Function buildAppendedArray

riverlog/river_log.go:330–360

(existingArrayBytes []byte, bounds []arrayElementBounds, keepStart int, newEntryBytes []byte)

}

func buildAppendedArray(existingArrayBytes []byte, bounds []arrayElementBounds, keepStart int, newEntryBytes []byte) []byte {
	totalLen := 0
	maxInt := int(^uint(0) >> 1)

	// Preallocation is an optimization only. If length math would overflow,
	// fall back to zero-capacity and let append grow as needed.
	if keepStart >= len(bounds) {
		if len(newEntryBytes) <= maxInt-2 {
			totalLen = 2 + len(newEntryBytes)
		}
	} else {
		// Kept suffix is contiguous in the original array bytes, so copy once.
		keptContentLen := bounds[len(bounds)-1].End - bounds[keepStart].Start
		if keptContentLen >= 0 && len(newEntryBytes) <= maxInt-3 && keptContentLen <= maxInt-3-len(newEntryBytes) {
			totalLen = 3 + keptContentLen + len(newEntryBytes) // [] + comma + new entry
		}
	}

	result := make([]byte, 0, totalLen)
	result = append(result, '[')

	if keepStart < len(bounds) {
		result = append(result, existingArrayBytes[bounds[keepStart].Start:bounds[len(bounds)-1].End]...)
		result = append(result, ',')
	}

	result = append(result, newEntryBytes...)
	result = append(result, ']')

	return result
}