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matterbridge/vendor/github.com/gomarkdown/markdown/parser/block.go

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package parser
import (
"bytes"
"html"
"regexp"
"strconv"
"unicode"
"github.com/gomarkdown/markdown/ast"
)
// Parsing block-level elements.
const (
charEntity = "&(?:#x[a-f0-9]{1,8}|#[0-9]{1,8}|[a-z][a-z0-9]{1,31});"
escapable = "[!\"#$%&'()*+,./:;<=>?@[\\\\\\]^_`{|}~-]"
)
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const (
captionTable = "Table: "
captionFigure = "Figure: "
captionQuote = "Quote: "
)
var (
reBackslashOrAmp = regexp.MustCompile("[\\&]")
reEntityOrEscapedChar = regexp.MustCompile("(?i)\\\\" + escapable + "|" + charEntity)
// blockTags is a set of tags that are recognized as HTML block tags.
// Any of these can be included in markdown text without special escaping.
blockTags = map[string]struct{}{
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"blockquote": {},
"del": {},
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"dd": {},
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"div": {},
"dl": {},
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"dt": {},
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"fieldset": {},
"form": {},
"h1": {},
"h2": {},
"h3": {},
"h4": {},
"h5": {},
"h6": {},
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// TODO: technically block but breaks Inline HTML (Simple).text
//"hr": {},
"iframe": {},
"ins": {},
"li": {},
"math": {},
"noscript": {},
"ol": {},
"pre": {},
"p": {},
"script": {},
"style": {},
"table": {},
"ul": {},
// HTML5
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"address": {},
"article": {},
"aside": {},
"canvas": {},
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"details": {},
"dialog": {},
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"figcaption": {},
"figure": {},
"footer": {},
"header": {},
"hgroup": {},
"main": {},
"nav": {},
"output": {},
"progress": {},
"section": {},
"video": {},
}
)
// sanitizeHeadingID returns a sanitized anchor name for the given text.
// Taken from https://github.com/shurcooL/sanitized_anchor_name/blob/master/main.go#L14:1
func sanitizeHeadingID(text string) string {
var anchorName []rune
var futureDash = false
for _, r := range text {
switch {
case unicode.IsLetter(r) || unicode.IsNumber(r):
if futureDash && len(anchorName) > 0 {
anchorName = append(anchorName, '-')
}
futureDash = false
anchorName = append(anchorName, unicode.ToLower(r))
default:
futureDash = true
}
}
if len(anchorName) == 0 {
return "empty"
}
return string(anchorName)
}
// Parse block-level data.
// Note: this function and many that it calls assume that
// the input buffer ends with a newline.
func (p *Parser) block(data []byte) {
// this is called recursively: enforce a maximum depth
if p.nesting >= p.maxNesting {
return
}
p.nesting++
// parse out one block-level construct at a time
for len(data) > 0 {
// attributes that can be specific before a block element:
//
// {#id .class1 .class2 key="value"}
if p.extensions&Attributes != 0 {
data = p.attribute(data)
}
if p.extensions&Includes != 0 {
f := p.readInclude
path, address, consumed := p.isInclude(data)
if consumed == 0 {
path, address, consumed = p.isCodeInclude(data)
f = p.readCodeInclude
}
if consumed > 0 {
included := f(p.includeStack.Last(), path, address)
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// if we find a caption below this, we need to include it in 'included', so
// that the caption will be part of the include text. (+1 to skip newline)
for _, caption := range []string{captionFigure, captionTable, captionQuote} {
if _, _, capcon := p.caption(data[consumed+1:], []byte(caption)); capcon > 0 {
included = append(included, data[consumed+1:consumed+1+capcon]...)
consumed += 1 + capcon
break // there can only be 1 caption.
}
}
p.includeStack.Push(path)
p.block(included)
p.includeStack.Pop()
data = data[consumed:]
continue
}
}
// user supplied parser function
if p.Opts.ParserHook != nil {
node, blockdata, consumed := p.Opts.ParserHook(data)
if consumed > 0 {
data = data[consumed:]
if node != nil {
p.addBlock(node)
if blockdata != nil {
p.block(blockdata)
p.finalize(node)
}
}
continue
}
}
// prefixed heading:
//
// # Heading 1
// ## Heading 2
// ...
// ###### Heading 6
if p.isPrefixHeading(data) {
data = data[p.prefixHeading(data):]
continue
}
// prefixed special heading:
// (there are no levels.)
//
// .# Abstract
if p.isPrefixSpecialHeading(data) {
data = data[p.prefixSpecialHeading(data):]
continue
}
// block of preformatted HTML:
//
// <div>
// ...
