cheat/vendor/github.com/alecthomas/chroma/v2/emitters.go

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package chroma
import (
"fmt"
)
// An Emitter takes group matches and returns tokens.
type Emitter interface {
// Emit tokens for the given regex groups.
Emit(groups []string, state *LexerState) Iterator
}
// SerialisableEmitter is an Emitter that can be serialised and deserialised to/from JSON.
type SerialisableEmitter interface {
Emitter
EmitterKind() string
}
// EmitterFunc is a function that is an Emitter.
type EmitterFunc func(groups []string, state *LexerState) Iterator
// Emit tokens for groups.
func (e EmitterFunc) Emit(groups []string, state *LexerState) Iterator {
return e(groups, state)
}
type Emitters []Emitter
type byGroupsEmitter struct {
Emitters
}
// ByGroups emits a token for each matching group in the rule's regex.
func ByGroups(emitters ...Emitter) Emitter {
return &byGroupsEmitter{Emitters: emitters}
}
func (b *byGroupsEmitter) EmitterKind() string { return "bygroups" }
func (b *byGroupsEmitter) Emit(groups []string, state *LexerState) Iterator {
iterators := make([]Iterator, 0, len(groups)-1)
if len(b.Emitters) != len(groups)-1 {
iterators = append(iterators, Error.Emit(groups, state))
// panic(errors.Errorf("number of groups %q does not match number of emitters %v", groups, emitters))
} else {
for i, group := range groups[1:] {
if b.Emitters[i] != nil {
iterators = append(iterators, b.Emitters[i].Emit([]string{group}, state))
}
}
}
return Concaterator(iterators...)
}
// ByGroupNames emits a token for each named matching group in the rule's regex.
func ByGroupNames(emitters map[string]Emitter) Emitter {
return EmitterFunc(func(groups []string, state *LexerState) Iterator {
iterators := make([]Iterator, 0, len(state.NamedGroups)-1)
if len(state.NamedGroups)-1 == 0 {
if emitter, ok := emitters[`0`]; ok {
iterators = append(iterators, emitter.Emit(groups, state))
} else {
iterators = append(iterators, Error.Emit(groups, state))
}
} else {
ruleRegex := state.Rules[state.State][state.Rule].Regexp
for i := 1; i < len(state.NamedGroups); i++ {
groupName := ruleRegex.GroupNameFromNumber(i)
group := state.NamedGroups[groupName]
if emitter, ok := emitters[groupName]; ok {
if emitter != nil {
iterators = append(iterators, emitter.Emit([]string{group}, state))
}
} else {
iterators = append(iterators, Error.Emit([]string{group}, state))
}
}
}
return Concaterator(iterators...)
})
}
// UsingByGroup emits tokens for the matched groups in the regex using a
// sublexer. Used when lexing code blocks where the name of a sublexer is
// contained within the block, for example on a Markdown text block or SQL
// language block.
//
// An attempt to load the sublexer will be made using the captured value from
// the text of the matched sublexerNameGroup. If a sublexer matching the
// sublexerNameGroup is available, then tokens for the matched codeGroup will
// be emitted using the sublexer. Otherwise, if no sublexer is available, then
// tokens will be emitted from the passed emitter.
//
// Example:
//
// var Markdown = internal.Register(MustNewLexer(
// &Config{
// Name: "markdown",
// Aliases: []string{"md", "mkd"},
// Filenames: []string{"*.md", "*.mkd", "*.markdown"},
// MimeTypes: []string{"text/x-markdown"},
// },
// Rules{
// "root": {
// {"^(```)(\\w+)(\\n)([\\w\\W]*?)(^```$)",
// UsingByGroup(
// 2, 4,
// String, String, String, Text, String,
// ),
// nil,
// },
// },
// },
// ))
//
// See the lexers/markdown.go for the complete example.
//
// Note: panic's if the number of emitters does not equal the number of matched
// groups in the regex.
func UsingByGroup(sublexerNameGroup, codeGroup int, emitters ...Emitter) Emitter {
return &usingByGroup{
SublexerNameGroup: sublexerNameGroup,
CodeGroup: codeGroup,
Emitters: emitters,
}
}
type usingByGroup struct {
SublexerNameGroup int `xml:"sublexer_name_group"`
CodeGroup int `xml:"code_group"`
Emitters Emitters `xml:"emitters"`
}
func (u *usingByGroup) EmitterKind() string { return "usingbygroup" }
func (u *usingByGroup) Emit(groups []string, state *LexerState) Iterator {
// bounds check
if len(u.Emitters) != len(groups)-1 {
panic("UsingByGroup expects number of emitters to be the same as len(groups)-1")
}
// grab sublexer
sublexer := state.Registry.Get(groups[u.SublexerNameGroup])
// build iterators
iterators := make([]Iterator, len(groups)-1)
for i, group := range groups[1:] {
if i == u.CodeGroup-1 && sublexer != nil {
var err error
iterators[i], err = sublexer.Tokenise(nil, groups[u.CodeGroup])
if err != nil {
panic(err)
}
} else if u.Emitters[i] != nil {
iterators[i] = u.Emitters[i].Emit([]string{group}, state)
}
}
return Concaterator(iterators...)
}
// UsingLexer returns an Emitter that uses a given Lexer for parsing and emitting.
//
// This Emitter is not serialisable.
func UsingLexer(lexer Lexer) Emitter {
return EmitterFunc(func(groups []string, _ *LexerState) Iterator {
it, err := lexer.Tokenise(&TokeniseOptions{State: "root", Nested: true}, groups[0])
if err != nil {
panic(err)
}
return it
})
}
type usingEmitter struct {
Lexer string `xml:"lexer,attr"`
}
func (u *usingEmitter) EmitterKind() string { return "using" }
func (u *usingEmitter) Emit(groups []string, state *LexerState) Iterator {
if state.Registry == nil {
panic(fmt.Sprintf("no LexerRegistry available for Using(%q)", u.Lexer))
}
lexer := state.Registry.Get(u.Lexer)
if lexer == nil {
panic(fmt.Sprintf("no such lexer %q", u.Lexer))
}
it, err := lexer.Tokenise(&TokeniseOptions{State: "root", Nested: true}, groups[0])
if err != nil {
panic(err)
}
return it
}
// Using returns an Emitter that uses a given Lexer reference for parsing and emitting.
//
// The referenced lexer must be stored in the same LexerRegistry.
func Using(lexer string) Emitter {
return &usingEmitter{Lexer: lexer}
}
type usingSelfEmitter struct {
State string `xml:"state,attr"`
}
func (u *usingSelfEmitter) EmitterKind() string { return "usingself" }
func (u *usingSelfEmitter) Emit(groups []string, state *LexerState) Iterator {
it, err := state.Lexer.Tokenise(&TokeniseOptions{State: u.State, Nested: true}, groups[0])
if err != nil {
panic(err)
}
return it
}
// UsingSelf is like Using, but uses the current Lexer.
func UsingSelf(stateName string) Emitter {
return &usingSelfEmitter{stateName}
}