Allow bare put action in transform output

transform/bg-transform now permit bare `put`, inserting the key that
triggered the action (`a:transform:echo put` puts `a`).

src/options.go

@@ -10,7 +10,6 @@ import (
 	"strconv"
 	"strings"
 	"time"
-	"unicode"
 
 	"github.com/junegunn/fzf/src/algo"
 	"github.com/junegunn/fzf/src/tui"
@@ -1734,10 +1733,10 @@ Loop:
 	return masked
 }
 
-func parseSingleActionList(str string) ([]*action, error) {
+func parseSingleActionList(str string, putAllowed bool) ([]*action, error) {
 	// We prepend a colon to satisfy argActionRegexp and remove it later
 	masked := maskActionContents(":" + str)[1:]
-	return parseActionList(masked, str, []*action{}, false)
+	return parseActionList(masked, str, []*action{}, putAllowed)
 }
 
 func parseActionList(masked string, original string, prevActions []*action, putAllowed bool) ([]*action, error) {
@@ -2043,8 +2042,7 @@ func parseKeymap(keymap map[tui.Event][]*action, str string) error {
 				}
 				key = firstKey(keys)
 			}
-			putAllowed := key.Type == tui.Rune && unicode.IsGraphic(key.Char)
-			keymap[key], err = parseActionList(pair[1], origPairStr[len(pair[0])+1:], keymap[key], putAllowed)
+			keymap[key], err = parseActionList(pair[1], origPairStr[len(pair[0])+1:], keymap[key], key.Printable())
 			if err != nil {
 				return err
 			}

src/options_test.go

@@ -572,7 +572,7 @@ func TestValidateSign(t *testing.T) {
 }
 
 func TestParseSingleActionList(t *testing.T) {
-	actions, _ := parseSingleActionList("Execute@foo+bar,baz@+up+up+reload:down+down")
+	actions, _ := parseSingleActionList("Execute@foo+bar,baz@+up+up+reload:down+down", false)
 	if len(actions) != 4 {
 		t.Errorf("Invalid number of actions parsed:%d", len(actions))
 	}
@@ -588,7 +588,7 @@ func TestParseSingleActionList(t *testing.T) {
 }
 
 func TestParseSingleActionListError(t *testing.T) {
-	_, err := parseSingleActionList("change-query(foobar)baz")
+	_, err := parseSingleActionList("change-query(foobar)baz", false)
 	if err == nil {
 		t.Errorf("Failed to detect error")
 	}

src/server.go

@@ -240,7 +240,7 @@ Loop:
 	}
 	body = body[:contentLength]
 
-	actions, err := parseSingleActionList(strings.Trim(string(body), "\r\n"))
+	actions, err := parseSingleActionList(strings.Trim(string(body), "\r\n"), false)
 	if err != nil {
 		return bad(err.Error())
 	}

src/terminal.go

@@ -6973,7 +6973,8 @@ func (t *Terminal) Loop() error {
 				})
 			case actTransform, actBgTransform:
 				capture(false, func(body string) {
-					if actions, err := parseSingleActionList(strings.Trim(body, "\r\n")); err == nil {
+					// Allow 'put' if the triggering key is a printable character
+					if actions, err := parseSingleActionList(strings.Trim(body, "\r\n"), event.Printable()); err == nil {
 						// NOTE: We're not properly passing the return value here
 						doActions(actions)
 					}

src/tui/tui.go

@@ -4,6 +4,7 @@ import (
 	"strconv"
 	"strings"
 	"time"
+	"unicode"
 
 	"github.com/junegunn/fzf/src/util"
 	"github.com/rivo/uniseg"
@@ -252,6 +253,12 @@ func (e Event) Comparable() Event {
 	return Event{e.Type, e.Char, nil}
 }
 
+// Printable returns true if the event is a printable character that can be
+// inserted into the query (e.g. via the 'put' action).
+func (e Event) Printable() bool {
+	return e.Type == Rune && unicode.IsGraphic(e.Char)
+}
+
 func (e Event) KeyName() string {
 	if me := e.MouseEvent; me != nil {
 		return me.Name()

test/test_core.rb

@@ -971,6 +971,24 @@ class TestCore < TestInteractive
     tmux.until { |lines| assert_includes lines[1], ' aabravo/aabravo' }
   end
 
+  def test_transform_put
+    tmux.send_keys %(seq 1000 | #{FZF} --bind 'a:transform:echo put'), :Enter
+    tmux.until { |lines| assert_equal 1000, lines.match_count }
+    tmux.send_keys :a
+    tmux.until { |lines| assert_equal '> a', lines.last }
+    tmux.send_keys :b
+    tmux.until { |lines| assert_equal '> ab', lines.last }
+  end
+
+  # The async callback runs in a later iteration, but 'put' must still insert
+  # the key that triggered the bg-transform (snapshot of the scheduling event).
+  def test_bg_transform_put
+    tmux.send_keys %(seq 1000 | #{FZF} --bind 'a:bg-transform:sleep 0.5; echo put'), :Enter
+    tmux.until { |lines| assert_equal 1000, lines.match_count }
+    tmux.send_keys 'ab'
+    tmux.until { |lines| assert_equal '> ba', lines.last }
+  end
+
   def test_accept_non_empty
     tmux.send_keys %(seq 1000 | #{fzf('--print-query --bind enter:accept-non-empty')}), :Enter
     tmux.until { |lines| assert_equal 1000, lines.match_count }