// </div>
if data[0] == '<' {
if i := p.html(data, true); i > 0 {
data = data[i:]
continue
}
}
// title block
//
// % stuff
// % more stuff
// % even more stuff
if p.extensions&Titleblock != 0 {
if data[0] == '%' {
if i := p.titleBlock(data, true); i > 0 {
data = data[i:]
continue
}
}
}
// blank lines. note: returns the # of bytes to skip
if i := p.isEmpty(data); i > 0 {
data = data[i:]
continue
}
// indented code block:
//
// func max(a, b int) int {
// if a > b {
// return a
// }
// return b
// }
if p.codePrefix(data) > 0 {
data = data[p.code(data):]
continue
}
// fenced code block:
//
// ``` go
// func fact(n int) int {
// if n <= 1 {
// return n
// }
// return n * fact(n-1)
// }
// ```
if p.extensions&FencedCode != 0 {
if i := p.fencedCodeBlock(data, true); i > 0 {
data = data[i:]
continue
}
}
// horizontal rule:
//
// ------
// or
// ******
// or
// ______
if p.isHRule(data) {
i := skipUntilChar(data, 0, '\n')
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hr := ast.HorizontalRule{}
hr.Literal = bytes.Trim(data[:i], " \n")
p.addBlock(&hr)
data = data[i:]
continue
}
// block quote:
//
// > A big quote I found somewhere
// > on the web
if p.quotePrefix(data) > 0 {
data = data[p.quote(data):]
continue
}
// aside:
//
// A> The proof is too large to fit
// A> in the margin.
if p.extensions&Mmark != 0 {
if p.asidePrefix(data) > 0 {
data = data[p.aside(data):]
continue
}
}
// figure block:
//
// !---
// ![Alt Text](img.jpg "This is an image")
// ![Alt Text](img2.jpg "This is a second image")
// !---
if p.extensions&Mmark != 0 {
if i := p.figureBlock(data, true); i > 0 {
data = data[i:]
continue
}
}
if p.extensions&Tables != 0 {
if i := p.table(data); i > 0 {
data = data[i:]
continue
}
}
// an itemized/unordered list:
//
// * Item 1
// * Item 2
//
// also works with + or -
if p.uliPrefix(data) > 0 {
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data = data[p.list(data, 0, 0, '.'):]
continue
}
// a numbered/ordered list:
//
// 1. Item 1
// 2. Item 2
if i := p.oliPrefix(data); i > 0 {
start := 0
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delim := byte('.')
if i > 2 {
if p.extensions&OrderedListStart != 0 {
s := string(data[:i-2])
start, _ = strconv.Atoi(s)
if start == 1 {
start = 0
}
}
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delim = data[i-2]
}
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data = data[p.list(data, ast.ListTypeOrdered, start, delim):]
continue
}
// definition lists:
//
// Term 1
// : Definition a
// : Definition b
//
// Term 2
// : Definition c
if p.extensions&DefinitionLists != 0 {
if p.dliPrefix(data) > 0 {
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data = data[p.list(data, ast.ListTypeDefinition, 0, '.'):]
continue
}
}
if p.extensions&MathJax != 0 {
if i := p.blockMath(data); i > 0 {
data = data[i:]
continue
}
}
// document matters:
//
// {frontmatter}/{mainmatter}/{backmatter}
if p.extensions&Mmark != 0 {
if i := p.documentMatter(data); i > 0 {
data = data[i:]
continue
}
}
// anything else must look like a normal paragraph
// note: this finds underlined headings, too
idx := p.paragraph(data)
data = data[idx:]
}
p.nesting--
}
func (p *Parser) addBlock(n ast.Node) ast.Node {
p.closeUnmatchedBlocks()
if p.attr != nil {
if c := n.AsContainer(); c != nil {
c.Attribute = p.attr
}
if l := n.AsLeaf(); l != nil {
l.Attribute = p.attr
}
p.attr = nil
}
return p.addChild(n)
}
func (p *Parser) isPrefixHeading(data []byte) bool {
if data[0] != '#' {
return false
}
if p.extensions&SpaceHeadings != 0 {
level := skipCharN(data, 0, '#', 6)
if level == len(data) || data[level] != ' ' {
return false
}
}
return true
}
func (p *Parser) prefixHeading(data []byte) int {
level := skipCharN(data, 0, '#', 6)
i := skipChar(data, level, ' ')
end := skipUntilChar(data, i, '\n')
skip := end
id := ""
if p.extensions&HeadingIDs != 0 {
j, k := 0, 0
// find start/end of heading id
for j = i; j < end-1 && (data[j] != '{' || data[j+1] != '#'); j++ {
}
for k = j + 1; k < end && data[k] != '}'; k++ {
}
// extract heading id iff found
if j < end && k < end {
id = string(data[j+2 : k])
end = j
skip = k + 1
for end > 0 && data[end-1] == ' ' {
end--
}
}
}
for end > 0 && data[end-1] == '#' {
if isBackslashEscaped(data, end-1) {
break
}
end--
}
for end > 0 && data[end-1] == ' ' {
end--
}
if end > i {
block := &ast.Heading{
HeadingID: id,
Level: level,
}
if id == "" && p.extensions&AutoHeadingIDs != 0 {
block.HeadingID = sanitizeHeadingID(string(data[i:end]))
p.allHeadingsWithAutoID = append(p.allHeadingsWithAutoID, block)
}
block.Content = data[i:end]
p.addBlock(block)
}
return skip
}
func (p *Parser) isPrefixSpecialHeading(data []byte) bool {
if p.extensions|Mmark == 0 {
return false
}
if len(data) < 4 {
return false
}
if data[0] != '.' {
return false
}
if data[1] != '#' {
return false
}
if data[2] == '#' { // we don't support level, so nack this.
