//
// Blackfriday Markdown Processor
// Available at http://github.com/russross/blackfriday
//
// Copyright © 2011 Russ Ross <russ@russross.com>.
// Distributed under the Simplified BSD License.
// See README.md for details.
//
//
//
// HTML rendering backend
//
//
package blackfriday
import (
"bytes"
"fmt"
"regexp"
"strconv"
"strings"
)
// Html renderer configuration options.
const (
HTML_SKIP_HTML = 1 << iota // skip preformatted HTML blocks
HTML_SKIP_STYLE // skip embedded <style> elements
HTML_SKIP_IMAGES // skip embedded images
HTML_SKIP_LINKS // skip all links
HTML_SAFELINK // only link to trusted protocols
HTML_NOFOLLOW_LINKS // only link with rel="nofollow"
HTML_NOREFERRER_LINKS // only link with rel="noreferrer"
HTML_HREF_TARGET_BLANK // add a blank target
HTML_TOC // generate a table of contents
HTML_OMIT_CONTENTS // skip the main contents (for a standalone table of contents)
HTML_COMPLETE_PAGE // generate a complete HTML page
HTML_USE_XHTML // generate XHTML output instead of HTML
HTML_USE_SMARTYPANTS // enable smart punctuation substitutions
HTML_SMARTYPANTS_FRACTIONS // enable smart fractions (with HTML_USE_SMARTYPANTS)
HTML_SMARTYPANTS_DASHES // enable smart dashes (with HTML_USE_SMARTYPANTS)
HTML_SMARTYPANTS_LATEX_DASHES // enable LaTeX-style dashes (with HTML_USE_SMARTYPANTS and HTML_SMARTYPANTS_DASHES)
HTML_SMARTYPANTS_ANGLED_QUOTES // enable angled double quotes (with HTML_USE_SMARTYPANTS) for double quotes rendering
HTML_SMARTYPANTS_QUOTES_NBSP // enable "French guillemets" (with HTML_USE_SMARTYPANTS)
HTML_FOOTNOTE_RETURN_LINKS // generate a link at the end of a footnote to return to the source
)
var (
alignments = []string{
"left",
"right",
"center",
}
// TODO: improve this regexp to catch all possible entities:
htmlEntity = regexp.MustCompile(`&[a-z]{2,5};`)
)
type HtmlRendererParameters struct {
// Prepend this text to each relative URL.
AbsolutePrefix string
// Add this text to each footnote anchor, to ensure uniqueness.
FootnoteAnchorPrefix string
// Show this text inside the <a> tag for a footnote return link, if the
// HTML_FOOTNOTE_RETURN_LINKS flag is enabled. If blank, the string
// <sup>[return]</sup> is used.
FootnoteReturnLinkContents string
// If set, add this text to the front of each Header ID, to ensure
// uniqueness.
HeaderIDPrefix string
// If set, add this text to the back of each Header ID, to ensure uniqueness.
HeaderIDSuffix string
}
// Html is a type that implements the Renderer interface for HTML output.
//
// Do not create this directly, instead use the HtmlRenderer function.
type Html struct {
flags int // HTML_* options
closeTag string // how to end singleton tags: either " />" or ">"
title string // document title
css string // optional css file url (used with HTML_COMPLETE_PAGE)
parameters HtmlRendererParameters
// table of contents data
tocMarker int
headerCount int
currentLevel int
toc *bytes.Buffer
// Track header IDs to prevent ID collision in a single generation.
headerIDs map[string]int
smartypants *smartypantsRenderer
}
const (
xhtmlClose = " />"
htmlClose = ">"
)
// HtmlRenderer creates and configures an Html object, which
// satisfies the Renderer interface.
//
// flags is a set of HTML_* options ORed together.
// title is the title of the document, and css is a URL for the document's
// stylesheet.
