 815, 829, 843, 859, 879, 891, 914, 932, 956, 974, 991, 1001, 1017, 1039, 1052, 1068, 1080, 1094, 1110, 1128, 1148, 1170, 1184, 1199, 1205, 1219, 1234, 1244, 1260, 1275, 1285, 1293, 1300, 1309, 1322, 1338, 1353, 1362, 1373, 1382, 1391, 1400, 1411}
+
+func (i actionType) String() string {
+	if i < 0 || i >= actionType(len(_actionType_index)-1) {
+		return "actionType(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _actionType_name[_actionType_index[i]:_actionType_index[i+1]]
+}
diff --git a/src/options.go b/src/options.go
index ca8b2476..0822817a 100644
--- a/src/options.go
+++ b/src/options.go
@@ -979,7 +979,7 @@ const (
 
 func init() {
 	executeRegexp = regexp.MustCompile(
-		`(?si)[:+](become|execute(?:-multi|-silent)?|reload(?:-sync)?|preview|(?:change|transform)-(?:header|query|prompt|border-label|preview-label)|change-preview-window|change-preview|(?:re|un)bind|pos|put)`)
+		`(?si)[:+](become|execute(?:-multi|-silent)?|reload(?:-sync)?|preview|(?:change|transform)-(?:header|query|prompt|border-label|preview-label)|transform|change-preview-window|change-preview|(?:re|un)bind|pos|put)`)
 	splitRegexp = regexp.MustCompile("[,:]+")
 	actionNameRegexp = regexp.MustCompile("(?i)^[a-z-]+")
 }
@@ -1086,7 +1086,7 @@ func parseActionList(masked string, original string, prevActions []*action, putA
 		case "backward-delete-char":
 			appendAction(actBackwardDeleteChar)
 		case "backward-delete-char/eof":
-			appendAction(actBackwardDeleteCharEOF)
+			appendAction(actBackwardDeleteCharEof)
 		case "backward-word":
 			appendAction(actBackwardWord)
 		case "clear-screen":
@@ -1094,7 +1094,7 @@ func parseActionList(masked string, original string, prevActions []*action, putA
 		case "delete-char":
 			appendAction(actDeleteChar)
 		case "delete-char/eof":
-			appendAction(actDeleteCharEOF)
+			appendAction(actDeleteCharEof)
 		case "deselect":
 			appendAction(actDeselect)
 		case "end-of-line":
@@ -1213,7 +1213,7 @@ func parseActionList(masked string, original string, prevActions []*action, putA
 			appendAction(actDisableSearch)
 		case "put":
 			if putAllowed {
-				appendAction(actRune)
+				appendAction(actChar)
 			} else {
 				exit("unable to put non-printable character")
 			}
@@ -1333,6 +1333,8 @@ func isExecuteAction(str string) actionType {
 		return actExecuteMulti
 	case "put":
 		return actPut
+	case "transform":
+		return actTransform
 	case "transform-border-label":
 		return actTransformBorderLabel
 	case "transform-preview-label":
diff --git a/src/terminal.go b/src/terminal.go
index 394be4fc..31339d3e 100644
--- a/src/terminal.go
+++ b/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
 			}
diff --git a/src/terminal_test.go b/src/terminal_test.go
index ebb6bda5..271c64a3 100644
--- a/src/terminal_test.go
+++ b/src/terminal_test.go
@@ -52,90 +52,90 @@ func TestReplacePlaceholder(t *testing.T) {
 	*/
 
 	// {}, preserve ansi
-	result = replacePlaceholder("echo {}", false, Delimiter{}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {}", false, Delimiter{}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}}  foo{{.I}}bar \x1b[31mbaz\x1b[m{{.O}}")
 
 	// {}, strip ansi
-	result = replacePlaceholder("echo {}", true, Delimiter{}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {}", true, Delimiter{}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}}  foo{{.I}}bar baz{{.O}}")
 
 	// {}, with multiple items
-	result = replacePlaceholder("echo {}", true, Delimiter{}, printsep, false, "query", items2)
+	result = replacePlaceholder("echo {}", true, Delimiter{}, printsep, false, "query", items2, actIgnore)
 	checkFormat("echo {{.O}}foo{{.I}}bar baz{{.O}}")
 
