Function ObjectEach

parser.go:1389–1498

SYS-REQ-007, SYS-REQ-030, SYS-REQ-031, SYS-REQ-032, SYS-REQ-054, SYS-REQ-084 ObjectEach iterates over the key-value pairs of a JSON object, invoking a given callback for each such entry

(data []byte, callback func(key []byte, value []byte, dataType ValueType, offset int) error, keys ...string)

// SYS-REQ-007, SYS-REQ-030, SYS-REQ-031, SYS-REQ-032, SYS-REQ-054, SYS-REQ-084
// ObjectEach iterates over the key-value pairs of a JSON object, invoking a given callback for each such entry
func ObjectEach(data []byte, callback func(key []byte, value []byte, dataType ValueType, offset int) error, keys ...string) (err error) {
	offset := 0

	// Descend to the desired key, if requested
	if len(keys) > 0 {
		if off := searchKeys(data, keys...); off == -1 {
			return KeyPathNotFoundError
		} else {
			offset = off
		}
	}

	// Validate and skip past opening brace
	if off := nextToken(data[offset:]); off == -1 {
		return MalformedObjectError
	} else if offset += off; data[offset] != '{' {
		return MalformedObjectError
	} else {
		offset++
	}

	// Skip to the first token inside the object, or stop if we find the ending brace
	if off := nextToken(data[offset:]); off == -1 {
		return MalformedJsonError
	} else if offset += off; data[offset] == '}' {
		return nil
	}

	// Loop pre-condition: data[offset] points to what should be either the next entry's key,
	// or the closing brace (if it's anything else, the JSON is malformed).
	// Every iteration either returns or advances offset past a token, so the loop
	// always exits via return; the former `offset < len(data)` guard was structurally
	// always true because internal nextToken/stringEnd calls return errors before
	// offset can reach len(data).
	for {
		// Step 1: find the next key
		var key []byte

		// Check what the the next token is: start of string, end of object, or something else (error)
		switch data[offset] {
		case '"':
			offset++ // accept as string and skip opening quote
		case '}':
			return nil // we found the end of the object; stop and return success
		default:
			return MalformedObjectError
		}

		// Find the end of the key string
		var keyEscaped bool
		if off, esc := stringEnd(data[offset:]); off == -1 {
			return MalformedJsonError
		} else {
			key, keyEscaped = data[offset:offset+off-1], esc
			offset += off
		}

		// Unescape the string if needed