LOL no.
Don't drink and stay up late at night trying to solve nasty problems, one just might decide writing a from-scratch JSON parser is the right thing to do. Instead of diving into nuances of existing solutions within the standard library and leveraging those. I am only committing this to history so that I can immediately delete it afterwards. As insurance against anyone trying to glorify this work as the product of some genius, I can point to this and say "yeah, some genius this guy is". Saturday-morning coffee-drinking me is laughing at Friday-night beer-drinking me. Note that if this project gets serious I won't pollute the git history like this. But as the project is young enough that most won't care about this early history, I feel like enshrining some self-deprecating humor into deep history is OK.
このコミットが含まれているのは:
Cory Slep
コミット
0a84346ab3
|
|
@ -0,0 +1,384 @@
|
|||
package pub
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"fmt"
|
||||
"unicode"
|
||||
"unicode/utf8"
|
||||
)
|
||||
|
||||
type scanState int
|
||||
|
||||
const (
|
||||
noScanState scanState = iota
|
||||
keyScanState
|
||||
valueScanState
|
||||
colonScanState
|
||||
commaOrEndScanState
|
||||
quotedLiteralScanState
|
||||
trueLiteralScanState
|
||||
falseLiteralScanState
|
||||
nullLiteralScanState
|
||||
numberLiteralScanState
|
||||
doneScanState
|
||||
)
|
||||
|
||||
type scanContext int
|
||||
|
||||
const (
|
||||
noScanContext scanContext = iota
|
||||
keyScanContext
|
||||
valueScanContext
|
||||
objectScanContext
|
||||
arrayScanContext
|
||||
)
|
||||
|
||||
type scanner struct {
|
||||
b *bytes.Buffer
|
||||
state scanState
|
||||
context []scanContext
|
||||
buf []byte
|
||||
literal []rune
|
||||
nextRuneEscaped bool
|
||||
seenOneDigit bool
|
||||
seenDecimalPoint bool
|
||||
seenDigitAfterDecimal bool
|
||||
seenExp bool
|
||||
seenCharAfterExp bool
|
||||
hasComma bool
|
||||
}
|
||||
|
||||
// Private implementation
|
||||
|
||||
func newScanner(b []byte) *scanner {
|
||||
return &scanner{
|
||||
b: bytes.NewBuffer(b),
|
||||
}
|
||||
}
|
||||
|
||||
func (s *scanner) push(c scanContext) {
|
||||
s.context = append(s.context, c)
|
||||
}
|
||||
|
||||
func (s *scanner) pop() {
|
||||
s.context = s.context[:len(s.context)-1]
|
||||
}
|
||||
|
||||
func (s *scanner) peek() scanContext {
|
||||
return s.context[len(s.context)-1]
|
||||
}
|
||||
|
||||
func (s *scanner) scan() error {
|
||||
buf := make([]byte, 0, 1)
|
||||
for !utf8.FullRune(buf) {
|
||||
buf = append(buf, s.b.Next(1)[0])
|
||||
}
|
||||
r, _ := utf8.DecodeRune(buf)
|
||||
if r == utf8.RuneError {
|
||||
return fmt.Errorf("Unrecognized utf8 bytes: %v", buf)
|
||||
}
|
||||
var err error
|
||||
switch s.state {
|
||||
case noScanState:
|
||||
err = s.noScanState(r)
|
||||
case keyScanState:
|
||||
err = s.keyScanState(r)
|
||||
case valueScanState:
|
||||
err = s.valueScanState(r)
|
||||
case colonScanState:
|
||||
err = s.colonScanState(r)
|
||||
case commaOrEndScanState:
|
||||
err = s.commaOrEndScanState(r)
|
||||
case quotedLiteralScanState:
|
||||
err = s.quotedLiteralScanState(r)
|
||||
case trueLiteralScanState:
|
||||
err = s.trueLiteralScanState(r)
|
||||
case falseLiteralScanState:
|
||||
err = s.falseLiteralScanState(r)
|
||||
case nullLiteralScanState:
|
||||
err = s.nullLiteralScanState(r)
|
||||
case numberLiteralScanState:
|
||||
err = s.numberLiteralScanState(r)
|
||||
case doneScanState:
|
||||
err = s.doneScanState(r)
|
||||
}
|
||||
return err
|
||||
}
|
||||
|
||||
func (s *scanner) noScanState(r rune) error {
|
||||
if r == '{' {
|
||||
s.state = keyScanState
|
||||
s.push(objectScanContext)
|
||||
s.hasComma = false
|
||||
} else if r == '[' {
|
||||
s.state = valueScanState
|
||||
s.push(arrayScanContext)
|
||||
s.hasComma = false
|
||||
} else if !unicode.IsSpace(r) {
|
||||
return fmt.Errorf("Disallowed JSON beginning rune: %s", r)
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
func (s *scanner) keyScanState(r rune) error {
|
||||
if r == '"' {
|
||||