// title and css are only used when HTML_COMPLETE_PAGE is selected.
func HtmlRenderer(flags int, title string, css string) Renderer {
return HtmlRendererWithParameters(flags, title, css, HtmlRendererParameters{})
}
func HtmlRendererWithParameters(flags int, title string,
css string, renderParameters HtmlRendererParameters) Renderer {
// configure the rendering engine
closeTag := htmlClose
if flags&HTML_USE_XHTML != 0 {
closeTag = xhtmlClose
}
if renderParameters.FootnoteReturnLinkContents == "" {
renderParameters.FootnoteReturnLinkContents = `<sup>[return]</sup>`
}
return &Html{
flags: flags,
closeTag: closeTag,
title: title,
css: css,
parameters: renderParameters,
headerCount: 0,
currentLevel: 0,
toc: new(bytes.Buffer),
headerIDs: make(map[string]int),
smartypants: smartypants(flags),
}
}
// Using if statements is a bit faster than a switch statement. As the compiler
// improves, this should be unnecessary this is only worthwhile because
// attrEscape is the single largest CPU user in normal use.
// Also tried using map, but that gave a ~3x slowdown.
func escapeSingleChar(char byte) (string, bool) {
if char == '"' {
return """, true
}
if char == '&' {
return "&", true
}
if char == '<' {
return "<", true
}
if char == '>' {
return ">", true
}
return "", false
}
func attrEscape(out *bytes.Buffer, src []byte) {
org := 0
for i, ch := range src {
if entity, ok := escapeSingleChar(ch); ok {
if i > org {
// copy all the normal characters since the last escape
out.Write(src[org:i])
}
org = i + 1
out.WriteString(entity)
}
}
if org < len(src) {
out.Write(src[org:])
}
}
func entityEscapeWithSkip(out *bytes.Buffer, src []byte, skipRanges [][]int) {
end := 0
for _, rang := range skipRanges {
attrEscape(out, src[end:rang[0]])
out.Write(src[rang[0]:rang[1]])
end = rang[1]
}
attrEscape(out, src[end:])
}
func (options *Html) GetFlags() int {
return options.flags
}
func (options *Html) TitleBlock(out *bytes.Buffer, text []byte) {
text = bytes.TrimPrefix(text, []byte("% "))
text = bytes.Replace(text, []byte("\n% "), []byte("\n"), -1)
out.WriteString("<h1 class=\"title\">")
out.Write(text)
out.WriteString("\n</h1>")
}
func (options *Html) Header(out *bytes.Buffer, text func() bool, level int, id string) {
marker := out.Len()
doubleSpace(out)
if id == "" && options.flags&HTML_TOC != 0 {
id = fmt.Sprintf("toc_%d", options.headerCount)
}
if id != "" {
id = options.ensureUniqueHeaderID(id)
if options.parameters.HeaderIDPrefix != "" {
id = options.parameters.HeaderIDPrefix + id
}
if options.parameters.HeaderIDSuffix != "" {
id = id + options.parameters.HeaderIDSuffix
}
out.WriteString(fmt.Sprintf("<h%d id=\"%s\">", level, id))
} else {
out.WriteString(fmt.Sprintf("<h%d>", level))
}
tocMarker := out.Len()
if !text() {
out.Truncate(marker)
return
}
// are we building a table of contents?
