Changed prefix closure to interface

- added interfaces Prefixer and Suffixer for handeling line pre- and
  suffix more go-idomatic
- added ScreenInfo struct to transfer informationa about the current
  screen settings better/shorter
- edited example strings

Author: [email protected]

list/example/main.go

@@ -29,20 +29,19 @@ func main() {
 		"Use 'q' or 'ctrl-c' to quit!",
 		"You can move the highlighted index up and down with the (arrow keys 'k' and 'j'.",
 		"Move to the beginning with 'g' and to the end with 'G'.",
-		"Sort the entrys with 's', but be carefull you can't unsort it again.",
+		"Sort the entrys with 's', but be carefull you can't restore the former order again.",
 		"The list can handel linebreaks,\nand has wordwrap enabled if the line gets to long.",
 		"You can select items with the space key which will select the line and mark it as such.",
 		"Ones you hit 'enter', the selected lines will be printed to StdOut and the program exits.",
 		"When you print the items there will be a loss of information,",
 		"since one can not say what was a line break within an item or what is a new item",
 		"Use '+' or '-' to move the item under the curser up and down.",
 		"The key 'v' inverts the selected state of each item.",
-		//"To toggle betwen only absolute itemnumbers and also relativ numbers, the 'r' key is your friend.",
+		"To toggle betwen only absolute item numbers and relativ numbers, the 'r' key is your friend.",
 	}
 	stringerList := list.MakeStringerList(itemList)
 
 	endResult := make(chan string, 1)
-	prefixFunc := list.AbsolutLinePrefix
 	list := list.NewModel()
 	list.AddItems(stringerList)
 
@@ -52,7 +51,6 @@ func main() {
 	list.SetEquals(func(first, second fmt.Stringer) bool { return first.String() == second.String() })
 	m := model{}
 	m.list = list
-	m.list.PrefixFunc = prefixFunc
 
 	m.endResult = endResult
 
@@ -95,6 +93,10 @@ func (m model) View() string {
 
 // update recives messages and the model and changes the model accordingly to the messages
 func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	if m.list.PrefixGen == nil {
+		// use default
+		m.list.PrefixGen = list.NewDefault()
+	}
 
 	switch msg := msg.(type) {
 	case tea.KeyMsg:
@@ -130,9 +132,12 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			}
 			m.list.Move(-j)
 			return m, nil
-		//case "r":
-		//	m.list.NumberRelative = !m.list.NumberRelative
-		//	return m, nil
+		case "r":
+			d, ok := m.list.PrefixGen.(*list.DefaultPrefixer)
+			if ok {
+				d.NumberRelative = !d.NumberRelative
+			}
+			return m, nil
 		case "m":
 			j := 1
 			if m.jump != "" {

list/list.go

@@ -32,6 +32,29 @@ type ViewPos struct {
 	LineOffset int
 }
 
+// ScreenInfo holds all information about the screen Area
+type ScreenInfo struct {
+	Width   int
+	Height  int
+	Profile termenv.Profile
+}
+
+// Prefixer is used to prefix all visible Lines.
+// Init gets called ones on the beginning of the Lines methode
+// and then Prefix ones, per line to draw, to generate according prefixes.
+type Prefixer interface {
+	InitPrefixer(ViewPos, ScreenInfo) int
+	Prefix(currentItem, currentLine int, selected, lastLine bool) string
+}
+
+// Suffixer is used to suffix all visible Lines.
+// InitSuffixer gets called ones on the beginning of the Lines methode
+// and then Suffix ones, per line to draw, to generate according suffixes.
+type Suffixer interface {
+	InitSuffixer(ViewPos, ScreenInfo) int
+	Suffix(currentItem, currentLine int, selected, lastLine bool) string
+}
+
 // Model is a bubbletea List of strings
 type Model struct {
 	focus bool
@@ -51,11 +74,8 @@ type Model struct {
 
