Add change-header and transform-header

Close #3237

5 files changed, 135 insertions, 33 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index e487db66..594c5a51 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,19 +1,22 @@
 CHANGELOG
 =========
 
-0.39.1
+0.40.0
 ------
-- Added `toggle-track` action. Temporarily enabling tracking is useful when
-  you want to see the surrounding items by deleting the query string.
-  ```sh
-  export FZF_CTRL_R_OPTS="
-    --preview 'echo {}' --preview-window up:3:hidden:wrap
-    --bind 'ctrl-/:toggle-preview'
-    --bind 'ctrl-t:toggle-track'
-    --bind 'ctrl-y:execute-silent(echo -n {2..} | pbcopy)+abort'
-    --color header:italic
-    --header 'Press CTRL-Y to copy command into clipboard'"
-  ```
+- New actions
+    - Added `change-header(...)`
+    - Added `transform-header(...)`
+    - Added `toggle-track` action. Temporarily enabling tracking is useful when
+      you want to see the surrounding items by deleting the query string.
+      ```sh
+      export FZF_CTRL_R_OPTS="
+        --preview 'echo {}' --preview-window up:3:hidden:wrap
+        --bind 'ctrl-/:toggle-preview'
+        --bind 'ctrl-t:toggle-track'
+        --bind 'ctrl-y:execute-silent(echo -n {2..} | pbcopy)+abort'
+        --color header:italic
+        --header 'Press CTRL-Y to copy command into clipboard'"
+      ```
 - Fixed `--track` behavior when used with `--tac`
     - However, using `--track` with `--tac` is not recommended. The resulting
       behavior can be very confusing.
diff --git a/man/man1/fzf.1 b/man/man1/fzf.1
index 834babee..acdde33e 100644
--- a/man/man1/fzf.1
+++ b/man/man1/fzf.1
@@ -1031,6 +1031,7 @@ A key or an event can be bound to one or more of the following actions.
     \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)
+    \fBchange-header(...)\fR           (change header to the given string; doesn't affect \fB--header-lines\fR)
     \fBchange-preview(...)\fR          (change \fB--preview\fR option)
     \fBchange-preview-label(...)\fR    (change \fB--preview-label\fR to the given string)
     \fBchange-preview-window(...)\fR   (change \fB--preview-window\fR option; rotate through the multiple option sets separated by '|')
@@ -1100,6 +1101,7 @@ A key or an event can be bound to one or more of the following actions.
     \fBtoggle-sort\fR
     \fBtoggle+up\fR                    \fIbtab    (shift-tab)\fR
     \fBtransform-border-label(...)\fR  (transform border label using an external command)
+    \fBtransform-header(...)\fR        (transform header using an external command)
     \fBtransform-preview-label(...)\fR (transform preview label using an external command)
     \fBtransform-prompt(...)\fR        (transform prompt string using an external command)
     \fBtransform-query(...)\fR         (transform query string using an external command)
diff --git a/src/options.go b/src/options.go
index e09e9b59..3718cf5a 100644
--- a/src/options.go
+++ b/src/options.go
@@ -927,7 +927,7 @@ const (
 
 func init() {
 	executeRegexp = regexp.MustCompile(
-		`(?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)`)
+		`(?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)`)
 	splitRegexp = regexp.MustCompile("[,:]+")
 	actionNameRegexp = regexp.MustCompile("(?i)^[a-z-]+")
 }
@@ -1249,6 +1249,8 @@ func isExecuteAction(str string) actionType {
 		return actPreview
 	case "change-border-label":
 		return actChangeBorderLabel
+	case "change-header":
+		return actChangeHeader
 	case "change-preview-label":
 		return actChangePreviewLabel
 	case "change-preview-window":
@@ -1273,6 +1275,8 @@ func isExecuteAction(str string) actionType {
 		return actTransformBorderLabel
 	case "transform-preview-label":
 		return actTransformPreviewLabel
+	case "transform-header":
+		return actTransformHeader
 	case "transform-prompt":
 		return actTransformPrompt
 	case "transform-query":
diff --git a/src/terminal.go b/src/terminal.go
index 20a15d9a..e3403a40 100644
--- a/src/terminal.go
+++ b/src/terminal.go
@@ -3,6 +3,7 @@ package fzf
 import (
 	"bufio"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"math"
 	"os"
@@ -310,6 +311,7 @@ const (
 	actBackwardWord
 	actCancel
 	actChangeBorderLabel
+	actChangeHeader
 	actChangePreviewLabel
 	actChangePrompt
 	actChangeQuery
@@ -356,6 +358,7 @@ const (
 	actTogglePreview
 	actTogglePreviewWrap
 	actTransformBorderLabel
+	actTransformHeader
 	actTransformPreviewLabel
 	actTransformPrompt
 	actTransformQuery
@@ -624,7 +627,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 		cycle:              opts.Cycle,
 		headerFirst:        opts.HeaderFirst,
 		headerLines:        opts.HeaderLines,
-		header:             header,
+		header:             []string{},
 		header0:            header,
 		ellipsis:           opts.Ellipsis,
 		ansi:               opts.Ansi,
@@ -883,10 +886,21 @@ func reverseStringArray(input []string) []string {
 	return reversed
 }
 
