Add opt and or expressions.

README.md

@@ -1,4 +1,6 @@
-# Railroad Diagrams
+# Railroad Diagrams (or Syntax Diagrams)
+
+Railroad diagrams are a way to visualize context-free grammars.
 
 ## How to Read
 
@@ -9,14 +11,22 @@ The following conventions are used:
 
 - The following diagram shows values `A`, `B` and `C`, which must be specified. The required values are defined on the
   main line of the diagram. (_ABNF_: `and = A B C`)
-  ![explain-and](./testdata/explain-and.svg)
+
+<img src="./testdata/explain-and.svg" alt="explain-and" height="100">
+
 - The following diagram shows the optional value `A`. The value can be bypassed by following the empty path.
   (_ABNF_: `opt = [A] B `)
-  ![explain-optional](./testdata/explain-optional.svg)
+
+<img src="./testdata/explain-optional.svg" alt="explain-optional" height="150">
+
+- In the example below `A`, `B` and `C` are options. The value can be chosen from the options.
+  (_ABNF_: `or = A / B / C`)
+
+<img src="./testdata/explain-or.svg" alt="explain-or" height="200">
 
 ## Example
 
-![example-svg](./testdata/example1.svg)
+<img src="./testdata/example1.svg" alt="example1" height="200">
 
 ## References
 

internal/svg/bypass.go

@@ -1,39 +1,29 @@
 package svg
 
-import "fmt"
+import (
+	"fmt"
+)
 
 type Bypass struct {
 	Element SVGable
 }
 
 func (b Bypass) SVG(start Point) (string, Point, Box) {
-	wrappedStart := Point{X: start.X + curveRadius*2, Y: start.Y}
-	wrappedSVG, wrappedEnd, wrappedBox := b.Element.SVG(wrappedStart)
+	_, _, wrappedBox := b.Element.SVG(start)
+	l := start.Y - wrappedBox.Position.Y + curveRadius
 
-	l := wrappedBox.Size.Y + (wrappedBox.Position.Y - start.Y) - curveRadius
-
-	curveStartSVG, curveStart, curveStartBox := CurveInvS{L: l}.SVG(start)
-	curveEndSVG, curveEnd, curveEndBox := CurveS{
-		L: curveStart.Y - wrappedEnd.Y - 2*curveRadius,
-	}.SVG(Point{
-		X: curveStart.X + wrappedBox.Size.X,
-		Y: curveStart.Y,
-	})
-	return fmt.Sprintf(
-		`<g class="rr-bypass">
-<line x1="%.1f" y1="%.1f" x2="%.1f" y2="%.1f" stroke="black"/>
-%s
-<line x1="%.1f" y1="%.1f" x2="%.1f" y2="%.1f" stroke="black"/>
+	curveStartSVG, curveStart, curveStartBox := Line{RelativeEnd: Point{X: 2 * curveRadius, Y: l}}.SVG(start)
+	wrappedSVG, wrappedEnd, wrappedBox := b.Element.SVG(curveStart)
+	curveEndSVG, curveEnd, curveEndBox := Line{RelativeEnd: Point{X: 2 * curveRadius, Y: -l}}.SVG(wrappedEnd)
+	return fmt.Sprintf(`
+<g class="rr-bypass">
+<line x1="%.1f" y1="%.1f" x2="%.1f" y2="%.1f" stroke="black"/>%s
 %s
-<line x1="%.1f" y1="%.1f" x2="%.1f" y2="%.1f" stroke="black"/>
 %s
 </g>`,
-		start.X, start.Y, wrappedStart.X, wrappedStart.Y,
-		wrappedSVG,
-		wrappedEnd.X, wrappedEnd.Y, curveEnd.X, curveEnd.Y,
-
+		start.X, start.Y, curveEnd.X, curveEnd.Y,
 		curveStartSVG,
-		curveStart.X, curveStart.Y, curveStart.X+wrappedBox.Size.X, curveStart.Y,
+		wrappedSVG,
 		curveEndSVG,
 	), curveEnd, curveStartBox.Combine(wrappedBox).Combine(curveEndBox)
 }