 	Wrap bool
 
-	PrefixFunc func(position ViewPos, height int) (func(currentIndex int, selected bool, wrapedIndex int) string, int)
-	// PrefixFunc     func(value fmt.Stringer, position ViewPos, selected bool) string
-	// PrefixWrapFunc func(value fmt.Stringer, position ViewPos, selected bool, wrapedIndex int) string
-	// SuffixFunc     func(value fmt.Stringer, position ViewPos, selected bool) string
-	// SuffixWrapFunc func(value fmt.Stringer, position ViewPos, selected bool, wrapedIndex int) string
+	// PrefixFunc func(position ViewPos, height int) (func(currentIndex int, selected bool, wrapedIndex int) string, int)
+	PrefixGen Prefixer
 
 	LineStyle     termenv.Style
 	SelectedStyle termenv.Style
@@ -113,13 +133,10 @@ func (m *Model) Lines() []string {
 		panic("Can't display with zero width or hight of Viewport")
 	}
 
-	var prefixFunc func(int, bool, int) string
+	// This is only used if the Lines methode is called befor the Update methode is called the first time
 	var holePrefixWidth int
-	if m.PrefixFunc != nil {
-		prefixFunc, holePrefixWidth = m.PrefixFunc(m.viewPos, height)
-	} else {
-		// use default
-		prefixFunc, holePrefixWidth = AbsolutLinePrefix(m.viewPos, height)
+	if m.PrefixGen != nil {
+		holePrefixWidth = m.PrefixGen.InitPrefixer(m.viewPos, ScreenInfo{Height: m.Height, Width: m.Width, Profile: termenv.ColorProfile()})
 	}
 
 	// Get actual content width
@@ -171,10 +188,9 @@ out:
 			// TODO hard limit the string length
 		}
 
-		// retrieve line prefix from prefix closure
 		var linePrefix string
-		if prefixFunc != nil {
-			linePrefix = prefixFunc(index, item.selected, 0)
+		if m.PrefixGen != nil {
+			linePrefix = m.PrefixGen.Prefix(index, 0, item.selected, item.wrapedLenght == 0)
 		}
 
 		// join pad and first line content
@@ -221,8 +237,8 @@ out:
 			// Pad left of line
 			// NOTE line break is not added here because it would mess with the highlighting
 			var wrapPrefix string
-			if prefixFunc != nil {
-				wrapPrefix = prefixFunc(index, item.selected, i+1)
+			if m.PrefixGen != nil {
+				wrapPrefix = m.PrefixGen.Prefix(index, i+1, item.selected, i == item.wrapedLenght-2)
 			}
 			padLine := fmt.Sprintf("%s%s", wrapPrefix, line)
 
@@ -249,6 +265,12 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	if !m.focus {
 		return m, nil
 	}
+
+	if m.PrefixGen == nil {
+		// use default
+		m.PrefixGen = NewDefault()
+	}
+
 	var cmd tea.Cmd
 
 	switch msg := msg.(type) {
@@ -780,30 +802,72 @@ func (m *Model) keepVisibleWrap(target int) (ViewPos, error) {
 	return ViewPos{ItemOffset: m.viewPos.ItemOffset, LineOffset: m.viewPos.LineOffset, Cursor: target}, nil
 }
 
-// AbsolutLinePrefix returns a function which will be used for prefix generation
-func AbsolutLinePrefix(position ViewPos, height int) (func(currentLine int, selected bool, wrapIndex int) string, int) {
-
-	PrefixWrap := false
+// DefaultPrefixer is the default struct used for Prefixing a line
+type DefaultPrefixer struct {
+	PrefixWrap bool
 
 	// Make clear where a item begins and where it ends
-	Seperator := "╭"
-	SeperatorWrap := "│"
+	Seperator     string
+	SeperatorWrap string
 
 	// Mark it so that even without color support all is explicit
-	CurrentMarker := ">"
-	SelectedPrefix := "*"
+	CurrentMarker  string
+	SelectedPrefix string
 
 	// enable Linenumber
-	Number := true
-	NumberRelative := false
+	Number         bool
+	NumberRelative bool
+
+	UnSelectedPrefix string
 
