mirror of
https://github.com/go-gitea/gitea
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927 lines
24 KiB
Go
927 lines
24 KiB
Go
//
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// Blackfriday Markdown Processor
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// Available at http://github.com/russross/blackfriday
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//
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// Copyright © 2011 Russ Ross <russ@russross.com>.
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// Distributed under the Simplified BSD License.
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// See README.md for details.
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//
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//
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//
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// Markdown parsing and processing
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//
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//
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// Blackfriday markdown processor.
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//
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// Translates plain text with simple formatting rules into HTML or LaTeX.
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package blackfriday
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import (
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"bytes"
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"fmt"
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"strings"
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"unicode/utf8"
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)
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const VERSION = "1.5"
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// These are the supported markdown parsing extensions.
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// OR these values together to select multiple extensions.
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const (
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EXTENSION_NO_INTRA_EMPHASIS = 1 << iota // ignore emphasis markers inside words
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EXTENSION_TABLES // render tables
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EXTENSION_FENCED_CODE // render fenced code blocks
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EXTENSION_AUTOLINK // detect embedded URLs that are not explicitly marked
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EXTENSION_STRIKETHROUGH // strikethrough text using ~~test~~
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EXTENSION_LAX_HTML_BLOCKS // loosen up HTML block parsing rules
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EXTENSION_SPACE_HEADERS // be strict about prefix header rules
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EXTENSION_HARD_LINE_BREAK // translate newlines into line breaks
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EXTENSION_TAB_SIZE_EIGHT // expand tabs to eight spaces instead of four
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EXTENSION_FOOTNOTES // Pandoc-style footnotes
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EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK // No need to insert an empty line to start a (code, quote, ordered list, unordered list) block
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EXTENSION_HEADER_IDS // specify header IDs with {#id}
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EXTENSION_TITLEBLOCK // Titleblock ala pandoc
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EXTENSION_AUTO_HEADER_IDS // Create the header ID from the text
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EXTENSION_BACKSLASH_LINE_BREAK // translate trailing backslashes into line breaks
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EXTENSION_DEFINITION_LISTS // render definition lists
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commonHtmlFlags = 0 |
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HTML_USE_XHTML |
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HTML_USE_SMARTYPANTS |
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HTML_SMARTYPANTS_FRACTIONS |
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HTML_SMARTYPANTS_DASHES |
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HTML_SMARTYPANTS_LATEX_DASHES
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commonExtensions = 0 |
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EXTENSION_NO_INTRA_EMPHASIS |
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EXTENSION_TABLES |
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EXTENSION_FENCED_CODE |
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EXTENSION_AUTOLINK |
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EXTENSION_STRIKETHROUGH |
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EXTENSION_SPACE_HEADERS |
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EXTENSION_HEADER_IDS |
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EXTENSION_BACKSLASH_LINE_BREAK |
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EXTENSION_DEFINITION_LISTS
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)
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// These are the possible flag values for the link renderer.
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// Only a single one of these values will be used; they are not ORed together.
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// These are mostly of interest if you are writing a new output format.
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const (
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LINK_TYPE_NOT_AUTOLINK = iota
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LINK_TYPE_NORMAL
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LINK_TYPE_EMAIL
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)
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// These are the possible flag values for the ListItem renderer.
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// Multiple flag values may be ORed together.
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// These are mostly of interest if you are writing a new output format.
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const (
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LIST_TYPE_ORDERED = 1 << iota
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LIST_TYPE_DEFINITION
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LIST_TYPE_TERM
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LIST_ITEM_CONTAINS_BLOCK
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LIST_ITEM_BEGINNING_OF_LIST
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LIST_ITEM_END_OF_LIST
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)
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// These are the possible flag values for the table cell renderer.
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// Only a single one of these values will be used; they are not ORed together.
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// These are mostly of interest if you are writing a new output format.
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const (
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TABLE_ALIGNMENT_LEFT = 1 << iota
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TABLE_ALIGNMENT_RIGHT
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TABLE_ALIGNMENT_CENTER = (TABLE_ALIGNMENT_LEFT | TABLE_ALIGNMENT_RIGHT)
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)
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// The size of a tab stop.
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const (
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TAB_SIZE_DEFAULT = 4
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TAB_SIZE_EIGHT = 8
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)
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// blockTags is a set of tags that are recognized as HTML block tags.
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// Any of these can be included in markdown text without special escaping.