internal/svg/settings.go

@@ -28,6 +28,11 @@ func SetCurveRadius(r float64) {
 	curveRadius = r
 }
 
+// GetCurveRadius returns the configured curve radius.
+func GetCurveRadius() float64 {
+	return curveRadius
+}
+
 // SetStrokeWidth sets the stroke width of the curve.
 func SetStrokeWidth(w float64) {
 	strokeWidth = w

internal/svg/svg.go

@@ -9,9 +9,9 @@ type SVGable interface {
 func DebugSVG(element SVGable, start Point) (string, Point, Box) {
 	svgElement, end, box := element.SVG(start)
 	return fmt.Sprintf(
-		`<g class="debug">
-<circle cx="%.1f" cy="%.1f" r="2" fill="transparent" stroke="green" stroke-width="0.5"/>
-%s
+		`
+<g class="debug">
+<circle cx="%.1f" cy="%.1f" r="2" fill="transparent" stroke="green" stroke-width="0.5"/>%s
 <circle cx="%.1f" cy="%.1f" r="2" fill="transparent" stroke="green" stroke-width="0.5"/>
 <rect x="%.1f" y="%.1f" width="%.1f" height="%.1f" fill="transparent" stroke="red" stroke-width="0.5"/>
 </g>`,

internal/svg/svg_test.go

@@ -8,22 +8,6 @@ import (
 
 func TestCurve(t *testing.T) {
 	if os.Getenv("GENERATE_SVG") != "" {
-		for idx, e := range []struct {
-			element SVGable
-			start   Point
-		}{
-			{CurveS{L: 10}, Point{X: 10, Y: 30}},
-			{CurveInvS{L: 10}, Point{X: 10, Y: 10}},
-		} {
-			svg, _, box := DebugSVG(e.element, e.start)
-			_ = os.WriteFile(fmt.Sprintf("testdata/curve%d.svg", idx), []byte(
-				fmt.Sprintf(
-					`<svg width="%.1f" height="%.1f" xmlns="http://www.w3.org/2000/svg">%s</svg>`,
-					box.Size.X+20, box.Size.Y+20, svg,
-				),
-			), 0644)
-		}
-
 		t.Run("lines", func(t *testing.T) {
 			for _, size := range []float64{1, 10} {
 				var combinedSVG string
@@ -55,7 +39,8 @@ func TestCurve(t *testing.T) {
 				}
 				_ = os.WriteFile(fmt.Sprintf("testdata/lines%.0f.svg", size), []byte(
 					fmt.Sprintf(
-						`<svg viewBox="%.1f %.1f %.1f %.1f" xmlns="http://www.w3.org/2000/svg">%s</svg>`,
+						`<svg viewBox="%.1f %.1f %.1f %.1f" xmlns="http://www.w3.org/2000/svg">%s
+</svg>`,
 						combinedBox.Position.X-10, combinedBox.Position.Y-10,
 						combinedBox.Size.X+20, combinedBox.Size.Y+20,
 						combinedSVG,
@@ -70,15 +55,15 @@ func TestCurve(t *testing.T) {
 			combinedBox := Box{Position: start}
 			for _, e := range []SVGable{
 				Start{},
-				CurveS{L: 10},
+				Line{RelativeEnd: Point{X: 10, Y: -10}},
 				Line{RelativeEnd: Point{X: 10, Y: 10}},
 				Bypass{
 					Element: TextBox{Text: "Hello,"},
 				},
 				Line{RelativeEnd: Point{X: 10, Y: -10}},
 				TextBox{Text: "World!", RoundedBorders: true},
 				Line{RelativeEnd: Point{X: 10}},
-				CurveInvS{L: 10},
+				Line{RelativeEnd: Point{X: 10, Y: 10}},
 				End{},
 			} {
 				svg, end, box := DebugSVG(e, start)
@@ -89,7 +74,8 @@ func TestCurve(t *testing.T) {
 			}
 			_ = os.WriteFile("testdata/total.svg", []byte(
 				fmt.Sprintf(
-					`<svg viewBox="%.1f %.1f %.1f %.1f" xmlns="http://www.w3.org/2000/svg">%s</svg>`,
+					`<svg viewBox="%.1f %.1f %.1f %.1f" xmlns="http://www.w3.org/2000/svg">%s
+</svg>`,
 					combinedBox.Position.X-10, combinedBox.Position.Y-10,
 					combinedBox.Size.X+20, combinedBox.Size.Y+20,
 					combinedSVG,