-	UnSelectedPrefix := ""
+	prefixWidth int
+	viewPos     ViewPos
+
+	markWidth int
+	numWidth  int
+
+	unmark string
+	mark   string
+
+	selectedString string
+	unselect       string
+
+	wrapSelectPad string
+	wrapUnSelePad string
+
+	sepItem string
+	sepWrap string
+}
+
+// NewDefault returns a DefautPrefixer with default values
+func NewDefault() *DefaultPrefixer {
+	return &DefaultPrefixer{
+		PrefixWrap: false,
+
+		// Make clear where a item begins and where it ends
+		Seperator:     "╭",
+		SeperatorWrap: "│",
+
+		// Mark it so that even without color support all is explicit
+		CurrentMarker:    ">",
+		SelectedPrefix:   "*",
+		UnSelectedPrefix: "",
+
+		// enable Linenumber
+		Number:         true,
+		NumberRelative: false,
+	}
+}
+
+// InitPrefixer returns a function which will be used for prefix generation
+func (d *DefaultPrefixer) InitPrefixer(position ViewPos, screen ScreenInfo) int {
+	d.viewPos = position
 
 	offset := position.ItemOffset
 
 	// Get separators width
-	widthItem := ansi.PrintableRuneWidth(Seperator)
-	widthWrap := ansi.PrintableRuneWidth(SeperatorWrap)
+	widthItem := ansi.PrintableRuneWidth(d.Seperator)
+	widthWrap := ansi.PrintableRuneWidth(d.SeperatorWrap)
 
 	// Find max width
 	sepWidth := widthItem
@@ -812,83 +876,83 @@ func AbsolutLinePrefix(position ViewPos, height int) (func(currentLine int, sele
 	}
 
 	// get widest possible number, for padding
-	numWidth := len(fmt.Sprintf("%d", offset+height-1))
+	d.numWidth = len(fmt.Sprintf("%d", offset+screen.Height))
 
 	// pad all prefixes to the same width for easy exchange
-	selectedString := SelectedPrefix
-	unselect := UnSelectedPrefix
-	selWid := ansi.PrintableRuneWidth(selectedString)
-	tmpWid := ansi.PrintableRuneWidth(unselect)
+	d.selectedString = d.SelectedPrefix
+	d.unselect = d.UnSelectedPrefix
+	selWid := ansi.PrintableRuneWidth(d.selectedString)
+	tmpWid := ansi.PrintableRuneWidth(d.unselect)
 
 	selectWidth := selWid
 	if tmpWid > selectWidth {
 		selectWidth = tmpWid
 	}
-	selectedString = strings.Repeat(" ", selectWidth-selWid) + selectedString
+	d.selectedString = strings.Repeat(" ", selectWidth-selWid) + d.selectedString
 
-	wrapSelectPad := strings.Repeat(" ", selectWidth)
-	wrapUnSelePad := strings.Repeat(" ", selectWidth)
-	if PrefixWrap {
-		wrapSelectPad = strings.Repeat(" ", selectWidth-selWid) + selectedString
-		wrapUnSelePad = strings.Repeat(" ", selectWidth-tmpWid) + unselect
+	d.wrapSelectPad = strings.Repeat(" ", selectWidth)
+	d.wrapUnSelePad = strings.Repeat(" ", selectWidth)
+	if d.PrefixWrap {
+		d.wrapSelectPad = strings.Repeat(" ", selectWidth-selWid) + d.selectedString
+		d.wrapUnSelePad = strings.Repeat(" ", selectWidth-tmpWid) + d.unselect
 	}
 
-	unselect = strings.Repeat(" ", selectWidth-tmpWid) + unselect
+	d.unselect = strings.Repeat(" ", selectWidth-tmpWid) + d.unselect
 
 	// pad all separators to the same width for easy exchange
-	sepItem := strings.Repeat(" ", sepWidth-widthItem) + Seperator
-	sepWrap := strings.Repeat(" ", sepWidth-widthWrap) + SeperatorWrap
+	d.sepItem = strings.Repeat(" ", sepWidth-widthItem) + d.Seperator
+	d.sepWrap = strings.Repeat(" ", sepWidth-widthWrap) + d.SeperatorWrap
 
