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Diffstat (limited to 'vendor/github.com/russross/blackfriday/markdown.go')
| -rw-r--r-- | vendor/github.com/russross/blackfriday/markdown.go | 931 |
1 files changed, 931 insertions, 0 deletions
diff --git a/vendor/github.com/russross/blackfriday/markdown.go b/vendor/github.com/russross/blackfriday/markdown.go new file mode 100644 index 00000000..1722a738 --- /dev/null +++ b/vendor/github.com/russross/blackfriday/markdown.go @@ -0,0 +1,931 @@ +// +// 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. +// + +// +// +// Markdown parsing and processing +// +// + +package blackfriday + +import ( + "bytes" + "fmt" + "strings" + "unicode/utf8" +) + +const VERSION = "1.5" + +// These are the supported markdown parsing extensions. +// OR these values together to select multiple extensions. +const ( + EXTENSION_NO_INTRA_EMPHASIS = 1 << iota // ignore emphasis markers inside words + EXTENSION_TABLES // render tables + EXTENSION_FENCED_CODE // render fenced code blocks + EXTENSION_AUTOLINK // detect embedded URLs that are not explicitly marked + EXTENSION_STRIKETHROUGH // strikethrough text using ~~test~~ + EXTENSION_LAX_HTML_BLOCKS // loosen up HTML block parsing rules + EXTENSION_SPACE_HEADERS // be strict about prefix header rules + EXTENSION_HARD_LINE_BREAK // translate newlines into line breaks + EXTENSION_TAB_SIZE_EIGHT // expand tabs to eight spaces instead of four + EXTENSION_FOOTNOTES // Pandoc-style footnotes + EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK // No need to insert an empty line to start a (code, quote, ordered list, unordered list) block + EXTENSION_HEADER_IDS // specify header IDs with {#id} + EXTENSION_TITLEBLOCK // Titleblock ala pandoc + EXTENSION_AUTO_HEADER_IDS // Create the header ID from the text + EXTENSION_BACKSLASH_LINE_BREAK // translate trailing backslashes into line breaks + EXTENSION_DEFINITION_LISTS // render definition lists + EXTENSION_JOIN_LINES // delete newline and join lines + + commonHtmlFlags = 0 | + HTML_USE_XHTML | + HTML_USE_SMARTYPANTS | + HTML_SMARTYPANTS_FRACTIONS | + HTML_SMARTYPANTS_DASHES | + HTML_SMARTYPANTS_LATEX_DASHES + + commonExtensions = 0 | + EXTENSION_NO_INTRA_EMPHASIS | + EXTENSION_TABLES | + EXTENSION_FENCED_CODE | + EXTENSION_AUTOLINK | + EXTENSION_STRIKETHROUGH | + EXTENSION_SPACE_HEADERS | + EXTENSION_HEADER_IDS | + EXTENSION_BACKSLASH_LINE_BREAK | + EXTENSION_DEFINITION_LISTS +) + +// These are the possible flag values for the link renderer. +// Only a single one of these values will be used; they are not ORed together. +// These are mostly of interest if you are writing a new output format. +const ( + LINK_TYPE_NOT_AUTOLINK = iota + LINK_TYPE_NORMAL + LINK_TYPE_EMAIL +) + +// These are the possible flag values for the ListItem renderer. +// Multiple flag values may be ORed together. +// These are mostly of interest if you are writing a new output format. +const ( + LIST_TYPE_ORDERED = 1 << iota + LIST_TYPE_DEFINITION + LIST_TYPE_TERM + LIST_ITEM_CONTAINS_BLOCK + LIST_ITEM_BEGINNING_OF_LIST + LIST_ITEM_END_OF_LIST +) + +// These are the possible flag values for the table cell renderer. +// Only a single one of these values will be used; they are not ORed together. +// These are mostly of interest if you are writing a new output format. +const ( + TABLE_ALIGNMENT_LEFT = 1 << iota + TABLE_ALIGNMENT_RIGHT + TABLE_ALIGNMENT_CENTER = (TABLE_ALIGNMENT_LEFT | TABLE_ALIGNMENT_RIGHT) +) + +// The size of a tab stop. +const ( + TAB_SIZE_DEFAULT = 4 + TAB_SIZE_EIGHT = 8 +) + +// 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. +var blockTags = map[string]struct{}{ + "blockquote": {}, + "del": {}, + "div": {}, + "dl": {}, + "fieldset": {}, + "form": {}, + "h1": {}, + "h2": {}, + "h3": {}, + "h4": {}, + "h5": {}, + "h6": {}, + "iframe": {}, + "ins": {}, + "math": {}, + "noscript": {}, + "ol": {}, + "pre": {}, + "p": {}, + "script": {}, + "style": {}, + "table": {}, + "ul": {}, + + // HTML5 + "address": {}, + "article": {}, + "aside": {}, + "canvas": {}, + "figcaption": {}, + "figure": {}, + "footer": {}, + "header": {}, + "hgroup": {}, + "main": {}, + "nav": {}, + "output": {}, + "progress": {}, + "section": {}, + "video": {}, +} + +// Renderer is the rendering interface. +// This is mostly of interest if you are implementing a new rendering format. +// +// When a byte slice is provided, it contains the (rendered) contents of the +// element. +// +// When a callback is provided instead, it will write the contents of the +// respective element directly to the output buffer and return true on success. +// If the callback returns false, the rendering function should reset the +// output buffer as though it had never been called. +// +// Currently Html and Latex implementations are provided +type Renderer interface { + // block-level callbacks + BlockCode(out *bytes.Buffer, text []byte, lang string) + BlockQuote(out *bytes.Buffer, text []byte) + BlockHtml(out *bytes.Buffer, text []byte) + Header(out *bytes.Buffer, text func() bool, level int, id string) + HRule(out *bytes.Buffer) + List(out *bytes.Buffer, text func() bool, flags int) + ListItem(out *bytes.Buffer, text []byte, flags int) + Paragraph(out *bytes.Buffer, text func() bool) + Table(out *bytes.Buffer, header []byte, body []byte, columnData []int) + TableRow(out *bytes.Buffer, text []byte) + TableHeaderCell(out *bytes.Buffer, text []byte, flags int) + TableCell(out *bytes.Buffer, text []byte, flags int) + Footnotes(out *bytes.Buffer, text func() bool) + FootnoteItem(out *bytes.Buffer, name, text []byte, flags int) + TitleBlock(out *bytes.Buffer, text []byte) + + // Span-level callbacks + AutoLink(out *bytes.Buffer, link []byte, kind int) + CodeSpan(out *bytes.Buffer, text []byte) + DoubleEmphasis(out *bytes.Buffer, text []byte) + Emphasis(out *bytes.Buffer, text []byte) + Image(out *bytes.Buffer, link []byte, title []byte, alt []byte) + LineBreak(out *bytes.Buffer) + Link(out *bytes.Buffer, link []byte, title []byte, content []byte) + RawHtmlTag(out *bytes.Buffer, tag []byte) + TripleEmphasis(out *bytes.Buffer, text []byte) + StrikeThrough(out *bytes.Buffer, text []byte) + FootnoteRef(out *bytes.Buffer, ref []byte, id int) + + // Low-level callbacks + Entity(out *bytes.Buffer, entity []byte) + NormalText(out *bytes.Buffer, text []byte) + + // Header and footer + DocumentHeader(out *bytes.Buffer) + DocumentFooter(out *bytes.Buffer) + + GetFlags() int +} + +// Callback functions for inline parsing. One such function is defined +// for each character that triggers a response when parsing inline data. +type inlineParser func(p *parser, out *bytes.Buffer, data []byte, offset int) int + +// Parser holds runtime state used by the parser. +// This is constructed by the Markdown function. +type parser struct { + r Renderer + refOverride ReferenceOverrideFunc + refs map[string]*reference + inlineCallback [256]inlineParser + flags int + nesting int + maxNesting int + insideLink bool + + // Footnotes need to be ordered as well as available to quickly check for + // presence. If a ref is also a footnote, it's stored both in refs and here + // in notes. Slice is nil if footnotes not enabled. + notes []*reference + notesRecord map[string]struct{} +} + +func (p *parser) getRef(refid string) (ref *reference, found bool) { + if p.refOverride != nil { + r, overridden := p.refOverride(refid) + if overridden { + if r == nil { + return nil, false + } + return &reference{ + link: []byte(r.Link), + title: []byte(r.Title), + noteId: 0, + hasBlock: false, + text: []byte(r.Text)}, true + } + } + // refs are case insensitive + ref, found = p.refs[strings.ToLower(refid)] + return ref, found +} + +func (p *parser) isFootnote(ref *reference) bool { + _, ok := p.notesRecord[string(ref.link)] + return ok +} + +// +// +// Public interface +// +// + +// Reference represents the details of a link. +// See the documentation in Options for more details on use-case. +type Reference struct { + // Link is usually the URL the reference points to. + Link string + // Title is the alternate text describing the link in more detail. + Title string + // Text is the optional text to override the ref with