return false
}
if p.extensions&SpaceHeadings != 0 {
if data[2] != ' ' {
return false
}
}
return true
}
func (p *Parser) prefixSpecialHeading(data []byte) int {
i := skipChar(data, 2, ' ') // ".#" skipped
end := skipUntilChar(data, i, '\n')
skip := end
id := ""
if p.extensions&HeadingIDs != 0 {
j, k := 0, 0
// find start/end of heading id
for j = i; j < end-1 && (data[j] != '{' || data[j+1] != '#'); j++ {
}
for k = j + 1; k < end && data[k] != '}'; k++ {
}
// extract heading id iff found
if j < end && k < end {
id = string(data[j+2 : k])
end = j
skip = k + 1
for end > 0 && data[end-1] == ' ' {
end--
}
}
}
for end > 0 && data[end-1] == '#' {
if isBackslashEscaped(data, end-1) {
break
}
end--
}
for end > 0 && data[end-1] == ' ' {
end--
}
if end > i {
block := &ast.Heading{
HeadingID: id,
IsSpecial: true,
Level: 1, // always level 1.
}
if id == "" && p.extensions&AutoHeadingIDs != 0 {
block.HeadingID = sanitizeHeadingID(string(data[i:end]))
p.allHeadingsWithAutoID = append(p.allHeadingsWithAutoID, block)
}
block.Literal = data[i:end]
block.Content = data[i:end]
p.addBlock(block)
}
return skip
}
func (p *Parser) isUnderlinedHeading(data []byte) int {
// test of level 1 heading
if data[0] == '=' {
i := skipChar(data, 1, '=')
i = skipChar(data, i, ' ')
if i < len(data) && data[i] == '\n' {
return 1
}
return 0
}
// test of level 2 heading
if data[0] == '-' {
i := skipChar(data, 1, '-')
i = skipChar(data, i, ' ')
if i < len(data) && data[i] == '\n' {
return 2
}
return 0
}
return 0
}
func (p *Parser) titleBlock(data []byte, doRender bool) int {
if data[0] != '%' {
return 0
}
splitData := bytes.Split(data, []byte("\n"))
var i int
for idx, b := range splitData {
if !bytes.HasPrefix(b, []byte("%")) {
i = idx // - 1
break
}
}
data = bytes.Join(splitData[0:i], []byte("\n"))
consumed := len(data)
data = bytes.TrimPrefix(data, []byte("% "))
data = bytes.Replace(data, []byte("\n% "), []byte("\n"), -1)
block := &ast.Heading{
Level: 1,
IsTitleblock: true,
}
block.Content = data
p.addBlock(block)
return consumed
}
func (p *Parser) html(data []byte, doRender bool) int {
var i, j int
// identify the opening tag
if data[0] != '<' {
return 0
}
curtag, tagfound := p.htmlFindTag(data[1:])
// handle special cases
if !tagfound {
// check for an HTML comment
if size := p.htmlComment(data, doRender); size > 0 {
return size
}
// check for an <hr> tag
if size := p.htmlHr(data, doRender); size > 0 {
return size
}
// no special case recognized
return 0
}
// look for an unindented matching closing tag
// followed by a blank line
found := false
/*
closetag := []byte("\n</" + curtag + ">")
j = len(curtag) + 1
for !found {
// scan for a closing tag at the beginning of a line
if skip := bytes.Index(data[j:], closetag); skip >= 0 {
j += skip + len(closetag)
} else {
break
}
// see if it is the only thing on the line
if skip := p.isEmpty(data[j:]); skip > 0 {
// see if it is followed by a blank line/eof
j += skip
if j >= len(data) {
found = true
i = j
} else {
if skip := p.isEmpty(data[j:]); skip > 0 {
j += skip
found = true
i = j
}
}
}
}
*/
// if not found, try a second pass looking for indented match
// but not if tag is "ins" or "del" (following original Markdown.pl)
if !found && curtag != "ins" && curtag != "del" {
i = 1
for i < len(data) {
i++
for i < len(data) && !(data[i-1] == '<' && data[i] == '/') {
i++
}
if i+2+len(curtag) >= len(data) {
break
}
j = p.htmlFindEnd(curtag, data[i-1:])
if j > 0 {
i += j - 1
found = true
break
}
}
}
if !found {
return 0
}
// the end of the block has been found
if doRender {
// trim newlines
end := backChar(data, i, '\n')
htmlBLock := &ast.HTMLBlock{Leaf: ast.Leaf{Content: data[:end]}}
p.addBlock(htmlBLock)
finalizeHTMLBlock(htmlBLock)
}
return i
}
func finalizeHTMLBlock(block *ast.HTMLBlock) {
block.Literal = block.Content
block.Content = nil
}
// HTML comment, lax form
func (p *Parser) htmlComment(data []byte, doRender bool) int {
i := p.inlineHTMLComment(data)
// needs to end with a blank line
if j := p.isEmpty(data[i:]); j > 0 {
size := i + j
if doRender {
// trim trailing newlines
end := backChar(data, size, '\n')
htmlBLock := &ast.HTMLBlock{Leaf: ast.Leaf{Content: data[:end]}}
p.addBlock(htmlBLock)
finalizeHTMLBlock(htmlBLock)
}
return size
