Method Read

internal/encoding/json/decode.go:69–152

Read returns the next JSON token. It will return an error if there is no valid token.

()

// Read returns the next JSON token.
// It will return an error if there is no valid token.
func (d *Decoder) Read() (Token, error) {
	const scalar = Null | Bool | Number | String

	defer func() { d.lastCall = readCall }()
	if d.lastCall == peekCall {
		return d.lastToken, d.lastErr
	}

	tok, err := d.parseNext()
	if err != nil {
		return Token{}, err
	}

	switch tok.kind {
	case EOF:
		if len(d.openStack) != 0 ||
			d.lastToken.kind&scalar|ObjectClose|ArrayClose == 0 {
			return Token{}, ErrUnexpectedEOF
		}

	case Null:
		if !d.isValueNext() {
			return Token{}, d.newSyntaxError(tok.pos, unexpectedFmt, tok.RawString())
		}

	case Bool, Number:
		if !d.isValueNext() {
			return Token{}, d.newSyntaxError(tok.pos, unexpectedFmt, tok.RawString())
		}

	case String:
		if d.isValueNext() {
			break
		}
		// This string token should only be for a field name.
		if d.lastToken.kind&(ObjectOpen|comma) == 0 {
			return Token{}, d.newSyntaxError(tok.pos, unexpectedFmt, tok.RawString())
		}
		if len(d.in) == 0 {
			return Token{}, ErrUnexpectedEOF
		}
		if c := d.in[0]; c != ':' {
			return Token{}, d.newSyntaxError(d.currPos(), `unexpected character %s, missing ":" after field name`, string(c))
		}
		tok.kind = Name
		d.consume(1)

	case ObjectOpen, ArrayOpen:
		if !d.isValueNext() {
			return Token{}, d.newSyntaxError(tok.pos, unexpectedFmt, tok.RawString())
		}
		d.openStack = append(d.openStack, tok.kind)

	case ObjectClose:
		if len(d.openStack) == 0 ||
			d.lastToken.kind&(Name|comma) != 0 ||
			d.openStack[len(d.openStack)-1] != ObjectOpen {
			return Token{}, d.newSyntaxError(tok.pos, unexpectedFmt, tok.RawString())