add graph algorithm

pkg/gui/presentation/graph/cell.go

@@ -0,0 +1,141 @@
+package graph
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/gui/style"
+)
+
+const mergeSymbol = '⏣'
+const commitSymbol = '⎔'
+
+type cellType int
+
+const (
+	CONNECTION cellType = iota
+	COMMIT
+	MERGE
+)
+
+type Cell struct {
+	up, down, left, right bool
+	cellType              cellType
+	rightStyle            *style.TextStyle
+	style                 style.TextStyle
+}
+
+func (cell *Cell) render() string {
+	up, down, left, right := cell.up, cell.down, cell.left, cell.right
+
+	first, second := getBoxDrawingChars(up, down, left, right)
+	var adjustedFirst rune
+	switch cell.cellType {
+	case CONNECTION:
+		adjustedFirst = first
+	case COMMIT:
+		adjustedFirst = commitSymbol
+	case MERGE:
+		adjustedFirst = mergeSymbol
+	}
+
+	var rightStyle *style.TextStyle
+	if cell.rightStyle == nil {
+		rightStyle = &cell.style
+	} else {
+		rightStyle = cell.rightStyle
+	}
+
+	// just doing this for the sake of easy testing, so that we don't need to
+	// assert on the style of a space given a space has no styling (assuming we
+	// stick to only using foreground styles)
+	var styledSecondChar string
+	if second == ' ' {
+		styledSecondChar = " "
+	} else {
+		styledSecondChar = rightStyle.Sprint(string(second))
+	}
+
+	return cell.style.Sprint(string(adjustedFirst)) + styledSecondChar
+}
+
+func (cell *Cell) reset() {
+	cell.up = false
+	cell.down = false
+	cell.left = false
+	cell.right = false
+}
+
+func (cell *Cell) setUp(style style.TextStyle) *Cell {
+	cell.up = true
+	cell.style = style
+	return cell
+}
+
+func (cell *Cell) setDown(style style.TextStyle) *Cell {
+	cell.down = true
+	cell.style = style
+	return cell
+}
+
+func (cell *Cell) setLeft(style style.TextStyle) *Cell {
+	cell.left = true
+	if !cell.up && !cell.down {
+		// vertical trumps left
+		cell.style = style
+	}
+	return cell
+}
+
+func (cell *Cell) setRight(style style.TextStyle, override bool) *Cell {
+	cell.right = true
+	if cell.rightStyle == nil || override {
+		cell.rightStyle = &style
+	}
+	return cell
+}
+
+func (cell *Cell) setStyle(style style.TextStyle) *Cell {
+	cell.style = style
+	return cell
+}
+
+func (cell *Cell) setType(cellType cellType) *Cell {
+	cell.cellType = cellType
+	return cell
+}
+
+func getBoxDrawingChars(up, down, left, right bool) (rune, rune) {
+	if up && down && left && right {
+		return '│', '─'
+	} else if up && down && left && !right {
+		return '│', ' '
+	} else if up && down && !left && right {
+		return '│', '─'
+	} else if up && down && !left && !right {
+		return '│', ' '
+	} else if up && !down && left && right {
+		return '┴', '─'
+	} else if up && !down && left && !right {
+		return '╯', ' '
+	} else if up && !down && !left && right {
+		return '╰', '─'
+	} else if up && !down && !left && !right {
+		return '╵', ' '
+	} else if !up && down && left && right {
+		return '┬', '─'
+	} else if !up && down && left && !right {
+		return '╮', ' '
+	} else if !up && down && !left && right {
+		return '╭', '─'
+	} else if !up && down && !left && !right {
+		return '╷', ' '
+	} else if !up && !down && left && right {
+		return '─', '─'
+	} else if !up && !down && left && !right {
+		return '─', ' '
+	} else if !up && !down && !left && right {
+		return '╶', '─'
+	} else if !up && !down && !left && !right {
+		return ' ', ' '
+	} else {
+		panic("should not be possible")
+	}
+}