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var blockTags = map[string]struct{}{
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"blockquote": {},
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"del": {},
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"div": {},
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"dl": {},
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"fieldset": {},
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"form": {},
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"h1": {},
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"h2": {},
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"h3": {},
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"h4": {},
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"h5": {},
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"h6": {},
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"iframe": {},
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"ins": {},
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"math": {},
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"noscript": {},
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"ol": {},
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"pre": {},
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"p": {},
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"script": {},
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"style": {},
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"table": {},
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"ul": {},
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// HTML5
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"address": {},
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"article": {},
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"aside": {},
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"canvas": {},
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"figcaption": {},
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"figure": {},
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"footer": {},
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"header": {},
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"hgroup": {},
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"main": {},
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"nav": {},
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"output": {},
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"progress": {},
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"section": {},
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"video": {},
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}
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// Renderer is the rendering interface.
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// This is mostly of interest if you are implementing a new rendering format.
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//
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// When a byte slice is provided, it contains the (rendered) contents of the
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// element.
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//
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// When a callback is provided instead, it will write the contents of the
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// respective element directly to the output buffer and return true on success.
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// If the callback returns false, the rendering function should reset the
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// output buffer as though it had never been called.
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//
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// Currently Html and Latex implementations are provided
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type Renderer interface {
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// block-level callbacks
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BlockCode(out *bytes.Buffer, text []byte, lang string)
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BlockQuote(out *bytes.Buffer, text []byte)
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BlockHtml(out *bytes.Buffer, text []byte)
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Header(out *bytes.Buffer, text func() bool, level int, id string)
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HRule(out *bytes.Buffer)
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List(out *bytes.Buffer, text func() bool, flags int)
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ListItem(out *bytes.Buffer, text []byte, flags int)
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Paragraph(out *bytes.Buffer, text func() bool)
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Table(out *bytes.Buffer, header []byte, body []byte, columnData []int)
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TableRow(out *bytes.Buffer, text []byte)
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TableHeaderCell(out *bytes.Buffer, text []byte, flags int)
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TableCell(out *bytes.Buffer, text []byte, flags int)
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Footnotes(out *bytes.Buffer, text func() bool)
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FootnoteItem(out *bytes.Buffer, name, text []byte, flags int)
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TitleBlock(out *bytes.Buffer, text []byte)
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// Span-level callbacks
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AutoLink(out *bytes.Buffer, link []byte, kind int)
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CodeSpan(out *bytes.Buffer, text []byte)
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DoubleEmphasis(out *bytes.Buffer, text []byte)
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Emphasis(out *bytes.Buffer, text []byte)
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Image(out *bytes.Buffer, link []byte, title []byte, alt []byte)
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LineBreak(out *bytes.Buffer)
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Link(out *bytes.Buffer, link []byte, title []byte, content []byte)
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RawHtmlTag(out *bytes.Buffer, tag []byte)
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TripleEmphasis(out *bytes.Buffer, text []byte)
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StrikeThrough(out *bytes.Buffer, text []byte)
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FootnoteRef(out *bytes.Buffer, ref []byte, id int)
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// Low-level callbacks
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Entity(out *bytes.Buffer, entity []byte)
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NormalText(out *bytes.Buffer, text []byte)
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// Header and footer
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DocumentHeader(out *bytes.Buffer)
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DocumentFooter(out *bytes.Buffer)
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GetFlags() int
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}
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// Callback functions for inline parsing. One such function is defined
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// for each character that triggers a response when parsing inline data.
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type inlineParser func(p *parser, out *bytes.Buffer, data []byte, offset int) int
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// Parser holds runtime state used by the parser.
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// This is constructed by the Markdown function.
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type parser struct {
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r Renderer
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refOverride ReferenceOverrideFunc
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refs map[string]*reference
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inlineCallback [256]inlineParser
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flags int
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nesting int
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maxNesting int
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insideLink bool
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// Footnotes need to be ordered as well as available to quickly check for
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// presence. If a ref is also a footnote, it's stored both in refs and here
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// in notes. Slice is nil if footnotes not enabled.
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notes []*reference
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}
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func (p *parser) getRef(refid string) (ref *reference, found bool) {
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if p.refOverride != nil {
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r, overridden := p.refOverride(refid)
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if overridden {
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if r == nil {
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return nil, false
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}
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return &reference{
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link: []byte(r.Link),
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title: []byte(r.Title),
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noteId: 0,
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hasBlock: false,
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text: []byte(r.Text)}, true
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}
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}
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// refs are case insensitive
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ref, found = p.refs[strings.ToLower(refid)]
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return ref, found
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}
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//
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//
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// Public interface
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//
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//
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// Reference represents the details of a link.
