1package chroma
2
3import (
4 "fmt"
5)
6
7// An Emitter takes group matches and returns tokens.
8type Emitter interface {
9 // Emit tokens for the given regex groups.
10 Emit(groups []string, state *LexerState) Iterator
11}
12
13// SerialisableEmitter is an Emitter that can be serialised and deserialised to/from JSON.
14type SerialisableEmitter interface {
15 Emitter
16 EmitterKind() string
17}
18
19// EmitterFunc is a function that is an Emitter.
20type EmitterFunc func(groups []string, state *LexerState) Iterator
21
22// Emit tokens for groups.
23func (e EmitterFunc) Emit(groups []string, state *LexerState) Iterator {
24 return e(groups, state)
25}
26
27type Emitters []Emitter
28
29type byGroupsEmitter struct {
30 Emitters
31}
32
33// ByGroups emits a token for each matching group in the rule's regex.
34func ByGroups(emitters ...Emitter) Emitter {
35 return &byGroupsEmitter{Emitters: emitters}
36}
37
38func (b *byGroupsEmitter) EmitterKind() string { return "bygroups" }
39
40func (b *byGroupsEmitter) Emit(groups []string, state *LexerState) Iterator {
41 iterators := make([]Iterator, 0, len(groups)-1)
42 if len(b.Emitters) != len(groups)-1 {
43 iterators = append(iterators, Error.Emit(groups, state))
44 // panic(errors.Errorf("number of groups %q does not match number of emitters %v", groups, emitters))
45 } else {
46 for i, group := range groups[1:] {
47 if b.Emitters[i] != nil {
48 iterators = append(iterators, b.Emitters[i].Emit([]string{group}, state))
49 }
50 }
51 }
52 return Concaterator(iterators...)
53}
54
55// ByGroupNames emits a token for each named matching group in the rule's regex.
56func ByGroupNames(emitters map[string]Emitter) Emitter {
57 return EmitterFunc(func(groups []string, state *LexerState) Iterator {
58 iterators := make([]Iterator, 0, len(state.NamedGroups)-1)
59 if len(state.NamedGroups)-1 == 0 {
60 if emitter, ok := emitters[`0`]; ok {
61 iterators = append(iterators, emitter.Emit(groups, state))
62 } else {
63 iterators = append(iterators, Error.Emit(groups, state))
64 }
65 } else {
66 ruleRegex := state.Rules[state.State][state.Rule].Regexp
67 for i := 1; i < len(state.NamedGroups); i++ {
68 groupName := ruleRegex.GroupNameFromNumber(i)
69 group := state.NamedGroups[groupName]
70 if emitter, ok := emitters[groupName]; ok {
71 if emitter != nil {
72 iterators = append(iterators, emitter.Emit([]string{group}, state))
73 }
74 } else {
75 iterators = append(iterators, Error.Emit([]string{group}, state))
76 }
77 }
78 }
79 return Concaterator(iterators...)
80 })
81}
82
83// UsingByGroup emits tokens for the matched groups in the regex using a
84// "sublexer". Used when lexing code blocks where the name of a sublexer is
85// contained within the block, for example on a Markdown text block or SQL
86// language block.
87//
88// The sublexer will be retrieved using sublexerGetFunc (typically
89// internal.Get), using the captured value from the matched sublexerNameGroup.
90//
91// If sublexerGetFunc returns a non-nil lexer for the captured sublexerNameGroup,
92// then tokens for the matched codeGroup will be emitted using the retrieved
93// lexer. Otherwise, if the sublexer is nil, then tokens will be emitted from
94// the passed emitter.
95//
96// Example:
97//
98// var Markdown = internal.Register(MustNewLexer(
99// &Config{
100// Name: "markdown",
101// Aliases: []string{"md", "mkd"},
102// Filenames: []string{"*.md", "*.mkd", "*.markdown"},
103// MimeTypes: []string{"text/x-markdown"},
104// },
105// Rules{
106// "root": {
107// {"^(```)(\\w+)(\\n)([\\w\\W]*?)(^```$)",
108// UsingByGroup(
109// internal.Get,
110// 2, 4,
111// String, String, String, Text, String,
112// ),
113// nil,
114// },
115// },
116// },
117// ))
118//
119// See the lexers/m/markdown.go for the complete example.
