mautrix-go/format/mdext/shortemphasis.go

97 lines
2.6 KiB
Go

// Copyright (c) 2024 Tulir Asokan
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
package mdext
import (
"github.com/yuin/goldmark"
"github.com/yuin/goldmark/ast"
"github.com/yuin/goldmark/parser"
"github.com/yuin/goldmark/text"
"github.com/yuin/goldmark/util"
)
var ShortEmphasis goldmark.Extender = &shortEmphasisExtender{}
type shortEmphasisExtender struct{}
func (s *shortEmphasisExtender) Extend(m goldmark.Markdown) {
m.Parser().AddOptions(parser.WithInlineParsers(
util.Prioritized(&italicsParser{}, 500),
util.Prioritized(&boldParser{}, 500),
))
}
type italicsDelimiterProcessor struct{}
func (p *italicsDelimiterProcessor) IsDelimiter(b byte) bool {
return b == '_'
}
func (p *italicsDelimiterProcessor) CanOpenCloser(opener, closer *parser.Delimiter) bool {
return opener.Char == closer.Char
}
func (p *italicsDelimiterProcessor) OnMatch(consumes int) ast.Node {
return ast.NewEmphasis(1)
}
var defaultItalicsDelimiterProcessor = &italicsDelimiterProcessor{}
type italicsParser struct{}
func (s *italicsParser) Trigger() []byte {
return []byte{'_'}
}
func (s *italicsParser) Parse(parent ast.Node, block text.Reader, pc parser.Context) ast.Node {
before := block.PrecendingCharacter()
line, segment := block.PeekLine()
node := parser.ScanDelimiter(line, before, 1, defaultItalicsDelimiterProcessor)
if node == nil || node.OriginalLength > 1 || before == '_' {
return nil
}
node.Segment = segment.WithStop(segment.Start + node.OriginalLength)
block.Advance(node.OriginalLength)
pc.PushDelimiter(node)
return node
}
type boldDelimiterProcessor struct{}
func (p *boldDelimiterProcessor) IsDelimiter(b byte) bool {
return b == '*'
}
func (p *boldDelimiterProcessor) CanOpenCloser(opener, closer *parser.Delimiter) bool {
return opener.Char == closer.Char
}
func (p *boldDelimiterProcessor) OnMatch(consumes int) ast.Node {
return ast.NewEmphasis(2)
}
var defaultBoldDelimiterProcessor = &boldDelimiterProcessor{}
type boldParser struct{}
func (s *boldParser) Trigger() []byte {
return []byte{'*'}
}
func (s *boldParser) Parse(parent ast.Node, block text.Reader, pc parser.Context) ast.Node {
before := block.PrecendingCharacter()
line, segment := block.PeekLine()
node := parser.ScanDelimiter(line, before, 1, defaultBoldDelimiterProcessor)
if node == nil || node.OriginalLength > 1 || before == '*' {
return nil
}
node.Segment = segment.WithStop(segment.Start + node.OriginalLength)
block.Advance(node.OriginalLength)
pc.PushDelimiter(node)
return node
}