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// See the documentation in Options for more details on use-case.
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type Reference struct {
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// Link is usually the URL the reference points to.
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Link string
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// Title is the alternate text describing the link in more detail.
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Title string
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// Text is the optional text to override the ref with if the syntax used was
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// [refid][]
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Text string
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}
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// ReferenceOverrideFunc is expected to be called with a reference string and
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// return either a valid Reference type that the reference string maps to or
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// nil. If overridden is false, the default reference logic will be executed.
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// See the documentation in Options for more details on use-case.
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type ReferenceOverrideFunc func(reference string) (ref *Reference, overridden bool)
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// Options represents configurable overrides and callbacks (in addition to the
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// extension flag set) for configuring a Markdown parse.
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type Options struct {
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// Extensions is a flag set of bit-wise ORed extension bits. See the
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// EXTENSION_* flags defined in this package.
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Extensions int
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// ReferenceOverride is an optional function callback that is called every
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// time a reference is resolved.
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//
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// In Markdown, the link reference syntax can be made to resolve a link to
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// a reference instead of an inline URL, in one of the following ways:
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//
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// * [link text][refid]
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// * [refid][]
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//
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// Usually, the refid is defined at the bottom of the Markdown document. If
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// this override function is provided, the refid is passed to the override
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// function first, before consulting the defined refids at the bottom. If
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// the override function indicates an override did not occur, the refids at
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// the bottom will be used to fill in the link details.
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ReferenceOverride ReferenceOverrideFunc
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}
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// MarkdownBasic is a convenience function for simple rendering.
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// It processes markdown input with no extensions enabled.
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func MarkdownBasic(input []byte) []byte {
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// set up the HTML renderer
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htmlFlags := HTML_USE_XHTML
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renderer := HtmlRenderer(htmlFlags, "", "")
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// set up the parser
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return MarkdownOptions(input, renderer, Options{Extensions: 0})
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}
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// Call Markdown with most useful extensions enabled
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// MarkdownCommon is a convenience function for simple rendering.
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// It processes markdown input with common extensions enabled, including:
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//
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// * Smartypants processing with smart fractions and LaTeX dashes
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//
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// * Intra-word emphasis suppression
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//
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// * Tables
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//
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// * Fenced code blocks
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//
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// * Autolinking
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//
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// * Strikethrough support
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//
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// * Strict header parsing
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//
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// * Custom Header IDs
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func MarkdownCommon(input []byte) []byte {
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// set up the HTML renderer
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renderer := HtmlRenderer(commonHtmlFlags, "", "")
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return MarkdownOptions(input, renderer, Options{
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Extensions: commonExtensions})
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}
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// Markdown is the main rendering function.
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// It parses and renders a block of markdown-encoded text.
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// The supplied Renderer is used to format the output, and extensions dictates
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// which non-standard extensions are enabled.
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//
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// To use the supplied Html or LaTeX renderers, see HtmlRenderer and
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// LatexRenderer, respectively.
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func Markdown(input []byte, renderer Renderer, extensions int) []byte {
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return MarkdownOptions(input, renderer, Options{
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Extensions: extensions})
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}
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// MarkdownOptions is just like Markdown but takes additional options through
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// the Options struct.
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func MarkdownOptions(input []byte, renderer Renderer, opts Options) []byte {
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// no point in parsing if we can't render
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if renderer == nil {
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return nil
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}
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extensions := opts.Extensions
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// fill in the render structure
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p := new(parser)
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p.r = renderer
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p.flags = extensions
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p.refOverride = opts.ReferenceOverride
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p.refs = make(map[string]*reference)
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p.maxNesting = 16
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p.insideLink = false
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// register inline parsers
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p.inlineCallback['*'] = emphasis
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p.inlineCallback['_'] = emphasis
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if extensions&EXTENSION_STRIKETHROUGH != 0 {
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p.inlineCallback['~'] = emphasis
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}
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p.inlineCallback['`'] = codeSpan
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p.inlineCallback['\n'] = lineBreak
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p.inlineCallback['['] = link
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p.inlineCallback['<'] = leftAngle
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p.inlineCallback['\\'] = escape
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p.inlineCallback['&'] = entity
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if extensions&EXTENSION_AUTOLINK != 0 {
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p.inlineCallback[':'] = autoLink
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}
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if extensions&EXTENSION_FOOTNOTES != 0 {
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p.notes = make([]*reference, 0)
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}
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first := firstPass(p, input)
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second := secondPass(p, first)
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return second
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}
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// first pass:
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// - normalize newlines
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// - extract references (outside of fenced code blocks)
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// - expand tabs (outside of fenced code blocks)
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// - copy everything else
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func firstPass(p *parser, input []byte) []byte {
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var out bytes.Buffer
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tabSize := TAB_SIZE_DEFAULT
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if p.flags&EXTENSION_TAB_SIZE_EIGHT != 0 {
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tabSize = TAB_SIZE_EIGHT
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}
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beg := 0
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lastFencedCodeBlockEnd := 0
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for beg < len(input) {
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// Find end of this line, then process the line.