s.state = quotedLiteralScanState
|
||||
s.push(keyScanContext)
|
||||
s.literal = make([]rune, 0, 1)
|
||||
} else if r == '}' {
|
||||
if s.hasComma {
|
||||
return fmt.Errorf("Disallowed } after comma")
|
||||
}
|
||||
s.pop()
|
||||
if len(s.context) == 0 {
|
||||
s.state = doneScanState
|
||||
} else {
|
||||
s.state = commaOrEndScanState
|
||||
}
|
||||
} else if !unicode.IsSpace(r) {
|
||||
return fmt.Errorf("Disallowed JSON looking for key rune: %s", r)
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
func (s *scanner) valueScanState(r rune) error {
|
||||
if r == '"' {
|
||||
s.state = quotedLiteralScanState
|
||||
s.push(valueScanContext)
|
||||
s.literal = make([]rune, 0, 1)
|
||||
} else if r == 't' { // true
|
||||
s.state = trueLiteralScanState
|
||||
s.literal = []rune{r}
|
||||
} else if r == 'f' { // false
|
||||
s.state = falseLiteralScanState
|
||||
s.literal = []rune{r}
|
||||
} else if r == 'n' { // null
|
||||
s.state = nullLiteralScanState
|
||||
s.literal = []rune{r}
|
||||
} else if r == '{' {
|
||||
s.state = keyScanState
|
||||
s.push(objectScanContext)
|
||||
s.hasComma = false
|
||||
} else if r == '[' {
|
||||
s.state = valueScanState
|
||||
s.push(arrayScanContext)
|
||||
s.hasComma = false
|
||||
} else if r == ']' {
|
||||
if s.peek() != arrayScanContext {
|
||||
return fmt.Errorf("Unexpected ] in wrong context for JSON string")
|
||||
} else if !s.hasComma {
|
||||
return fmt.Errorf("Unexpected ] after comma in JSON string")
|
||||
}
|
||||
s.pop()
|
||||
if len(s.context) == 0 {
|
||||
s.state = doneScanState
|
||||
} else {
|
||||
s.state = commaOrEndScanState
|
||||
}
|
||||
} else if r == '-' || unicode.IsDigit(r) {
|
||||
s.state = numberLiteralScanState
|
||||
s.literal = []rune{r}
|
||||
s.seenOneDigit = unicode.IsDigit(r)
|
||||
s.seenDecimalPoint = false
|
||||
s.seenDigitAfterDecimal = false
|
||||
s.seenExp = false
|
||||
s.seenCharAfterExp = false
|
||||
} else if !unicode.IsSpace(r) {
|
||||
return fmt.Errorf("Disallowed JSON looking for key rune: %s", r)
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
func (s *scanner) colonScanState(r rune) error {
|
||||
if r == ':' {
|
||||
s.state = valueScanState
|
||||
} else if !unicode.IsSpace(r) {
|
||||
return fmt.Errorf("Disallowed JSON looking for key rune: %s", r)
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
func (s *scanner) commaOrEndScanState(r rune) error {
|
||||
if r == ',' {
|
||||
s.state = keyScanState
|
||||
s.hasComma = true
|
||||
return nil
|
||||
}
|
||||
switch s.peek() {
|
||||
case objectScanContext:
|
||||
if r == '}' {
|
||||
s.pop()
|
||||
if len(s.context) == 0 {
|
||||
s.state = doneScanState
|
||||
}
|
||||
return nil
|
||||
}
|
||||
case arrayScanContext:
|
||||
if r == ']' {
|
||||
s.pop()
|
||||
if len(s.context) == 0 {
|
||||
s.state = doneScanState
|
||||
}
|
||||
return nil
|
||||
}
|
||||
default:
|
||||
return fmt.Errorf("Disallowed internal context when in commaOrEndScanState: %v", s.peek())
|
||||
}
|
||||
if !unicode.IsSpace(r) {
|
||||
return fmt.Errorf("Disallowed JSON looking for comma or end scan state: %s", r)
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
func (s *scanner) quotedLiteralScanState(r rune) error {
|
||||
done := false
|
||||
if r == '"' && !s.nextRuneEscaped {
|
||||
done = true
|
||||
s.nextRuneEscaped = false
|
||||
} else if r == '\\' {
|
||||
s.nextRuneEscaped = !s.nextRuneEscaped
|
||||
} else {
|
||||
s.nextRuneEscaped = false
|
||||
}
|
||||
if done {
|
||||
switch s.peek() {
|
||||
case keyScanContext:
|
||||
s.state = colonScanState
|
||||
s.pop()
|
||||
if len(s.context) == 0 {
|
||||
return fmt.Errorf("Quoted literal key has no parent context")
|
||||
}
|
||||
case valueScanContext:
|
||||
s.state = commaOrEndScanState
|
||||
s.pop()
|
||||
if len(s.context) == 0 {
|
||||
return fmt.Errorf("Quoted literal value has no parent context")
|
||||
}
|
||||
default:
|
||||
return fmt.Errorf("Disallowed context when parsing quoted literal: %v", s.peek())
|
||||
}
|
||||
} else {
|
||||
