all: comply with linter recommendations

10 files changed, 130 insertions, 84 deletions

diff --git a/Makefile b/Makefile
index 17088d1..b2d6ff9 100644
--- a/Makefile
+++ b/Makefile
@@ -6,9 +6,11 @@
 all: test lint
 
 lint:
-	-revive ./...
 	-fieldalignment ./...
 	-shadow ./...
+	-golangci-lint run \
+		--presets bugs,metalinter,performance,unused \
+		./...
 
 test:
 	go test -coverprofile=cover.out ./...
diff --git a/attribute_entry.go b/attribute_entry.go
index c1d329f..98db699 100644
--- a/attribute_entry.go
+++ b/attribute_entry.go
@@ -22,11 +22,12 @@ func newAttributeEntry() AttributeEntry {
 }
 
 func (entry *AttributeEntry) apply(key, val string) {
-	if key[0] == '!' {
+	switch {
+	case key[0] == '!':
 		delete(*entry, strings.TrimSpace(key[1:]))
-	} else if key[len(key)-1] == '!' {
+	case key[len(key)-1] == '!':
 		delete(*entry, strings.TrimSpace(key[:len(key)-1]))
-	} else {
+	default:
 		(*entry)[key] = val
 	}
 }
diff --git a/cell_format.go b/cell_format.go
index a37ec88..054ac08 100644
--- a/cell_format.go
+++ b/cell_format.go
@@ -37,13 +37,14 @@ func parseCellFormat(raw string) (cf *cellFormat) {
 		if len(raw) == 0 {
 			return nil
 		}
-		if raw[0] == '*' {
+		switch raw[0] {
+		case '*':
 			cf.ndupCol = n
 			x = 1
-		} else if raw[0] == '+' {
+		case '+':
 			cf.nspanCol = n
 			x = 1
-		} else if raw[0] == '.' {
+		case '.':
 			cf.nspanCol = n
 			n, raw = parseCellFormatDigits(raw[1:])
 			if n == 0 {
@@ -56,7 +57,7 @@ func parseCellFormat(raw string) (cf *cellFormat) {
 			}
 			x = 1
 			cf.nspanRow = n
-		} else {
+		default:
 			return nil
 		}
 	}
diff --git a/element.go b/element.go
index 1accd88..ea20a6c 100644
--- a/element.go
+++ b/element.go
@@ -101,7 +101,8 @@ func (el *element) getVideoSource() string {
 		isVimeo = true
 	}
 
-	if isYoutube {
+	switch {
+	case isYoutube:
 		u.Scheme = `https`
 		u.Host = `www.youtube.com`
 		u.Path = `/embed/` + src
@@ -143,7 +144,7 @@ func (el *element) getVideoSource() string {
 			q = append(q, attrNameYoutubeLang+`=`+vstr)
 		}
 
-	} else if isVimeo {
+	case isVimeo:
 		u.Scheme = `https`
 		u.Host = `player.vimeo.com`
 		u.Path = `/video/` + src
@@ -159,7 +160,7 @@ func (el *element) getVideoSource() string {
 			fragment = `at=` + vstr
 		}
 
-	} else {
+	default:
 		for _, vstr = range el.options {
 			switch vstr {
 			case optNameAutoplay, optNameLoop:
@@ -729,15 +730,16 @@ func (el *element) postParseParagraphAsQuote(lines [][]byte) bool {
 	secondLastIdx = len(lines) - 2
 
 	for x, line = range lines[:len(lines)-1] {
-		if x == 0 {
+		switch x {
+		case 0:
 			if x == secondLastIdx {
 				el.Write(line[1 : len(line)-1])
 			} else {
 				el.Write(line[1:])
 			}
-		} else if x == secondLastIdx {
+		case secondLastIdx:
 			el.Write(line[:len(line)-1])
-		} else {
+		default:
 			el.Write(line)
 		}
 		el.WriteByte('\n')
@@ -828,10 +830,8 @@ func (el *element) toHTML(doc *Document, w io.Writer) {
 					label = href
 				}
 			}
-		} else {
-			if len(label) == 0 {
-				label = anchor.label
-			}
+		} else if len(label) == 0 {
+			label = anchor.label
 		}
 		fmt.Fprintf(w, `<a href="#%s">%s</a>`, href, label)
 