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end := beg
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for end < len(input) && input[end] != '\n' && input[end] != '\r' {
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end++
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}
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if p.flags&EXTENSION_FENCED_CODE != 0 {
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// track fenced code block boundaries to suppress tab expansion
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// and reference extraction inside them:
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if beg >= lastFencedCodeBlockEnd {
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if i := p.fencedCodeBlock(&out, input[beg:], false); i > 0 {
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lastFencedCodeBlockEnd = beg + i
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}
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}
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}
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// add the line body if present
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if end > beg {
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if end < lastFencedCodeBlockEnd { // Do not expand tabs while inside fenced code blocks.
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out.Write(input[beg:end])
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} else if refEnd := isReference(p, input[beg:], tabSize); refEnd > 0 {
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beg += refEnd
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continue
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} else {
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expandTabs(&out, input[beg:end], tabSize)
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}
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}
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if end < len(input) && input[end] == '\r' {
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end++
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}
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if end < len(input) && input[end] == '\n' {
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end++
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}
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out.WriteByte('\n')
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beg = end
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}
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// empty input?
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if out.Len() == 0 {
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out.WriteByte('\n')
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}
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return out.Bytes()
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}
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// second pass: actual rendering
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func secondPass(p *parser, input []byte) []byte {
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var output bytes.Buffer
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p.r.DocumentHeader(&output)
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p.block(&output, input)
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if p.flags&EXTENSION_FOOTNOTES != 0 && len(p.notes) > 0 {
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p.r.Footnotes(&output, func() bool {
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flags := LIST_ITEM_BEGINNING_OF_LIST
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for i := 0; i < len(p.notes); i += 1 {
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ref := p.notes[i]
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var buf bytes.Buffer
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if ref.hasBlock {
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flags |= LIST_ITEM_CONTAINS_BLOCK
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p.block(&buf, ref.title)
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} else {
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p.inline(&buf, ref.title)
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}
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p.r.FootnoteItem(&output, ref.link, buf.Bytes(), flags)
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flags &^= LIST_ITEM_BEGINNING_OF_LIST | LIST_ITEM_CONTAINS_BLOCK
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}
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return true
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})
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}
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p.r.DocumentFooter(&output)
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if p.nesting != 0 {
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panic("Nesting level did not end at zero")
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}
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return output.Bytes()
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}
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|
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//
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// Link references
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//
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// This section implements support for references that (usually) appear
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// as footnotes in a document, and can be referenced anywhere in the document.
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// The basic format is:
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//
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// [1]: http://www.google.com/ "Google"
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// [2]: http://www.github.com/ "Github"
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//
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// Anywhere in the document, the reference can be linked by referring to its
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// label, i.e., 1 and 2 in this example, as in:
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//
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// This library is hosted on [Github][2], a git hosting site.
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//
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// Actual footnotes as specified in Pandoc and supported by some other Markdown
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// libraries such as php-markdown are also taken care of. They look like this:
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//
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// This sentence needs a bit of further explanation.[^note]
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//
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// [^note]: This is the explanation.
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//
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// Footnotes should be placed at the end of the document in an ordered list.
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// Inline footnotes such as:
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//
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// Inline footnotes^[Not supported.] also exist.
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//
|
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// are not yet supported.
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|
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// References are parsed and stored in this struct.
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type reference struct {
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link []byte
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title []byte
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noteId int // 0 if not a footnote ref
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hasBlock bool
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text []byte
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}
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|
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func (r *reference) String() string {
|
|
return fmt.Sprintf("{link: %q, title: %q, text: %q, noteId: %d, hasBlock: %v}",
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r.link, r.title, r.text, r.noteId, r.hasBlock)
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}
|
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|
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// Check whether or not data starts with a reference link.
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// 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]
|
|
}
|