package extension
import (
"unicode"
"github.com/yuin/goldmark"
gast "github.com/yuin/goldmark/ast"
"github.com/yuin/goldmark/parser"
"github.com/yuin/goldmark/text"
"github.com/yuin/goldmark/util"
)
var uncloseCounterKey = parser.NewContextKey()
type unclosedCounter struct {
Single int
Double int
}
func (u *unclosedCounter) Reset() {
u.Single = 0
u.Double = 0
}
func getUnclosedCounter(pc parser.Context) *unclosedCounter {
v := pc.Get(uncloseCounterKey)
if v == nil {
v = &unclosedCounter{}
pc.Set(uncloseCounterKey, v)
}
return v.(*unclosedCounter)
}
// TypographicPunctuation is a key of the punctuations that can be replaced with
// typographic entities.
type TypographicPunctuation int
const (
// LeftSingleQuote is ' .
LeftSingleQuote TypographicPunctuation = iota + 1
// RightSingleQuote is ' .
RightSingleQuote
// LeftDoubleQuote is " .
LeftDoubleQuote
// RightDoubleQuote is " .
RightDoubleQuote
// EnDash is -- .
EnDash
// EmDash is --- .
EmDash
// Ellipsis is ... .
Ellipsis
// LeftAngleQuote is << .
LeftAngleQuote
// RightAngleQuote is >> .
RightAngleQuote
// Apostrophe is ' .
Apostrophe
typographicPunctuationMax
)
// An TypographerConfig struct is a data structure that holds configuration of the
// Typographer extension.
type TypographerConfig struct {
Substitutions [][]byte
}
func newDefaultSubstitutions() [][]byte {
replacements := make([][]byte, typographicPunctuationMax)
replacements[LeftSingleQuote] = []byte("‘")
replacements[RightSingleQuote] = []byte("’")
replacements[LeftDoubleQuote] = []byte("“")
replacements[RightDoubleQuote] = []byte("”")
replacements[EnDash] = []byte("–")
replacements[EmDash] = []byte("—")
replacements[Ellipsis] = []byte("…")
replacements[LeftAngleQuote] = []byte("«")
replacements[RightAngleQuote] = []byte("»")
replacements[Apostrophe] = []byte("’")
return replacements
}
// SetOption implements SetOptioner.
func (b *TypographerConfig) SetOption(name parser.OptionName, value interface{}) {
switch name {
case optTypographicSubstitutions:
b.Substitutions = value.([][]byte)
}
}
// A TypographerOption interface sets options for the TypographerParser.
type TypographerOption interface {
parser.Option
SetTypographerOption(*TypographerConfig)
}
const optTypographicSubstitutions parser.OptionName = "TypographicSubstitutions"
// TypographicSubstitutions is a list of the substitutions for the Typographer extension.
type TypographicSubstitutions map[TypographicPunctuation][]byte
type withTypographicSubstitutions struct {
value [][]byte
}
func (o *withTypographicSubstitutions) SetParserOption(c *parser.Config) {
c.Options[optTypographicSubstitutions] = o.value
}
func (o *withTypographicSubstitutions) SetTypographerOption(p *TypographerConfig) {
p.Substitutions = o.value
}
// WithTypographicSubstitutions is a functional otpion that specify replacement text
// for punctuations.
func WithTypographicSubstitutions[T []byte | string](values map[TypographicPunctuation]T) TypographerOption {
replacements := newDefaultSubstitutions()
for k, v := range values {
replacements[k] = []byte(v)
}
return &withTypographicSubstitutions{replacements}
}
type typographerDelimiterProcessor struct {
}
func (p *typographerDelimiterProcessor) IsDelimiter(b byte) bool {
return b == '\'' || b == '"'
}
func (p *typographerDelimiterProcessor) CanOpenCloser(opener, closer *parser.Delimiter) bool {
return opener.Char == closer.Char
}
func (p *typographerDelimiterProcessor) OnMatch(consumes int) gast.Node {
return nil
}
var defaultTypographerDelimiterProcessor = &typographerDelimiterProcessor{}
type typographerParser struct {
TypographerConfig
}
// NewTypographerParser return a new InlineParser that parses
// typographer expressions.
func NewTypographerParser(opts ...TypographerOption) parser.InlineParser {
p := &typographerParser{
TypographerConfig: TypographerConfig{
Substitutions: newDefaultSubstitutions(),
},
}
for _, o := range opts {
o.SetTypographerOption(&p.TypographerConfig)
}
return p
}
func (s *typographerParser) Trigger() []byte {
return []byte{'\'', '"', '-', '.', ',', '<', '>', '*', '['}
}
func (s *typographerParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node {
line, _ := block.PeekLine()
c := line[0]
if len(line) > 2 {
if c == '-' {
if s.Substitutions[EmDash] != nil && line[1] == '-' && line[2] == '-' { // ---
node := gast.NewString(s.Substitutions[EmDash])
node.SetCode(true)
block.Advance(3)
return node
}
} else if c == '.' {
if s.Substitutions[Ellipsis] != nil && line[1] == '.' && line[2] == '.' { // ...
