Function ReHashCode

pkg/expression/scalar_function.go:728–758

ReHashCode is used after we change the argument in place.

(sf *ScalarFunction)

// ReHashCode is used after we change the argument in place.
func ReHashCode(sf *ScalarFunction) {
	sf.hashcode = sf.hashcode[:0]
	sf.hashcode = append(sf.hashcode, scalarFunctionFlag)
	sf.hashcode = codec.EncodeCompactBytes(sf.hashcode, hack.Slice(sf.FuncName.L))
	for _, arg := range sf.GetArgs() {
		sf.hashcode = append(sf.hashcode, arg.HashCode()...)
	}
	// Cast is a special case. The RetType should also be considered as an argument.
	// Please see `newFunctionImpl()` for detail.
	if sf.FuncName.L == ast.Cast {
		evalTp := sf.RetType.EvalType()
		sf.hashcode = append(sf.hashcode, byte(evalTp))
	}
	if sf.FuncName.L == ast.Grouping {
		sf.hashcode = codec.EncodeInt(sf.hashcode, int64(sf.Function.(*BuiltinGroupingImplSig).GetGroupingMode()))
		marks := sf.Function.(*BuiltinGroupingImplSig).GetMetaGroupingMarks()
		sf.hashcode = codec.EncodeInt(sf.hashcode, int64(len(marks)))
		for _, mark := range marks {
			sf.hashcode = codec.EncodeInt(sf.hashcode, int64(len(mark)))
			// we need to sort map keys to ensure the hashcode is deterministic.
			keys := make([]uint64, 0, len(mark))
			for k := range mark {
				keys = append(keys, k)
			}
			slices.Sort(keys)
			for _, k := range keys {
				sf.hashcode = codec.EncodeInt(sf.hashcode, int64(k))
			}
		}
	}
}

// ResolveIndices implements Expression interface.
func (sf *ScalarFunction) ResolveIndices(schema *Schema) (Expression, error) {