 	// pad right of prefix, with length of current pointer
-	mark := CurrentMarker
-	markWidth := ansi.PrintableRuneWidth(mark)
-	unmark := strings.Repeat(" ", markWidth)
+	d.mark = d.CurrentMarker
+	d.markWidth = ansi.PrintableRuneWidth(d.mark)
+	d.unmark = strings.Repeat(" ", d.markWidth)
 
 	// Get the hole prefix width
-	holePrefixWidth := numWidth + selectWidth + sepWidth + markWidth
-
-	// Closure varibale
-	currentCursor := position.Cursor
-
-	return func(currentIndex int, selected bool, wrapIndex int) string {
-		// if a number is set, prepend first line with number and both with enough spaces
-		firstPad := strings.Repeat(" ", numWidth)
-		var wrapPad string
-		var lineNum int
-		if Number {
-			lineNum = lineNumber(NumberRelative, currentCursor, currentIndex)
-		}
-		number := fmt.Sprintf("%d", lineNum)
-		// since digits are only single bytes, len is sufficient:
-		firstPad = strings.Repeat(" ", numWidth-len(number)) + number
-		// pad wrapped lines
-		wrapPad = strings.Repeat(" ", numWidth)
-		// Selecting: handle highlighting and prefixing of selected lines
-		selString := unselect
-
-		wrapPrePad := wrapUnSelePad
-		if selected {
-			selString = selectedString
-			wrapPrePad = wrapSelectPad
-		}
+	d.prefixWidth = d.numWidth + selectWidth + sepWidth + d.markWidth
 
-		// Current: handle highlighting of current item/first-line
-		curPad := unmark
-		if currentIndex == position.Cursor {
-			curPad = mark
-		}
+	return d.prefixWidth
+}
 
-		// join all prefixes
-		var wrapPrefix, linePrefix string
+// Prefix prefixes a given line
+func (d *DefaultPrefixer) Prefix(currentIndex int, wrapIndex int, selected, lastLine bool) string {
+	// if a number is set, prepend first line with number and both with enough spaces
+	firstPad := strings.Repeat(" ", d.numWidth)
+	var wrapPad string
+	var lineNum int
+	if d.Number {
+		lineNum = lineNumber(d.NumberRelative, d.viewPos.Cursor, currentIndex)
+	}
+	number := fmt.Sprintf("%d", lineNum)
+	// since digits are only single bytes, len is sufficient:
+	firstPad = strings.Repeat(" ", d.numWidth-len(number)) + number
+	// pad wrapped lines
+	wrapPad = strings.Repeat(" ", d.numWidth)
+	// Selecting: handle highlighting and prefixing of selected lines
+	selString := d.unselect
 
-		linePrefix = strings.Join([]string{firstPad, selString, sepItem, curPad}, "")
-		if wrapIndex > 0 {
-			wrapPrefix = strings.Join([]string{wrapPad, wrapPrePad, sepWrap, unmark}, "") // don't prefix wrap lines with CurrentMarker (unmark)
-			return wrapPrefix
-		}
+	wrapPrePad := d.wrapUnSelePad
+	if selected {
+		selString = d.selectedString
+		wrapPrePad = d.wrapSelectPad
+	}
+
+	// Current: handle highlighting of current item/first-line
+	curPad := d.unmark
+	if currentIndex == d.viewPos.Cursor {
+		curPad = d.mark
+	}
+
+	// join all prefixes
+	var wrapPrefix, linePrefix string
+
+	linePrefix = strings.Join([]string{firstPad, selString, d.sepItem, curPad}, "")
+	if wrapIndex > 0 {
+		wrapPrefix = strings.Join([]string{wrapPad, wrapPrePad, d.sepWrap, d.unmark}, "") // don't prefix wrap lines with CurrentMarker (unmark)
+		return wrapPrefix
+	}
 
-		return linePrefix
-	}, holePrefixWidth
+	return linePrefix
 }
 
 // lineNumber returns line number of the given index