@@ -851,13 +851,14 @@ func (el *element) toHTML(doc *Document, w io.Writer) {
 		htmlWriteSection(doc, el, w)
 
 	case elKindParagraph:
-		if el.isStyleAdmonition() {
+		switch {
+		case el.isStyleAdmonition():
 			htmlWriteBlockAdmonition(el, w)
-		} else if el.isStyleQuote() {
+		case el.isStyleQuote():
 			htmlWriteBlockQuote(el, w)
-		} else if el.isStyleVerse() {
+		case el.isStyleVerse():
 			htmlWriteBlockVerse(el, w)
-		} else {
+		default:
 			htmlWriteParagraphBegin(el, w)
 		}
 
@@ -893,11 +894,12 @@ func (el *element) toHTML(doc *Document, w io.Writer) {
 			label.Write(el.rawLabel.Bytes())
 		}
 
-		if el.isStyleQandA() {
+		switch {
+		case el.isStyleQandA():
 			format = _htmlListDescriptionItemQandABegin
-		} else if el.isStyleHorizontal() {
+		case el.isStyleHorizontal():
 			format = _htmlListDescriptionItemHorizontalBegin
-		} else {
+		default:
 			format = _htmlListDescriptionItemBegin
 		}
 		fmt.Fprintf(w, format, label.String())
@@ -919,13 +921,14 @@ func (el *element) toHTML(doc *Document, w io.Writer) {
 		htmlWriteBlockImage(doc, el, w)
 
 	case elKindBlockOpen:
-		if el.isStyleAdmonition() {
+		switch {
+		case el.isStyleAdmonition():
 			htmlWriteBlockAdmonition(el, w)
-		} else if el.isStyleQuote() {
+		case el.isStyleQuote():
 			htmlWriteBlockQuote(el, w)
-		} else if el.isStyleVerse() {
+		case el.isStyleVerse():
 			htmlWriteBlockVerse(el, w)
-		} else {
+		default:
 			htmlWriteBlockOpenBegin(el, w)
 		}
 
@@ -1054,13 +1057,14 @@ func (el *element) toHTML(doc *Document, w io.Writer) {
 		fmt.Fprint(w, "\n</div>")
 
 	case elKindParagraph:
-		if el.isStyleAdmonition() {
+		switch {
+		case el.isStyleAdmonition():
 			fmt.Fprint(w, _htmlAdmonitionEnd)
-		} else if el.isStyleQuote() {
+		case el.isStyleQuote():
 			htmlWriteBlockQuoteEnd(el, w)
-		} else if el.isStyleVerse() {
+		case el.isStyleVerse():
 			htmlWriteBlockVerseEnd(el, w)
-		} else {
+		default:
 			fmt.Fprint(w, "</p>\n</div>")
 		}
 
@@ -1069,11 +1073,13 @@ func (el *element) toHTML(doc *Document, w io.Writer) {
 
 	case elKindListDescriptionItem:
 		var format string
-		if el.isStyleQandA() {
+
+		switch {
+		case el.isStyleQandA():
 			format = "\n</li>"
-		} else if el.isStyleHorizontal() {
+		case el.isStyleHorizontal():
 			format = "\n</td>\n</tr>"
-		} else {
+		default:
 			format = "\n</dd>"
 		}
 		fmt.Fprint(w, format)
@@ -1093,13 +1099,14 @@ func (el *element) toHTML(doc *Document, w io.Writer) {
 		}
 
