1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
|
package participle
import (
"fmt"
"reflect"
"github.com/alecthomas/participle/lexer"
)
// A structLexer lexes over the tags of struct fields while tracking the current field.
type structLexer struct {
s reflect.Type
field int
indexes [][]int
lexer *lexer.PeekingLexer
}
func lexStruct(s reflect.Type) (*structLexer, error) {
indexes, err := collectFieldIndexes(s)
if err != nil {
return nil, err
}
slex := &structLexer{
s: s,
indexes: indexes,
}
if len(slex.indexes) > 0 {
tag := fieldLexerTag(slex.Field().StructField)
slex.lexer, err = lexer.Upgrade(lexer.LexString(tag))
if err != nil {
return nil, err
}
}
return slex, nil
}
// NumField returns the number of fields in the struct associated with this structLexer.
func (s *structLexer) NumField() int {
return len(s.indexes)
}
type structLexerField struct {
reflect.StructField
Index []int
}
// Field returns the field associated with the current token.
func (s *structLexer) Field() structLexerField {
return s.GetField(s.field)
}
func (s *structLexer) GetField(field int) structLexerField {
if field >= len(s.indexes) {
field = len(s.indexes) - 1
}
return structLexerField{
StructField: s.s.FieldByIndex(s.indexes[field]),
Index: s.indexes[field],
}
}
func (s *structLexer) Peek() (lexer.Token, error) {
field := s.field
lex := s.lexer
for {
token, err := lex.Peek(0)
if err != nil {
return token, err
}
if !token.EOF() {
token.Pos.Line = field + 1
return token, nil
}
field++
if field >= s.NumField() {
return lexer.EOFToken(token.Pos), nil
}
tag := fieldLexerTag(s.GetField(field).StructField)
lex, err = lexer.Upgrade(lexer.LexString(tag))
if err != nil {
return token, err
}
}
}
func (s *structLexer) Next() (lexer.Token, error) {
token, err := s.lexer.Next()
if err != nil {
return token, err
}
if !token.EOF() {
token.Pos.Line = s.field + 1
return token, nil
}
if s.field+1 >= s.NumField() {
return lexer.EOFToken(token.Pos), nil
}
s.field++
tag := fieldLexerTag(s.Field().StructField)
s.lexer, err = lexer.Upgrade(lexer.LexString(tag))
if err != nil {
return token, err
}
return s.Next()
}
func fieldLexerTag(field reflect.StructField) string {
if tag, ok := field.Tag.Lookup("parser"); ok {
return tag
}
return string(field.Tag)
}
// Recursively collect flattened indices for top-level fields and embedded fields.
func collectFieldIndexes(s reflect.Type) (out [][]int, err error) {
if s.Kind() != reflect.Struct {
return nil, fmt.Errorf("expected a struct but got %q", s)
}
defer decorate(&err, s.String)
for i := 0; i < s.NumField(); i++ {
f := s.Field(i)
switch {
case f.Anonymous: // nolint: gocritic
children, err := collectFieldIndexes(f.Type)
if err != nil {
return nil, err
}
for _, idx := range children {
out = append(out, append(f.Index, idx...))
}
case f.PkgPath != "":
continue
case fieldLexerTag(f) != "":
out = append(out, f.Index)
}
}
return
}
|
