Merge branch 'johan/quit-if-one-screen'

Fixes #113

m/pager.go

@@ -70,6 +70,9 @@ type Pager struct {
 
 	WrapLongLines bool
 
+	// Ref: https://github.com/walles/moar/issues/113
+	QuitIfOneScreen bool
+
 	// Ref: https://github.com/walles/moar/issues/94
 	ScrollLeftHint  twin.Cell
 	ScrollRightHint twin.Cell
@@ -207,6 +210,7 @@ func (p *Pager) Quit() {
 	p.preHelpState = nil
 }
 
+// Negative deltas move left instead
 func (p *Pager) moveRight(delta int) {
 	if p.ShowLineNumbers && delta > 0 {
 		p.ShowLineNumbers = false
@@ -460,8 +464,27 @@ func (p *Pager) StartPaging(screen twin.Screen) {
 	spinner := ""
 	for !p.quit {
 		if len(screen.Events()) == 0 {
-			// Nothing more to process for now, redraw the screen!
-			p.redraw(spinner)
+			// Nothing more to process for now, redraw the screen
+			overflow := p.redraw(spinner)
+
+			// Ref:
+			// https://github.com/gwsw/less/blob/ff8869aa0485f7188d942723c9fb50afb1892e62/command.c#L828-L831
+			if p.QuitIfOneScreen && overflow == didFit && !p.isShowingHelp {
+				// Do the slow (atomic) checks only if the fast ones (no locking
+				// required) passed
+				if p.reader.done.Load() && p.reader.highlightingDone.Load() {
+					// Ref:
+					// https://github.com/walles/moar/issues/113#issuecomment-1368294132
+					p.ShowLineNumbers = false // Requires a redraw to take effect, see below
+					p.DeInit = false
+					p.quit = true
+
+					// Without this the line numbers setting ^ won't take effect
+					p.redraw(spinner)
+
+					break
+				}
+			}
 		}
 
 		event := <-screen.Events()
@@ -519,7 +542,7 @@ func (p *Pager) StartPaging(screen twin.Screen) {
 func (p *Pager) ReprintAfterExit() error {
 	// Figure out how many screen lines are used by pager contents
 
-	renderedScreenLines, _ := p.renderScreenLines()
+	renderedScreenLines, _, _ := p.renderScreenLines()
 	screenLinesCount := len(renderedScreenLines)
 
 	_, screenHeight := p.screen.Size()

m/reader.go

@@ -34,7 +34,7 @@ type Reader struct {
 	replaced bool
 
 	done             *atomic.Bool
-	highlightingDone *atomic.Bool // Used by tests
+	highlightingDone *atomic.Bool
 	moreLinesAdded   chan bool
 }
 
@@ -489,26 +489,30 @@ func (r *Reader) GetLine(lineNumberOneBased int) *Line {
 }
 
 // GetLines gets the indicated lines from the input
-func (r *Reader) GetLines(firstLineOneBased int, wantedLineCount int) *InputLines {
+//
+// Overflow state will be didFit if we returned all lines we currently have, or
+// didOverflow otherwise.
+func (r *Reader) GetLines(firstLineOneBased int, wantedLineCount int) (*InputLines, overflowState) {
 	r.lock.Lock()
 	defer r.lock.Unlock()
 	return r.getLinesUnlocked(firstLineOneBased, wantedLineCount)
 }
 
-func (r *Reader) getLinesUnlocked(firstLineOneBased int, wantedLineCount int) *InputLines {
+func (r *Reader) getLinesUnlocked(firstLineOneBased int, wantedLineCount int) (*InputLines, overflowState) {
 	if firstLineOneBased < 1 {
 		firstLineOneBased = 1
 	}
 
 	if len(r.lines) == 0 {
 		return &InputLines{
-			lines: nil,
+				lines: nil,
 
-			// The line number set here won't matter, we'll clip it anyway when we get it back
-			firstLineOneBased: 0,
+				// The line number set here won't matter, we'll clip it anyway when we get it back
+				firstLineOneBased: 0,
 
-			statusText: r.createStatusUnlocked(0),
-		}
+				statusText: r.createStatusUnlocked(0),
+			},
+			didFit // Empty files always fit
 	}
 
 	firstLineZeroBased := firstLineOneBased - 1
@@ -530,11 +534,18 @@ func (r *Reader) getLinesUnlocked(firstLineOneBased int, wantedLineCount int) *I
 		return r.getLinesUnlocked(firstLineOneBased, wantedLineCount)
 	}
 
-	return &InputLines{
-		lines:             r.lines[firstLineZeroBased : lastLineZeroBased+1],
-		firstLineOneBased: firstLineOneBased,
-		statusText:        r.createStatusUnlocked(lastLineZeroBased + 1),
+	returnLines := r.lines[firstLineZeroBased : lastLineZeroBased+1]
+	overflow := didFit
+	if len(returnLines) != len(r.lines) {
+		overflow = didOverflow // We're not returning all available lines
 	}
+
+	return &InputLines{
+			lines:             returnLines,
+			firstLineOneBased: firstLineOneBased,
+			statusText:        r.createStatusUnlocked(lastLineZeroBased + 1),
+		},
+		overflow
 }
 