s.literal = append(s.literal, r)
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
func (s *scanner) trueLiteralScanState(r rune) error {
|
||||
switch len(s.literal) {
|
||||
case 1:
|
||||
if r != 'r' {
|
||||
return fmt.Errorf("Unexpected rune for 'true' literal: %v", r)
|
||||
}
|
||||
case 2:
|
||||
if r != 'u' {
|
||||
return fmt.Errorf("Unexpected rune for 'true' literal: %v", r)
|
||||
}
|
||||
case 3:
|
||||
if r != 'e' {
|
||||
return fmt.Errorf("Unexpected rune for 'true' literal: %v", r)
|
||||
}
|
||||
s.state = commaOrEndScanState
|
||||
default:
|
||||
return fmt.Errorf("Unexpected internal literal length for 'true' literal: %v", s.literal)
|
||||
}
|
||||
s.literal = append(s.literal, r)
|
||||
return nil
|
||||
}
|
||||
|
||||
func (s *scanner) falseLiteralScanState(r rune) error {
|
||||
switch len(s.literal) {
|
||||
case 1:
|
||||
if r != 'a' {
|
||||
return fmt.Errorf("Unexpected rune for 'false' literal: %v", r)
|
||||
}
|
||||
case 2:
|
||||
if r != 'l' {
|
||||
return fmt.Errorf("Unexpected rune for 'false' literal: %v", r)
|
||||
}
|
||||
case 3:
|
||||
if r != 's' {
|
||||
return fmt.Errorf("Unexpected rune for 'false' literal: %v", r)
|
||||
}
|
||||
case 4:
|
||||
if r != 'e' {
|
||||
return fmt.Errorf("Unexpected rune for 'false' literal: %v", r)
|
||||
}
|
||||
s.state = commaOrEndScanState
|
||||
default:
|
||||
return fmt.Errorf("Unexpected internal literal length for 'false' literal: %v", s.literal)
|
||||
}
|
||||
s.literal = append(s.literal, r)
|
||||
return nil
|
||||
}
|
||||
|
||||
func (s *scanner) nullLiteralScanState(r rune) error {
|
||||
switch len(s.literal) {
|
||||
case 1:
|
||||
if r != 'u' {
|
||||
return fmt.Errorf("Unexpected rune for 'null' literal: %v", r)
|
||||
}
|
||||
case 2:
|
||||
if r != 'l' {
|
||||
return fmt.Errorf("Unexpected rune for 'null' literal: %v", r)
|
||||
}
|
||||
case 3:
|
||||
if r != 'l' {
|
||||
return fmt.Errorf("Unexpected rune for 'null' literal: %v", r)
|
||||
}
|
||||
s.state = commaOrEndScanState
|
||||
default:
|
||||
return fmt.Errorf("Unexpected internal literal length for 'null' literal: %v", s.literal)
|
||||
}
|
||||
s.literal = append(s.literal, r)
|
||||
return nil
|
||||
}
|
||||
|
||||
func (s *scanner) numberLiteralScanState(r rune) error {
|
||||
if unicode.IsDigit(r) {
|
||||
s.seenOneDigit = true
|
||||
if s.seenDecimalPoint {
|
||||
s.seenDigitAfterDecimal = true
|
||||
}
|
||||
if s.seenExp {
|
||||
s.seenCharAfterExp = true
|
||||
}
|
||||
} else if r == '.' {
|
||||
if !s.seenOneDigit {
|
||||
return fmt.Errorf("invalid number: decimal point before any digits")
|
||||
} else if s.seenDecimalPoint {
|
||||
return fmt.Errorf("invalid number: multiple decimal points")
|
||||
} else if s.seenExp {
|
||||
return fmt.Errorf("invalid number: cannot have decimal in exponent")
|
||||
}
|
||||
s.seenDecimalPoint = true
|
||||
} else if r == 'e' || r == 'E' {
|
||||
if !s.seenOneDigit {
|
||||
return fmt.Errorf("invalid number: e notation before digit")
|
||||
} else if s.seenDecimalPoint && !s.seenDigitAfterDecimal {
|
||||
return fmt.Errorf("invalid number: e notation before digit after a decimal point")
|
||||
} else if s.seenExp {
|
||||
return fmt.Errorf("invalid number: multiple e notations")
|
||||
}
|
||||
s.seenExp = true
|
||||
} else if r == '+' || r == '-' {
|
||||
if !s.seenExp {
|
||||
return fmt.Errorf("invalid number: cannot have +/- outside of e notation")
|
||||
} else if s.seenCharAfterExp {
|
||||
return fmt.Errorf("invalid number: +/- must follow e notation")
|
||||
}
|
||||
s.seenCharAfterExp = true
|
||||
} else {
|
||||
// Attempt to handle it as if already in next state.
|
||||
s.state = commaOrEndScanState
|
||||
return s.commaOrEndScanState(r)
|
||||
}
|
||||
s.literal = append(s.literal, r)
|
||||
return nil
|
||||
}
|
||||
|
||||
func (s *scanner) doneScanState(r rune) error {
|
||||
if !unicode.IsSpace(r) {
|
||||
return fmt.Errorf("Disallowed character after reading JSON: %s", r)
|
||||
}
|
||||
return nil
|
||||
}
|
||||
読み込み中…
新しいイシューから参照