// See https://dev.mysql.com/doc/refman/5.7/en/string-comparison-functions.html
func builtinStrcmp(args []types.Datum, _ context.Context) (d types.Datum, err error) {
if args[0].IsNull() || args[1].IsNull() {
return d, nil
}
left, err := args[0].ToString()
if err != nil {
return d, errors.Trace(err)
}
right, err := args[1].ToString()
if err != nil {
return d, errors.Trace(err)
}
res := types.CompareString(left, right)
d.SetInt64(int64(res))
return d, nil
}
// See https://dev.mysql.com/doc/refman/5.7/en/type-conversion.html
func evalCompare(a interface{}, b interface{}) (int, error) {
// TODO: support compare time type with other types
switch x := a.(type) {
case float64:
switch y := b.(type) {
case float64:
return types.CompareFloat64(x, y), nil
case string:
return compareFloatString(x, y)
}
case int64:
switch y := b.(type) {
case int64:
return types.CompareInt64(x, y), nil
case uint64:
return types.CompareInteger(x, y), nil
case string:
return compareFloatString(float64(x), y)
}
case uint64:
switch y := b.(type) {
case uint64:
return types.CompareUint64(x, y), nil
case int64:
return -types.CompareInteger(y, x), nil
case string:
return compareFloatString(float64(x), y)
}
case mysql.Decimal:
switch y := b.(type) {
case mysql.Decimal:
return x.Cmp(y), nil
case string:
f, err := mysql.ConvertToDecimal(y)
if err != nil {
return 0, err
}
return x.Cmp(f), nil
}
case string:
switch y := b.(type) {
case string:
return types.CompareString(x, y), nil
case int64:
return compareStringFloat(x, float64(y))
case uint64:
return compareStringFloat(x, float64(y))
case float64:
return compareStringFloat(x, y)
case mysql.Decimal:
f, err := mysql.ConvertToDecimal(x)
if err != nil {
return 0, err
}
return f.Cmp(y), nil
case mysql.Time:
n, err := y.CompareString(x)
return -n, err
case mysql.Duration:
n, err := y.CompareString(x)
return -n, err
}
case mysql.Time:
switch y := b.(type) {
case mysql.Time:
return x.Compare(y), nil
case string:
return x.CompareString(y)
}
case mysql.Duration:
switch y := b.(type) {
case mysql.Duration:
return x.Compare(y), nil
case string:
return x.CompareString(y)
}
}
return 0, errors.Errorf("invalid compare type %T cmp %T", a, b)
}