simulate python 2.7 built-in __hash__ of string object

python_string_built_in_hash.go

import "math/big"

// simulate python 2.7 built-in __hash__ of string object
func hash(s string) *big.Int {
	if len(s) == 0 {
		return big.NewInt(0)
	}
	value := big.NewInt(int64([]byte(s)[0]) << 7)
	for _, v := range []byte(s) {
		value = value.Xor(value.Mul(value, big.NewInt(1000003)), big.NewInt(int64(v)))
	}
	value = value.Xor(value, big.NewInt(int64(len(s))))
	if value.Int64() == -1 {
		value.SetInt64(-2)
	}
	return value
}