Add --gap option to put empty lines between items

5 files changed, 105 insertions, 21 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 80b6491a..3ea88846 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,21 @@
 CHANGELOG
 =========
 
+0.56.0
+------
+- Added `--gap[=N]` option to display empty lines between items.
+    - This can be useful to visually separate adjacent multi-line items.
+      ```sh
+      # All bash functions, highlighted
+      declare -f | perl -0777 -pe 's/^}\n/}\0/gm' |
+        bat --plain --language bash --color always |
+        fzf --read0 --ansi --reverse --multi --highlight-line --gap
+      ```
+    - Or just to make the list easier to read. For single-line items, you probably want to set `--color gutter:-1` as well to hide the gutter.
+      ```sh
+      fzf --gap --color gutter:-1
+      ```
+
 0.55.0
 ------
 _Release highlights: https://junegunn.github.io/fzf/releases/0.55.0/_
diff --git a/man/man1/fzf.1 b/man/man1/fzf.1
index 321327ab..59e21815 100644
--- a/man/man1/fzf.1
+++ b/man/man1/fzf.1
@@ -208,6 +208,9 @@ Indicator for wrapped lines. The default is '↳ ' or '> ' depending on
 .B "\-\-no\-multi\-line"
 Disable multi-line display of items when using \fB\-\-read0\fR
 .TP
+.BI "\-\-gap" "[=N]"
+Render empty lines between each item
+.TP
 .B "\-\-keep\-right"
 Keep the right end of the line visible when it's too long. Effective only when
 the query string is empty.
diff --git a/src/options.go b/src/options.go
index 62c8c0c3..b0ab6b1d 100644
--- a/src/options.go
+++ b/src/options.go
@@ -56,6 +56,7 @@ Usage: fzf [options]
     --wrap                  Enable line wrap
     --wrap-sign=STR         Indicator for wrapped lines
     --no-multi-line         Disable multi-line display of items when using --read0
+    --gap[=N]               Render empty lines between each item
     --keep-right            Keep the right end of the line visible on overflow
     --scroll-off=LINES      Number of screen lines to keep above or below when
                             scrolling to the top or to the bottom (default: 0)
@@ -473,6 +474,7 @@ type Options struct {
 	Header       []string
 	HeaderLines  int
 	HeaderFirst  bool
+	Gap          int
 	Ellipsis     *string
 	Scrollbar    *string
 	Margin       [4]sizeSpec
@@ -579,6 +581,7 @@ func defaultOptions() *Options {
 		Header:       make([]string, 0),
 		HeaderLines:  0,
 		HeaderFirst:  false,
+		Gap:          0,
 		Ellipsis:     nil,
 		Scrollbar:    nil,
 		Margin:       defaultMargin(),
@@ -2343,6 +2346,12 @@ func parseOptions(index *int, opts *Options, allArgs []string) error {
 			opts.HeaderFirst = true
 		case "--no-header-first":
 			opts.HeaderFirst = false
+		case "--gap":
+			if opts.Gap, err = optionalNumeric(allArgs, &i, 1); err != nil {
+				return err
+			}
+		case "--no-gap":
+			opts.Gap = 0
 		case "--ellipsis":
 			str, err := nextString(allArgs, &i, "ellipsis string required")
 			if err != nil {
@@ -2630,6 +2639,10 @@ func parseOptions(index *int, opts *Options, allArgs []string) error {
 				if opts.HeaderLines, err = atoi(value); err != nil {
 					return err
 				}
+			} else if match, value := optString(arg, "--gap="); match {
+				if opts.Gap, err = atoi(value); err != nil {
+					return err
+				}
 			} else if match, value := optString(arg, "--ellipsis="); match {
 				str := firstLine(value)
 				opts.Ellipsis = &str
diff --git a/src/terminal.go b/src/terminal.go
index 535f5e3a..ce299de4 100644
--- a/src/terminal.go
+++ b/src/terminal.go
@@ -245,6 +245,7 @@ type Terminal struct {
 	hscroll            bool
 	hscrollOff         int
 	scrollOff          int
+	gap                int
 	wordRubout         string
 	wordNext           string
 	cx                 int
@@ -825,6 +826,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox, executor *util.Executor
 		headerVisible:      true,
 		headerFirst:        opts.HeaderFirst,
 		headerLines:        opts.HeaderLines,
+		gap:                opts.Gap,
 		header:             []string{},
 		header0:            opts.Header,
 		ansi:               opts.Ansi,
@@ -1136,15 +1138,23 @@ func (t *Terminal) wrapCols() int {
 	return util.Max(t.window.Width()-(t.pointerLen+t.markerLen+1), 1)
 }
 
+// Number of lines the item takes including the gap
 func (t *Terminal) numItemLines(item *Item, atMost int) (int, bool) {
+	var numLines int
 	if !t.wrap && !t.multiLine {
-		return 1, false
+		numLines = 1 + t.gap
+		return numLines, numLines > atMost
 	}
+	var overflow bool
 	if !t.wrap && t.multiLine {
-		return item.text.NumLines(atMost)
+		numLines, overflow = item.text.NumLines(atMost)
+	} else {
+		var lines [][]rune
+		lines, overflow = item.text.Lines(t.multiLine, atMost, t.wrapCols(), t.wrapSignWidth, t.tabstop)
+		numLines = len(lines)
 	}
-	lines, overflow := item.text.Lines(t.multiLine, atMost, t.wrapCols(), t.wrapSignWidth, t.tabstop)
-	return len(lines), overflow
+	numLines += t.gap
+	return numLines, overflow || numLines > atMost
 }
 
 func (t *Terminal) itemLines(item *Item, atMost int) ([][]rune, bool) {
@@ -2050,6 +2060,21 @@ func (t *Terminal) printHeader() {
 	t.wrap = wrap
 }
 
