Add pos(...) action to move the cursor to the numeric position

# Put the cursor on the 10th item
  seq 100 | fzf --sync --bind 'start:pos(10)'

  # Put the cursor on the 10th to last item
  seq 100 | fzf --sync --bind 'start:pos(-10)'

Close #3069
Close #395

CHANGELOG.md

@@ -12,6 +12,15 @@ CHANGELOG
   # Send actions to the server
   curl -XPOST localhost:6266 -d 'reload(seq 100)+change-prompt(hundred> )'
   ```
+- Added `pos(...)` action to move the cursor to the numeric position
+    - `first` and `last` are equivalent to `pos(1)` and `pos(-1)` respectively
+  ```sh
+  # Put the cursor on the 10th item
+  seq 100 | fzf --sync --bind 'start:pos(10)'
+
+  # Put the cursor on the 10th to last item
+  seq 100 | fzf --sync --bind 'start:pos(-10)'
+  ```
 - Added `next-selected` and `prev-selected` actions to move between selected
   items
   ```sh

man/man1/fzf.1

@@ -979,7 +979,7 @@ A key or an event can be bound to one or more of the following actions.
     \fBend-of-line\fR                \fIctrl-e  end\fR
     \fBexecute(...)\fR               (see below for the details)
     \fBexecute-silent(...)\fR        (see below for the details)
-    \fBfirst\fR                      (move to the first match)
+    \fBfirst\fR                      (move to the first match; same as \fBpos(1)\fR)
     \fBforward-char\fR               \fIctrl-f  right\fR
     \fBforward-word\fR               \fIalt-f   shift-right\fR
     \fBignore\fR
@@ -987,13 +987,14 @@ A key or an event can be bound to one or more of the following actions.
     \fBjump-accept\fR                (jump and accept)
     \fBkill-line\fR
     \fBkill-word\fR                  \fIalt-d\fR
-    \fBlast\fR                       (move to the last match)
+    \fBlast\fR                       (move to the last match; same as \fBpos(-1)\fR)
     \fBnext-history\fR               (\fIctrl-n\fR on \fB--history\fR)
     \fBnext-selected\fR              (move to the next selected item)
     \fBpage-down\fR                  \fIpgdn\fR
     \fBpage-up\fR                    \fIpgup\fR
     \fBhalf-page-down\fR
     \fBhalf-page-up\fR
+    \fBpos(...)\fR                   (move cursor to the numeric position; negative number to count from the end)
     \fBprev-history\fR               (\fIctrl-p\fR on \fB--history\fR)
     \fBprev-selected\fR              (move to the previous selected item)
     \fBpreview(...)\fR               (see below for the details)

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)`)
+		`(?si)[:+](execute(?:-multi|-silent)?|reload|preview|change-query|change-prompt|change-preview-window|change-preview|(?:re|un)bind|pos)`)
 	splitRegexp = regexp.MustCompile("[,:]+")
 	actionNameRegexp = regexp.MustCompile("(?i)^[a-z-]+")
 }
@@ -1197,6 +1197,8 @@ func isExecuteAction(str string) actionType {
 		return actChangePrompt
 	case "change-query":
 		return actChangeQuery
+	case "pos":
+		return actPosition
 	case "execute":
 		return actExecute
 	case "execute-silent":

src/terminal.go

@@ -297,6 +297,7 @@ const (
 	actUp
 	actPageUp
 	actPageDown
+	actPosition
 	actHalfPageUp
 	actHalfPageDown
 	actJump
@@ -2837,6 +2838,16 @@ func (t *Terminal) Loop() {
 			case actLast:
 				t.vset(t.merger.Length() - 1)
 				req(reqList)
+			case actPosition:
+				if n, e := strconv.Atoi(a.a); e == nil {
+					if n > 0 {
+						n--
+					} else if n < 0 {
+						n += t.merger.Length()
+					}
+					t.vset(n)
+					req(reqList)
+				}
 			case actUnixLineDiscard:
 				beof = len(t.input) == 0
 				if t.cx > 0 {

test/test_go.rb

@@ -1605,6 +1605,21 @@ class TestGoFZF < TestBase
     tmux.send_keys :Enter
   end
 
+  def test_pos
+    tmux.send_keys %(seq 1000 | #{FZF} --bind 'a:pos(3),b:pos(-3),c:pos(1),d:pos(-1),e:pos(0)' --preview 'echo {}/{}'), :Enter
+    tmux.until { |lines| assert_equal 1000, lines.match_count }
+    tmux.send_keys :a
+    tmux.until { |lines| assert_includes lines[1], ' 3/3' }
+    tmux.send_keys :b
+    tmux.until { |lines| assert_includes lines[1], ' 998/998' }
+    tmux.send_keys :c
+    tmux.until { |lines| assert_includes lines[1], ' 1/1' }
+    tmux.send_keys :d
+    tmux.until { |lines| assert_includes lines[1], ' 1000/1000' }
+    tmux.send_keys :e
+    tmux.until { |lines| assert_includes lines[1], ' 1/1' }
+  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 }