+func (t *Terminal) changeHeader(header string) bool {
+	lines := strings.Split(strings.TrimSuffix(header, "\n"), "\n")
+	switch t.layout {
+	case layoutDefault, layoutReverseList:
+		lines = reverseStringArray(lines)
+	}
+	needFullRedraw := len(t.header0) != len(lines)
+	t.header0 = lines
+	return needFullRedraw
+}
+
 // UpdateHeader updates the header
 func (t *Terminal) UpdateHeader(header []string) {
 	t.mutex.Lock()
-	t.header = append(append([]string{}, t.header0...), header...)
+	t.header = header
 	t.mutex.Unlock()
 	t.reqBox.Set(reqHeader, nil)
 }
@@ -1345,7 +1359,7 @@ func (t *Terminal) move(y int, x int, clear bool) {
 	case layoutDefault:
 		y = h - y - 1
 	case layoutReverseList:
-		n := 2 + len(t.header)
+		n := 2 + len(t.header0) + len(t.header)
 		if t.noInfoLine() {
 			n--
 		}
@@ -1493,7 +1507,7 @@ func (t *Terminal) printInfo() {
 }
 
 func (t *Terminal) printHeader() {
-	if len(t.header) == 0 {
+	if len(t.header0)+len(t.header) == 0 {
 		return
 	}
 	max := t.window.Height()
@@ -1504,7 +1518,7 @@ func (t *Terminal) printHeader() {
 		}
 	}
 	var state *ansiState
-	for idx, lineStr := range t.header {
+	for idx, lineStr := range append(append([]string{}, t.header0...), t.header...) {
 		line := idx
 		if !t.headerFirst {
 			line++
@@ -1538,7 +1552,7 @@ func (t *Terminal) printList() {
 		if t.layout == layoutDefault {
 			i = maxy - 1 - j
 		}
-		line := i + 2 + len(t.header)
+		line := i + 2 + len(t.header0) + len(t.header)
 		if t.noInfoLine() {
 			line--
 		}
@@ -2276,12 +2290,12 @@ func (t *Terminal) redraw() {
 	t.printAll()
 }
 