+func (t *Terminal) canSpanMultiLines() bool {
+	return t.multiLine || t.wrap || t.gap > 0
+}
+
+func (t *Terminal) renderEmptyLine(line int, barRange [2]int) {
+	t.move(line, 0, true)
+	t.markEmptyLine(line)
+	// If the screen is not filled with the list in non-multi-line mode,
+	// scrollbar is not visible at all. But in multi-line mode, we may need
+	// to redraw the scrollbar character at the end.
+	if t.canSpanMultiLines() {
+		t.prevLines[line].hasBar = t.printBar(line, true, barRange)
+	}
+}
+
 func (t *Terminal) printList() {
 	t.constrain()
 	barLength, barStart := t.getScrollbar()
@@ -2070,14 +2095,7 @@ func (t *Terminal) printList() {
 			item := t.merger.Get(itemCount + t.offset)
 			line = t.printItem(item, line, maxy, itemCount, itemCount == t.cy-t.offset, barRange)
 		} else if !t.prevLines[line].empty {
-			t.move(line, 0, true)
-			t.markEmptyLine(line)
-			// If the screen is not filled with the list in non-multi-line mode,
-			// scrollbar is not visible at all. But in multi-line mode, we may need
-			// to redraw the scrollbar character at the end.
-			if t.multiLine || t.wrap {
-				t.prevLines[line].hasBar = t.printBar(line, true, barRange)
-			}
+			t.renderEmptyLine(line, barRange)
 		}
 	}
 }
@@ -2125,9 +2143,6 @@ func (t *Terminal) printItem(result Result, line int, maxLine int, index int, cu
 		prevLine.queryLen == newLine.queryLen &&
 		prevLine.result == newLine.result {
 		t.prevLines[line].hasBar = printBar(line, false)
-		if !t.multiLine && !t.wrap {
-			return line
-		}
 		return line + numLines - 1
 	}
 
@@ -2214,6 +2229,10 @@ func (t *Terminal) printItem(result Result, line int, maxLine int, index int, cu
 		}
 		finalLineNum = t.printHighlighted(result, base, match, false, true, line, maxLine, forceRedraw, preTask, postTask)
 	}
+	for i := 0; i < t.gap && finalLineNum < maxLine; i++ {
+		finalLineNum++
+		t.renderEmptyLine(finalLineNum, barRange)
+	}
 	return finalLineNum
 }
 
@@ -2275,7 +2294,7 @@ func (t *Terminal) printHighlighted(result Result, colBase tui.ColorPair, colMat
 	allOffsets := result.colorOffsets(charOffsets, t.theme, colBase, colMatch, current)
 
 	maxLines := 1
-	if t.multiLine || t.wrap {
+	if t.canSpanMultiLines() {
 		maxLines = maxLineNum - lineNum + 1
 	}
 	lines, overflow := t.itemLines(item, maxLines)
@@ -2285,7 +2304,7 @@ func (t *Terminal) printHighlighted(result Result, colBase tui.ColorPair, colMat
 	topCutoff := false
 	skipLines := 0
 	wrapped := false
-	if t.multiLine || t.wrap {
+	if t.canSpanMultiLines() {
 		// Cut off the upper lines in the 'default' layout
 		if t.layout == layoutDefault && !current && maxLines == numItemLines && overflow {
 			lines, _ = t.itemLines(item, math.MaxInt)
@@ -4875,7 +4894,7 @@ func (t *Terminal) constrain() {
 	for tries := 0; tries < maxLines; tries++ {
 		numItems := maxLines
 		// How many items can be fit on screen including the current item?
-		if (t.multiLine || t.wrap) && t.merger.Length() > 0 {
+		if t.canSpanMultiLines() && t.merger.Length() > 0 {
 			numItemsFound := 0
 			linesSum := 0
 
@@ -4930,12 +4949,12 @@ func (t *Terminal) constrain() {
 				for {
 					prevOffset := newOffset
 					numItems := t.merger.Length()
-					itemLines := 1
-					if (t.multiLine || t.wrap) && t.cy < numItems {
+					itemLines := 1 + t.gap
+					if t.canSpanMultiLines() && t.cy < numItems {
 						itemLines, _ = t.numItemLines(t.merger.Get(t.cy).item, maxLines)
 					}
 					linesBefore := t.cy - newOffset
-					if t.multiLine || t.wrap {
+					if t.canSpanMultiLines() {
 						linesBefore = 0
 						for i := newOffset; i < t.cy && i < numItems; i++ {
 							lines, _ := t.numItemLines(t.merger.Get(i).item, maxLines-linesBefore-itemLines)
diff --git a/test/test_go.rb b/test/test_go.rb
index 8f627baf..2a462157 100755
--- a/test/test_go.rb
+++ b/test/test_go.rb
@@ -3392,6 +3392,40 @@ class TestGoFZF < TestBase
       assert lines[1]&.end_with?('1000││')
     end
   end
+
+  def test_gap
+    tmux.send_keys %[seq 100 | #{FZF} --gap --border --reverse], :Enter
+    block = <<~BLOCK
+      ╭─────────────────
+      │ >
+      │   100/100 ──────
+      │ > 1
+      │
+      │   2
+      │
+      │   3
+      │
+      │   4
+    BLOCK
+    tmux.until { assert_block(block, _1) }
+  end
+
+  def test_gap_2
+    tmux.send_keys %[seq 100 | #{FZF} --gap=2 --border --reverse], :Enter
+    block = <<~BLOCK
+      ╭─────────────────
+      │ >
+      │   100/100 ──────
+      │ > 1
+      │
+      │
+      │   2
+      │
+      │
+      │   3
+    BLOCK
+    tmux.until { assert_block(block, _1) }
+  end
 end
 
 module TestShell