Function stringEnd

parser.go:281–326

SYS-REQ-045 Tries to find the end of string Support if string contains escaped quote symbols.

(data []byte)

// Tries to find the end of string
// Support if string contains escaped quote symbols.
func stringEnd(data []byte) (int, bool) {
	// fast path: SIMD-scan for the first '"' or '\'. If no '\' precedes the
	// first '"' (the overwhelmingly common case for JSON string values),
	// the quote is unescaped and we return directly — skipping the per-byte
	// escape-tracking loop. Bound: bytes.IndexByte finds the first match in
	// either direction, so firstBackslash > firstQuote (or == -1) is exactly
	// the condition "no backslash precedes the closing quote", which is
	// equivalent to the slow loop's `escaped == false` state at the quote.
	firstQuote := bytes.IndexByte(data, '"')
	if firstQuote == -1 {
		// Slow path's tail semantics: return -1 with escaped flag true iff
		// at least one '\' was encountered before end-of-input.
		return -1, bytes.IndexByte(data, '\\') != -1
	}
	firstBackslash := bytes.IndexByte(data, '\\')
	if firstBackslash == -1 || firstBackslash > firstQuote {
		return firstQuote + 1, false
	}
	// Slow path: at least one '\' precedes the first '"' — the per-byte
	// walker is needed to disambiguate escaped vs. unescaped quotes.
	escaped := false
	for i, c := range data {
		if c == '"' {
			if !escaped {
				return i + 1, false
			} else {
				j := i - 1
				for {
					if j < 0 || data[j] != '\\' {
						return i + 1, true // even number of backslashes
					}
					j--
					if j < 0 || data[j] != '\\' {
						break // odd number of backslashes
					}
					j--

				}
			}
		} else if c == '\\' {
			escaped = true
		}
	}

	return -1, escaped
}

// SYS-REQ-046
// Find end of the data structure, array or object.