if options.flags&HTML_TOC != 0 {
options.TocHeaderWithAnchor(out.Bytes()[tocMarker:], level, id)
}
out.WriteString(fmt.Sprintf("</h%d>\n", level))
}
func (options *Html) BlockHtml(out *bytes.Buffer, text []byte) {
if options.flags&HTML_SKIP_HTML != 0 {
return
}
doubleSpace(out)
out.Write(text)
out.WriteByte('\n')
}
func (options *Html) HRule(out *bytes.Buffer) {
doubleSpace(out)
out.WriteString("<hr")
out.WriteString(options.closeTag)
out.WriteByte('\n')
}
func (options *Html) BlockCode(out *bytes.Buffer, text []byte, lang string) {
doubleSpace(out)
// parse out the language names/classes
count := 0
for _, elt := range strings.Fields(lang) {
if elt[0] == '.' {
elt = elt[1:]
}
if len(elt) == 0 {
continue
}
if count == 0 {
out.WriteString("<pre><code class=\"language-")
} else {
out.WriteByte(' ')
}
attrEscape(out, []byte(elt))
count++
}
if count == 0 {
out.WriteString("<pre><code>")
} else {
out.WriteString("\">")
}
attrEscape(out, text)
out.WriteString("</code></pre>\n")
}
func (options *Html) BlockQuote(out *bytes.Buffer, text []byte) {
doubleSpace(out)
out.WriteString("<blockquote>\n")
out.Write(text)
out.WriteString("</blockquote>\n")
}
func (options *Html) Table(out *bytes.Buffer, header []byte, body []byte, columnData []int) {
doubleSpace(out)
out.WriteString("<table>\n<thead>\n")
out.Write(header)
out.WriteString("</thead>\n\n<tbody>\n")
out.Write(body)
out.WriteString("</tbody>\n</table>\n")
}
func (options *Html) TableRow(out *bytes.Buffer, text []byte) {
doubleSpace(out)
out.WriteString("<tr>\n")
out.Write(text)
out.WriteString("\n</tr>\n")
}
func (options *Html) TableHeaderCell(out *bytes.Buffer, text []byte, align int) {
doubleSpace(out)
switch align {
case TABLE_ALIGNMENT_LEFT:
out.WriteString("<th align=\"left\">")
case TABLE_ALIGNMENT_RIGHT:
out.WriteString("<th align=\"right\">")
case TABLE_ALIGNMENT_CENTER:
out.WriteString("<th align=\"center\">")
default:
out.WriteString("<th>")
}
out.Write(text)
out.WriteString("</th>")
}
func (options *Html) TableCell(out *bytes.Buffer, text []byte, align int) {
doubleSpace(out)
switch align {
case TABLE_ALIGNMENT_LEFT:
out.WriteString("<td align=\"left\">")
case TABLE_ALIGNMENT_RIGHT:
out.WriteString("<td align=\"right\">")
case TABLE_ALIGNMENT_CENTER:
out.WriteString("<td align=\"center\">")
default:
out.WriteString("<td>")
}
out.Write(text)
out.WriteString("</td>")
}
func (options *Html) Footnotes(out *bytes.Buffer, text func() bool) {
out.WriteString("<div class=\"footnotes\">\n")
options.HRule(out)
options.List(out, text, LIST_TYPE_ORDERED)
out.WriteString("</div>\n")
}
func (options *Html) FootnoteItem(out *bytes.Buffer, name, text []byte, flags int) {
if flags&LIST_ITEM_CONTAINS_BLOCK != 0 || flags&LIST_ITEM_BEGINNING_OF_LIST != 0 {
doubleSpace(out)
}
slug := slugify(name)
out.WriteString(`<li id="`)
out.WriteString(`fn:`)
out.WriteString(options.parameters.FootnoteAnchorPrefix)
out.Write(slug)
out.WriteString(`">`)
out.Write(text)
if options.flags&HTML_FOOTNOTE_RETURN_LINKS != 0 {
out.WriteString(` <a class="footnote-return" href="#`)
out.WriteString(`fnref:`)
out.WriteString(options.parameters.FootnoteAnchorPrefix)
out.Write(slug)
out.WriteString(`">`)
out.WriteString(options.parameters.FootnoteReturnLinkContents)
out.WriteString(`</a>`)
}
out.WriteString("</li>\n")
}
