88c2e24360
This PR adds mathematical rendering with KaTeX. The first step is to add a Goldmark extension that detects the latex (and tex) mathematics delimiters. The second step to make this extension only run if math support is enabled. The second step is to then add KaTeX CSS and JS to the head which will load after the dom is rendered. Fix #3445 Signed-off-by: Andrew Thornton <art27@cantab.net> Signed-off-by: Andrew Thornton <art27@cantab.net> Co-authored-by: silverwind <me@silverwind.io> Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
123 lines
3.4 KiB
Go
123 lines
3.4 KiB
Go
// Copyright 2022 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package math
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import (
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"bytes"
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"github.com/yuin/goldmark/ast"
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"github.com/yuin/goldmark/parser"
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"github.com/yuin/goldmark/text"
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"github.com/yuin/goldmark/util"
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)
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type blockParser struct {
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parseDollars bool
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}
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// NewBlockParser creates a new math BlockParser
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func NewBlockParser(parseDollarBlocks bool) parser.BlockParser {
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return &blockParser{
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parseDollars: parseDollarBlocks,
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}
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}
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// Open parses the current line and returns a result of parsing.
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func (b *blockParser) Open(parent ast.Node, reader text.Reader, pc parser.Context) (ast.Node, parser.State) {
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line, segment := reader.PeekLine()
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pos := pc.BlockOffset()
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if pos == -1 || len(line[pos:]) < 2 {
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return nil, parser.NoChildren
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}
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dollars := false
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if b.parseDollars && line[pos] == '$' && line[pos+1] == '$' {
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dollars = true
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} else if line[pos] != '\\' || line[pos+1] != '[' {
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return nil, parser.NoChildren
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}
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node := NewBlock(dollars, pos)
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// Now we need to check if the ending block is on the segment...
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endBytes := []byte{'\\', ']'}
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if dollars {
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endBytes = []byte{'$', '$'}
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}
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idx := bytes.Index(line[pos+2:], endBytes)
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if idx >= 0 {
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segment.Stop = segment.Start + idx + 2
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reader.Advance(segment.Len() - 1)
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segment.Start += 2
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node.Lines().Append(segment)
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node.Closed = true
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return node, parser.Close | parser.NoChildren
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}
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reader.Advance(segment.Len() - 1)
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segment.Start += 2
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node.Lines().Append(segment)
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return node, parser.NoChildren
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}
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// Continue parses the current line and returns a result of parsing.
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func (b *blockParser) Continue(node ast.Node, reader text.Reader, pc parser.Context) parser.State {
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block := node.(*Block)
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if block.Closed {
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return parser.Close
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}
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line, segment := reader.PeekLine()
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w, pos := util.IndentWidth(line, 0)
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if w < 4 {
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if block.Dollars {
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i := pos
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for ; i < len(line) && line[i] == '$'; i++ {
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}
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length := i - pos
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if length >= 2 && util.IsBlank(line[i:]) {
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reader.Advance(segment.Stop - segment.Start - segment.Padding)
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block.Closed = true
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return parser.Close
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}
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} else if len(line[pos:]) > 1 && line[pos] == '\\' && line[pos+1] == ']' && util.IsBlank(line[pos+2:]) {
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reader.Advance(segment.Stop - segment.Start - segment.Padding)
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block.Closed = true
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return parser.Close
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}
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}
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pos, padding := util.IndentPosition(line, 0, block.Indent)
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seg := text.NewSegmentPadding(segment.Start+pos, segment.Stop, padding)
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node.Lines().Append(seg)
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reader.AdvanceAndSetPadding(segment.Stop-segment.Start-pos-1, padding)
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return parser.Continue | parser.NoChildren
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}
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// Close will be called when the parser returns Close.
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func (b *blockParser) Close(node ast.Node, reader text.Reader, pc parser.Context) {
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// noop
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}
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// CanInterruptParagraph returns true if the parser can interrupt paragraphs,
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// otherwise false.
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func (b *blockParser) CanInterruptParagraph() bool {
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return true
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}
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// CanAcceptIndentedLine returns true if the parser can open new node when
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// the given line is being indented more than 3 spaces.
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func (b *blockParser) CanAcceptIndentedLine() bool {
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return false
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}
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// Trigger returns a list of characters that triggers Parse method of
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// this parser.
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// If Trigger returns a nil, Open will be called with any lines.
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//
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// We leave this as nil as our parse method is quick enough
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func (b *blockParser) Trigger() []byte {
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return nil
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}
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