Merge branch 'johan/mark-jump'

Fixes #175.

go.mod

@@ -5,7 +5,10 @@ go 1.20
 require (
 	github.com/alecthomas/chroma/v2 v2.12.0
 	github.com/google/go-cmp v0.5.9
+	github.com/klauspost/compress v1.17.4
 	github.com/sirupsen/logrus v1.8.1
+	github.com/ulikunitz/xz v0.5.11
+	golang.org/x/exp v0.0.0-20240103183307-be819d1f06fc
 	golang.org/x/sys v0.1.0
 	golang.org/x/term v0.0.0-20210503060354-a79de5458b56
 	gotest.tools/v3 v3.3.0
@@ -13,7 +16,5 @@ require (
 
 require (
 	github.com/dlclark/regexp2 v1.10.0 // indirect
-	github.com/klauspost/compress v1.17.4 // indirect
 	github.com/stretchr/testify v1.7.0 // indirect
-	github.com/ulikunitz/xz v0.5.11 // indirect
 )

go.sum

@@ -28,6 +28,8 @@ github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9dec
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/exp v0.0.0-20240103183307-be819d1f06fc h1:ao2WRsKSzW6KuUY9IWPwWahcHCgR0s52IfwutMfEbdM=
+golang.org/x/exp v0.0.0-20240103183307-be819d1f06fc/go.mod h1:iRJReGqOEeBhDZGkGbynYwcHlctCvnjTYIamk7uXpHI=
 golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=

m/pager.go

@@ -97,6 +97,11 @@ type Pager struct {
 
 	// Length of the longest line displayed. This is used for limiting scrolling to the right.
 	longestLineLength int
+
+	// Bookmarks that you can come back to.
+	//
+	// Ref: https://github.com/walles/moar/issues/175
+	marks map[rune]scrollPosition
 }
 
 type _PreHelpState struct {
@@ -122,12 +127,14 @@ Moving around
 * Arrow keys
 * Alt key plus left / right arrow steps one column at a time
 * Left / right can be used to hide / show line numbers
+* Home and End for start / end of the document
+* 'g' for going to a specific line number
+* 'm' sets a mark, you will be asked for a letter to label it with
+* ' (single quote) jumps to the mark
 * CTRL-p moves to the previous line
 * CTRL-n moves to the next line
-* 'g' for going to a specific line number
 * PageUp / 'b' and PageDown / 'f'
 * SPACE moves down a page
-* Home and End for start / end of the document
 * < / 'gg' to go to the start of the document
 * > / 'G' to go to the end of the document
 * 'h', 'l' for left and right (as in vim)
@@ -309,6 +316,7 @@ func (p *Pager) StartPaging(screen twin.Screen, chromaStyle *chroma.Style, chrom
 	p.screen = screen
 	p.linePrefix = getLineColorPrefix(chromaStyle, chromaFormatter)
 	p.mode = PagerModeViewing{pager: p}
+	p.marks = make(map[rune]scrollPosition)
 
 	go func() {
 		for range p.reader.moreLinesAdded {

m/pagermode-jump-to-mark.go

@@ -0,0 +1,84 @@
+package m
+
+import (
+	"sort"
+
+	"github.com/walles/moar/twin"
+	"golang.org/x/exp/maps"
+)
+
+type PagerModeJumpToMark struct {
+	pager *Pager
+}
+
+func (m PagerModeJumpToMark) drawFooter(_ string, _ string) {
+	p := m.pager
+
+	_, height := p.screen.Size()
+
+	pos := 0
+	for _, token := range m.getMarkPrompt() {
+		p.screen.SetCell(pos, height-1, twin.NewCell(token, twin.StyleDefault))
+		pos++
+	}
+}
+
+func (m PagerModeJumpToMark) getMarkPrompt() string {
+	// Special case having zero, one or multiple marks
+	if len(m.pager.marks) == 0 {
+		return "No marks set, press 'm' to set one!"
+	}
+
+	if len(m.pager.marks) == 1 {
+		for key := range m.pager.marks {
+			return "Jump to your mark: " + string(key)
+		}
+	}
+
+	// Multiple marks, list them
+	marks := maps.Keys(m.pager.marks)
+	sort.Slice(marks, func(i, j int) bool {
+		return marks[i] < marks[j]
+	})
+
+	prompt := "Jump to one of these marks: "
+	for i, mark := range marks {
+		if i > 0 {
+			prompt += ", "
+		}
+		prompt += string(mark)
+	}
+
+	return prompt
+}
+
+func (m PagerModeJumpToMark) onKey(key twin.KeyCode) {
+	p := m.pager
+
+	switch key {
+	case twin.KeyEnter, twin.KeyEscape:
+		// Never mind I
+		p.mode = PagerModeViewing{pager: p}
+
+	default:
+		// Never mind II
+		p.mode = PagerModeViewing{pager: p}
+		p.mode.onKey(key)
+	}
+}
+
+func (m PagerModeJumpToMark) onRune(char rune) {
+	if len(m.pager.marks) == 0 && char == 'm' {
+		//nolint:gosimple // The linter's advice is just wrong here
+		m.pager.mode = PagerModeMark{pager: m.pager}
+		return
+	}
+
+	destination, ok := m.pager.marks[char]
+	if ok {
+		m.pager.scrollPosition = destination
+	}
+
+	//nolint:gosimple // The linter's advice is just wrong here
+	m.pager.mode = PagerModeViewing{pager: m.pager}
+}

m/pagermode-mark.go

@@ -0,0 +1,44 @@
+package m
+
+import "github.com/walles/moar/twin"
+
+type PagerModeMark struct {
+	pager *Pager
+}
+
+func (m PagerModeMark) drawFooter(_ string, _ string) {
+	p := m.pager
+
+	_, height := p.screen.Size()
+
+	pos := 0
+	for _, token := range "Press any key to label your mark: " {
+		p.screen.SetCell(pos, height-1, twin.NewCell(token, twin.StyleDefault))
+		pos++
+	}
+
+	// Add a cursor
+	p.screen.SetCell(pos, height-1, twin.NewCell(' ', twin.StyleDefault.WithAttr(twin.AttrReverse)))
+}
+
+func (m PagerModeMark) onKey(key twin.KeyCode) {
+	p := m.pager
+
+	switch key {
+	case twin.KeyEnter, twin.KeyEscape:
+		// Never mind I
+		p.mode = PagerModeViewing{pager: p}
+
+	default:
+		// Never mind II
+		p.mode = PagerModeViewing{pager: p}
+		p.mode.onKey(key)
+	}
+}
+
+func (m PagerModeMark) onRune(char rune) {
+	m.pager.marks[char] = m.pager.scrollPosition
+
+	//nolint:gosimple // The linter's advice is just wrong here
+	m.pager.mode = PagerModeViewing{pager: m.pager}
+}

m/pagermode-viewing.go

@@ -162,6 +162,14 @@ func (m PagerModeViewing) onRune(char rune) {
 	case 'p', 'N':
 		p.scrollToPreviousSearchHit()
 
+	case 'm':
+		p.mode = PagerModeMark{pager: p}
+		p.TargetLineNumber = nil
+
+	case '\'':
+		p.mode = PagerModeJumpToMark{pager: p}
+		p.TargetLineNumber = nil
+
 	case 'w':
 		p.WrapLongLines = !p.WrapLongLines