Use ElementStyle as a value instead of pointer, so we can drop all the annoying nil checks

baseelement.go

@@ -16,27 +16,27 @@ type BaseElement struct {
 	Token  string
 	Prefix string
 	Suffix string
-	Style  *ElementStyle
+	Style  ElementStyle
 }
 
-func color(c string) (uint8, error) {
+func color(c *string) (uint8, error) {
-	if len(c) == 0 {
+	if c == nil || len(*c) == 0 {
 		return 0, errors.New("Invalid color")
 	}
-	if c[0] == '#' {
+	if (*c)[0] == '#' {
-		i, err := hexToANSIColor(c)
+		i, err := hexToANSIColor(*c)
 		return uint8(i), err
 	}
-	i, err := strconv.Atoi(c)
+	i, err := strconv.Atoi(*c)
 	return uint8(i), err
 }
 
-func colorSeq(c string) (string, error) {
+func colorSeq(c *string) (string, error) {
-	if len(c) == 0 {
+	if c == nil || len(*c) == 0 {
 		return "", errors.New("Invalid color")
 	}
 
-	col, err := colorful.Hex(c)
+	col, err := colorful.Hex(*c)
 	if err != nil {
 		return "", err
 	}
@@ -44,13 +44,13 @@ func colorSeq(c string) (string, error) {
 	return fmt.Sprintf("%d;%d;%dm", uint8(col.R*255), uint8(col.G*255), uint8(col.B*255)), nil
 }
 
-func renderText(w io.Writer, rules *ElementStyle, s string) {
+func renderText(w io.Writer, rules ElementStyle, s string) {
 	if len(s) == 0 {
 		return
 	}
 
 	// FIXME: ugly true-color ANSI support hack
-	if rules != nil && os.Getenv("COLORTERM") == "truecolor" {
+	if os.Getenv("COLORTERM") == "truecolor" {
 		bg, err := colorSeq(rules.BackgroundColor)
 		if err == nil {
 			s = "\x1b[48;2;" + bg + s
@@ -63,16 +63,18 @@ func renderText(w io.Writer, rules *ElementStyle, s string) {
 
 	out := aurora.Reset(s)
 
-	if rules != nil {
+	if rules.Color != nil {
 		i, err := color(rules.Color)
 		if err == nil {
 			out = out.Index(i)
 		}
-		i, err = color(rules.BackgroundColor)
+	}
+	if rules.BackgroundColor != nil {
+		i, err := color(rules.BackgroundColor)
 		if err == nil {
 			out = out.BgIndex(i)
 		}
-
+	}
 	if rules.Underline != nil && *rules.Underline {
 		out = out.Underline()
 	}
@@ -94,7 +96,6 @@ func renderText(w io.Writer, rules *ElementStyle, s string) {
 	if rules.Blink != nil && *rules.Blink {
 		out = out.Blink()
 	}
-	}
 
 	_, _ = w.Write([]byte(out.String()))
 }
@@ -106,12 +107,10 @@ func (e *BaseElement) Render(w io.Writer, node *bf.Node, tr *TermRenderer) error
 	}()
 
 	rules := tr.blockStack.With(e.Style)
-	if rules != nil {
 	renderText(w, rules, rules.Prefix)
 	defer func() {
 		renderText(w, rules, rules.Suffix)
 	}()
-	}
 
 	renderText(w, rules, e.Token)
 	return nil

blockstack.go

@@ -6,7 +6,7 @@ import (
 
 type BlockElement struct {
 	Block *bytes.Buffer
-	Style *ElementStyle
+	Style ElementStyle
 }
 
 type BlockStack []BlockElement
@@ -29,7 +29,7 @@ func (s BlockStack) Indent() uint {
 	var i uint
 
 	for _, v := range s {
-		if v.Style == nil || v.Style.Indent == nil {
+		if v.Style.Indent == nil {
 			continue
 		}
 		i += *v.Style.Indent
@@ -42,7 +42,7 @@ func (s BlockStack) Margin() uint {
 	var i uint
 
 	for _, v := range s {
-		if v.Style == nil || v.Style.Margin == nil {
+		if v.Style.Margin == nil {
 			continue
 		}
 		i += *v.Style.Margin
@@ -69,6 +69,6 @@ func (s BlockStack) Current() BlockElement {
 	return s[len(s)-1]
 }
 
