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// Copyright 2022 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package math
import (
"bytes"
"github.com/yuin/goldmark/ast"
"github.com/yuin/goldmark/parser"
"github.com/yuin/goldmark/text"
"github.com/yuin/goldmark/util"
)
type blockParser struct {
parseDollars bool
}
// NewBlockParser creates a new math BlockParser
func NewBlockParser(parseDollarBlocks bool) parser.BlockParser {
return &blockParser{
parseDollars: parseDollarBlocks,
}
}
// Open parses the current line and returns a result of parsing.
func (b *blockParser) Open(parent ast.Node, reader text.Reader, pc parser.Context) (ast.Node, parser.State) {
line, segment := reader.PeekLine()
pos := pc.BlockOffset()
if pos == -1 || len(line[pos:]) < 2 {
return nil, parser.NoChildren
}
dollars := false
if b.parseDollars && line[pos] == '$' && line[pos+1] == '$' {
dollars = true
} else if line[pos] != '\\' || line[pos+1] != '[' {
return nil, parser.NoChildren
}
node := NewBlock(dollars, pos)
// Now we need to check if the ending block is on the segment...
endBytes := []byte{'\\', ']'}
if dollars {
endBytes = []byte{'$', '$'}
}
idx := bytes.Index(line[pos+2:], endBytes)
if idx >= 0 {
segment.Stop = segment.Start + idx + 2
reader.Advance(segment.Len() - 1)
segment.Start += 2
node.Lines().Append(segment)
node.Closed = true
return node, parser.Close | parser.NoChildren
}
reader.Advance(segment.Len() - 1)
segment.Start += 2
node.Lines().Append(segment)
return node, parser.NoChildren
}
// Continue parses the current line and returns a result of parsing.
func (b *blockParser) Continue(node ast.Node, reader text.Reader, pc parser.Context) parser.State {
block := node.(*Block)
if block.Closed {
return parser.Close
}
line, segment := reader.PeekLine()
w, pos := util.IndentWidth(line, 0)
if w < 4 {
if block.Dollars {
i := pos
for ; i < len(line) && line[i] == '$'; i++ {
}
length := i - pos
if length >= 2 && util.IsBlank(line[i:]) {
reader.Advance(segment.Stop - segment.Start - segment.Padding)
block.Closed = true
return parser.Close
}
} else if len(line[pos:]) > 1 && line[pos] == '\\' && line[pos+1] == ']' && util.IsBlank(line[pos+2:]) {
reader.Advance(segment.Stop - segment.Start - segment.Padding)
block.Closed = true
return parser.Close
}
}
pos, padding := util.IndentPosition(line, 0, block.Indent)
seg := text.NewSegmentPadding(segment.Start+pos, segment.Stop, padding)
node.Lines().Append(seg)
reader.AdvanceAndSetPadding(segment.Stop-segment.Start-pos-1, padding)
return parser.Continue | parser.NoChildren
}
// Close will be called when the parser returns Close.
func (b *blockParser) Close(node ast.Node, reader text.Reader, pc parser.Context) {
// noop
}
// CanInterruptParagraph returns true if the parser can interrupt paragraphs,
// otherwise false.
func (b *blockParser) CanInterruptParagraph() bool {
return true
}
// CanAcceptIndentedLine returns true if the parser can open new node when
// the given line is being indented more than 3 spaces.
func (b *blockParser) CanAcceptIndentedLine() bool {
return false
}
// Trigger returns a list of characters that triggers Parse method of
// this parser.
// If Trigger returns a nil, Open will be called with any lines.
//
// We leave this as nil as our parse method is quick enough
func (b *blockParser) Trigger() []byte {
return nil
}
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