Panic if TAB character is seen on input. Make more symbols private.

Author: dmullis

canvas.go

@@ -2,7 +2,8 @@
 Package goat formats "ASCII-art" drawings into Github-flavored Markdown.
 
  <goat>
- porcelain API
+ porcelain API  · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·
+
                             BuildAndWriteSVG()
                                .----------.
      ASCII-art                |            |                      Markdown
@@ -11,9 +12,8 @@ Package goat formats "ASCII-art" drawings into Github-flavored Markdown.
                                '----------'
 
 
-   ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·
+ deep API   · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·
 
- plumbing API
                                 Canvas{}
                NewCanvas() .-------------------.  WriteSVGBody()
                            |                   |    .-------.
@@ -156,8 +156,8 @@ func (c *Canvas) runeAt(i Index) rune {
 	return ' '
 }
 
-// NewCanvas creates a new canvas with contents read from the given io.Reader.
-// Content should be newline delimited.
+// NewCanvas creates a fully-populated Canvas according to GoAT-formatted text read from
+// an io.Reader, consuming all bytes available.
 func NewCanvas(in io.Reader) (c Canvas) {
 	//  XX  Move this function to top of file.
 	width := 0
@@ -185,6 +185,9 @@ func NewCanvas(in io.Reader) (c Canvas) {
 			//	fmt.Printf("linestr=\"%s\"\n", lineStr)
 			//	fmt.Printf("r == 0x%x\n", r)
 			//}
+			if r == '	' {
+				panic("TAB character found on input")
+			}
 			i := Index{w, height}
 			c.data[i] = r
 			w++
@@ -221,7 +224,7 @@ func (c *Canvas) MoveToText() {
 
 // Drawable represents anything that can Draw itself.
 type Drawable interface {
-	Draw(out io.Writer)
+	draw(out io.Writer)
 }
 
 // Line represents a straight segment between two points 'start' and 'stop', where
@@ -349,27 +352,28 @@ const (
 	W			// West
 )
 
+// WriteSVGBody writes the entire content of a Canvas out to a stream in SVG format.
 func (c *Canvas) WriteSVGBody(dst io.Writer) {
 	writeBytes(dst, "<g transform='translate(8,16)'>\n")
 
 	for _, l := range c.Lines() {
-		l.Draw(dst)
+		l.draw(dst)
 	}
 
 	for _, tI := range c.Triangles() {
-		tI.Draw(dst)
+		tI.draw(dst)
 	}
 
 	for _, c := range c.RoundedCorners() {
-		c.Draw(dst)
+		c.draw(dst)
 	}
 
 	for _, c := range c.Circles() {
-		c.Draw(dst)
+		c.draw(dst)
 	}
 
 	for _, bI := range c.Bridges() {
-		bI.Draw(dst)
+		bI.draw(dst)
 	}
 
 	writeText(dst, c)

index.go

@@ -6,12 +6,12 @@ type Index struct {
 	X, Y int
 }
 
-// Pixel represents the CSS-pixel coordinates for an Index.
-type Pixel Index  // XX different units -- create separate base type?
+// pixel represents the CSS-pixel coordinates for an Index.
+type pixel Index  // XX different units -- create separate base type?
 
-func (i *Index) asPixel() Pixel {
+func (i *Index) asPixel() pixel {
 	// TODO  define constants rather than hard-wire width and height of cell
-	return Pixel{
+	return pixel{
 		X: i.X * 8,
 		Y: i.Y * 16}
 }

svg.go

@@ -13,8 +13,7 @@ type SVG struct {
 	Height int
 }
 
-// See:
-//    https://drafts.csswg.org/mediaqueries-5/#prefers-color-scheme
+// See: https://drafts.csswg.org/mediaqueries-5/#prefers-color-scheme
 func (s SVG) String(svgColorLightScheme, svgColorDarkScheme string) string {
 	style := fmt.Sprintf(
 		`<style type="text/css">
@@ -81,12 +80,12 @@ func writeText(out io.Writer, canvas *Canvas) {
 `)
 	for _, textObj := range canvas.Text() {
 		// usual, baseline case
-		textObj.Draw(out)
+		textObj.draw(out)
 	}
 }
 
 // Draw a straight line as an SVG path.
-func (l Line) Draw(out io.Writer) {
+func (l Line) draw(out io.Writer) {
 	start := l.start.asPixel()
 	stop := l.stop.asPixel()
 
@@ -214,7 +213,7 @@ func (l Line) Draw(out io.Writer) {
 }
 
 // Draw a solid triangle as an SVG polygon element.
-func (t Triangle) Draw(out io.Writer) {
+func (t Triangle) draw(out io.Writer) {
 	// https://www.w3.org/TR/SVG/shapes.html#PolygonElement
 
 	/*
@@ -320,7 +319,7 @@ func (t Triangle) Draw(out io.Writer) {
 }
 
 // Draw a solid circle as an SVG circle element.
-func (c *Circle) Draw(out io.Writer) {
+func (c *Circle) draw(out io.Writer) {
 	var fill string
 	if c.bold {
 		fill = "currentColor"
@@ -339,7 +338,7 @@ func (c *Circle) Draw(out io.Writer) {
 }
 
 // Draw a single text character as an SVG text element.
-func (t Text) Draw(out io.Writer) {
+func (t Text) draw(out io.Writer) {
 	p := t.start.asPixel()
 	c := t.str
 
@@ -390,7 +389,7 @@ func (t Text) Draw(out io.Writer) {
 }
 
 // Draw a rounded corner as an SVG elliptical arc element.
-func (c *RoundedCorner) Draw(out io.Writer) {
+func (c *RoundedCorner) draw(out io.Writer) {
 	// https://www.w3.org/TR/SVG/paths.html#PathDataEllipticalArcCommands
 
 	x, y := c.start.asPixelXY()
@@ -432,7 +431,7 @@ func (c *RoundedCorner) Draw(out io.Writer) {
 }
 
 // Draw a bridge as an SVG elliptical arc element.
-func (b Bridge) Draw(out io.Writer) {
+func (b Bridge) draw(out io.Writer) {
 	x, y := b.start.asPixelXY()
 	sweepFlag := 1