func (options *Html) List(out *bytes.Buffer, text func() bool, flags int) {
marker := out.Len()
doubleSpace(out)
if flags&LIST_TYPE_DEFINITION != 0 {
out.WriteString("<dl>")
} else if flags&LIST_TYPE_ORDERED != 0 {
out.WriteString("<ol>")
} else {
out.WriteString("<ul>")
}
if !text() {
out.Truncate(marker)
return
}
if flags&LIST_TYPE_DEFINITION != 0 {
out.WriteString("</dl>\n")
} else if flags&LIST_TYPE_ORDERED != 0 {
out.WriteString("</ol>\n")
} else {
out.WriteString("</ul>\n")
}
}
func (options *Html) ListItem(out *bytes.Buffer, text []byte, flags int) {
if (flags&LIST_ITEM_CONTAINS_BLOCK != 0 && flags&LIST_TYPE_DEFINITION == 0) ||
flags&LIST_ITEM_BEGINNING_OF_LIST != 0 {
doubleSpace(out)
}
if flags&LIST_TYPE_TERM != 0 {
out.WriteString("<dt>")
} else if flags&LIST_TYPE_DEFINITION != 0 {
out.WriteString("<dd>")
} else {
out.WriteString("<li>")
}
out.Write(text)
if flags&LIST_TYPE_TERM != 0 {
out.WriteString("</dt>\n")
} else if flags&LIST_TYPE_DEFINITION != 0 {
out.WriteString("</dd>\n")
} else {
out.WriteString("</li>\n")
}
}
func (options *Html) Paragraph(out *bytes.Buffer, text func() bool) {
marker := out.Len()
doubleSpace(out)
out.WriteString("<p>")
if !text() {
out.Truncate(marker)
return
}
out.WriteString("</p>\n")
}
func (options *Html) AutoLink(out *bytes.Buffer, link []byte, kind int) {
skipRanges := htmlEntity.FindAllIndex(link, -1)
if options.flags&HTML_SAFELINK != 0 && !isSafeLink(link) && kind != LINK_TYPE_EMAIL {
// mark it but don't link it if it is not a safe link: no smartypants
out.WriteString("<tt>")
entityEscapeWithSkip(out, link, skipRanges)
out.WriteString("</tt>")
return
}
out.WriteString("<a href=\"")
if kind == LINK_TYPE_EMAIL {
out.WriteString("mailto:")
} else {
options.maybeWriteAbsolutePrefix(out, link)
}
entityEscapeWithSkip(out, link, skipRanges)
var relAttrs []string
if options.flags&HTML_NOFOLLOW_LINKS != 0 && !isRelativeLink(link) {
relAttrs = append(relAttrs, "nofollow")
}
if options.flags&HTML_NOREFERRER_LINKS != 0 && !isRelativeLink(link) {
relAttrs = append(relAttrs, "noreferrer")
}
if len(relAttrs) > 0 {
out.WriteString(fmt.Sprintf("\" rel=\"%s", strings.Join(relAttrs, " ")))
}
// blank target only add to external link
if options.flags&HTML_HREF_TARGET_BLANK != 0 && !isRelativeLink(link) {
out.WriteString("\" target=\"_blank")
}
out.WriteString("\">")
// Pretty print: if we get an email address as
// an actual URI, e.g. `mailto:foo@bar.com`, we don't
// want to print the `mailto:` prefix
switch {
case bytes.HasPrefix(link, []byte("mailto://")):
attrEscape(out, link[len("mailto://"):])
case bytes.HasPrefix(link, []byte("mailto:")):
attrEscape(out, link[len("mailto:"):])
default:
entityEscapeWithSkip(out, link, skipRanges)
}
out.WriteString("</a>")
}
func (options *Html) CodeSpan(out *bytes.Buffer, text []byte) {
out.WriteString("<code>")
attrEscape(out, text)
out.WriteString("</code>")
}
func (options *Html) DoubleEmphasis(out *bytes.Buffer, text []byte) {
out.WriteString("<strong>")
out.Write(text)
out.WriteString("</strong>")
}
func (options *Html) Emphasis(out *bytes.Buffer, text []byte) {
if len(text) == 0 {
return
}
out.WriteString("<em>")
out.Write(text)
out.WriteString("</em>")
}
func (options *Html) maybeWriteAbsolutePrefix(out *bytes.Buffer, link []byte) {