 // Replace reader contents with the given text and mark as done

m/reader_test.go

@@ -58,7 +58,7 @@ func testGetLineCount(t *testing.T, reader *Reader) {
 func testGetLines(t *testing.T, reader *Reader) {
 	t.Logf("Testing file: %s...", *reader.name)
 
-	lines := reader.GetLines(1, 10)
+	lines, _ := reader.GetLines(1, 10)
 	if len(lines.lines) > 10 {
 		t.Errorf("Asked for 10 lines, got too many: %d", len(lines.lines))
 	}
@@ -70,14 +70,14 @@ func testGetLines(t *testing.T, reader *Reader) {
 	}
 
 	// Test clipping at the end
-	lines = reader.GetLines(math.MaxInt32, 10)
+	lines, _ = reader.GetLines(math.MaxInt32, 10)
 	if len(lines.lines) != 10 {
 		t.Errorf("Asked for 10 lines but got %d", len(lines.lines))
 		return
 	}
 
 	startOfLastSection := lines.firstLineOneBased
-	lines = reader.GetLines(startOfLastSection, 10)
+	lines, _ = reader.GetLines(startOfLastSection, 10)
 	if lines.firstLineOneBased != startOfLastSection {
 		t.Errorf("Expected start line %d when asking for the last 10 lines, got %d",
 			startOfLastSection, lines.firstLineOneBased)
@@ -89,7 +89,7 @@ func testGetLines(t *testing.T, reader *Reader) {
 		return
 	}
 
-	lines = reader.GetLines(startOfLastSection+1, 10)
+	lines, _ = reader.GetLines(startOfLastSection+1, 10)
 	if lines.firstLineOneBased != startOfLastSection {
 		t.Errorf("Expected start line %d when asking for the last+1 10 lines, got %d",
 			startOfLastSection, lines.firstLineOneBased)
@@ -101,7 +101,7 @@ func testGetLines(t *testing.T, reader *Reader) {
 		return
 	}
 
-	lines = reader.GetLines(startOfLastSection-1, 10)
+	lines, _ = reader.GetLines(startOfLastSection-1, 10)
 	if lines.firstLineOneBased != startOfLastSection-1 {
 		t.Errorf("Expected start line %d when asking for the last-1 10 lines, got %d",
 			startOfLastSection, lines.firstLineOneBased)
@@ -232,10 +232,15 @@ func TestGetLongLine(t *testing.T) {
 		panic(err)
 	}
 
-	lines := reader.GetLines(1, 5)
+	lines, overflow := reader.GetLines(1, 5)
 	assert.Equal(t, lines.firstLineOneBased, 1)
 	assert.Equal(t, len(lines.lines), 1)
 
+	// This fits because we got all (one) input lines. Given the line length the
+	// line is unlikely to fit on screen, but that's not what this didFit is
+	// about.
+	assert.Equal(t, overflow, didFit)
+
 	line := lines.lines[0]
 	assert.Assert(t, strings.HasPrefix(line.Plain(), "1 2 3 4"), "<%s>", line)
 	assert.Assert(t, strings.HasSuffix(line.Plain(), "0123456789"), line)
@@ -255,7 +260,8 @@ func getReaderWithLineCount(totalLines int) *Reader {
 func testStatusText(t *testing.T, fromLine int, toLine int, totalLines int, expected string) {
 	testMe := getReaderWithLineCount(totalLines)
 	linesRequested := toLine - fromLine + 1
-	statusText := testMe.GetLines(fromLine, linesRequested).statusText
+	lines, _ := testMe.GetLines(fromLine, linesRequested)
+	statusText := lines.statusText
 	assert.Equal(t, statusText, expected)
 }
 
@@ -276,8 +282,9 @@ func TestStatusText(t *testing.T) {
 		panic(err)
 	}
 
-	statusText := testMe.GetLines(0, 0).statusText
-	assert.Equal(t, statusText, "empty: <empty>")
+	line, overflow := testMe.GetLines(0, 0)
+	assert.Equal(t, line.statusText, "empty: <empty>")
+	assert.Equal(t, overflow, didFit) // Empty always fits
 }
 
 func testCompressedFile(t *testing.T, filename string) {
@@ -291,7 +298,8 @@ func testCompressedFile(t *testing.T, filename string) {
 		panic(err)
 	}
 
-	assert.Equal(t, reader.GetLines(1, 5).lines[0].Plain(), "This is a compressed file", "%s", filename)
+	lines, _ := reader.GetLines(1, 5)
+	assert.Equal(t, lines.lines[0].Plain(), "This is a compressed file", "%s", filename)
 }
 
 func TestCompressedFiles(t *testing.T) {