if the syntax used was + // [refid][] + Text string +} + +// ReferenceOverrideFunc is expected to be called with a reference string and +// return either a valid Reference type that the reference string maps to or +// nil. If overridden is false, the default reference logic will be executed. +// See the documentation in Options for more details on use-case. +type ReferenceOverrideFunc func(reference string) (ref *Reference, overridden bool) + +// Options represents configurable overrides and callbacks (in addition to the +// extension flag set) for configuring a Markdown parse. +type Options struct { + // Extensions is a flag set of bit-wise ORed extension bits. See the + // EXTENSION_* flags defined in this package. + Extensions int + + // ReferenceOverride is an optional function callback that is called every + // time a reference is resolved. + // + // In Markdown, the link reference syntax can be made to resolve a link to + // a reference instead of an inline URL, in one of the following ways: + // + // * [link text][refid] + // * [refid][] + // + // Usually, the refid is defined at the bottom of the Markdown document. If + // this override function is provided, the refid is passed to the override + // function first, before consulting the defined refids at the bottom. If + // the override function indicates an override did not occur, the refids at + // the bottom will be used to fill in the link details. + ReferenceOverride ReferenceOverrideFunc +} + +// MarkdownBasic is a convenience function for simple rendering. +// It processes markdown input with no extensions enabled. +func MarkdownBasic(input []byte) []byte { + // set up the HTML renderer + htmlFlags := HTML_USE_XHTML + renderer := HtmlRenderer(htmlFlags, "", "") + + // set up the parser + return MarkdownOptions(input, renderer, Options{Extensions: 0}) +} + +// Call Markdown with most useful extensions enabled +// MarkdownCommon is a convenience function for simple rendering. +// It processes markdown input with common extensions enabled, including: +// +// * Smartypants processing with smart fractions and LaTeX dashes +// +// * Intra-word emphasis suppression +// +// * Tables +// +// * Fenced code blocks +// +// * Autolinking +// +// * Strikethrough support +// +// * Strict header parsing +// +// * Custom Header IDs +func MarkdownCommon(input []byte) []byte { + // set up the HTML renderer + renderer := HtmlRenderer(commonHtmlFlags, "", "") + return MarkdownOptions(input, renderer, Options{ + Extensions: commonExtensions}) +} + +// Markdown is the main rendering function. +// It parses and renders a block of markdown-encoded text. +// The supplied Renderer is used to format the output, and extensions dictates +// which non-standard extensions are enabled. +// +// To use the supplied Html or LaTeX renderers, see HtmlRenderer and +// LatexRenderer, respectively. +func Markdown(input []byte, renderer Renderer, extensions int) []byte { + return MarkdownOptions(input, renderer, Options{ + Extensions: extensions}) +} + +// MarkdownOptions is just like Markdown but takes additional options through +// the Options struct. +func MarkdownOptions(input []byte, renderer Renderer, opts Options) []byte { + // no point in parsing if we can't render + if renderer == nil { + return nil + } + + extensions := opts.Extensions + + // fill in the render structure + p := new(parser) + p.r = renderer + p.flags = extensions + p.refOverride = opts.ReferenceOverride + p.refs = make(map[string]*reference) + p.maxNesting = 16 + p.insideLink = false + + // register inline parsers + p.inlineCallback['*'] = emphasis + p.inlineCallback['_'] = emphasis + if extensions&EXTENSION_STRIKETHROUGH != 0 { + p.inlineCallback['~'] = emphasis + } + p.inlineCallback['`'] = codeSpan + p.inlineCallback['\n'] = lineBreak + p.inlineCallback['['] = link + p.inlineCallback['<'] = leftAngle + p.inlineCallback['\\'] = escape + p.inlineCallback['&'] = entity + + if extensions&EXTENSION_AUTOLINK != 0 { + p.inlineCallback[':'] = autoLink + } + + if extensions&EXTENSION_FOOTNOTES != 0 { + p.notes = make([]*reference, 