if options.parameters.AbsolutePrefix != "" && isRelativeLink(link) && link[0] != '.' {
out.WriteString(options.parameters.AbsolutePrefix)
if link[0] != '/' {
out.WriteByte('/')
}
}
}
func (options *Html) Image(out *bytes.Buffer, link []byte, title []byte, alt []byte) {
if options.flags&HTML_SKIP_IMAGES != 0 {
return
}
out.WriteString("<img src=\"")
options.maybeWriteAbsolutePrefix(out, link)
attrEscape(out, link)
out.WriteString("\" alt=\"")
if len(alt) > 0 {
attrEscape(out, alt)
}
if len(title) > 0 {
out.WriteString("\" title=\"")
attrEscape(out, title)
}
out.WriteByte('"')
out.WriteString(options.closeTag)
}
func (options *Html) LineBreak(out *bytes.Buffer) {
out.WriteString("<br")
out.WriteString(options.closeTag)
out.WriteByte('\n')
}
func (options *Html) Link(out *bytes.Buffer, link []byte, title []byte, content []byte) {
if options.flags&HTML_SKIP_LINKS != 0 {
// write the link text out but don't link it, just mark it with typewriter font
out.WriteString("<tt>")
attrEscape(out, content)
out.WriteString("</tt>")
return
}
if options.flags&HTML_SAFELINK != 0 && !isSafeLink(link) {
// write the link text out but don't link it, just mark it with typewriter font
out.WriteString("<tt>")
attrEscape(out, content)
out.WriteString("</tt>")
return
}
out.WriteString("<a href=\"")
options.maybeWriteAbsolutePrefix(out, link)
attrEscape(out, link)
if len(title) > 0 {
out.WriteString("\" title=\"")
attrEscape(out, title)
}
var relAttrs []string
if options.flags&HTML_NOFOLLOW_LINKS != 0 && !isRelativeLink(link) {
relAttrs = append(relAttrs, "nofollow")
}
if options.flags&HTML_NOREFERRER_LINKS != 0 && !isRelativeLink(link) {
relAttrs = append(relAttrs, "noreferrer")
}
if len(relAttrs) > 0 {
out.WriteString(fmt.Sprintf("\" rel=\"%s", strings.Join(relAttrs, " ")))
}
// blank target only add to external link
if options.flags&HTML_HREF_TARGET_BLANK != 0 && !isRelativeLink(link) {
out.WriteString("\" target=\"_blank")
}
out.WriteString("\">")
out.Write(content)
out.WriteString("</a>")
return
}
func (options *Html) RawHtmlTag(out *bytes.Buffer, text []byte) {
if options.flags&HTML_SKIP_HTML != 0 {
return
}
if options.flags&HTML_SKIP_STYLE != 0 && isHtmlTag(text, "style") {
return
}
if options.flags&HTML_SKIP_LINKS != 0 && isHtmlTag(text, "a") {
return
}
if options.flags&HTML_SKIP_IMAGES != 0 && isHtmlTag(text, "img") {
return
}
out.Write(text)
}
func (options *Html) TripleEmphasis(out *bytes.Buffer, text []byte) {
out.WriteString("<strong><em>")
out.Write(text)
out.WriteString("</em></strong>")
}
func (options *Html) StrikeThrough(out *bytes.Buffer, text []byte) {
out.WriteString("<del>")
out.Write(text)
out.WriteString("</del>")
}
func (options *Html) FootnoteRef(out *bytes.Buffer, ref []byte, id int) {
slug := slugify(ref)
out.WriteString(`<sup class="footnote-ref" id="`)
out.WriteString(`fnref:`)
out.WriteString(options.parameters.FootnoteAnchorPrefix)
out.Write(slug)
out.WriteString(`"><a rel="footnote" href="#`)
out.WriteString(`fn:`)
out.WriteString(options.parameters.FootnoteAnchorPrefix)
out.Write(slug)
out.WriteString(`">`)
out.WriteString(strconv.Itoa(id))
out.WriteString(`</a></sup>`)
}
func (options *Html) Entity(out *bytes.Buffer, entity []byte) {
out.Write(entity)
}
func (options *Html) NormalText(out *bytes.Buffer, text []byte) {
if options.flags&HTML_USE_SMARTYPANTS != 0 {
