Add transform-query(...) action

Test case authored by @SpicyLemon

Close #1930
Close #2465
Close #2559
Close #2509 (e.g. fzf --bind 'space:transform-query:printf %s%s {q} {}')

2 files changed, 24 insertions, 6 deletions

diff --git a/src/options.go b/src/options.go
index f25b6e73..1288fbe4 100644
--- a/src/options.go
+++ b/src/options.go
@@ -890,7 +890,7 @@ const (
 
 func init() {
 	executeRegexp = regexp.MustCompile(
-		`(?si)[:+](execute(?:-multi|-silent)?|reload|preview|change-query|change-prompt|change-preview-window|change-preview|(?:re|un)bind|pos|put)`)
+		`(?si)[:+](execute(?:-multi|-silent)?|reload|preview|change-query|change-prompt|change-preview-window|change-preview|(?:re|un)bind|pos|put|transform-query)`)
 	splitRegexp = regexp.MustCompile("[,:]+")
 	actionNameRegexp = regexp.MustCompile("(?i)^[a-z-]+")
 }
@@ -1207,6 +1207,8 @@ func isExecuteAction(str string) actionType {
 		return actExecuteMulti
 	case "put":
 		return actPut
+	case "transform-query":
+		return actTransformQuery
 	}
 	return actIgnore
 }
diff --git a/src/terminal.go b/src/terminal.go
index 68a099cf..2d18f791 100644
--- a/src/terminal.go
+++ b/src/terminal.go
@@ -308,6 +308,7 @@ const (
 	actToggleSort
 	actTogglePreview
 	actTogglePreviewWrap
+	actTransformQuery
 	actPreview
 	actChangePreview
 	actChangePreviewWindow
@@ -2014,10 +2015,11 @@ func (t *Terminal) redraw(clear bool) {
 	t.printAll()
 }
 
-func (t *Terminal) executeCommand(template string, forcePlus bool, background bool) {
+func (t *Terminal) executeCommand(template string, forcePlus bool, background bool, captureFirstLine bool) string {
+	line := ""
 	valid, list := t.buildPlusList(template, forcePlus)
 	if !valid {
-		return
+		return line
 	}
 	command := t.replacePlaceholder(template, forcePlus, string(t.input), list)
 	cmd := util.ExecCommand(command, false)
@@ -2033,11 +2035,21 @@ func (t *Terminal) executeCommand(template string, forcePlus bool, background bo
 		t.refresh()
 	} else {
 		t.tui.Pause(false)
-		cmd.Run()
+		if captureFirstLine {
+			out, _ := cmd.StdoutPipe()
+			reader := bufio.NewReader(out)
+			cmd.Start()
+			line, _ = reader.ReadString('\n')
+			line = strings.TrimRight(line, "\r\n")
+			cmd.Wait()
+		} else {
+			cmd.Run()
+		}
 		t.tui.Resume(false, false)
 	}
 	t.executing.Set(false)
 	cleanTemporaryFiles()
+	return line
 }
 
 func (t *Terminal) hasPreviewer() bool {
@@ -2610,9 +2622,9 @@ func (t *Terminal) Loop() {
 			switch a.t {
 			case actIgnore:
 			case actExecute, actExecuteSilent:
-				t.executeCommand(a.a, false, a.t == actExecuteSilent)
+				t.executeCommand(a.a, false, a.t == actExecuteSilent, false)
 			case actExecuteMulti:
-				t.executeCommand(a.a, true, false)
+				t.executeCommand(a.a, true, false, false)
 			case actInvalid:
 				t.mutex.Unlock()
 				return false
@@ -2635,6 +2647,10 @@ func (t *Terminal) Loop() {
 					t.previewed.version = 0
 					req(reqPreviewRefresh)
 				}
+			case actTransformQuery:
+				query := t.executeCommand(a.a, false, true, true)
+				t.input = []rune(query)
+				t.cx = len(t.input)
 			case actToggleSort:
 				t.sort = !t.sort
 				changed = true