-func (t *Terminal) executeCommand(template string, forcePlus bool, background bool, captureFirstLine bool) string {
+func (t *Terminal) executeCommand(template string, forcePlus bool, background bool, capture bool, firstLineOnly bool) string {
 	line := ""
 	valid, list := t.buildPlusList(template, forcePlus)
-	// captureFirstLine is used for transform-{prompt,query} and we don't want to
+	// 'capture' is used for transform-* and we don't want to
 	// return an empty string in those cases
-	if !valid && !captureFirstLine {
+	if !valid && !capture {
 		return line
 	}
 	command := t.replacePlaceholder(template, forcePlus, string(t.input), list)
@@ -2298,12 +2312,17 @@ func (t *Terminal) executeCommand(template string, forcePlus bool, background bo
 		t.redraw()
 		t.refresh()
 	} else {
-		if captureFirstLine {
+		if capture {
 			out, _ := cmd.StdoutPipe()
 			reader := bufio.NewReader(out)
 			cmd.Start()
-			line, _ = reader.ReadString('\n')
-			line = strings.TrimRight(line, "\r\n")
+			if firstLineOnly {
+				line, _ = reader.ReadString('\n')
+				line = strings.TrimRight(line, "\r\n")
+			} else {
+				bytes, _ := io.ReadAll(reader)
+				line = string(bytes)
+			}
 			cmd.Wait()
 		} else {
 			cmd.Run()
@@ -2921,9 +2940,9 @@ func (t *Terminal) Loop() {
 					}
 				}
 			case actExecute, actExecuteSilent:
-				t.executeCommand(a.a, false, a.t == actExecuteSilent, false)
+				t.executeCommand(a.a, false, a.t == actExecuteSilent, false, false)
 			case actExecuteMulti:
-				t.executeCommand(a.a, true, false, false)
+				t.executeCommand(a.a, true, false, false, false)
 			case actInvalid:
 				t.mutex.Unlock()
 				return false
@@ -2957,11 +2976,11 @@ func (t *Terminal) Loop() {
 					req(reqPreviewRefresh)
 				}
 			case actTransformPrompt:
-				prompt := t.executeCommand(a.a, false, true, true)
+				prompt := t.executeCommand(a.a, false, true, true, true)
 				t.prompt, t.promptLen = t.parsePrompt(prompt)
 				req(reqPrompt)
 			case actTransformQuery:
-				query := t.executeCommand(a.a, false, true, true)
+				query := t.executeCommand(a.a, false, true, true, true)
 				t.input = []rune(query)
 				t.cx = len(t.input)
 			case actToggleSort:
@@ -3010,6 +3029,19 @@ func (t *Terminal) Loop() {
 			case actChangeQuery:
 				t.input = []rune(a.a)
 				t.cx = len(t.input)
+			case actTransformHeader:
+				header := t.executeCommand(a.a, false, true, true, false)
+				if t.changeHeader(header) {
+					req(reqFullRedraw)
+				} else {
+					req(reqHeader)
+				}
+			case actChangeHeader:
+				if t.changeHeader(a.a) {
+					req(reqFullRedraw)
+				} else {
+					req(reqHeader)
+				}
 			case actChangeBorderLabel:
 				if t.border != nil {
 					t.borderLabel, t.borderLabelLen = t.ansiLabelPrinter(a.a, &tui.ColBorderLabel, false)
@@ -3022,13 +3054,13 @@ func (t *Terminal) Loop() {
 				}
 			case actTransformBorderLabel:
 				if t.border != nil {
-					label := t.executeCommand(a.a, false, true, true)
+					label := t.executeCommand(a.a, false, true, true, true)
 					t.borderLabel, t.borderLabelLen = t.ansiLabelPrinter(label, &tui.ColBorderLabel, false)
 					req(reqRedrawBorderLabel)
 				}
 			case actTransformPreviewLabel:
 				if t.pborder != nil {
-					label := t.executeCommand(a.a, false, true, true)
+					label := t.executeCommand(a.a, false, true, true, true)
 					t.previewLabel, t.previewLabelLen = t.ansiLabelPrinter(label, &tui.ColPreviewLabel, false)
 					req(reqRedrawPreviewLabel)
 				}
@@ -3358,7 +3390,7 @@ func (t *Terminal) Loop() {
 				// Translate coordinates
 				mx -= t.window.Left()
 				my -= t.window.Top()
-				min := 2 + len(t.header)
+				min := 2 + len(t.header0) + len(t.header)
 				if t.noInfoLine() {
 					min--
 				}
@@ -3627,7 +3659,7 @@ func (t *Terminal) vset(o int) bool {
 }
 
 func (t *Terminal) maxItems() int {
-	max := t.window.Height() - 2 - len(t.header)
+	max := t.window.Height() - 2 - len(t.header0) - len(t.header)
 	if t.noInfoLine() {
 		max++
 	}
diff --git a/test/test_go.rb b/test/test_go.rb
index d1fa2c37..34884550 100755
--- a/test/test_go.rb
+++ b/test/test_go.rb
@@ -1865,6 +1865,67 @@ class TestGoFZF < TestBase
     tmux.until { |lines| assert_equal '>', lines.last }
   end
 
+  def test_change_and_transform_header
+    [
+      'space:change-header:$(seq 4)',
+      'space:transform-header:seq 4'
+    ].each_with_index do |binding, i|
+      tmux.send_keys %(seq 3 | #{FZF} --header-lines 2 --header bar --bind "#{binding}"), :Enter
+      expected = <<~OUTPUT
+        > 3
+          2
+          1
+          bar
+          1/1
+        >
+      OUTPUT
+      tmux.until { assert_block(expected, _1) }
+      tmux.send_keys :Space
+      expected = <<~OUTPUT
+        > 3
+          2
+          1
+          1
+          2
+          3
+          4
+          1/1
+        >
+      OUTPUT
+      tmux.until { assert_block(expected, _1) }
+      next unless i.zero?
+
+      teardown
+      setup
+    end
+  end
+
+  def test_change_header
+    tmux.send_keys %(seq 3 | #{FZF} --header-lines 2 --header bar --bind "space:change-header:$(seq 4)"), :Enter
+    expected = <<~OUTPUT
+      > 3
+        2
+        1
+        bar
+        1/1
+      >
+    OUTPUT
+    tmux.until { assert_block(expected, _1) }
+    tmux.send_keys :Space
+    expected = <<~OUTPUT
+      > 3
+        2
+        1
+        1
+        2
+        3
+        4
+        1/1
+      >
+    OUTPUT
+    tmux.until { assert_block(expected, _1) }
+  end
+
   def test_change_query
     tmux.send_keys %(: | #{FZF} --query foo --bind space:change-query:foobar), :Enter
     tmux.until { |lines| assert_equal 0, lines.item_count }