0) + p.notesRecord = make(map[string]struct{}) + } + + first := firstPass(p, input) + second := secondPass(p, first) + return second +} + +// first pass: +// - normalize newlines +// - extract references (outside of fenced code blocks) +// - expand tabs (outside of fenced code blocks) +// - copy everything else +func firstPass(p *parser, input []byte) []byte { + var out bytes.Buffer + tabSize := TAB_SIZE_DEFAULT + if p.flags&EXTENSION_TAB_SIZE_EIGHT != 0 { + tabSize = TAB_SIZE_EIGHT + } + beg := 0 + lastFencedCodeBlockEnd := 0 + for beg < len(input) { + // Find end of this line, then process the line. + end := beg + for end < len(input) && input[end] != '\n' && input[end] != '\r' { + end++ + } + + if p.flags&EXTENSION_FENCED_CODE != 0 { + // track fenced code block boundaries to suppress tab expansion + // and reference extraction inside them: + if beg >= lastFencedCodeBlockEnd { + if i := p.fencedCodeBlock(&out, input[beg:], false); i > 0 { + lastFencedCodeBlockEnd = beg + i + } + } + } + + // add the line body if present + if end > beg { + if end < lastFencedCodeBlockEnd { // Do not expand tabs while inside fenced code blocks. + out.Write(input[beg:end]) + } else if refEnd := isReference(p, input[beg:], tabSize); refEnd > 0 { + beg += refEnd + continue + } else { + expandTabs(&out, input[beg:end], tabSize) + } + } + + if end < len(input) && input[end] == '\r' { + end++ + } + if end < len(input) && input[end] == '\n' { + end++ + } + out.WriteByte('\n') + + beg = end + } + + // empty input? + if out.Len() == 0 { + out.WriteByte('\n') + } + + return out.Bytes() +} + +// second pass: actual rendering +func secondPass(p *parser, input []byte) []byte { + var output bytes.Buffer + + p.r.DocumentHeader(&output) + p.block(&output, input) + + if p.flags&EXTENSION_FOOTNOTES != 0 && len(p.notes) > 0 { + p.r.Footnotes(&output, func() bool { + flags := LIST_ITEM_BEGINNING_OF_LIST + for i := 0; i < len(p.notes); i += 1 { + ref := p.notes[i] + var buf bytes.Buffer + if ref.hasBlock { + flags |= LIST_ITEM_CONTAINS_BLOCK + p.block(&buf, ref.title) + } else { + p.inline(&buf, ref.title) + } + p.r.FootnoteItem(&output, ref.link, buf.Bytes(), flags) + flags &^= LIST_ITEM_BEGINNING_OF_LIST | LIST_ITEM_CONTAINS_BLOCK + } + + return true + }) + } + + p.r.DocumentFooter(&output) + + if p.nesting != 0 { + panic("Nesting level did not end at zero") + } + + return output.Bytes() +} + +// +// Link references +// +// This section implements support for references that (usually) appear +// as footnotes in a document, and can be referenced anywhere in the document. +// The basic format is: +// +// [1]: http://www.google.com/ "Google" +// [2]: http://www.github.com/ "Github" +// +// Anywhere in the document, the reference can be linked by referring to its +// label, i.e., 1 and 2 in this example, as in: +// +// This library is hosted on [Github][2], a git hosting site. +// +// Actual footnotes as specified in Pandoc and supported by some other Markdown +// libraries such as php-markdown are also taken care of. They look like this: +// +// This sentence needs a bit of further explanation.[^note] +// +// [^note]: This is the explanation. +// +// Footnotes should be placed at the end of the document in an ordered list. +// Inline footnotes such as: +// +// Inline footnotes^[Not supported.] also exist. +// +// are not yet supported. + +// References are parsed and stored in this struct. +type reference struct { + link []byte + title []byte + noteId int // 0 if not a footnote ref + hasBlock bool + text []byte +} + +func (r *reference) String() string { + return fmt.Sprintf("{link: %q, title: %q, text: %q, noteId: %d, hasBlock: %v}", + r.link, r.title, r.text, r.noteId, r.hasBlock) +} + +// Check whether or not data starts with a reference link. +// If so, it is parsed and stored in the list of references +// (in the render struct). +// Returns the number of bytes to skip to move past it, +// or zero if the first line is not a reference. +func isReference(p *parser, data []byte, tabSize int) int { + // up to 3 optional leading spaces + if