// // 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. // // // Functions to parse block-level elements. // package blackfriday import ( "bytes" "html" "regexp" "strings" "unicode" ) const ( charEntity = "&(?:#x[a-f0-9]{1,8}|#[0-9]{1,8}|[a-z][a-z0-9]{1,31});" escapable = "[!\"#$%&'()*+,./:;<=>?@[\\\\\\]^_`{|}~-]" ) var ( reBackslashOrAmp = regexp.MustCompile("[\\&]") reEntityOrEscapedChar = regexp.MustCompile("(?i)\\\\" + escapable + "|" + charEntity) ) // Parse block-level data. // Note: this function and many that it calls assume that // the input buffer ends with a newline. func (p *Markdown) 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 { // prefixed heading: // // # Heading 1 // ## Heading 2 // ... // ###### Heading 6 if p.isPrefixHeading(data) { data = data[p.prefixHeading(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) { p.addBlock(HorizontalRule, nil) var i int for i = 0; i < len(data) && data[i] != '\n'; i++ { } 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 } // table: // // Name | Age | Phone // ------|-----|--------- // Bob | 31 | 555-1234 // Alice | 27 | 555-4321 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 { data = data[p.list(data, 0):] continue } // a numbered/ordered list: // // 1. Item 1 // 2. Item 2 if p.oliPrefix(data) > 0 { data = data[p.list(data, ListTypeOrdered):] continue } // definition lists: // // Term 1 // : Definition a // : Definition b // // Term 2 // : Definition c if p.extensions&DefinitionLists != 0 { if p.dliPrefix(data) > 0 { data = data[p.list(data, ListTypeDefinition):] continue } } // anything else must look like a normal paragraph // note: this finds underlined headings, too data = data[p.paragraph(data):] } p.nesting-- } func (p *Markdown) addBlock(typ NodeType, content []byte) *Node { p.closeUnmatchedBlocks() container := p.addChild(typ, 0) container.content = content return container } func (p *Markdown) isPrefixHeading(data []byte) bool { if data[0] != '#' { return false } if p.extensions&SpaceHeadings != 0 { level := 0 for level < 6 && level < len(data) && data[level] == '#' { level++ } if level == len(data) || data[level] != ' ' { return false } } return true } func (p *Markdown) prefixHeading(data []byte) int { level := 0 for level < 6 && level < len(data) && data[level] == '#' { level++ } 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 { if id == "" && p.extensions&AutoHeadingIDs != 0 { id = SanitizedAnchorName(string(data[i:end])) } block := p.addBlock(Heading, data[i:end]) block.HeadingID = id block.Level = level } return skip } func (p *Markdown) 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 *Markdown) 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 := p.addBlock(Heading, data) block.Level = 1 block.IsTitleblock = true return consumed } func (p *Markdown) 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 := i for end > 0 && data[end-1] == '\n' { end-- } finalizeHTMLBlock(p.addBlock(HTMLBlock, data[:end])) } return i } func finalizeHTMLBlock(block *Node) { block.Literal = block.content block.content = nil } // HTML comment, lax form func (p *Markdown) 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 := size for end > 0 && data[end-1] == '\n' { end-- } block := p.addBlock(HTMLBlock, data[:end]) finalizeHTMLBlock(block) } return size } return 0 } // HR, which is the only self-closing block tag considered func (p *Markdown) 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 := size for end > 0 && data[end-1] == '\n' { end-- } finalizeHTMLBlock(p.addBlock(HTMLBlock, data[:end])) } return size } } return 0 } func (p *Markdown) htmlFindTag(data []byte) (string, bool) { i := 0 for i < len(data) && isalnum(data[i]) { i++ } key := string(data[:i]) if _, ok := blockTags[key]; ok { return key, true } return "", false } func (p *Markdown) 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 (*Markdown) 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 } } if i < len(data) && data[i] == '\n' { i++ } return i } func (*Markdown) 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 info is not nil, it gets set to the syntax specified in the fence line. func isFenceLine(data []byte, info *string, oldmarker string) (end int, marker string) { i, size := 0, 0 // skip up to three spaces for i < len(data) && i < 3 && data[i] == ' ' { i++ } // check for the marker characters: ~ or ` if i >= len(data) { return 0, "" } if data[i] != '~' && data[i] != '`' { return 0, "" } c := data[i] // the whole line must be the same char or whitespace for i < len(data) && 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 info