forked from c-bata/go-prompt
-
Notifications
You must be signed in to change notification settings - Fork 2
/
lexer.go
131 lines (109 loc) · 3.24 KB
/
lexer.go
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
package prompt
import (
istrings "github.com/joeycumines/go-prompt/strings"
)
// Lexer is a streaming lexer that takes in a piece of text
// and streams tokens with the Next() method
type Lexer interface {
Init(string) // Reset the lexer's state and initialise it with the given input.
// Next returns the next Token and a bool flag
// which is false when the end of input has been reached.
Next() (Token, bool)
}
// Token is a single unit of text returned by a Lexer.
type Token interface {
Color() Color // Color of the token's text
BackgroundColor() Color
DisplayAttributes() []DisplayAttribute
FirstByteIndex() istrings.ByteNumber // Index of the last byte of this token
LastByteIndex() istrings.ByteNumber // Index of the last byte of this token
}
// SimpleToken as the default implementation of Token.
type SimpleToken struct {
color Color
backgroundColor Color
displayAttributes []DisplayAttribute
lastByteIndex istrings.ByteNumber
firstByteIndex istrings.ByteNumber
}
type SimpleTokenOption func(*SimpleToken)
func SimpleTokenWithColor(c Color) SimpleTokenOption {
return func(t *SimpleToken) {
t.color = c
}
}
func SimpleTokenWithBackgroundColor(c Color) SimpleTokenOption {
return func(t *SimpleToken) {
t.backgroundColor = c
}
}
func SimpleTokenWithDisplayAttributes(attrs ...DisplayAttribute) SimpleTokenOption {
return func(t *SimpleToken) {
t.displayAttributes = attrs
}
}
// Create a new SimpleToken.
func NewSimpleToken(firstIndex, lastIndex istrings.ByteNumber, opts ...SimpleTokenOption) *SimpleToken {
t := &SimpleToken{
firstByteIndex: firstIndex,
lastByteIndex: lastIndex,
}
for _, opt := range opts {
opt(t)
}
return t
}
// Retrieve the text color of this token.
func (t *SimpleToken) Color() Color {
return t.color
}
// Retrieve the background color of this token.
func (t *SimpleToken) BackgroundColor() Color {
return t.backgroundColor
}
// Retrieve the display attributes of this token eg. bold, underline.
func (t *SimpleToken) DisplayAttributes() []DisplayAttribute {
return t.displayAttributes
}
// The index of the last byte of the lexeme.
func (t *SimpleToken) LastByteIndex() istrings.ByteNumber {
return t.lastByteIndex
}
// The index of the first byte of the lexeme.
func (t *SimpleToken) FirstByteIndex() istrings.ByteNumber {
return t.firstByteIndex
}
// LexerFunc is a function implementing
// a simple lexer that receives a string
// and returns a complete slice of Tokens.
type LexerFunc func(string) []Token
// EagerLexer is a wrapper around LexerFunc that
// transforms an eager lexer which produces an
// array with all tokens at once into a streaming
// lexer compatible with go-prompt.
type EagerLexer struct {
lexFunc LexerFunc
tokens []Token
currentIndex int
}
// Create a new EagerLexer.
func NewEagerLexer(fn LexerFunc) *EagerLexer {
return &EagerLexer{
lexFunc: fn,
}
}
// Initialise the lexer with the given input.
func (l *EagerLexer) Init(input string) {
l.tokens = l.lexFunc(input)
l.currentIndex = 0
}
// Return the next token and true if the operation
// was successful.
func (l *EagerLexer) Next() (Token, bool) {
if l.currentIndex >= len(l.tokens) {
return nil, false
}
result := l.tokens[l.currentIndex]
l.currentIndex++
return result, true
}