/
delimiter.go
238 lines (204 loc) · 6.19 KB
/
delimiter.go
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package parser
import (
"fmt"
"strings"
"github.com/yuin/goldmark/ast"
"github.com/yuin/goldmark/text"
"github.com/yuin/goldmark/util"
)
// A DelimiterProcessor interface provides a set of functions about
// Delimiter nodes.
type DelimiterProcessor interface {
// IsDelimiter returns true if given character is a delimiter, otherwise false.
IsDelimiter(byte) bool
// CanOpenCloser returns true if given opener can close given closer, otherwise false.
CanOpenCloser(opener, closer *Delimiter) bool
// OnMatch will be called when new matched delimiter found.
// OnMatch should return a new Node correspond to the matched delimiter.
OnMatch(consumes int) ast.Node
}
// A Delimiter struct represents a delimiter like '*' of the Markdown text.
type Delimiter struct {
ast.BaseInline
Segment text.Segment
// CanOpen is set true if this delimiter can open a span for a new node.
// See https://spec.commonmark.org/0.30/#can-open-emphasis for details.
CanOpen bool
// CanClose is set true if this delimiter can close a span for a new node.
// See https://spec.commonmark.org/0.30/#can-open-emphasis for details.
CanClose bool
// Length is a remaining length of this delimiter.
Length int
// OriginalLength is a original length of this delimiter.
OriginalLength int
// Char is a character of this delimiter.
Char byte
// PreviousDelimiter is a previous sibling delimiter node of this delimiter.
PreviousDelimiter *Delimiter
// NextDelimiter is a next sibling delimiter node of this delimiter.
NextDelimiter *Delimiter
// Processor is a DelimiterProcessor associated with this delimiter.
Processor DelimiterProcessor
}
// Inline implements Inline.Inline.
func (d *Delimiter) Inline() {}
// Dump implements Node.Dump.
func (d *Delimiter) Dump(source []byte, level int) {
fmt.Printf("%sDelimiter: \"%s\"\n", strings.Repeat(" ", level), string(d.Text(source)))
}
var kindDelimiter = ast.NewNodeKind("Delimiter")
// Kind implements Node.Kind.
func (d *Delimiter) Kind() ast.NodeKind {
return kindDelimiter
}
// Text implements Node.Text.
func (d *Delimiter) Text(source []byte) []byte {
return d.Segment.Value(source)
}
// ConsumeCharacters consumes delimiters.
func (d *Delimiter) ConsumeCharacters(n int) {
d.Length -= n
d.Segment = d.Segment.WithStop(d.Segment.Start + d.Length)
}
// CalcComsumption calculates how many characters should be used for opening
// a new span correspond to given closer.
func (d *Delimiter) CalcComsumption(closer *Delimiter) int {
if (d.CanClose || closer.CanOpen) && (d.OriginalLength+closer.OriginalLength)%3 == 0 && closer.OriginalLength%3 != 0 {
return 0
}
if d.Length >= 2 && closer.Length >= 2 {
return 2
}
return 1
}
// NewDelimiter returns a new Delimiter node.
func NewDelimiter(canOpen, canClose bool, length int, char byte, processor DelimiterProcessor) *Delimiter {
c := &Delimiter{
BaseInline: ast.BaseInline{},
CanOpen: canOpen,
CanClose: canClose,
Length: length,
OriginalLength: length,
Char: char,
PreviousDelimiter: nil,
NextDelimiter: nil,
Processor: processor,
}
return c
}
// ScanDelimiter scans a delimiter by given DelimiterProcessor.
func ScanDelimiter(line []byte, before rune, min int, processor DelimiterProcessor) *Delimiter {
i := 0
c := line[i]
j := i
if !processor.IsDelimiter(c) {
return nil
}
for ; j < len(line) && c == line[j]; j++ {
}
if (j - i) >= min {
after := rune(' ')
if j != len(line) {
after = util.ToRune(line, j)
}
var canOpen, canClose bool
beforeIsPunctuation := util.IsPunctRune(before)
beforeIsWhitespace := util.IsSpaceRune(before)
afterIsPunctuation := util.IsPunctRune(after)
afterIsWhitespace := util.IsSpaceRune(after)
isLeft := !afterIsWhitespace &&
(!afterIsPunctuation || beforeIsWhitespace || beforeIsPunctuation)
isRight := !beforeIsWhitespace &&
(!beforeIsPunctuation || afterIsWhitespace || afterIsPunctuation)
if line[i] == '_' {
canOpen = isLeft && (!isRight || beforeIsPunctuation)
canClose = isRight && (!isLeft || afterIsPunctuation)
} else {
canOpen = isLeft
canClose = isRight
}
return NewDelimiter(canOpen, canClose, j-i, c, processor)
}
return nil
}
// ProcessDelimiters processes the delimiter list in the context.
// Processing will be stop when reaching the bottom.
//
// If you implement an inline parser that can have other inline nodes as
// children, you should call this function when nesting span has closed.
func ProcessDelimiters(bottom ast.Node, pc Context) {
lastDelimiter := pc.LastDelimiter()
if lastDelimiter == nil {
return
}
var closer *Delimiter
if bottom != nil {
if bottom != lastDelimiter {
for c := lastDelimiter.PreviousSibling(); c != nil && c != bottom; {
if d, ok := c.(*Delimiter); ok {
closer = d
}
c = c.PreviousSibling()
}
}
} else {
closer = pc.FirstDelimiter()
}
if closer == nil {
pc.ClearDelimiters(bottom)
return
}
for closer != nil {
if !closer.CanClose {
closer = closer.NextDelimiter
continue
}
consume := 0
found := false
maybeOpener := false
var opener *Delimiter
for opener = closer.PreviousDelimiter; opener != nil && opener != bottom; opener = opener.PreviousDelimiter {
if opener.CanOpen && opener.Processor.CanOpenCloser(opener, closer) {
maybeOpener = true
consume = opener.CalcComsumption(closer)
if consume > 0 {
found = true
break
}
}
}
if !found {
next := closer.NextDelimiter
if !maybeOpener && !closer.CanOpen {
pc.RemoveDelimiter(closer)
}
closer = next
continue
}
opener.ConsumeCharacters(consume)
closer.ConsumeCharacters(consume)
node := opener.Processor.OnMatch(consume)
parent := opener.Parent()
child := opener.NextSibling()
for child != nil && child != closer {
next := child.NextSibling()
node.AppendChild(node, child)
child = next
}
parent.InsertAfter(parent, opener, node)
for c := opener.NextDelimiter; c != nil && c != closer; {
next := c.NextDelimiter
pc.RemoveDelimiter(c)
c = next
}
if opener.Length == 0 {
pc.RemoveDelimiter(opener)
}
if closer.Length == 0 {
next := closer.NextDelimiter
pc.RemoveDelimiter(closer)
closer = next
}
}
pc.ClearDelimiters(bottom)
}