options.Smartypants(out, text)
} else {
attrEscape(out, text)
}
}
func (options *Html) Smartypants(out *bytes.Buffer, text []byte) {
smrt := smartypantsData{false, false}
// first do normal entity escaping
var escaped bytes.Buffer
attrEscape(&escaped, text)
text = escaped.Bytes()
mark := 0
for i := 0; i < len(text); i++ {
if action := options.smartypants[text[i]]; action != nil {
if i > mark {
out.Write(text[mark:i])
}
previousChar := byte(0)
if i > 0 {
previousChar = text[i-1]
}
i += action(out, &smrt, previousChar, text[i:])
mark = i + 1
}
}
if mark < len(text) {
out.Write(text[mark:])
}
}
func (options *Html) DocumentHeader(out *bytes.Buffer) {
if options.flags&HTML_COMPLETE_PAGE == 0 {
return
}
ending := ""
if options.flags&HTML_USE_XHTML != 0 {
out.WriteString("<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Transitional//EN\" ")
out.WriteString("\"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd\">\n")
out.WriteString("<html xmlns=\"http://www.w3.org/1999/xhtml\">\n")
ending = " /"
} else {
out.WriteString("<!DOCTYPE html>\n")
out.WriteString("<html>\n")
}
out.WriteString("<head>\n")
out.WriteString(" <title>")
options.NormalText(out, []byte(options.title))
out.WriteString("</title>\n")
out.WriteString(" <meta name=\"GENERATOR\" content=\"Blackfriday Markdown Processor v")
out.WriteString(VERSION)
out.WriteString("\"")
out.WriteString(ending)
out.WriteString(">\n")
out.WriteString(" <meta charset=\"utf-8\"")
out.WriteString(ending)
out.WriteString(">\n")
if options.css != "" {
out.WriteString(" <link rel=\"stylesheet\" type=\"text/css\" href=\"")
attrEscape(out, []byte(options.css))
out.WriteString("\"")
out.WriteString(ending)
out.WriteString(">\n")
}
out.WriteString("</head>\n")
out.WriteString("<body>\n")
options.tocMarker = out.Len()
}
func (options *Html) DocumentFooter(out *bytes.Buffer) {
// finalize and insert the table of contents
if options.flags&HTML_TOC != 0 {
options.TocFinalize()
// now we have to insert the table of contents into the document
var temp bytes.Buffer
// start by making a copy of everything after the document header
temp.Write(out.Bytes()[options.tocMarker:])
// now clear the copied material from the main output buffer
out.Truncate(options.tocMarker)
// corner case spacing issue
if options.flags&HTML_COMPLETE_PAGE != 0 {
out.WriteByte('\n')
}
// insert the table of contents
out.WriteString("<nav>\n")
out.Write(options.toc.Bytes())
out.WriteString("</nav>\n")
// corner case spacing issue
if options.flags&HTML_COMPLETE_PAGE == 0 && options.flags&HTML_OMIT_CONTENTS == 0 {
out.WriteByte('\n')
}
// write out everything that came after it
if options.flags&HTML_OMIT_CONTENTS == 0 {
out.Write(temp.Bytes())
}
}
if options.flags&HTML_COMPLETE_PAGE != 0 {
out.WriteString("\n</body>\n")
out.WriteString("</html>\n")
}
}
func (options *Html) TocHeaderWithAnchor(text []byte, level int, anchor string) {
for level > options.currentLevel {
switch {
case bytes.HasSuffix(options.toc.Bytes(), []byte("</li>\n")):
// this sublist can nest underneath a header
size := options.toc.Len()
options.toc.Truncate(size - len("</li>\n"))
case options.currentLevel > 0:
options.toc.WriteString("<li>")
}
if options.toc.Len() > 0 {
options.toc.WriteByte('\n')
}
options.toc.WriteString("<ul>\n")
options.currentLevel++
}