}
return 0
}
// HR, which is the only self-closing block tag considered
func (p *Parser) htmlHr(data []byte, doRender bool) int {
if len(data) < 4 {
return 0
}
if data[0] != '<' || (data[1] != 'h' && data[1] != 'H') || (data[2] != 'r' && data[2] != 'R') {
return 0
}
if data[3] != ' ' && data[3] != '/' && data[3] != '>' {
// not an <hr> tag after all; at least not a valid one
return 0
}
i := 3
for i < len(data) && data[i] != '>' && data[i] != '\n' {
i++
}
if i < len(data) && data[i] == '>' {
i++
if j := p.isEmpty(data[i:]); j > 0 {
size := i + j
if doRender {
// trim newlines
end := backChar(data, size, '\n')
htmlBlock := &ast.HTMLBlock{Leaf: ast.Leaf{Content: data[:end]}}
p.addBlock(htmlBlock)
finalizeHTMLBlock(htmlBlock)
}
return size
}
}
return 0
}
func (p *Parser) htmlFindTag(data []byte) (string, bool) {
i := skipAlnum(data, 0)
key := string(data[:i])
if _, ok := blockTags[key]; ok {
return key, true
}
return "", false
}
func (p *Parser) htmlFindEnd(tag string, data []byte) int {
// assume data[0] == '<' && data[1] == '/' already tested
if tag == "hr" {
return 2
}
// check if tag is a match
closetag := []byte("</" + tag + ">")
if !bytes.HasPrefix(data, closetag) {
return 0
}
i := len(closetag)
// check that the rest of the line is blank
skip := 0
if skip = p.isEmpty(data[i:]); skip == 0 {
return 0
}
i += skip
skip = 0
if i >= len(data) {
return i
}
if p.extensions&LaxHTMLBlocks != 0 {
return i
}
if skip = p.isEmpty(data[i:]); skip == 0 {
// following line must be blank
return 0
}
return i + skip
}
func (*Parser) isEmpty(data []byte) int {
// it is okay to call isEmpty on an empty buffer
if len(data) == 0 {
return 0
}
var i int
for i = 0; i < len(data) && data[i] != '\n'; i++ {
if data[i] != ' ' && data[i] != '\t' {
return 0
}
}
i = skipCharN(data, i, '\n', 1)
return i
}
func (*Parser) isHRule(data []byte) bool {
i := 0
// skip up to three spaces
for i < 3 && data[i] == ' ' {
i++
}
// look at the hrule char
if data[i] != '*' && data[i] != '-' && data[i] != '_' {
return false
}
c := data[i]
// the whole line must be the char or whitespace
n := 0
for i < len(data) && data[i] != '\n' {
switch {
case data[i] == c:
n++
case data[i] != ' ':
return false
}
i++
}
return n >= 3
}
// isFenceLine checks if there's a fence line (e.g., ``` or ``` go) at the beginning of data,
// and returns the end index if so, or 0 otherwise. It also returns the marker found.
// If syntax is not nil, it gets set to the syntax specified in the fence line.
func isFenceLine(data []byte, syntax *string, oldmarker string) (end int, marker string) {
i, size := 0, 0
n := len(data)
// skip up to three spaces
for i < n && i < 3 && data[i] == ' ' {
i++
}
// check for the marker characters: ~ or `
if i >= n {
return 0, ""
}
if data[i] != '~' && data[i] != '`' {
return 0, ""
}
c := data[i]
// the whole line must be the same char or whitespace
for i < n && data[i] == c {
size++
i++
}
// the marker char must occur at least 3 times
if size < 3 {
return 0, ""
}
marker = string(data[i-size : i])
// if this is the end marker, it must match the beginning marker
if oldmarker != "" && marker != oldmarker {
return 0, ""
}
// TODO(shurcooL): It's probably a good idea to simplify the 2 code paths here
// into one, always get the syntax, and discard it if the caller doesn't care.
if syntax != nil {
syn := 0
i = skipChar(data, i, ' ')
if i >= n {
if i == n {
return i, marker
}
return 0, ""
}
syntaxStart := i
if data[i] == '{' {
i++
syntaxStart++
for i < n && data[i] != '}' && data[i] != '\n' {
syn++
i++
}
if i >= n || data[i] != '}' {
return 0, ""
}
// strip all whitespace at the beginning and the end
// of the {} block
for syn > 0 && isSpace(data[syntaxStart]) {
syntaxStart++
syn--
}
for syn > 0 && isSpace(data[syntaxStart+syn-1]) {
syn--
}
i++
} else {
for i < n && !isSpace(data[i]) {
syn++
i++
}
}
*syntax = string(data[syntaxStart : syntaxStart+syn])
}
i = skipChar(data, i, ' ')
if i >= n || data[i] != '\n' {
if i == n {
return i, marker
}
return 0, ""
}
return i + 1, marker // Take newline into account.
}
// fencedCodeBlock returns the end index if data contains a fenced code block at the beginning,
// or 0 otherwise. It writes to out if doRender is true, otherwise it has no side effects.
