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grammar_token.go
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/
grammar_token.go
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package xjson
import "errors"
type GrammarToken string
const (
GrammarInit GrammarToken = "Init"
Key GrammarToken = "Key"
Dot GrammarToken = "Dot"
GrammarEscape GrammarToken = "GrammarEscape"
BeginArrayIndex GrammarToken = "BeginArrayIndex"
EndArrayIndex GrammarToken = "EndArrayIndex"
ArrayIndex GrammarToken = "ArrayIndex"
EOF GrammarToken = "EOF"
)
type GrammarStatus int
const (
KeyStatus GrammarStatus = 0x0004
DotStatus GrammarStatus = 0x0008
BeginArrayIndexStatus GrammarStatus = 0x0010
EndArrayIndexStatus GrammarStatus = 0x0020
ArrayIndexStatus GrammarStatus = 0x0040
)
type GrammarTokenType struct {
T GrammarToken
Value string
}
func GrammarTokenize(str string) ([]*GrammarTokenType, error) {
//bytes := []byte(str)
var result []*GrammarTokenType
var values []byte
status := GrammarInit
for i := 0; i < len(str); i++ {
b := str[i]
switch status {
case GrammarInit:
status, values = InitGrammarStatus(b, values)
break
case Key:
if b == '\\' {
status = GrammarEscape
break
} else if isGrammarLetter(b) || isDigit(b) {
values = append(values, b)
} else if b == '[' {
t := &GrammarTokenType{
T: Key,
Value: string(values),
}
result = append(result, t)
values = nil
values = append(values, b)
t = &GrammarTokenType{
T: BeginArrayIndex,
Value: string(values),
}
result = append(result, t)
status = ArrayIndex
values = nil
} else {
t := &GrammarTokenType{
T: Key,
Value: string(values),
}
result = append(result, t)
values = nil
status, values = InitGrammarStatus(b, values)
break
}
case GrammarEscape:
if i < len(str) {
for ; i < len(str); i++ {
if str[i] == '\\' {
i++ //skip escape
if i < len(str) {
values = append(values, str[i])
}
} else if str[i] == '[' {
t := &GrammarTokenType{
T: Key,
Value: string(values),
}
result = append(result, t)
values = nil
values = append(values, str[i])
t = &GrammarTokenType{
T: BeginArrayIndex,
Value: string(values),
}
result = append(result, t)
status = ArrayIndex
values = nil
break
} else {
values = append(values, str[i])
}
}
}
if len(values) == 0 {
// compatible a\.[0]
break
}
t := &GrammarTokenType{
T: Key,
Value: string(values),
}
result = append(result, t)
values = nil
status = GrammarInit
break
case Dot:
t := &GrammarTokenType{
T: Dot,
Value: string(values),
}
result = append(result, t)
values = nil
status, values = InitGrammarStatus(b, values)
break
case ArrayIndex:
if isDigit(b) {
values = append(values, b)
} else if b == ']' {
t := &GrammarTokenType{
T: ArrayIndex,
Value: string(values),
}
result = append(result, t)
values = make([]byte, 0)
values = append(values, b)
status = EndArrayIndex
} else {
return nil, errors.New("invalid array index ]")
}
case EndArrayIndex:
t := &GrammarTokenType{
T: EndArrayIndex,
Value: string(values),
}
result = append(result, t)
values = nil
status, values = InitGrammarStatus(b, values)
break
}
}
if len(values) > 0 {
t := &GrammarTokenType{
T: status,
Value: string(values),
}
result = append(result, t)
}
return result, nil
}
func InitGrammarStatus(b byte, values []byte) (GrammarToken, []byte) {
if b == '\\' {
return GrammarEscape, values
}
if isGrammarLetter(b) || isDigit(b) {
values = append(values, b)
return Key, values
}
if b == '.' {
values = append(values, b)
return Dot, values
}
return GrammarInit, values
}
func isGrammarLetter(b byte) bool {
if b == '[' || b == ']' {
return false
}
return b >= 65 && b <= 122
}
type GrammarTokenReader struct {
tokens []*GrammarTokenType
pos uint64
}
func NewGrammarTokenReader(tokens []*GrammarTokenType) *GrammarTokenReader {
return &GrammarTokenReader{tokens: tokens, pos: 0}
}
func (t *GrammarTokenReader) Read() *GrammarTokenType {
if int(t.pos) >= len(t.tokens) {
return &GrammarTokenType{
T: EOF,
}
}
tokenType := t.tokens[t.pos]
t.pos += 1
return tokenType
}
func (t *GrammarTokenReader) HasNext() bool {
return t.pos < uint64(len(t.tokens))
}