for level < options.currentLevel {
options.toc.WriteString("</ul>")
if options.currentLevel > 1 {
options.toc.WriteString("</li>\n")
}
options.currentLevel--
}
options.toc.WriteString("<li><a href=\"#")
if anchor != "" {
options.toc.WriteString(anchor)
} else {
options.toc.WriteString("toc_")
options.toc.WriteString(strconv.Itoa(options.headerCount))
}
options.toc.WriteString("\">")
options.headerCount++
options.toc.Write(text)
options.toc.WriteString("</a></li>\n")
}
func (options *Html) TocHeader(text []byte, level int) {
options.TocHeaderWithAnchor(text, level, "")
}
func (options *Html) TocFinalize() {
for options.currentLevel > 1 {
options.toc.WriteString("</ul></li>\n")
options.currentLevel--
}
if options.currentLevel > 0 {
options.toc.WriteString("</ul>\n")
}
}
func isHtmlTag(tag []byte, tagname string) bool {
found, _ := findHtmlTagPos(tag, tagname)
return found
}
// Look for a character, but ignore it when it's in any kind of quotes, it
// might be JavaScript
func skipUntilCharIgnoreQuotes(html []byte, start int, char byte) int {
inSingleQuote := false
inDoubleQuote := false
inGraveQuote := false
i := start
for i < len(html) {
switch {
case html[i] == char && !inSingleQuote && !inDoubleQuote && !inGraveQuote:
return i
case html[i] == '\'':
inSingleQuote = !inSingleQuote
case html[i] == '"':
inDoubleQuote = !inDoubleQuote
case html[i] == '`':
inGraveQuote = !inGraveQuote
}
i++
}
return start
}
func findHtmlTagPos(tag []byte, tagname string) (bool, int) {
i := 0
if i < len(tag) && tag[0] != '<' {
return false, -1
}
i++
i = skipSpace(tag, i)
if i < len(tag) && tag[i] == '/' {
i++
}
i = skipSpace(tag, i)
j := 0
for ; i < len(tag); i, j = i+1, j+1 {
if j >= len(tagname) {
break
}
if strings.ToLower(string(tag[i]))[0] != tagname[j] {
return false, -1
}
}
if i == len(tag) {
return false, -1
}
rightAngle := skipUntilCharIgnoreQuotes(tag, i, '>')
if rightAngle > i {
return true, rightAngle
}
return false, -1
}
func skipUntilChar(text []byte, start int, char byte) int {
i := start
for i < len(text) && text[i] != char {
i++
}
return i
}
func skipSpace(tag []byte, i int) int {
for i < len(tag) && isspace(tag[i]) {
i++
}
return i
}
func skipChar(data []byte, start int, char byte) int {
i := start
for i < len(data) && data[i] == char {
i++
}
return i
}
func doubleSpace(out *bytes.Buffer) {
if out.Len() > 0 {
out.WriteByte('\n')
}
}
func isRelativeLink(link []byte) (yes bool) {
// a tag begin with '#'
if link[0] == '#' {
return true
}
// link begin with '/' but not '//', the second maybe a protocol relative link
if len(link) >= 2 && link[0] == '/' && link[1] != '/' {
return true
}
// only the root '/'
if len(link) == 1 && link[0] == '/' {
return true
}
// current directory : begin with "./"
if bytes.HasPrefix(link, []byte("./")) {
return true
}
// parent directory : begin with "../"
if bytes.HasPrefix(link, []byte("../")) {
return true
}
return false
}
func (options *Html) ensureUniqueHeaderID(id string) string {
for count, found := options.headerIDs[id]; found; count, found = options.headerIDs[id] {
tmp := fmt.Sprintf("%s-%d", id, count+1)
if _, tmpFound := options.headerIDs[tmp]; !tmpFound {
options.headerIDs[id] = count + 1
id = tmp
} else {
id = id + "-1"
}
}
if _, found := options.headerIDs[id]; !found {
options.headerIDs[id] = 0
}
return id
}