// If doRender is true, a final newline is mandatory to recognize the fenced code block.
func (p *Parser) fencedCodeBlock(data []byte, doRender bool) int {
var syntax string
beg, marker := isFenceLine(data, &syntax, "")
if beg == 0 || beg >= len(data) {
return 0
}
var work bytes.Buffer
work.WriteString(syntax)
work.WriteByte('\n')
for {
// safe to assume beg < len(data)
// check for the end of the code block
fenceEnd, _ := isFenceLine(data[beg:], nil, marker)
if fenceEnd != 0 {
beg += fenceEnd
break
}
// copy the current line
end := skipUntilChar(data, beg, '\n') + 1
// did we reach the end of the buffer without a closing marker?
if end >= len(data) {
return 0
}
// verbatim copy to the working buffer
if doRender {
work.Write(data[beg:end])
}
beg = end
}
if doRender {
codeBlock := &ast.CodeBlock{
IsFenced: true,
}
codeBlock.Content = work.Bytes() // TODO: get rid of temp buffer
if p.extensions&Mmark == 0 {
p.addBlock(codeBlock)
finalizeCodeBlock(codeBlock)
return beg
}
// Check for caption and if found make it a figure.
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if captionContent, id, consumed := p.caption(data[beg:], []byte(captionFigure)); consumed > 0 {
figure := &ast.CaptionFigure{}
caption := &ast.Caption{}
figure.HeadingID = id
p.Inline(caption, captionContent)
p.addBlock(figure)
codeBlock.AsLeaf().Attribute = figure.AsContainer().Attribute
p.addChild(codeBlock)
finalizeCodeBlock(codeBlock)
p.addChild(caption)
p.finalize(figure)
beg += consumed
return beg
}
// Still here, normal block
p.addBlock(codeBlock)
finalizeCodeBlock(codeBlock)
}
return beg
}
func unescapeChar(str []byte) []byte {
if str[0] == '\\' {
return []byte{str[1]}
}
return []byte(html.UnescapeString(string(str)))
}
func unescapeString(str []byte) []byte {
if reBackslashOrAmp.Match(str) {
return reEntityOrEscapedChar.ReplaceAllFunc(str, unescapeChar)
}
return str
}
func finalizeCodeBlock(code *ast.CodeBlock) {
c := code.Content
if code.IsFenced {
newlinePos := bytes.IndexByte(c, '\n')
firstLine := c[:newlinePos]
rest := c[newlinePos+1:]
code.Info = unescapeString(bytes.Trim(firstLine, "\n"))
code.Literal = rest
} else {
code.Literal = c
}
code.Content = nil
}
// returns blockquote prefix length
func (p *Parser) quotePrefix(data []byte) int {
i := 0
n := len(data)
for i < 3 && i < n && data[i] == ' ' {
i++
}
if i < n && data[i] == '>' {
if i+1 < n && data[i+1] == ' ' {
return i + 2
}
return i + 1
}
return 0
}
// blockquote ends with at least one blank line
// followed by something without a blockquote prefix
func (p *Parser) terminateBlockquote(data []byte, beg, end int) bool {
if p.isEmpty(data[beg:]) <= 0 {
return false
}
if end >= len(data) {
return true
}
return p.quotePrefix(data[end:]) == 0 && p.isEmpty(data[end:]) == 0
}
// parse a blockquote fragment
func (p *Parser) quote(data []byte) int {
var raw bytes.Buffer
beg, end := 0, 0
for beg < len(data) {
end = beg
// Step over whole lines, collecting them. While doing that, check for
// fenced code and if one's found, incorporate it altogether,
// irregardless of any contents inside it
for end < len(data) && data[end] != '\n' {
if p.extensions&FencedCode != 0 {
if i := p.fencedCodeBlock(data[end:], false); i > 0 {
// -1 to compensate for the extra end++ after the loop:
end += i - 1
break
}
}
end++
}
end = skipCharN(data, end, '\n', 1)
if pre := p.quotePrefix(data[beg:]); pre > 0 {
// skip the prefix
beg += pre
} else if p.terminateBlockquote(data, beg, end) {
break
}
// this line is part of the blockquote
raw.Write(data[beg:end])
beg = end
}
if p.extensions&Mmark == 0 {
block := p.addBlock(&ast.BlockQuote{})
p.block(raw.Bytes())
p.finalize(block)
return end
}
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if captionContent, id, consumed := p.caption(data[end:], []byte(captionQuote)); consumed > 0 {
figure := &ast.CaptionFigure{}
caption := &ast.Caption{}
figure.HeadingID = id
p.Inline(caption, captionContent)
p.addBlock(figure) // this discard any attributes
block := &ast.BlockQuote{}
block.AsContainer().Attribute = figure.AsContainer().Attribute
p.addChild(block)
p.block(raw.Bytes())
p.finalize(block)
p.addChild(caption)
p.finalize(figure)
end += consumed
return end
}
block := p.addBlock(&ast.BlockQuote{})
p.block(raw.Bytes())
p.finalize(block)
return end
}
// returns prefix length for block code
func (p *Parser) codePrefix(data []byte) int {
n := len(data)
if n >= 1 && data[0] == '\t' {
return 1
}
if n >= 4 && data[3] == ' ' && data[2] == ' ' && data[1] == ' ' && data[0] == ' ' {
return 4
}
return 0
}
