Function contains

json/string.go:74–76

contains returns a mask that can be used to determine if any of the bytes in `n` are equal to `b`. If a byte's MSB is set in the mask then that byte is equal to `b`. The result is only valid if `b`, and each byte in `n`, is below 0x80.

(n uint64, b byte)

// that byte is equal to `b`. The result is only valid if `b`, and each
// byte in `n`, is below 0x80.
func contains(n uint64, b byte) uint64 {
	return (n ^ expand(b)) - lsb
}

// expand puts the specified byte into each of the 8 bytes of a uint64.
func expand(b byte) uint64 {