 	case elKindBlockOpen:
-		if el.isStyleAdmonition() {
+		switch {
+		case el.isStyleAdmonition():
 			fmt.Fprint(w, _htmlAdmonitionEnd)
-		} else if el.isStyleQuote() {
+		case el.isStyleQuote():
 			htmlWriteBlockQuoteEnd(el, w)
-		} else if el.isStyleVerse() {
+		case el.isStyleVerse():
 			htmlWriteBlockVerseEnd(el, w)
-		} else {
+		default:
 			fmt.Fprint(w, "\n</div>\n</div>")
 		}
 	case elKindBlockExcerpts:
diff --git a/element_table.go b/element_table.go
index 3e9c07d..ad94e2a 100644
--- a/element_table.go
+++ b/element_table.go
@@ -174,8 +174,7 @@ func (table *elementTable) initializeClassAndStyles(ea *elementAttribute) {
 		}
 	}
 	for _, k = range ea.options {
-		switch k {
-		case optNameAutowidth:
+		if k == optNameAutowidth {
 			withWidth = true
 			table.classes.add(classNameFitContent)
 
diff --git a/html_backend.go b/html_backend.go
index d2fafea..be17c2f 100644
--- a/html_backend.go
+++ b/html_backend.go
@@ -819,7 +819,8 @@ func htmlWriteBlockVideo(el *element, out io.Writer) {
 
 	fmt.Fprintf(out, "\n<div class=%q>", attrValueContent)
 
-	if isYoutube {
+	switch {
+	case isYoutube:
 		var (
 			optFullscreen string
 			noFullscreen  bool
@@ -830,9 +831,9 @@ func htmlWriteBlockVideo(el *element, out io.Writer) {
 			optFullscreen = ` allowfullscreen`
 		}
 		fmt.Fprintf(out, _htmlBlockVideoYoutube, width, height, src, optFullscreen)
-	} else if isVimeo {
+	case isVimeo:
 		fmt.Fprintf(out, _htmlBlockVideoVimeo, width, height, src)
-	} else {
+	default:
 		var (
 			optControls = ` controls`
 
@@ -932,16 +933,17 @@ func htmlWriteFooter(doc *Document, out io.Writer) {
 // htmlWriteFootnote generate HTML content for footnote.
 // Each unique footnote will have its id, so it can be referenced at footer.
 func htmlWriteFootnote(el *element, out io.Writer) {
-	if len(el.ID) != 0 {
+	switch {
+	case len(el.ID) != 0:
 		// The first footnote with explicit ID.
 		fmt.Fprintf(out, `<sup class="footnote" id="_footnote_%s">[<a id="_footnoteref_%d" class="footnote" href="#_footnotedef_%d" title="View footnote.">%d</a>]</sup>`,
 			el.ID, el.level, el.level, el.level)
 
-	} else if len(el.key) != 0 {
+	case len(el.key) != 0:
 		// The first footnote without ID.
 		fmt.Fprintf(out, `<sup class="footnote">[<a id="_footnoteref_%d" class="footnote" href="#_footnotedef_%d" title="View footnote.">%d</a>]</sup>`,
 			el.level, el.level, el.level)
-	} else {
+	default:
 		// The next footnote with same ID.
 		fmt.Fprintf(out, `<sup class="footnoteref">[<a class="footnote" href="#_footnotedef_%d" title="View footnote.">%d</a>]</sup>`,
 			el.level, el.level)
@@ -1110,13 +1112,14 @@ func htmlWriteInlinePass(doc *Document, el *element, out io.Writer) {
 
 func htmlWriteListDescription(el *element, out io.Writer) {
 	var openTag string
-	if el.isStyleQandA() {
+	switch {
+	case el.isStyleQandA() == true:
 		htmlWriteBlockBegin(el, out, `qlist qanda`)
 		openTag = "\n<ol>"
-	} else if el.isStyleHorizontal() {
+	case el.isStyleHorizontal() == true:
 		htmlWriteBlockBegin(el, out, `hdlist`)
 		openTag = "\n<table>"
-	} else {
+	default:
 		htmlWriteBlockBegin(el, out, `dlist`)
 		openTag = "\n<dl>"
 	}
@@ -1125,11 +1128,12 @@ func htmlWriteListDescription(el *element, out io.Writer) {
 }
 