func (p *Parser) code(data []byte) int {
var work bytes.Buffer
i := 0
for i < len(data) {
beg := i
i = skipUntilChar(data, i, '\n')
i = skipCharN(data, i, '\n', 1)
blankline := p.isEmpty(data[beg:i]) > 0
if pre := p.codePrefix(data[beg:i]); pre > 0 {
beg += pre
} else if !blankline {
// non-empty, non-prefixed line breaks the pre
i = beg
break
}
// verbatim copy to the working buffer
if blankline {
work.WriteByte('\n')
} else {
work.Write(data[beg:i])
}
}
// trim all the \n off the end of work
workbytes := work.Bytes()
eol := backChar(workbytes, len(workbytes), '\n')
if eol != len(workbytes) {
work.Truncate(eol)
}
work.WriteByte('\n')
codeBlock := &ast.CodeBlock{
IsFenced: false,
}
// TODO: get rid of temp buffer
codeBlock.Content = work.Bytes()
p.addBlock(codeBlock)
finalizeCodeBlock(codeBlock)
return i
}
// returns unordered list item prefix
func (p *Parser) uliPrefix(data []byte) int {
// start with up to 3 spaces
i := skipCharN(data, 0, ' ', 3)
if i >= len(data)-1 {
return 0
}
// need one of {'*', '+', '-'} followed by a space or a tab
if (data[i] != '*' && data[i] != '+' && data[i] != '-') ||
(data[i+1] != ' ' && data[i+1] != '\t') {
return 0
}
return i + 2
}
// returns ordered list item prefix
func (p *Parser) oliPrefix(data []byte) int {
// start with up to 3 spaces
i := skipCharN(data, 0, ' ', 3)
// count the digits
start := i
for i < len(data) && data[i] >= '0' && data[i] <= '9' {
i++
}
if start == i || i >= len(data)-1 {
return 0
}
// we need >= 1 digits followed by a dot and a space or a tab
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if data[i] != '.' && data[i] != ')' || !(data[i+1] == ' ' || data[i+1] == '\t') {
return 0
}
return i + 2
}
// returns definition list item prefix
func (p *Parser) dliPrefix(data []byte) int {
if len(data) < 2 {
return 0
}
// need a ':' followed by a space or a tab
if data[0] != ':' || !(data[1] == ' ' || data[1] == '\t') {
return 0
}
i := skipChar(data, 0, ' ')
return i + 2
}
// parse ordered or unordered list block
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func (p *Parser) list(data []byte, flags ast.ListType, start int, delim byte) int {
i := 0
flags |= ast.ListItemBeginningOfList
list := &ast.List{
ListFlags: flags,
Tight: true,
Start: start,
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Delimiter: delim,
}
block := p.addBlock(list)
for i < len(data) {
skip := p.listItem(data[i:], &flags)
if flags&ast.ListItemContainsBlock != 0 {
list.Tight = false
}
i += skip
if skip == 0 || flags&ast.ListItemEndOfList != 0 {
break
}
flags &= ^ast.ListItemBeginningOfList
}
above := block.GetParent()
finalizeList(list)
p.tip = above
return i
}
// Returns true if the list item is not the same type as its parent list
func (p *Parser) listTypeChanged(data []byte, flags *ast.ListType) bool {
if p.dliPrefix(data) > 0 && *flags&ast.ListTypeDefinition == 0 {
return true
} else if p.oliPrefix(data) > 0 && *flags&ast.ListTypeOrdered == 0 {
return true
} else if p.uliPrefix(data) > 0 && (*flags&ast.ListTypeOrdered != 0 || *flags&ast.ListTypeDefinition != 0) {
return true
}
return false
}
// Returns true if block ends with a blank line, descending if needed
// into lists and sublists.
func endsWithBlankLine(block ast.Node) bool {
// TODO: figure this out. Always false now.
for block != nil {
//if block.lastLineBlank {
//return true
//}
switch block.(type) {
case *ast.List, *ast.ListItem:
block = ast.GetLastChild(block)
default:
return false
}
}
return false
}
func finalizeList(list *ast.List) {
items := list.Parent.GetChildren()
lastItemIdx := len(items) - 1
for i, item := range items {
isLastItem := i == lastItemIdx
// check for non-final list item ending with blank line:
if !isLastItem && endsWithBlankLine(item) {
list.Tight = false
break
}
// recurse into children of list item, to see if there are spaces
// between any of them:
subItems := item.GetParent().GetChildren()
lastSubItemIdx := len(subItems) - 1
for j, subItem := range subItems {
isLastSubItem := j == lastSubItemIdx
if (!isLastItem || !isLastSubItem) && endsWithBlankLine(subItem) {
list.Tight = false
break
}
}
}
}
// Parse a single list item.
// Assumes initial prefix is already removed if this is a sublist.
func (p *Parser) listItem(data []byte, flags *ast.ListType) int {
// keep track of the indentation of the first line
itemIndent := 0
if data[0] == '\t' {
itemIndent += 4
} else {
for itemIndent < 3 && data[itemIndent] == ' ' {
itemIndent++
}
}
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var (
bulletChar byte = '*'
delimiter byte = '.'