 	// {..}, strip leading whitespaces, preserve ansi
-	result = replacePlaceholder("echo {..}", false, Delimiter{}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {..}", false, Delimiter{}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}}foo{{.I}}bar \x1b[31mbaz\x1b[m{{.O}}")
 
 	// {..}, strip leading whitespaces, strip ansi
-	result = replacePlaceholder("echo {..}", true, Delimiter{}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {..}", true, Delimiter{}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}}foo{{.I}}bar baz{{.O}}")
 
 	// {q}
-	result = replacePlaceholder("echo {} {q}", true, Delimiter{}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {} {q}", true, Delimiter{}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}}  foo{{.I}}bar baz{{.O}} {{.O}}query{{.O}}")
 
 	// {q}, multiple items
-	result = replacePlaceholder("echo {+}{q}{+}", true, Delimiter{}, printsep, false, "query 'string'", items2)
+	result = replacePlaceholder("echo {+}{q}{+}", true, Delimiter{}, printsep, false, "query 'string'", items2, actIgnore)
 	checkFormat("echo {{.O}}foo{{.I}}bar baz{{.O}} {{.O}}FOO{{.I}}BAR BAZ{{.O}}{{.O}}query {{.I}}string{{.I}}{{.O}}{{.O}}foo{{.I}}bar baz{{.O}} {{.O}}FOO{{.I}}BAR BAZ{{.O}}")
 
-	result = replacePlaceholder("echo {}{q}{}", true, Delimiter{}, printsep, false, "query 'string'", items2)
+	result = replacePlaceholder("echo {}{q}{}", true, Delimiter{}, printsep, false, "query 'string'", items2, actIgnore)
 	checkFormat("echo {{.O}}foo{{.I}}bar baz{{.O}}{{.O}}query {{.I}}string{{.I}}{{.O}}{{.O}}foo{{.I}}bar baz{{.O}}")
 
-	result = replacePlaceholder("echo {1}/{2}/{2,1}/{-1}/{-2}/{}/{..}/{n.t}/\\{}/\\{1}/\\{q}/{3}", true, Delimiter{}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {1}/{2}/{2,1}/{-1}/{-2}/{}/{..}/{n.t}/\\{}/\\{1}/\\{q}/{3}", true, Delimiter{}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}}foo{{.I}}bar{{.O}}/{{.O}}baz{{.O}}/{{.O}}bazfoo{{.I}}bar{{.O}}/{{.O}}baz{{.O}}/{{.O}}foo{{.I}}bar{{.O}}/{{.O}}  foo{{.I}}bar baz{{.O}}/{{.O}}foo{{.I}}bar baz{{.O}}/{n.t}/{}/{1}/{q}/{{.O}}{{.O}}")
 
-	result = replacePlaceholder("echo {1}/{2}/{-1}/{-2}/{..}/{n.t}/\\{}/\\{1}/\\{q}/{3}", true, Delimiter{}, printsep, false, "query", items2)
+	result = replacePlaceholder("echo {1}/{2}/{-1}/{-2}/{..}/{n.t}/\\{}/\\{1}/\\{q}/{3}", true, Delimiter{}, printsep, false, "query", items2, actIgnore)
 	checkFormat("echo {{.O}}foo{{.I}}bar{{.O}}/{{.O}}baz{{.O}}/{{.O}}baz{{.O}}/{{.O}}foo{{.I}}bar{{.O}}/{{.O}}foo{{.I}}bar baz{{.O}}/{n.t}/{}/{1}/{q}/{{.O}}{{.O}}")
 