node := gast.NewString(s.Substitutions[Ellipsis])
node.SetCode(true)
block.Advance(3)
return node
}
return nil
}
}
if len(line) > 1 {
if c == '<' {
if s.Substitutions[LeftAngleQuote] != nil && line[1] == '<' { // <<
node := gast.NewString(s.Substitutions[LeftAngleQuote])
node.SetCode(true)
block.Advance(2)
return node
}
return nil
} else if c == '>' {
if s.Substitutions[RightAngleQuote] != nil && line[1] == '>' { // >>
node := gast.NewString(s.Substitutions[RightAngleQuote])
node.SetCode(true)
block.Advance(2)
return node
}
return nil
} else if s.Substitutions[EnDash] != nil && c == '-' && line[1] == '-' { // --
node := gast.NewString(s.Substitutions[EnDash])
node.SetCode(true)
block.Advance(2)
return node
}
}
if c == '\'' || c == '"' {
before := block.PrecendingCharacter()
d := parser.ScanDelimiter(line, before, 1, defaultTypographerDelimiterProcessor)
if d == nil {
return nil
}
counter := getUnclosedCounter(pc)
if c == '\'' {
if s.Substitutions[Apostrophe] != nil {
// Handle decade abbrevations such as '90s
if d.CanOpen && !d.CanClose && len(line) > 3 &&
util.IsNumeric(line[1]) && util.IsNumeric(line[2]) && line[3] == 's' {
after := rune(' ')
if len(line) > 4 {
after = util.ToRune(line, 4)
}
if len(line) == 3 || util.IsSpaceRune(after) || util.IsPunctRune(after) {
node := gast.NewString(s.Substitutions[Apostrophe])
node.SetCode(true)
block.Advance(1)
return node
}
}
// special cases: 'twas, 'em, 'net
if len(line) > 1 && (unicode.IsPunct(before) || unicode.IsSpace(before)) &&
(line[1] == 't' || line[1] == 'e' || line[1] == 'n' || line[1] == 'l') {
node := gast.NewString(s.Substitutions[Apostrophe])
node.SetCode(true)
block.Advance(1)
return node
}
// Convert normal apostrophes. This is probably more flexible than necessary but
// converts any apostrophe in between two alphanumerics.
if len(line) > 1 && (unicode.IsDigit(before) || unicode.IsLetter(before)) &&
(unicode.IsLetter(util.ToRune(line, 1))) {
node := gast.NewString(s.Substitutions[Apostrophe])
node.SetCode(true)
block.Advance(1)
return node
}
}
if s.Substitutions[LeftSingleQuote] != nil && d.CanOpen && !d.CanClose {
nt := LeftSingleQuote
// special cases: Alice's, I'm, Don't, You'd
if len(line) > 1 && (line[1] == 's' || line[1] == 'm' || line[1] == 't' || line[1] == 'd') &&
(len(line) < 3 || util.IsPunct(line[2]) || util.IsSpace(line[2])) {
nt = RightSingleQuote
}
// special cases: I've, I'll, You're
if len(line) > 2 && ((line[1] == 'v' && line[2] == 'e') ||
(line[1] == 'l' && line[2] == 'l') || (line[1] == 'r' && line[2] == 'e')) &&
(len(line) < 4 || util.IsPunct(line[3]) || util.IsSpace(line[3])) {
nt = RightSingleQuote
}
if nt == LeftSingleQuote {
counter.Single++
}
node := gast.NewString(s.Substitutions[nt])
node.SetCode(true)
block.Advance(1)
return node
}
if s.Substitutions[RightSingleQuote] != nil {
// plural possesive and abbreviations: Smiths', doin'
if len(line) > 1 && unicode.IsSpace(util.ToRune(line, 0)) || unicode.IsPunct(util.ToRune(line, 0)) &&
(len(line) > 2 && !unicode.IsDigit(util.ToRune(line, 1))) {
node := gast.NewString(s.Substitutions[RightSingleQuote])
node.SetCode(true)
block.Advance(1)
return node
}
}
if s.Substitutions[RightSingleQuote] != nil && counter.Single > 0 {
isClose := d.CanClose && !d.CanOpen
maybeClose := d.CanClose && d.CanOpen && len(line) > 1 && unicode.IsPunct(util.ToRune(line, 1)) &&
(len(line) == 2 || (len(line) > 2 && util.IsPunct(line[2]) || util.IsSpace(line[2])))
if isClose || maybeClose {
node := gast.NewString(s.Substitutions[RightSingleQuote])
node.SetCode(true)
block.Advance(1)
counter.Single--
return node
}
}
}
if c == '"' {
if s.Substitutions[LeftDoubleQuote] != nil && d.CanOpen && !d.CanClose {
node := gast.NewString(s.Substitutions[LeftDoubleQuote])
node.SetCode(true)
block.Advance(1)
counter.Double++
return node
}
if s.Substitutions[RightDoubleQuote] != nil && counter.Double > 0 {
isClose := d.CanClose && !d.CanOpen
maybeClose := d.CanClose && d.CanOpen && len(line) > 1 && (unicode.IsPunct(util.ToRune(line, 1))) &&
(len(line) == 2 || (len(line) > 2 && util.IsPunct(line[2]) || util.IsSpace(line[2])))
if isClose || maybeClose {
// special case: "Monitor 21""
if len(line) > 1 && line[1] == '"' && unicode.IsDigit(before) {
return nil
}
node := gast.NewString(s.Substitutions[RightDoubleQuote])
node.SetCode(true)
block.Advance(1)
counter.Double--
return node
}
}
}
}
return nil
}
func (s *typographerParser) CloseBlock(parent gast.Node, pc parser.Context) {
getUnclosedCounter(pc).Reset()
}
type typographer struct {
options []TypographerOption
}
// Typographer is an extension that replaces punctuations with typographic entities.
var Typographer = &typographer{}
// NewTypographer returns a new Extender that replaces punctuations with typographic entities.
func NewTypographer(opts ...TypographerOption) goldmark.Extender {
return &typographer{
options: opts,
}
}
func (e *typographer) Extend(m goldmark.Markdown) {
m.Parser().AddOptions(parser.WithInlineParsers(
util.Prioritized(NewTypographerParser(e.options...), 9999),
))
}