-func (s BlockStack) With(child *ElementStyle) *ElementStyle {
+func (s BlockStack) With(child ElementStyle) ElementStyle {
 	return cascadeStyle(s.Current().Style, child, true)
 }

codeblock.go

@@ -13,19 +13,16 @@ type CodeBlockElement struct {
 }
 
 func (e *CodeBlockElement) Render(w io.Writer, node *bf.Node, tr *TermRenderer) error {
-	var theme string
 	var indent uint
 	var margin uint
 	rules := tr.style[CodeBlock]
-	if rules != nil {
 	if rules.Indent != nil {
 		indent = *rules.Indent
 	}
 	if rules.Margin != nil {
 		margin = *rules.Margin
 	}
-		theme = rules.Theme
+	theme := rules.Theme
-	}
 
 	iw := &IndentWriter{
 		Indent: indent + margin,

document.go

@@ -18,26 +18,22 @@ func (e *DocumentElement) Render(w io.Writer, node *bf.Node, tr *TermRenderer) e
 	}
 	tr.blockStack.Push(be)
 
-	if rules != nil {
 	renderText(tr.blockStack.Current().Block, rules, rules.Prefix)
-	}
 	return nil
 }
 
 func (e *DocumentElement) Finish(w io.Writer, node *bf.Node, tr *TermRenderer) error {
 	var indent uint
 	var margin uint
-	var suffix string
 	rules := tr.style[Document]
-	if rules != nil {
 	if rules.Indent != nil {
 		indent = *rules.Indent
 	}
 	if rules.Margin != nil {
 		margin = *rules.Margin
 	}
-		suffix = rules.Suffix
+	suffix := rules.Suffix
-	}
+
 	pw := &PaddingWriter{
 		Padding: uint(tr.WordWrap) - margin,
 		PadFunc: func(wr io.Writer) {

gold.go

@@ -21,7 +21,7 @@ type TermRenderer struct {
 	BaseURL  string
 	WordWrap int
 
-	style      map[StyleType]*ElementStyle
+	style      map[StyleType]ElementStyle
 	blockStack BlockStack
 	table      TableElement
 }
@@ -56,13 +56,13 @@ func NewTermRenderer(stylePath string) (*TermRenderer, error) {
 }
 
 func NewTermRendererFromBytes(b []byte) (*TermRenderer, error) {
-	e := make(map[string]*ElementStyle)
+	e := make(map[string]ElementStyle)
 	err := json.Unmarshal(b, &e)
 	if err != nil {
 		return nil, err
 	}
 	tr := &TermRenderer{}
-	tr.style = make(map[StyleType]*ElementStyle)
+	tr.style = make(map[StyleType]ElementStyle)
 
 	for k, v := range e {
 		t, err := keyToType(k)

heading.go

@@ -32,14 +32,12 @@ func (e *HeadingElement) Render(w io.Writer, node *bf.Node, tr *TermRenderer) er
 		rules = cascadeStyles(false, rules, tr.style[H6])
 	}
 
-	if rules != nil {
 	if rules.Indent != nil {
 		indent = *rules.Indent
 	}
 	if rules.Margin != nil {
 		margin = *rules.Margin
 	}
-	}
 
 	iw := &IndentWriter{
 		Indent: indent + margin,

link.go

@@ -35,8 +35,8 @@ func (e *LinkElement) Render(w io.Writer, node *bf.Node, tr *TermRenderer) error
 	}
 
 	if len(node.LinkData.Destination) > 0 {
-		style := *tr.style[Link]
 		pre := " "
+		style := tr.style[Link]
 		if !textRendered {
 			pre = ""
 			style.Prefix = ""
@@ -46,7 +46,7 @@ func (e *LinkElement) Render(w io.Writer, node *bf.Node, tr *TermRenderer) error
 		el := &BaseElement{
 			Token:  resolveRelativeURL(tr.BaseURL, string(node.LinkData.Destination)),
 			Prefix: pre,
-			Style:  &style,
+			Style:  style,
 		}
 		err := el.Render(w, node, tr)
 		if err != nil {

list.go

@@ -29,17 +29,14 @@ func (e *ListElement) Render(w io.Writer, node *bf.Node, tr *TermRenderer) error
 func (e *ListElement) Finish(w io.Writer, node *bf.Node, tr *TermRenderer) error {
 	var indent uint
 	var margin uint
-	var suffix string
 	rules := tr.blockStack.Current().Style
-	if rules != nil {
 	if rules.Indent != nil {
 		indent = *rules.Indent
 	}
 	if rules.Margin != nil {
 		margin = *rules.Margin
 	}
-		suffix = rules.Suffix
+	suffix := rules.Suffix
-	}
 	renderText(tr.blockStack.Current().Block, rules, suffix)
 