)
i := p.uliPrefix(data)
if i == 0 {
i = p.oliPrefix(data)
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if i > 0 {
delimiter = data[i-2]
}
} else {
bulletChar = data[i-2]
}
if i == 0 {
i = p.dliPrefix(data)
// reset definition term flag
if i > 0 {
*flags &= ^ast.ListTypeTerm
}
}
if i == 0 {
// if in definition list, set term flag and continue
if *flags&ast.ListTypeDefinition != 0 {
*flags |= ast.ListTypeTerm
} else {
return 0
}
}
// skip leading whitespace on first line
i = skipChar(data, i, ' ')
// find the end of the line
line := i
for i > 0 && i < len(data) && data[i-1] != '\n' {
i++
}
// get working buffer
var raw bytes.Buffer
// put the first line into the working buffer
raw.Write(data[line:i])
line = i
// process the following lines
containsBlankLine := false
sublist := 0
gatherlines:
for line < len(data) {
i++
// find the end of this line
for i < len(data) && data[i-1] != '\n' {
i++
}
// if it is an empty line, guess that it is part of this item
// and move on to the next line
if p.isEmpty(data[line:i]) > 0 {
containsBlankLine = true
line = i
continue
}
// calculate the indentation
indent := 0
indentIndex := 0
if data[line] == '\t' {
indentIndex++
indent += 4
} else {
for indent < 4 && line+indent < i && data[line+indent] == ' ' {
indent++
indentIndex++
}
}
chunk := data[line+indentIndex : i]
// evaluate how this line fits in
switch {
// is this a nested list item?
case (p.uliPrefix(chunk) > 0 && !p.isHRule(chunk)) || p.oliPrefix(chunk) > 0 || p.dliPrefix(chunk) > 0:
// to be a nested list, it must be indented more
// if not, it is either a different kind of list
// or the next item in the same list
if indent <= itemIndent {
if p.listTypeChanged(chunk, flags) {
*flags |= ast.ListItemEndOfList
} else if containsBlankLine {
*flags |= ast.ListItemContainsBlock
}
break gatherlines
}
if containsBlankLine {
*flags |= ast.ListItemContainsBlock
}
// is this the first item in the nested list?
if sublist == 0 {
sublist = raw.Len()
// in the case of dliPrefix we are too late and need to search back for the definition item, which
// should be on the previous line, we then adjust sublist to start there.
if p.dliPrefix(chunk) > 0 {
sublist = backUntilChar(raw.Bytes(), raw.Len()-1, '\n')
}
}
// is this a nested prefix heading?
case p.isPrefixHeading(chunk), p.isPrefixSpecialHeading(chunk):
// if the heading is not indented, it is not nested in the list
// and thus ends the list
if containsBlankLine && indent < 4 {
*flags |= ast.ListItemEndOfList
break gatherlines
}
*flags |= ast.ListItemContainsBlock
// anything following an empty line is only part
// of this item if it is indented 4 spaces
// (regardless of the indentation of the beginning of the item)
case containsBlankLine && indent < 4:
if *flags&ast.ListTypeDefinition != 0 && i < len(data)-1 {
// is the next item still a part of this list?
next := i
for next < len(data) && data[next] != '\n' {
next++
}
for next < len(data)-1 && data[next] == '\n' {
next++
}
if i < len(data)-1 && data[i] != ':' && next < len(data)-1 && data[next] != ':' {
*flags |= ast.ListItemEndOfList
}
} else {
*flags |= ast.ListItemEndOfList
}
break gatherlines
// a blank line means this should be parsed as a block
case containsBlankLine:
raw.WriteByte('\n')
*flags |= ast.ListItemContainsBlock
}
// if this line was preceded by one or more blanks,
// re-introduce the blank into the buffer
if containsBlankLine {
containsBlankLine = false
raw.WriteByte('\n')
}
// add the line into the working buffer without prefix
raw.Write(data[line+indentIndex : i])
line = i
}
rawBytes := raw.Bytes()
listItem := &ast.ListItem{
ListFlags: *flags,
Tight: false,
BulletChar: bulletChar,
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Delimiter: delimiter,
}
p.addBlock(listItem)
// render the contents of the list item
if *flags&ast.ListItemContainsBlock != 0 && *flags&ast.ListTypeTerm == 0 {
// intermediate render of block item, except for definition term
if sublist > 0 {
p.block(rawBytes[:sublist])
p.block(rawBytes[sublist:])
} else {
p.block(rawBytes)
}
} else {
// intermediate render of inline item
para := &ast.Paragraph{}
if sublist > 0 {
para.Content = rawBytes[:sublist]
} else {
para.Content = rawBytes
}
p.addChild(para)
if sublist > 0 {
p.block(rawBytes[sublist:])
}
}
return line
}
// render a single paragraph that has already been parsed out
func (p *Parser) renderParagraph(data []byte) {
if len(data) == 0 {
return
}
// trim leading spaces
beg := skipChar(data, 0, ' ')
end := len(data)
// trim trailing newline
if data[len(data)-1] == '\n' {
end--
}
// trim trailing spaces
for end > beg && data[end-1] == ' ' {
end--
}
para := &ast.Paragraph{}
para.Content = data[beg:end]
p.addBlock(para)
}
// blockMath handle block surround with $$
func (p *Parser) blockMath(data []byte) int {
if len(data) <= 4 || data[0] != '$' || data[1] != '$' || data[2] == '$' {
return 0
}
// find next $$
var end int
for end = 2; end+1 < len(data) && (data[end] != '$' || data[end+1] != '$'); end++ {
}
// $$ not match
if end+1 == len(data) {
return 0
}
// render the display math
mathBlock := &ast.MathBlock{}
mathBlock.Literal = data[2:end]
p.addBlock(mathBlock)
return end + 2
}
func (p *Parser) paragraph(data []byte) int {
// prev: index of 1st char of previous line
// line: index of 1st char of current line
// i: index of cursor/end of current line
var prev, line, i int
tabSize := tabSizeDefault
if p.extensions&TabSizeEight != 0 {
tabSize = tabSizeDouble
}
// keep going until we find something to mark the end of the paragraph
for i < len(data) {
// mark the beginning of the current line
prev = line
current := data[i:]
line = i
// did we find a reference or a footnote? If so, end a paragraph
// preceding it and report that we have consumed up to the end of that
// reference:
if refEnd := isReference(p, current, tabSize); refEnd > 0 {
p.renderParagraph(data[:i])
return i + refEnd
}
// did we find a blank line marking the end of the paragraph?