len(data) < 4 { + return 0 + } + i := 0 + for i < 3 && data[i] == ' ' { + i++ + } + + noteId := 0 + + // id part: anything but a newline between brackets + if data[i] != '[' { + return 0 + } + i++ + if p.flags&EXTENSION_FOOTNOTES != 0 { + if i < len(data) && data[i] == '^' { + // we can set it to anything here because the proper noteIds will + // be assigned later during the second pass. It just has to be != 0 + noteId = 1 + i++ + } + } + idOffset := i + for i < len(data) && data[i] != '\n' && data[i] != '\r' && data[i] != ']' { + i++ + } + if i >= len(data) || data[i] != ']' { + return 0 + } + idEnd := i + + // spacer: colon (space | tab)* newline? (space | tab)* + i++ + if i >= len(data) || data[i] != ':' { + return 0 + } + i++ + for i < len(data) && (data[i] == ' ' || data[i] == '\t') { + i++ + } + if i < len(data) && (data[i] == '\n' || data[i] == '\r') { + i++ + if i < len(data) && data[i] == '\n' && data[i-1] == '\r' { + i++ + } + } + for i < len(data) && (data[i] == ' ' || data[i] == '\t') { + i++ + } + if i >= len(data) { + return 0 + } + + var ( + linkOffset, linkEnd int + titleOffset, titleEnd int + lineEnd int + raw []byte + hasBlock bool + ) + + if p.flags&EXTENSION_FOOTNOTES != 0 && noteId != 0 { + linkOffset, linkEnd, raw, hasBlock = scanFootnote(p, data, i, tabSize) + lineEnd = linkEnd + } else { + linkOffset, linkEnd, titleOffset, titleEnd, lineEnd = scanLinkRef(p, data, i) + } + if lineEnd == 0 { + return 0 + } + + // a valid ref has been found + + ref := &reference{ + noteId: noteId, + hasBlock: hasBlock, + } + + if noteId > 0 { + // reusing the link field for the id since footnotes don't have links + ref.link = data[idOffset:idEnd] + // if footnote, it's not really a title, it's the contained text + ref.title = raw + } else { + ref.link = data[linkOffset:linkEnd] + ref.title = data[titleOffset:titleEnd] + } + + // id matches are case-insensitive + id := string(bytes.ToLower(data[idOffset:idEnd])) + + p.refs[id] = ref + + return lineEnd +} + +func scanLinkRef(p *parser, data []byte, i int) (linkOffset, linkEnd, titleOffset, titleEnd, lineEnd int) { + // link: whitespace-free sequence, optionally between angle brackets + if data[i] == '<' { + i++ + } + linkOffset = i + if i == len(data) { + return + } + for i < len(data) && data[i] != ' ' && data[i] != '\t' && data[i] != '\n' && data[i] != '\r' { + i++ + } + linkEnd = i + if data[linkOffset] == '<' && data[linkEnd-1] == '>' { + linkOffset++ + linkEnd-- + } + + // optional spacer: (space | tab)* (newline | '\'' | '"' | '(' ) + for i < len(data) && (data[i] == ' ' || data[i] == '\t') { + i++ + } + if i < len(data) && data[i] != '\n' && data[i] != '\r' && data[i] != '\'' && data[i] != '"' && data[i] != '(' { + return + } + + // compute end-of-line + if i >= len(data) || data[i] == '\r' || data[i] == '\n' { + lineEnd = i + } + if i+1 < len(data) && data[i] == '\r' && data[i+1] == '\n' { + lineEnd++ + } + + // optional (space|tab)* spacer after a newline + if lineEnd > 0 { + i = lineEnd + 1 + for i < len(data) && (data[i] == ' ' || data[i] == '\t') { + i++ + } + } + + // optional title: any non-newline sequence enclosed in '"() alone on its line + if i+1 < len(data) && (data[i] == '\'' || data[i] == '"' || data[i] == '(') { + i++ + titleOffset = i + + // look for EOL + for i < len(data) && data[i] != '\n' && data[i] != '\r' { + i++ + } + if i+1 < len(data) && data[i] == '\n' && data[i+1] == '\r' { + titleEnd = i + 1 + } else { + titleEnd = i + } + + // step back + i-- + for i > titleOffset && (data[i] == ' ' || data[i] == '\t') { + i-- + } + if i > titleOffset && (data[i] == '\'' || data[i] == '"' || data[i] == ')') { + lineEnd = titleEnd + titleEnd = i + } + } + + return +} + +// The first bit of this logic is the same as (*parser).listItem, but the rest +// is much simpler. This function simply finds the entire block and shifts it +// over by one tab if it is indeed a block (just returns the line if it's not). +// blockEnd is the end of the section in the input buffer, and contents is the +// extracted text that was shifted over one tab. It will need to be