Add become(...) action that replaces current fzf process

Close #3159

CHANGELOG.md

@@ -4,6 +4,15 @@ CHANGELOG
 0.38.0
 ------
 - New actions
+    - `become(...)` - Replace the current fzf process with the specified
+      command using `execve(2)` system call. This action enables a simpler
+      alternative to using `--expect` and checking the output in the wrapping
+      script.
+      ```sh
+      # Open selected files in different editors
+      fzf --multi --bind 'enter:become($EDITOR {+}),ctrl-n:become(nano {+})'
+      ```
+        - This action is not supported on Windows
     - `show-preview`
     - `hide-preview`
 - Bug fixes

man/man1/fzf.1

@@ -999,6 +999,7 @@ A key or an event can be bound to one or more of the following actions.
     \fBbackward-delete-char/eof\fR     (same as \fBbackward-delete-char\fR except aborts fzf if query is empty)
     \fBbackward-kill-word\fR           \fIalt-bs\fR
     \fBbackward-word\fR                \fIalt-b   shift-left\fR
+    \fBbecome(...)\fR                  (replace fzf process with the specified command; see below for the details)
     \fBbeginning-of-line\fR            \fIctrl-a  home\fR
     \fBcancel\fR                       (clear query string if not empty, abort fzf otherwise)
     \fBchange-border-label(...)\fR     (change \fB--border-label\fR to the given string)
@@ -1143,6 +1144,14 @@ On *nix systems, fzf runs the command with \fB$SHELL -c\fR if \fBSHELL\fR is
 set, otherwise with \fBsh -c\fR, so in this case make sure that the command is
 POSIX-compliant.
 
+\fBbecome(...)\fR action is similar to \fBexecute(...)\fR, but it replaces the
+current fzf process with the specifed command using \fBexecve(2)\fR system
+call.
+
+    \fBfzf --bind "enter:become(vim {})"\fR
+
+\fBbecome(...)\fR is not supported on Windows.
+
 .SS RELOAD INPUT
 
 \fBreload(...)\fR action is used to dynamically update the input list

src/options.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/junegunn/fzf/src/algo"
 	"github.com/junegunn/fzf/src/tui"
+	"github.com/junegunn/fzf/src/util"
 
 	"github.com/mattn/go-runewidth"
 	"github.com/mattn/go-shellwords"
@@ -921,7 +922,7 @@ const (
 
 func init() {
 	executeRegexp = regexp.MustCompile(
-		`(?si)[:+](execute(?:-multi|-silent)?|reload(?:-sync)?|preview|(?:change|transform)-(?: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)-(?:query|prompt|border-label|preview-label)|change-preview-window|change-preview|(?:re|un)bind|pos|put)`)
 	splitRegexp = regexp.MustCompile("[,:]+")
 	actionNameRegexp = regexp.MustCompile("(?i)^[a-z-]+")
 }
@@ -1171,6 +1172,10 @@ func parseActionList(masked string, original string, prevActions []*action, putA
 					actions = append(actions, &action{t: t, a: actionArg})
 				}
 				switch t {
+				case actBecome:
+					if util.IsWindows() {
+						exit("become action is not supported on Windows")
+					}
 				case actUnbind, actRebind:
 					parseKeyChordsImpl(actionArg, spec[0:offset]+" target required", exit)
 				case actChangePreviewWindow:
@@ -1223,6 +1228,8 @@ func isExecuteAction(str string) actionType {
 
 	prefix := actionNameRegexp.FindString(str)
 	switch prefix {
+	case "become":
+		return actBecome
 	case "reload":
 		return actReload
 	case "reload-sync":

src/terminal.go

@@ -6,6 +6,7 @@ import (
 	"io/ioutil"
 	"math"
 	"os"
+	"os/exec"
 	"os/signal"
 	"regexp"
 	"sort"
@@ -387,6 +388,7 @@ const (
 	actDeselect
 	actUnbind
 	actRebind
+	actBecome
 )
 