if n := p.isEmpty(current); n > 0 {
// did this blank line followed by a definition list item?
if p.extensions&DefinitionLists != 0 {
if i < len(data)-1 && data[i+1] == ':' {
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listLen := p.list(data[prev:], ast.ListTypeDefinition, 0, '.')
return prev + listLen
}
}
p.renderParagraph(data[:i])
return i + n
}
// an underline under some text marks a heading, so our paragraph ended on prev line
if i > 0 {
if level := p.isUnderlinedHeading(current); level > 0 {
// render the paragraph
p.renderParagraph(data[:prev])
// ignore leading and trailing whitespace
eol := i - 1
for prev < eol && data[prev] == ' ' {
prev++
}
for eol > prev && data[eol-1] == ' ' {
eol--
}
block := &ast.Heading{
Level: level,
}
if p.extensions&AutoHeadingIDs != 0 {
block.HeadingID = sanitizeHeadingID(string(data[prev:eol]))
p.allHeadingsWithAutoID = append(p.allHeadingsWithAutoID, block)
}
block.Content = data[prev:eol]
p.addBlock(block)
// find the end of the underline
return skipUntilChar(data, i, '\n')
}
}
// if the next line starts a block of HTML, then the paragraph ends here
if p.extensions&LaxHTMLBlocks != 0 {
if data[i] == '<' && p.html(current, false) > 0 {
// rewind to before the HTML block
p.renderParagraph(data[:i])
return i
}
}
// if there's a prefixed heading or a horizontal rule after this, paragraph is over
if p.isPrefixHeading(current) || p.isPrefixSpecialHeading(current) || p.isHRule(current) {
p.renderParagraph(data[:i])
return i
}
// if there's a fenced code block, paragraph is over
if p.extensions&FencedCode != 0 {
if p.fencedCodeBlock(current, false) > 0 {
p.renderParagraph(data[:i])
return i
}
}
// if there's a figure block, paragraph is over
if p.extensions&Mmark != 0 {
if p.figureBlock(current, false) > 0 {
p.renderParagraph(data[:i])
return i
}
}
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// if there's a table, paragraph is over
if p.extensions&Tables != 0 {
if j, _, _ := p.tableHeader(current, false); j > 0 {
p.renderParagraph(data[:i])
return i
}
}
// if there's a definition list item, prev line is a definition term
if p.extensions&DefinitionLists != 0 {
if p.dliPrefix(current) != 0 {
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ret := p.list(data[prev:], ast.ListTypeDefinition, 0, '.')
return ret + prev
}
}
// if there's a list after this, paragraph is over
if p.extensions&NoEmptyLineBeforeBlock != 0 {
if p.uliPrefix(current) != 0 ||
p.oliPrefix(current) != 0 ||
p.quotePrefix(current) != 0 ||
p.codePrefix(current) != 0 {
p.renderParagraph(data[:i])
return i
}
}
// otherwise, scan to the beginning of the next line
nl := bytes.IndexByte(data[i:], '\n')
if nl >= 0 {
i += nl + 1
} else {
i += len(data[i:])
}
}
p.renderParagraph(data[:i])
return i
}
// skipChar advances i as long as data[i] == c
func skipChar(data []byte, i int, c byte) int {
n := len(data)
for i < n && data[i] == c {
i++
}
return i
}
// like skipChar but only skips up to max characters
func skipCharN(data []byte, i int, c byte, max int) int {
n := len(data)
for i < n && max > 0 && data[i] == c {
i++
max--
}
return i
}
// skipUntilChar advances i as long as data[i] != c
func skipUntilChar(data []byte, i int, c byte) int {
n := len(data)
for i < n && data[i] != c {
i++
}
return i
}
func skipAlnum(data []byte, i int) int {
n := len(data)
for i < n && isAlnum(data[i]) {
i++
}
return i
}
func skipSpace(data []byte, i int) int {
n := len(data)
for i < n && isSpace(data[i]) {
i++
}
return i
}
func backChar(data []byte, i int, c byte) int {
for i > 0 && data[i-1] == c {
i--
}
return i
}
func backUntilChar(data []byte, i int, c byte) int {
for i > 0 && data[i-1] != c {
i--
}
return i
}