-
Notifications
You must be signed in to change notification settings - Fork 0
/
parser.go
151 lines (120 loc) · 3.72 KB
/
parser.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
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
package gosoon
import (
"errors"
_"fmt"
)
type ParsedJson interface {
AttributeValue(string) string
AttributeIsNull(string) bool
}
type parser struct {
unparsedJson string
savedError error
}
type parserResult struct {
keyValues map[string]string
}
type condition func(string) bool
func Json(rawJson string) (json ParsedJson, err error) {
json, err = parser{unparsedJson: rawJson}.parse()
return
}
func JsonString(rawJson string) (stringsValue string, err error) {
if len(rawJson) < 2 || rawJson[0] != '"' {
err = errors.New("Invalid JSON string, must begin in double quote")
}
for i := 1; i < len(rawJson); i += 1 {
if []rune(rawJson)[i] == '"' {
return
}
if []rune(rawJson)[i] == '\\' {
if []rune(rawJson)[i+1] == '"' {
i += 1
} else {
stringsValue += map[rune]string{
'n': "\n",
'r': "\r",
'f': "\f",
'b': "\b",
'∕': "∕",
'\\': "\\",
't': "\t" }[[]rune(rawJson)[i+1]]
i += 2
}
}
stringsValue += string([]rune(rawJson)[i])
}
return "", errors.New("Invald JSON string, must end in double quote")
}
func (self parser) parse() (json ParsedJson, err error) {
result := parserResult{}
keyValueMappings := map[string]string{}
self.swallowWhitespaceUntil(func(json string) bool {
return rune(json[0]) == '{'
}, "must begin with '{'")
self.removeCurrentRune()
self.swallowWhitespace()
if self.runesRemain() && self.currentRune() == '"' {
key, _ := JsonString(self.unparsedJson)
self.unparsedJson = self.unparsedJson[len(key)+2:len(self.unparsedJson)]
self.swallowWhitespace()
self.removeCurrentRune()
self.swallowWhitespace()
value, _ := JsonString(self.unparsedJson)
self.unparsedJson = self.unparsedJson[len(key)+3:len(self.unparsedJson)]
keyValueMappings[key] = value
}
self.swallowWhitespaceUntil(func(json string) bool {
return rune(json[0]) == '}'
}, "must end with '}'")
self.removeCurrentRune()
self.swallowRemainder()
err = self.savedError
result.setMap(keyValueMappings)
json = result
return
}
func (self *parserResult) setMap(pairs map[string]string) {
self.keyValues = pairs
}
func (self parserResult) AttributeIsNull(attribute string) bool {
return true
}
func (self parserResult) AttributeValue(attribute string) string {
item, ok := self.keyValues[attribute]
if ok {
return item
}
return ""
}
func (self *parser) swallowWhitespaceUntil(cond condition, errorMessage string) {
self.swallowWhitespace()
if self.savedError == nil && (!self.runesRemain() || !cond(self.unparsedJson)) {
self.savedError = errors.New("Invalid JSON given, " + errorMessage)
}
}
func (self *parser) swallowRemainder() {
self.swallowWhitespace()
if self.runesRemain() {
self.savedError = errors.New("runes should not come after the final '}'")
}
}
func (self *parser) swallowWhitespace() {
for self.savedError == nil && self.runesRemain() && self.isWhiteSpace(self.currentRune()) {
self.removeCurrentRune()
}
}
func (self parser) runesRemain() bool {
return len(self.unparsedJson) != 0
}
func (self parser) currentRune() rune {
return rune(self.unparsedJson[0])
}
func (self *parser) removeCurrentRune() {
if self.runesRemain() {
self.unparsedJson = (self.unparsedJson)[1:len(self.unparsedJson)]
}
}
func (self *parser) isWhiteSpace(r rune) bool {
return r == ' ' || r == '\t' || r == '\n'
}