120//
121// Note: panic's if the number of emitters does not equal the number of matched
122// groups in the regex.
123func UsingByGroup(sublexerNameGroup, codeGroup int, emitters ...Emitter) Emitter {
124 return &usingByGroup{
125 SublexerNameGroup: sublexerNameGroup,
126 CodeGroup: codeGroup,
127 Emitters: emitters,
128 }
129}
130
131type usingByGroup struct {
132 SublexerNameGroup int `xml:"sublexer_name_group"`
133 CodeGroup int `xml:"code_group"`
134 Emitters Emitters `xml:"emitters"`
135}
136
137func (u *usingByGroup) EmitterKind() string { return "usingbygroup" }
138func (u *usingByGroup) Emit(groups []string, state *LexerState) Iterator {
139 // bounds check
140 if len(u.Emitters) != len(groups)-1 {
141 panic("UsingByGroup expects number of emitters to be the same as len(groups)-1")
142 }
143
144 // grab sublexer
145 sublexer := state.Registry.Get(groups[u.SublexerNameGroup])
146
147 // build iterators
148 iterators := make([]Iterator, len(groups)-1)
149 for i, group := range groups[1:] {
150 if i == u.CodeGroup-1 && sublexer != nil {
151 var err error
152 iterators[i], err = sublexer.Tokenise(nil, groups[u.CodeGroup])
153 if err != nil {
154 panic(err)
155 }
156 } else if u.Emitters[i] != nil {
157 iterators[i] = u.Emitters[i].Emit([]string{group}, state)
158 }
159 }
160 return Concaterator(iterators...)
161}
162
163// UsingLexer returns an Emitter that uses a given Lexer for parsing and emitting.
164//
165// This Emitter is not serialisable.
166func UsingLexer(lexer Lexer) Emitter {
167 return EmitterFunc(func(groups []string, _ *LexerState) Iterator {
168 it, err := lexer.Tokenise(&TokeniseOptions{State: "root", Nested: true}, groups[0])
169 if err != nil {
170 panic(err)
171 }
172 return it
173 })
174}
175
176type usingEmitter struct {
177 Lexer string `xml:"lexer,attr"`
178}
179
180func (u *usingEmitter) EmitterKind() string { return "using" }
181
182func (u *usingEmitter) Emit(groups []string, state *LexerState) Iterator {
183 if state.Registry == nil {
184 panic(fmt.Sprintf("no LexerRegistry available for Using(%q)", u.Lexer))
185 }
186 lexer := state.Registry.Get(u.Lexer)
187 if lexer == nil {
188 panic(fmt.Sprintf("no such lexer %q", u.Lexer))
189 }
190 it, err := lexer.Tokenise(&TokeniseOptions{State: "root", Nested: true}, groups[0])
191 if err != nil {
192 panic(err)
193 }
194 return it
195}
196
197// Using returns an Emitter that uses a given Lexer reference for parsing and emitting.
198//
199// The referenced lexer must be stored in the same LexerRegistry.
200func Using(lexer string) Emitter {
201 return &usingEmitter{Lexer: lexer}
202}
203
204type usingSelfEmitter struct {
205 State string `xml:"state,attr"`
206}
207
208func (u *usingSelfEmitter) EmitterKind() string { return "usingself" }
209
210func (u *usingSelfEmitter) Emit(groups []string, state *LexerState) Iterator {
211 it, err := state.Lexer.Tokenise(&TokeniseOptions{State: u.State, Nested: true}, groups[0])
212 if err != nil {
213 panic(err)
214 }
215 return it
216}
217
218// UsingSelf is like Using, but uses the current Lexer.
219func UsingSelf(stateName string) Emitter {
220 return &usingSelfEmitter{stateName}
221}