 func htmlWriteListDescriptionEnd(el *element, out io.Writer) {
-	if el.isStyleQandA() {
+	switch {
+	case el.isStyleQandA() == true:
 		fmt.Fprintf(out, "\n</ol>\n</div>")
-	} else if el.isStyleHorizontal() {
+	case el.isStyleHorizontal() == true:
 		fmt.Fprintf(out, "\n</table>\n</div>")
-	} else {
+	default:
 		fmt.Fprintf(out, "\n</dl>\n</div>")
 	}
 }
diff --git a/inline_parser.go b/inline_parser.go
index 09aa5a1..2f18aaf 100644
--- a/inline_parser.go
+++ b/inline_parser.go
@@ -73,6 +73,12 @@ func (pi *inlineParser) do() {
 			pi.prev = pi.c
 			continue
 		}
+
+		// We use if-condition with "continue" to break and continue
+		// the for-loop, so it is not possible to use switch-case
+		// here.
+		//
+		//nolint:gocritic
 		if pi.c == '+' {
 			if pi.isEscaped {
 				pi.escape()
@@ -250,6 +256,12 @@ func (pi *inlineParser) do() {
 				pi.escape()
 				continue
 			}
+
+			// We use if-condition with "continue" to break and
+			// continue the for-loop, so it is not possible
+			// to use switch-case here.
+			//
+			//nolint:gocritic
 			if pi.nextc == '<' {
 				if pi.parseCrossRef() {
 					continue
diff --git a/parser.go b/parser.go
index 66efc51..b80bbeb 100644
--- a/parser.go
+++ b/parser.go
@@ -375,6 +375,12 @@ func applySubstitutions(doc *Document, content []byte) []byte {
 	)
 	for x < len(raw) {
 		c = raw[x]
+
+		// We use if-condition with "continue" to break and continue
+		// the for-loop, so it is not possible to use switch-case
+		// here.
+		//
+		//nolint:gocritic
 		if c == '{' {
 			newRaw, ok = parseAttrRef(doc, raw, x)
 			if ok {
@@ -462,7 +468,7 @@ func generateID(doc *Document, str string) string {
 		bout = append(bout, '_')
 	} else if !ascii.IsAlpha(bout[0]) && bout[0] != '_' {
 		bout = append(bout, '_')
-		copy(bout[1:], bout[:])
+		copy(bout[1:], bout)
 		bout[0] = '_'
 	}
 
@@ -471,17 +477,18 @@ func generateID(doc *Document, str string) string {
 
 func isAdmonition(line []byte) bool {
 	var x int
-	if bytes.HasPrefix(line, []byte(admonitionCaution)) {
+	switch {
+	case bytes.HasPrefix(line, []byte(admonitionCaution)):
 		x = len(admonitionCaution)
-	} else if bytes.HasPrefix(line, []byte(admonitionImportant)) {
+	case bytes.HasPrefix(line, []byte(admonitionImportant)):
 		x = len(admonitionImportant)
-	} else if bytes.HasPrefix(line, []byte(admonitionNote)) {
+	case bytes.HasPrefix(line, []byte(admonitionNote)):
 		x = len(admonitionNote)
-	} else if bytes.HasPrefix(line, []byte(admonitionTip)) {
+	case bytes.HasPrefix(line, []byte(admonitionTip)):
 		x = len(admonitionTip)
-	} else if bytes.HasPrefix(line, []byte(admonitionWarning)) {
+	case bytes.HasPrefix(line, []byte(admonitionWarning)):
 		x = len(admonitionWarning)
-	} else {
+	default:
 		return false
 	}
 	if x >= len(line) {
@@ -810,9 +817,10 @@ func whatKindOfLine(line []byte) (kind int, spaces, got []byte) {
 		}
 	}
 