string, and discard it if the caller doesn't care. if info != nil { infoLength := 0 i = skipChar(data, i, ' ') if i >= len(data) { if i == len(data) { return i, marker } return 0, "" } infoStart := i if data[i] == '{' { i++ infoStart++ for i < len(data) && data[i] != '}' && data[i] != '\n' { infoLength++ i++ } if i >= len(data) || data[i] != '}' { return 0, "" } // strip all whitespace at the beginning and the end // of the {} block for infoLength > 0 && isspace(data[infoStart]) { infoStart++ infoLength-- } for infoLength > 0 && isspace(data[infoStart+infoLength-1]) { infoLength-- } i++ i = skipChar(data, i, ' ') } else { for i < len(data) && !isverticalspace(data[i]) { infoLength++ i++ } } *info = strings.TrimSpace(string(data[infoStart : infoStart+infoLength])) } if i == len(data) { return i, marker } if i > len(data) || data[i] != '\n' { 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 *Markdown) fencedCodeBlock(data []byte, doRender bool) int { var info string beg, marker := isFenceLine(data, &info, "") if beg == 0 || beg >= len(data) { return 0 } fenceLength := beg - 1 var work bytes.Buffer work.Write([]byte(info)) 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 { block := p.addBlock(CodeBlock, work.Bytes()) // TODO: get rid of temp buffer block.IsFenced = true block.FenceLength = fenceLength finalizeCodeBlock(block) } 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(block *Node) { if block.IsFenced { newlinePos := bytes.IndexByte(block.content, '\n') firstLine := block.content[:newlinePos] rest := block.content[newlinePos+1:] block.Info = unescapeString(bytes.Trim(firstLine, "\n")) block.Literal = rest } else { block.Literal = block.content } block.content = nil } func (p *Markdown) table(data []byte) int { table := p.addBlock(Table, nil) i, columns := p.tableHeader(data) if i == 0 { p.tip = table.Parent table.Unlink() return 0 } p.addBlock(TableBody, nil) for i < len(data) { pipes, rowStart := 0, i for ; i < len(data) && data[i] != '\n'; i++ { if data[i] == '|' { pipes++ } } if pipes == 0 { i = rowStart break } // include the newline in data sent to tableRow if i < len(data) && data[i] == '\n' { i++ } p.tableRow(data[rowStart:i], columns, false) } return i } // check if the specified position is preceded by an odd number of backslashes func isBackslashEscaped(data []byte, i int) bool { backslashes := 0 for i-backslashes-1 >= 0 && data[i-backslashes-1] == '\\' { backslashes++ } return backslashes&1 == 1 } func (p *Markdown) tableHeader(data []byte) (size int, columns []CellAlignFlags) { i := 0 colCount := 1 for i = 0; i < len(data) && data[i] != '\n'; i++ { if data[i] == '|' && !isBackslashEscaped(data, i) { colCount++ } } // doesn't look like a table header if colCount == 1 { return } // include the newline in the data sent to tableRow j := i if j < len(data) && data[j] == '\n' { j++ } header := data[:j] // column count ignores pipes at beginning or end of line if data[0] == '|' { colCount-- } if i > 2 && data[i-1] == '|' && !isBackslashEscaped(data, i-1) { colCount-- } columns = make([]CellAlignFlags, colCount) // move on to the header underline i++ if i >= len(data) { return } if data[i] == '|' && !isBackslashEscaped(data, i) { i++ } i = skipChar(data, i, ' ') // each column header is of form: / *:?-+:? *|/ with # dashes + # colons >= 3 // and trailing | optional on last column col := 0 for i < len(data) && data[i] != '\n' { dashes := 0 if data[i] == ':' { i++ columns[col] |= TableAlignmentLeft dashes++ } for i < len(data) && data[i] == '-' { i++ dashes++ } if i < len(data) && data[i] == ':' { i++ columns[col] |= TableAlignmentRight dashes++ } for i < len(data) && data[i] == ' ' { i++ } if i == len(data) { return } // end of column test is messy switch { case dashes < 3: // not a valid column return case data[i] == '|' && !isBackslashEscaped(data, i): // marker found, now skip past trailing whitespace col++ i++ for i < len(data) && data[i] == ' ' { i++ } // trailing junk found after last column if col >= colCount && i < len(data) && data[i] != '\n' { return } case (data[i] != '|' || isBackslashEscaped(data, i)) && col+1 < colCount: // something else found where marker was required return case data[i] == '\n': // marker is optional for the last column col++ default: // trailing junk found after last column return } } if col != colCount { return } p.addBlock(TableHead, nil) p.tableRow(header, columns, true) size = i if size < len(data) && data[size] == '\n' { size++ } return } func (p *Markdown) tableRow(data []byte, columns []CellAlignFlags, header bool) { p.addBlock(TableRow, nil) i, col := 0, 0 if data[i] == '|' && !isBackslashEscaped(data, i) { i++ } for col = 0; col < len(columns) && i < len(data); col++ { for i < len(data) && data[i] == ' ' { i++ } cellStart := i for i < len(data) && (data[i] != '|' || isBackslashEscaped(data, i)) && data[i] != '\n' { i++ } cellEnd := i // skip the end-of-cell marker, possibly taking us past end of buffer i++ for cellEnd > cellStart && cellEnd-1 < len(data) && data[cellEnd-1] == ' ' { cellEnd-- } cell := p.addBlock(TableCell, data[cellStart:cellEnd]) cell.IsHeader = header cell.Align = columns[col] } // pad it out with empty columns to get the right number for ; col < len(columns); col++ { cell := p.addBlock(TableCell, nil) cell.IsHeader = header cell.Align = columns[col] } // silently ignore rows with too many cells } // returns blockquote prefix length func (p *Markdown) quotePrefix(data []byte) int { i := 0 for i < 3 && i < len(data) && data[i] == ' ' { i++ } if i < len(data) && data[i] == '>' { if i+1 < len(data) && 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 *Markdown) 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 *Markdown) quote(data []byte) int { block := p.addBlock(BlockQuote, nil) 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++ } if end < len(data) && data[end] == '\n' { end++ } 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 } p.block(raw.Bytes()) p.finalize(block) return end } // returns prefix length for block code func (p *Markdown) codePrefix(data []byte) int { if len(data) >= 1 && data[0] == '\t' { return 1 } if len(data) >= 4 && data[0] == ' ' && data[1] == ' ' && data[2] == ' ' && data[3] == ' ' { return 4 } return 0 } func (p *Markdown) code(data []byte) int { var work bytes.Buffer i := 0 for i < len(data) { beg := i for i < len(data) && data[i] != '\n' { i++ } if i < len(data) && data[i] == '\n' { i++ } 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 := len(workbytes) for eol > 0 && workbytes[eol-1] == '\n' { eol-- } if eol != len(workbytes) { work.Truncate(eol) } work.WriteByte('\n') block := p.addBlock(CodeBlock, work.Bytes()) // TODO: get rid of temp buffer block.IsFenced = false finalizeCodeBlock(block) return i } // returns unordered list item prefix func (p *Markdown) uliPrefix(data []byte) int { i := 0 // start with up to 3 spaces for i < len(data) && i < 3 && data[i] == ' ' { i++ } 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 *Markdown) oliPrefix(data []byte) int { i := 0 // start with up to 3 spaces for i < 3 && i < len(data) && data[i] == ' ' { i++ } // 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 if data[i] != '.' || !(data[i+1] == ' ' || data[i+1] == '\t') { return 0 } return i + 2 } // returns definition list item prefix func (p *Markdown) dliPrefix(data []byte) int { if len(data) < 2 { return 0 } i := 0 // need a ':' followed by a space or a tab if data[i] != ':' || !(data[i+1] == ' ' || data[i+1] == '\t') { return 0 } for i < len(data) && data[i] == ' ' { i++ } return i + 2 } // parse ordered or unordered list block func (p *Markdown) list(data []byte, flags ListType) int { i := 0 flags |= ListItemBeginningOfList block := p.addBlock(List, nil) block.ListFlags = flags block.Tight = true for i < len(data) { skip := p.listItem(data[i:], &flags) if flags&ListItemContainsBlock != 0 { block.ListData.Tight = false } i += skip if skip == 0 || flags&ListItemEndOfList != 0 { break } flags &= ^ListItemBeginningOfList } above := block.Parent finalizeList(block) p.tip = above return i } // Returns true if the list item is not the same type as its parent list func (p *Markdown) listTypeChanged(data []byte, flags *ListType) bool { if p.dliPrefix(data) > 0 && *flags&ListTypeDefinition == 0 { return true } else if p.oliPrefix(data) > 0 && *flags&ListTypeOrdered == 0 { return true } else if p.uliPrefix(data) > 0 && (*flags&ListTypeOrdered != 0 || *flags&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 *Node) bool { // TODO: figure this out. Always false now. for block != nil { //if block.lastLineBlank { //return true //} t := block.Type if t == List || t == Item { block = block.LastChild } else { break } } return false } func finalizeList(block *Node) { block.open = false item := block.FirstChild for item != nil { // check for non-final list item ending with blank line: if endsWithBlankLine(item) && item.Next != nil { block.ListData.Tight = false break } // recurse into children of list item, to see if there are spaces // between any of them: subItem := item.FirstChild for subItem != nil { if endsWithBlankLine(subItem) && (item.Next != nil || subItem.Next != nil) { block.ListData.Tight = false break } subItem = subItem.Next } item = item.Next } } // Parse a single list item. // Assumes initial prefix is already removed if this is a sublist. func (p *Markdown) listItem(data []byte, flags *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++ } } var bulletChar byte = '*' i := p.uliPrefix(data) if i == 0 { i = p.oliPrefix(data) } else { bulletChar = data[i-2] } if i == 0 { i = p.dliPrefix(data) // reset definition term flag if i > 0 { *flags &= ^ListTypeTerm } } if i == 0 { // if in definition list, set term flag and continue if *flags&ListTypeDefinition != 0 { *flags |= ListTypeTerm } else { return 0 } } // skip leading whitespace on first line for i < len(data) && data[i] == ' ' { 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 codeBlockMarker := "" 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] if p.extensions&FencedCode != 0 { // determine if in or out of codeblock // if in codeblock, ignore normal list processing _, marker := isFenceLine(chunk, nil, codeBlockMarker) if marker != "" { if codeBlockMarker == "" { // start of codeblock codeBlockMarker = marker } else { // end of codeblock. codeBlockMarker = "" } } // we are in a codeblock, write line, and continue if codeBlockMarker != "" || marker != "" { raw.Write(data[line+indentIndex : i]) line = i continue gatherlines } } // 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 |= ListItemEndOfList } else if containsBlankLine { *flags |= ListItemContainsBlock } break gatherlines } if containsBlankLine { *flags |= ListItemContainsBlock } // is this the first item in the nested list? if sublist == 0 { sublist = raw.Len() } // is this a nested prefix heading? case p.isPrefixHeading(chunk): // if the heading is not indented, it is not nested in the list // and thus ends the list if containsBlankLine && indent < 4 { *flags |= ListItemEndOfList break gatherlines } *flags |= 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&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] != ':' && data[next] != ':' { *flags |= ListItemEndOfList } } else { *flags |= ListItemEndOfList } break gatherlines // a blank line means this should be parsed as a block case containsBlankLine: raw.WriteByte('\n') *flags |= 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() block := p.addBlock(Item, nil) block.ListFlags = *flags block.Tight = false block.BulletChar = bulletChar block.Delimiter = '.' // Only '.' is possible in Markdown, but ')' will also be possible in CommonMark // render the contents of the list item if *flags&ListItemContainsBlock != 0 && *flags&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 if sublist > 0 { child := p.addChild(Paragraph, 0) child.content = rawBytes[:sublist] p.block(rawBytes[sublist:]) } else { child := p.addChild(Paragraph, 0) child.content = rawBytes } } return line } // render a single paragraph that has already been parsed out func (p *Markdown) renderParagraph(data []byte) { if len(data) == 0 { return } // trim leading spaces beg := 0 for data[beg] == ' ' { beg++ } end := len(data) // trim trailing newline if data[len(data)-1] == '\n' { end-- } // trim trailing spaces for end > beg && data[end-1] == ' ' { end-- } p.addBlock(Paragraph, data[beg:end]) } func (p *Markdown) 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] == ':' { return p.list(data[prev:], ListTypeDefinition) } } 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-- } id := "" if p.extensions&AutoHeadingIDs != 0 { id = SanitizedAnchorName(string(data[prev:eol])) } block := p.addBlock(Heading, data[prev:eol]) block.Level = level block.HeadingID = id // find the end of the underline for i < len(data) && data[i] != '\n' { i++ } return i } } // 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.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 definition list item, prev line is a definition term if p.extensions&DefinitionLists != 0 { if p.dliPrefix(current) != 0 { ret := p.list(data[prev:], ListTypeDefinition) return ret } } // 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 } func skipChar(data []byte, start int, char byte) int { i := start for i < len(data) && data[i] == char { i++ } return i } func skipUntilChar(text []byte, start int, char byte) int { i := start for i < len(text) && text[i] != char { i++ } return i } // SanitizedAnchorName returns a sanitized anchor name for the given text. // // It implements the algorithm specified in the package comment. func SanitizedAnchorName(text string) string { var anchorName []rune 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 } } return string(anchorName) }