120 lines
2.8 KiB
Go
120 lines
2.8 KiB
Go
// Copyright 2022 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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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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)
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type inlineParser struct {
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start []byte
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end []byte
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}
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var defaultInlineDollarParser = &inlineParser{
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start: []byte{'$'},
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end: []byte{'$'},
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}
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// NewInlineDollarParser returns a new inline parser
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func NewInlineDollarParser() parser.InlineParser {
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return defaultInlineDollarParser
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}
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var defaultInlineBracketParser = &inlineParser{
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start: []byte{'\\', '('},
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end: []byte{'\\', ')'},
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}
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// NewInlineDollarParser returns a new inline parser
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func NewInlineBracketParser() parser.InlineParser {
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return defaultInlineBracketParser
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}
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// Trigger triggers this parser on $ or \
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func (parser *inlineParser) Trigger() []byte {
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return parser.start[0:1]
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}
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func isAlphanumeric(b byte) bool {
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// Github only cares about 0-9A-Za-z
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return (b >= '0' && b <= '9') || (b >= 'A' && b <= 'Z') || (b >= 'a' && b <= 'z')
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}
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// Parse parses the current line and returns a result of parsing.
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func (parser *inlineParser) Parse(parent ast.Node, block text.Reader, pc parser.Context) ast.Node {
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line, _ := block.PeekLine()
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if !bytes.HasPrefix(line, parser.start) {
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// We'll catch this one on the next time round
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return nil
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}
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precedingCharacter := block.PrecendingCharacter()
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if precedingCharacter < 256 && isAlphanumeric(byte(precedingCharacter)) {
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// need to exclude things like `a$` from being considered a start
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return nil
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}
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// move the opener marker point at the start of the text
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opener := len(parser.start)
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// Now look for an ending line
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ender := opener
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for {
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pos := bytes.Index(line[ender:], parser.end)
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if pos < 0 {
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return nil
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}
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ender += pos
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// Now we want to check the character at the end of our parser section
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// that is ender + len(parser.end)
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pos = ender + len(parser.end)
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if len(line) <= pos {
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break
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}
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if !isAlphanumeric(line[pos]) {
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break
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}
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// move the pointer onwards
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ender += len(parser.end)
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}
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block.Advance(opener)
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_, pos := block.Position()
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node := NewInline()
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segment := pos.WithStop(pos.Start + ender - opener)
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node.AppendChild(node, ast.NewRawTextSegment(segment))
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block.Advance(ender - opener + len(parser.end))
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trimBlock(node, block)
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return node
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}
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func trimBlock(node *Inline, block text.Reader) {
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if node.IsBlank(block.Source()) {
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return
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}
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// trim first space and last space
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first := node.FirstChild().(*ast.Text)
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if !(!first.Segment.IsEmpty() && block.Source()[first.Segment.Start] == ' ') {
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return
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}
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last := node.LastChild().(*ast.Text)
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if !(!last.Segment.IsEmpty() && block.Source()[last.Segment.Stop-1] == ' ') {
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return
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}
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first.Segment = first.Segment.WithStart(first.Segment.Start + 1)
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last.Segment = last.Segment.WithStop(last.Segment.Stop - 1)
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}
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