-	result = replacePlaceholder("echo {+1}/{+2}/{+-1}/{+-2}/{+..}/{n.t}/\\{}/\\{1}/\\{q}/{+3}", true, Delimiter{}, printsep, false, "query", items2)
+	result = replacePlaceholder("echo {+1}/{+2}/{+-1}/{+-2}/{+..}/{n.t}/\\{}/\\{1}/\\{q}/{+3}", true, Delimiter{}, printsep, false, "query", items2, actIgnore)
 	checkFormat("echo {{.O}}foo{{.I}}bar{{.O}} {{.O}}FOO{{.I}}BAR{{.O}}/{{.O}}baz{{.O}} {{.O}}BAZ{{.O}}/{{.O}}baz{{.O}} {{.O}}BAZ{{.O}}/{{.O}}foo{{.I}}bar{{.O}} {{.O}}FOO{{.I}}BAR{{.O}}/{{.O}}foo{{.I}}bar baz{{.O}} {{.O}}FOO{{.I}}BAR BAZ{{.O}}/{n.t}/{}/{1}/{q}/{{.O}}{{.O}} {{.O}}{{.O}}")
 
 	// forcePlus
-	result = replacePlaceholder("echo {1}/{2}/{-1}/{-2}/{..}/{n.t}/\\{}/\\{1}/\\{q}/{3}", true, Delimiter{}, printsep, true, "query", items2)
+	result = replacePlaceholder("echo {1}/{2}/{-1}/{-2}/{..}/{n.t}/\\{}/\\{1}/\\{q}/{3}", true, Delimiter{}, printsep, true, "query", items2, actIgnore)
 	checkFormat("echo {{.O}}foo{{.I}}bar{{.O}} {{.O}}FOO{{.I}}BAR{{.O}}/{{.O}}baz{{.O}} {{.O}}BAZ{{.O}}/{{.O}}baz{{.O}} {{.O}}BAZ{{.O}}/{{.O}}foo{{.I}}bar{{.O}} {{.O}}FOO{{.I}}BAR{{.O}}/{{.O}}foo{{.I}}bar baz{{.O}} {{.O}}FOO{{.I}}BAR BAZ{{.O}}/{n.t}/{}/{1}/{q}/{{.O}}{{.O}} {{.O}}{{.O}}")
 
 	// Whitespace preserving flag with "'" delimiter
-	result = replacePlaceholder("echo {s1}", true, Delimiter{str: &delim}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {s1}", true, Delimiter{str: &delim}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}}  foo{{.O}}")
 
-	result = replacePlaceholder("echo {s2}", true, Delimiter{str: &delim}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {s2}", true, Delimiter{str: &delim}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}}bar baz{{.O}}")
 
-	result = replacePlaceholder("echo {s}", true, Delimiter{str: &delim}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {s}", true, Delimiter{str: &delim}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}}  foo{{.I}}bar baz{{.O}}")
 
-	result = replacePlaceholder("echo {s..}", true, Delimiter{str: &delim}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {s..}", true, Delimiter{str: &delim}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}}  foo{{.I}}bar baz{{.O}}")
 
 	// Whitespace preserving flag with regex delimiter
 	regex = regexp.MustCompile(`\w+`)
 
-	result = replacePlaceholder("echo {s1}", true, Delimiter{regex: regex}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {s1}", true, Delimiter{regex: regex}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}}  {{.O}}")
 
-	result = replacePlaceholder("echo {s2}", true, Delimiter{regex: regex}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {s2}", true, Delimiter{regex: regex}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}}{{.I}}{{.O}}")
 
-	result = replacePlaceholder("echo {s3}", true, Delimiter{regex: regex}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {s3}", true, Delimiter{regex: regex}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}} {{.O}}")
 
 	// No match
-	result = replacePlaceholder("echo {}/{+}", true, Delimiter{}, printsep, false, "query", []*Item{nil, nil})
+	result = replacePlaceholder("echo {}/{+}", true, Delimiter{}, printsep, false, "query", []*Item{nil, nil}, actIgnore)
 	check("echo /")
 
 	// No match, but with selections
-	result = replacePlaceholder("echo {}/{+}", true, Delimiter{}, printsep, false, "query", []*Item{nil, item1})
+	result = replacePlaceholder("echo {}/{+}", true, Delimiter{}, printsep, false, "query", []*Item{nil, item1}, actIgnore)
 	checkFormat("echo /{{.O}}  foo{{.I}}bar baz{{.O}}")
 