 type placeholderFlags struct {
@@ -2237,7 +2239,7 @@ func (t *Terminal) redraw() {
 
 func (t *Terminal) executeCommand(template string, forcePlus bool, background bool, captureFirstLine bool) string {
 	line := ""
-	valid, list := t.buildPlusList(template, forcePlus, false)
+	valid, list := t.buildPlusList(template, forcePlus)
 	// captureFirstLine is used for transform-{prompt,query} and we don't want to
 	// return an empty string in those cases
 	if !valid && !captureFirstLine {
@@ -2297,10 +2299,10 @@ func (t *Terminal) currentItem() *Item {
 	return nil
 }
 
-func (t *Terminal) buildPlusList(template string, forcePlus bool, forceEvaluation bool) (bool, []*Item) {
+func (t *Terminal) buildPlusList(template string, forcePlus bool) (bool, []*Item) {
 	current := t.currentItem()
 	slot, plus, query := hasPreviewFlags(template)
-	if !forceEvaluation && !(!slot || query || (forcePlus || plus) && len(t.selected) > 0) {
+	if !(!slot || query || (forcePlus || plus) && len(t.selected) > 0) {
 		return current != nil, []*Item{current, current}
 	}
 
@@ -2625,7 +2627,7 @@ func (t *Terminal) Loop() {
 
 	refreshPreview := func(command string) {
 		if len(command) > 0 && t.canPreview() {
-			_, list := t.buildPlusList(command, false, false)
+			_, list := t.buildPlusList(command, false)
 			t.cancelPreview()
 			t.previewBox.Set(reqPreviewEnqueue, previewRequest{command, t.pwindow, t.evaluateScrollOffset(), list})
 		}
@@ -2860,6 +2862,21 @@ func (t *Terminal) Loop() {
 		doAction = func(a *action) bool {
 			switch a.t {
 			case actIgnore:
+			case actBecome:
+				_, list := t.buildPlusList(a.a, false)
+				command := t.replacePlaceholder(a.a, false, string(t.input), list)
+				shell := os.Getenv("SHELL")
+				if len(shell) == 0 {
+					shell = "sh"
+				}
+				shellPath, err := exec.LookPath(shell)
+				if err == nil {
+					t.tui.Close()
+					if t.history != nil {
+						t.history.append(string(t.input))
+					}
+					syscall.Exec(shellPath, []string{shell, "-c", command}, os.Environ())
+				}
 			case actExecute, actExecuteSilent:
 				t.executeCommand(a.a, false, a.t == actExecuteSilent, false)
 			case actExecuteMulti:
@@ -2881,7 +2898,7 @@ func (t *Terminal) Loop() {
 					t.activePreviewOpts.Toggle()
 					updatePreviewWindow(false)
 					if t.canPreview() {
-						valid, list := t.buildPlusList(t.previewOpts.command, false, false)
+						valid, list := t.buildPlusList(t.previewOpts.command, false)
 						if valid {
 							t.cancelPreview()
 							t.previewBox.Set(reqPreviewEnqueue,
@@ -3360,7 +3377,7 @@ func (t *Terminal) Loop() {
 			case actReload, actReloadSync:
 				t.failed = nil
 
-				valid, list := t.buildPlusList(a.a, false, false)
+				valid, list := t.buildPlusList(a.a, false)
 				if !valid {
 					// We run the command even when there's no match
 					// 1. If the template doesn't have any slots

test/test_go.rb

@@ -2643,6 +2643,13 @@ class TestGoFZF < TestBase
     tmux.send_keys :Space
     tmux.until { |lines| assert_includes lines, '/1/1/' }
   end
+
+  def test_become
+    tmux.send_keys "seq 10 | #{FZF} --bind 'enter:become:seq 100 | #{FZF}'", :Enter
+    tmux.until { |lines| assert_equal 10, lines.item_count }
+    tmux.send_keys :Enter
+    tmux.until { |lines| assert_equal 100, lines.item_count }
+  end
 end
 
 module TestShell