go/markdown
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Improved performance

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This commit is contained in:
Eduard Urbach
2024-04-02 10:44:47 +02:00
parent f75ea823a9
commit 09245c5e92
6 changed files with 138 additions and 40 deletions
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101
Render.go
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@ -10,8 +10,9 @@ var (
headerEnd = []string{"</h1>", "</h2>", "</h3>", "</h4>", "</h5>", "</h6>"}
)
// renderer represents a Markdown to HTML renderer.
type renderer struct {
out strings.Builder
out []byte
paragraphLevel int
quoteLevel int
listLevel int
@ -29,15 +30,17 @@ func Render(markdown string) string {
lineStart = 0
)
r.out = make([]byte, 0, nextPowerOf2(uint32(len(markdown)+4)))
for {
if i > len(markdown) {
r.closeAll()
for range r.quoteLevel {
r.out.WriteString("</blockquote>")
r.WriteString("</blockquote>")
}
return r.out.String()
return string(r.out)
}
if i != len(markdown) && markdown[i] != '\n' {
@ -56,15 +59,15 @@ func Render(markdown string) string {
func (r *renderer) processLine(line string) {
if r.inCodeBlock {
if strings.HasPrefix(line, "```") {
r.out.WriteString("</code></pre>")
r.WriteString("</code></pre>")
r.inCodeBlock = false
r.codeLines = 0
} else {
if r.codeLines != 0 {
r.out.WriteByte('\n')
r.WriteByte('\n')
}
r.out.WriteString(html.EscapeString(line))
r.WriteString(html.EscapeString(line))
r.codeLines++
}
@ -82,13 +85,13 @@ func (r *renderer) processLine(line string) {
r.closeParagraphs()
for range newQuoteLevel - r.quoteLevel {
r.out.WriteString("<blockquote>")
r.WriteString("<blockquote>")
}
} else if newQuoteLevel < r.quoteLevel {
r.closeParagraphs()
for range r.quoteLevel - newQuoteLevel {
r.out.WriteString("</blockquote>")
r.WriteString("</blockquote>")
}
}
@ -105,9 +108,9 @@ func (r *renderer) processLine(line string) {
space := strings.IndexByte(line, ' ')
if space > 0 && space <= 6 {
r.out.WriteString(headerStart[space-1])
r.WriteString(headerStart[space-1])
r.writeText(line[space+1:])
r.out.WriteString(headerEnd[space-1])
r.WriteString(headerEnd[space-1])
}
return
@ -117,13 +120,13 @@ func (r *renderer) processLine(line string) {
line = strings.TrimSpace(line[1:])
if r.listLevel == 0 {
r.out.WriteString("<ul>")
r.WriteString("<ul>")
r.listLevel++
}
r.out.WriteString("<li>")
r.WriteString("<li>")
r.writeText(line)
r.out.WriteString("</li>")
r.WriteString("</li>")
return
case '`':
@ -132,11 +135,11 @@ func (r *renderer) processLine(line string) {
if !r.inCodeBlock {
if language != "" {
r.out.WriteString("<pre><code class=\"language-")
r.out.WriteString(html.EscapeString(language))
r.out.WriteString("\">")
r.WriteString("<pre><code class=\"language-")
r.WriteString(html.EscapeString(language))
r.WriteString("\">")
} else {
r.out.WriteString("<pre><code>")
r.WriteString("<pre><code>")
}
r.inCodeBlock = true
@ -150,7 +153,7 @@ func (r *renderer) processLine(line string) {
line = line[1:]
if r.tableLevel == 0 {
r.out.WriteString("<table><thead>")
r.WriteString("<table><thead>")
r.tableLevel++
}
@ -160,30 +163,30 @@ func (r *renderer) processLine(line string) {
pipe := strings.IndexByte(line, '|')
if pipe == -1 {
r.out.WriteString("</tr>")
r.WriteString("</tr>")
return
}
content := strings.TrimSpace(line[:pipe])
if strings.HasPrefix(content, "---") {
r.out.WriteString("</thead><tbody>")
r.WriteString("</thead><tbody>")
r.tableHeaderWritten = true
return
}
if column == 0 {
r.out.WriteString("<tr>")
r.WriteString("<tr>")
}
if r.tableHeaderWritten {
r.out.WriteString("<td>")
r.WriteString("<td>")
r.writeText(content)
r.out.WriteString("</td>")
r.WriteString("</td>")
} else {
r.out.WriteString("<th>")
r.WriteString("<th>")
r.writeText(content)
r.out.WriteString("</th>")
r.WriteString("</th>")
}
line = line[pipe+1:]
@ -192,13 +195,13 @@ func (r *renderer) processLine(line string) {
}
if r.paragraphLevel == 0 {
r.out.WriteString("<p>")
r.WriteString("<p>")
r.paragraphLevel++
r.writeText(line)
return
}
r.out.WriteByte(' ')
r.WriteByte(' ')
r.writeText(line)
}
@ -212,7 +215,7 @@ func (r *renderer) closeAll() {
// closeParagraphs closes open paragraphs.
func (r *renderer) closeParagraphs() {
for range r.paragraphLevel {
r.out.WriteString("</p>")
r.WriteString("</p>")
}
r.paragraphLevel = 0
@ -221,7 +224,7 @@ func (r *renderer) closeParagraphs() {
// closeLists closes open lists.
func (r *renderer) closeLists() {
for range r.listLevel {
r.out.WriteString("</ul>")
r.WriteString("</ul>")
}
r.listLevel = 0
@ -230,7 +233,7 @@ func (r *renderer) closeLists() {
// closeTables closes open tables.
func (r *renderer) closeTables() {
for range r.tableLevel {
r.out.WriteString("</tbody></table>")
r.WriteString("</tbody></table>")
}
r.tableLevel = 0
@ -253,7 +256,7 @@ func (r *renderer) writeText(markdown string) {
for {
if i == len(markdown) {
r.out.WriteString(html.EscapeString(markdown[tokenStart:]))
r.WriteString(html.EscapeString(markdown[tokenStart:]))
return
}
@ -261,7 +264,7 @@ func (r *renderer) writeText(markdown string) {
switch c {
case '[':
r.out.WriteString(html.EscapeString(markdown[tokenStart:i]))
r.WriteString(html.EscapeString(markdown[tokenStart:i]))
tokenStart = i
textStart = i
case ']':
@ -279,11 +282,11 @@ func (r *renderer) writeText(markdown string) {
linkText := markdown[textStart+1 : textEnd]
linkURL := markdown[urlStart+1 : i]
r.out.WriteString("<a href=\"")
r.out.WriteString(sanitizeURL(linkURL))
r.out.WriteString("\">")
r.out.WriteString(html.EscapeString(linkText))
r.out.WriteString("</a>")
r.WriteString("<a href=\"")
r.WriteString(sanitizeURL(linkURL))
r.WriteString("\">")
r.WriteString(html.EscapeString(linkText))
r.WriteString("</a>")
textStart = -1
textEnd = -1
@ -307,3 +310,27 @@ func sanitizeURL(linkURL string) string {
return html.EscapeString(linkURL)
}
// WriteByte adds a single byte to the output.
func (r *renderer) WriteByte(b byte) error {
r.out = append(r.out, b)
return nil
}
// WriteString adds a string to the output.
func (r *renderer) WriteString(text string) (int, error) {
r.out = append(r.out, text...)
return len(text), nil
}
// nextPowerOf2 calculates the next 32-bit power of 2.
func nextPowerOf2(x uint32) uint32 {
x--
x |= x >> 1
x |= x >> 2
x |= x >> 4
x |= x >> 8
x |= x >> 16
x++
return x
}