-	if line[0] == ':' {
+	switch line[0] {
+	case ':':
 		kind = lineKindAttribute
-	} else if line[0] == '[' {
+	case '[':
 		var (
 			newline = bytes.TrimRight(line, " \t")
 			l       = len(newline)
@@ -838,26 +846,28 @@ func whatKindOfLine(line []byte) (kind int, spaces, got []byte) {
 			}
 		}
 		return lineKindAttributeElement, spaces, line
-	} else if line[0] == '=' {
+	case '=':
 		var subs = bytes.Fields(line)
 
-		if bytes.Equal(subs[0], []byte(`==`)) {
+		switch string(subs[0]) {
+		case `==`:
 			kind = elKindSectionL1
-		} else if bytes.Equal(subs[0], []byte(`===`)) {
+		case `===`:
 			kind = elKindSectionL2
-		} else if bytes.Equal(subs[0], []byte(`====`)) {
+		case `====`:
 			kind = elKindSectionL3
-		} else if bytes.Equal(subs[0], []byte(`=====`)) {
+		case `=====`:
 			kind = elKindSectionL4
-		} else if bytes.Equal(subs[0], []byte(`======`)) {
+		case `======`:
 			kind = elKindSectionL5
 		}
-	} else if line[0] == '.' {
-		if len(line) <= 1 {
+	case '.':
+		switch {
+		case len(line) <= 1:
 			kind = lineKindText
-		} else if ascii.IsAlnum(line[1]) {
+		case ascii.IsAlnum(line[1]):
 			kind = lineKindBlockTitle
-		} else {
+		default:
 			x = 0
 			for ; x < len(line); x++ {
 				if line[x] == '.' {
@@ -869,7 +879,7 @@ func whatKindOfLine(line []byte) (kind int, spaces, got []byte) {
 				}
 			}
 		}
-	} else if line[0] == '*' || line[0] == '-' {
+	case '*', '-':
 		if len(line) <= 1 {
 			kind = lineKindText
 			return kind, spaces, line
@@ -904,13 +914,17 @@ func whatKindOfLine(line []byte) (kind int, spaces, got []byte) {
 			kind = lineKindText
 		}
 		return kind, spaces, line
-
-	} else if bytes.Equal(line, []byte(`+`)) {
-		kind = lineKindListContinue
-	} else if bytes.Equal(line, []byte(`----`)) {
-		kind = elKindBlockListing
-	} else if isLineDescriptionItem(line) {
-		kind = elKindListDescriptionItem
+	default:
+		switch string(line) {
+		case `+`:
+			kind = lineKindListContinue
+		case `----`:
+			kind = elKindBlockListing
+		default:
+			if isLineDescriptionItem(line) {
+				kind = elKindListDescriptionItem
+			}
+		}
 	}
 	return kind, spaces, line
 }
diff --git a/section_counters.go b/section_counters.go
index 0a5ba86..f51bd7a 100644
--- a/section_counters.go
+++ b/section_counters.go
@@ -16,16 +16,17 @@ type sectionCounters struct {
 }
 
 func (sec *sectionCounters) set(level int) *sectionCounters {
-	if level == sec.curr {
+	switch {
+	case level == sec.curr:
 		sec.nums[level]++
-	} else if level > sec.curr {
+	case level > sec.curr:
 		// Check if the section level out of sequence.
 		if level > sec.curr+1 {
 			level = sec.curr + 1
 		}
 		sec.nums[level] = 1
 		sec.curr = level
-	} else {
+	default:
 		var x int
 		for x = sec.curr; x > level; x-- {
 			sec.nums[x] = 0
diff --git a/table_parser.go b/table_parser.go
index 4f9c7f8..3a5f56e 100644
--- a/table_parser.go
+++ b/table_parser.go
@@ -79,6 +79,11 @@ func (pt *tableParser) toCells() {
 	tokenTrim = strings.TrimSpace(token)
 	l = len(tokenTrim)
 	for {
+		// We use if-condition with "continue" to break and continue
+		// the for-loop, so it is not possible to use switch-case
+		// here.
+		//
+		//nolint:gocritic
 		if c == '\n' {
 			if l > 0 {
 				cell.writeString(token)