 	pw := &PaddingWriter{

paragraph.go

@@ -13,7 +13,7 @@ type ParagraphElement struct {
 }
 
 func (e *ParagraphElement) Render(w io.Writer, node *bf.Node, tr *TermRenderer) error {
-	var rules *ElementStyle
+	var rules ElementStyle
 	if node.Parent != nil && node.Parent.Type == bf.Item {
 		// list item
 		rules = tr.style[List]
@@ -27,31 +27,26 @@ func (e *ParagraphElement) Render(w io.Writer, node *bf.Node, tr *TermRenderer)
 		tr.blockStack.Push(be)
 	}
 
-	if rules != nil {
 	renderText(w, tr.blockStack.Current().Style, rules.Prefix)
-	}
 	return nil
 }
 
 func (e *ParagraphElement) Finish(w io.Writer, node *bf.Node, tr *TermRenderer) error {
 	var indent uint
 	var margin uint
-	var suffix string
 	rules := tr.blockStack.Current().Style
 	if node.Parent != nil && node.Parent.Type == bf.Item {
 		// remove indent & margin for list items
 		rules = tr.blockStack.Current().Style
 	}
 
-	if rules != nil {
 	if rules.Indent != nil {
 		indent = *rules.Indent
 	}
 	if rules.Margin != nil {
 		margin = *rules.Margin
 	}
-		suffix = rules.Suffix
+	suffix := rules.Suffix
-	}
 	renderText(tr.blockStack.Current().Block, rules, suffix)
 
 	pw := &PaddingWriter{

style.go

@@ -45,8 +45,8 @@ const (
 )
 
 type ElementStyle struct {
-	Color           string `json:"color"`
+	Color           *string `json:"color"`
-	BackgroundColor string `json:"background_color"`
+	BackgroundColor *string `json:"background_color"`
 	Underline       *bool   `json:"underline"`
 	Bold            *bool   `json:"bold"`
 	Italic          *bool   `json:"italic"`
@@ -63,8 +63,8 @@ type ElementStyle struct {
 	Suffix          string  `json:"suffix"`
 }
 
-func cascadeStyles(onlyColors bool, s ...*ElementStyle) *ElementStyle {
+func cascadeStyles(onlyColors bool, s ...ElementStyle) ElementStyle {
-	var r *ElementStyle
+	var r ElementStyle
 
 	for _, v := range s {
 		r = cascadeStyle(r, v, onlyColors)
@@ -72,15 +72,8 @@ func cascadeStyles(onlyColors bool, s ...*ElementStyle) *ElementStyle {
 	return r
 }
 
-func cascadeStyle(parent *ElementStyle, child *ElementStyle, onlyColors bool) *ElementStyle {
+func cascadeStyle(parent ElementStyle, child ElementStyle, onlyColors bool) ElementStyle {
-	if parent == nil {
+	s := child
-		return child
-	}
-
-	s := ElementStyle{}
-	if child != nil {
-		s = *child
-	}
 
 	s.Color = parent.Color
 	s.BackgroundColor = parent.BackgroundColor
@@ -99,14 +92,12 @@ func cascadeStyle(parent *ElementStyle, child *ElementStyle, onlyColors bool) *E
 		s.Blink = parent.Blink
 	}
 
-	if child != nil {
+	if child.Color != nil {
-		if child.Color != "" {
 		s.Color = child.Color
 	}
-		if child.BackgroundColor != "" {
+	if child.BackgroundColor != nil {
 		s.BackgroundColor = child.BackgroundColor
 	}
-
 	if child.Indent != nil {
 		s.Indent = child.Indent
 	}
@@ -140,9 +131,8 @@ func cascadeStyle(parent *ElementStyle, child *ElementStyle, onlyColors bool) *E
 	if child.Blink != nil {
 		s.Blink = child.Blink
 	}
-	}
 
-	return &s
+	return s
 }
 
 func hexToANSIColor(h string) (int, error) {

table.go

@@ -26,14 +26,13 @@ func (e *TableElement) Render(w io.Writer, node *bf.Node, tr *TermRenderer) erro
 	var indent uint
 	var margin uint
 	rules := tr.style[Table]
-	if rules != nil {
 	if rules.Indent != nil {
 		indent = *rules.Indent
 	}
 	if rules.Margin != nil {
 		margin = *rules.Margin
 	}
-	}
+
 	iw := &IndentWriter{
 		Indent: indent + margin,
 		IndentFunc: func(wr io.Writer) {