 	// String delimiter
-	result = replacePlaceholder("echo {}/{1}/{2}", true, Delimiter{str: &delim}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {}/{1}/{2}", true, Delimiter{str: &delim}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}}  foo{{.I}}bar baz{{.O}}/{{.O}}foo{{.O}}/{{.O}}bar baz{{.O}}")
 
 	// Regex delimiter
 	regex = regexp.MustCompile("[oa]+")
 	// foo'bar baz
-	result = replacePlaceholder("echo {}/{1}/{3}/{2..3}", true, Delimiter{regex: regex}, printsep, false, "query", items1)
+	result = replacePlaceholder("echo {}/{1}/{3}/{2..3}", true, Delimiter{regex: regex}, printsep, false, "query", items1, actIgnore)
 	checkFormat("echo {{.O}}  foo{{.I}}bar baz{{.O}}/{{.O}}f{{.O}}/{{.O}}r b{{.O}}/{{.O}}{{.I}}bar b{{.O}}")
 
 	/*
@@ -198,18 +198,23 @@ func TestReplacePlaceholder(t *testing.T) {
 	// query flag is not removed after parsing, so it gets doubled
 	// while the double q is invalid, it is useful here for testing purposes
 	templateToOutput[`{q}`] = "{{.O}}" + query + "{{.O}}"
+	templateToOutput[`{fzf:query}`] = "{{.O}}" + query + "{{.O}}"
+	templateToOutput[`{fzf:action}`] = "backward-delete-char-eof"
 
 	// IV. escaping placeholder
 	templateToOutput[`\{}`] = `{}`
+	templateToOutput[`\{q}`] = `{q}`
+	templateToOutput[`\{fzf:query}`] = `{fzf:query}`
+	templateToOutput[`\{fzf:action}`] = `{fzf:action}`
 	templateToOutput[`\{++}`] = `{++}`
 	templateToOutput[`{++}`] = templateToOutput[`{+}`]
 
 	for giveTemplate, wantOutput := range templateToOutput {
-		result = replacePlaceholder(giveTemplate, stripAnsi, Delimiter{}, printsep, forcePlus, query, items3)
+		result = replacePlaceholder(giveTemplate, stripAnsi, Delimiter{}, printsep, forcePlus, query, items3, actBackwardDeleteCharEof)
 		checkFormat(wantOutput)
 	}
 	for giveTemplate, wantOutput := range templateToFile {
-		path := replacePlaceholder(giveTemplate, stripAnsi, Delimiter{}, printsep, forcePlus, query, items3)
+		path := replacePlaceholder(giveTemplate, stripAnsi, Delimiter{}, printsep, forcePlus, query, items3, actIgnore)
 
 		data, err := readFile(path)
 		if err != nil {
@@ -566,7 +571,7 @@ func testCommands(t *testing.T, tests []testCase) {
 		gotOutput := replacePlaceholder(
 			test.give.template, stripAnsi, delimiter, printsep, forcePlus,
 			test.give.query,
-			test.give.allItems)
+			test.give.allItems, actIgnore)
 		switch {
 		case test.want.output != "":
 			if gotOutput != test.want.output {
diff --git a/test/test_go.rb b/test/test_go.rb
index 5a9c48b7..771064ee 100755
--- a/test/test_go.rb
+++ b/test/test_go.rb
@@ -2016,6 +2016,13 @@ class TestGoFZF < TestBase
     tmux.until { |lines| assert_equal '> RAB', lines[-1] }
   end
 
+  def test_transform
+    tmux.send_keys %{#{FZF} --bind 'focus:transform:echo "change-prompt({fzf:action})"'}, :Enter
+    tmux.until { |lines| assert_equal 'start', lines[-1] }
+    tmux.send_keys :Up
+    tmux.until { |lines| assert_equal 'up', lines[-1] }
+  end
+
   def test_clear_selection
     tmux.send_keys %(seq 100 | #{FZF} --multi --bind space:clear-selection), :Enter
     tmux.until { |lines| assert_equal 100, lines.match_count }