rendered at +// the end of the document. +func scanFootnote(p *parser, data []byte, i, indentSize int) (blockStart, blockEnd int, contents []byte, hasBlock bool) { + if i == 0 || len(data) == 0 { + return + } + + // skip leading whitespace on first line + for i < len(data) && data[i] == ' ' { + i++ + } + + blockStart = i + + // find the end of the line + blockEnd = i + for 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[blockEnd:i]) + blockEnd = i + + // process the following lines + containsBlankLine := false + +gatherLines: + for blockEnd < 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[blockEnd:i]) > 0 { + containsBlankLine = true + blockEnd = i + continue + } + + n := 0 + if n = isIndented(data[blockEnd:i], indentSize); n == 0 { + // this is the end of the block. + // we don't want to include this last line in the index. + break gatherLines + } + + // if there were blank lines before this one, insert a new one now + if containsBlankLine { + raw.WriteByte('\n') + containsBlankLine = false + } + + // get rid of that first tab, write to buffer + raw.Write(data[blockEnd+n : i]) + hasBlock = true + + blockEnd = i + } + + if data[blockEnd-1] != '\n' { + raw.WriteByte('\n') + } + + contents = raw.Bytes() + + return +} + +// +// +// Miscellaneous helper functions +// +// + +// Test if a character is a punctuation symbol. +// Taken from a private function in regexp in the stdlib. +func ispunct(c byte) bool { + for _, r := range []byte("!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~") { + if c == r { + return true + } + } + return false +} + +// Test if a character is a whitespace character. +func isspace(c byte) bool { + return c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == '\f' || c == '\v' +} + +// Test if a character is letter. +func isletter(c byte) bool { + return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') +} + +// Test if a character is a letter or a digit. +// TODO: check when this is looking for ASCII alnum and when it should use unicode +func isalnum(c byte) bool { + return (c >= '0' && c <= '9') || isletter(c) +} + +// Replace tab characters with spaces, aligning to the next TAB_SIZE column. +// always ends output with a newline +func expandTabs(out *bytes.Buffer, line []byte, tabSize int) { + // first, check for common cases: no tabs, or only tabs at beginning of line + i, prefix := 0, 0 + slowcase := false + for i = 0; i < len(line); i++ { + if line[i] == '\t' { + if prefix == i { + prefix++ + } else { + slowcase = true + break + } + } + } + + // no need to decode runes if all tabs are at the beginning of the line + if !slowcase { + for i = 0; i < prefix*tabSize; i++ { + out.WriteByte(' ') + } + out.Write(line[prefix:]) + return + } + + // the slow case: we need to count runes to figure out how + // many spaces to insert for each tab + column := 0 + i = 0 + for i < len(line) { + start := i + for i < len(line) && line[i] != '\t' { + _, size := utf8.DecodeRune(line[i:]) + i += size + column++ + } + + if i > start { + out.Write(line[start:i]) + } + + if i >= len(line) { + break + } + + for { + out.WriteByte(' ') + column++ + if column%tabSize == 0 { + break + } + } + + i++ + } +} + +// Find if a line counts as indented or not. +// Returns number of characters the indent is (0 = not indented). +func isIndented(data []byte, indentSize int) int { + if len(data) == 0 { + return 0 + } + if data[0] == '\t' { + return 1 + } + if len(data) < indentSize { + return 0 + } + for i := 0; i < indentSize; i++ { + if data[i] != ' ' { + return 0 + } + } + return indentSize +} + +// Create a url-safe slug for fragments +func slugify(in []byte) []byte { + if len(in) == 0 { + return in + } + out := make([]byte, 0, len(in)) + sym := false + + for _, ch := range in { + if isalnum(ch) { + sym = false + out = append(out, ch) + } else if sym { + continue + } else { + out = append(out, '-') + sym = true + } + } + var a, b int + var ch byte + for a, ch = range out { + if ch != '-' { + break + } + } + for b = len(out) - 1; b > 0; b-- { + if out[b] != '-' { + break + } + } + return out[a : b+1] +} |