Golang types.Compare函数代码示例

func (e *Evaluator) handleComparisonOp(o *ast.BinaryOperationExpr) bool {
	a, b := types.Coerce(o.L.GetValue(), o.R.GetValue())
	if types.IsNil(a) || types.IsNil(b) {
		// for <=>, if a and b are both nil, return true.
		// if a or b is nil, return false.
		if o.Op == opcode.NullEQ {
			if types.IsNil(a) || types.IsNil(b) {
				o.SetValue(oneI64)
			} else {
				o.SetValue(zeroI64)
			}
		} else {
			o.SetValue(nil)
		}
		return true
	}

	n, err := types.Compare(a, b)
	if err != nil {
		e.err = errors.Trace(err)
		return false
	}

	r, err := getCompResult(o.Op, n)
	if err != nil {
		e.err = errors.Trace(err)
		return false
	}
	if r {
		o.SetValue(oneI64)
	} else {
		o.SetValue(zeroI64)
	}
	return true
}

// Less implements sort.Interface Less interface.
func (t *orderByTable) Less(i, j int) bool {
	for index, asc := range t.Ascs {
		v1 := t.Rows[i].Key[index]
		v2 := t.Rows[j].Key[index]

		ret, err := types.Compare(v1, v2)
		if err != nil {
			// we just have to log this error and skip it.
			// TODO: record this error and handle it out later.
			log.Errorf("compare %v %v err %v", v1, v2, err)
		}

		if !asc {
			ret = -ret
		}

		if ret < 0 {
			return true
		} else if ret > 0 {
			return false
		}
	}

	return false
}

func replaceRow(ctx context.Context, t table.Table, handle int64, replaceRow []interface{}) error {
	row, err := t.Row(ctx, handle)
	if err != nil {
		return errors.Trace(err)
	}

	result := 0
	isReplace := false
	touched := make(map[int]bool, len(row))
	for i, val := range row {
		result, err = types.Compare(val, replaceRow[i])
		if err != nil {
			return errors.Trace(err)
		}
		if result != 0 {
			touched[i] = true
			isReplace = true
		}
	}

	if isReplace {
		variable.GetSessionVars(ctx).AddAffectedRows(1)
		if err = t.UpdateRecord(ctx, handle, row, replaceRow, touched); err != nil {
			return errors.Trace(err)
		}
	}

	return nil
}

func (e *Evaluator) caseExpr(v *ast.CaseExpr) bool {
	var target interface{} = true
	if v.Value != nil {
		target = v.Value.GetValue()
	}
	if target != nil {
		for _, val := range v.WhenClauses {
			cmp, err := types.Compare(target, val.Expr.GetValue())
			if err != nil {
				e.err = errors.Trace(err)
				return false
			}
			if cmp == 0 {
				v.SetValue(val.Result.GetValue())
				return true
			}
		}
	}
	if v.ElseClause != nil {
		v.SetValue(v.ElseClause.GetValue())
	} else {
		v.SetValue(nil)
	}
	return true
}

func (e *Evaluator) checkAnyResult(cs *ast.CompareSubqueryExpr, lv interface{}, result []interface{}) (interface{}, error) {
	hasNull := false
	for _, v := range result {
		if v == nil {
			hasNull = true
			continue
		}

		comRes, err := types.Compare(lv, v)
		if err != nil {
			return nil, errors.Trace(err)
		}

		res, err := getCompResult(cs.Op, comRes)
		if err != nil {
			return nil, errors.Trace(err)
		}
		if res {
			return true, nil
		}
	}

	if hasNull {
		// If no matched but we get null, return null.
		// Like `insert t (c) values (1),(2),(null)`, then
		// `select 0 > any (select c from t)`, returns null.
		return nil, nil
	}

	return false, nil
}

func (e *Evaluator) checkInList(not bool, in interface{}, list []interface{}) (interface{}, error) {
	hasNull := false
	for _, v := range list {
		if types.IsNil(v) {
			hasNull = true
			continue
		}

		r, err := types.Compare(in, v)
		if err != nil {
			return nil, errors.Trace(err)
		}

		if r == 0 {
			return !not, nil
		}
	}

	if hasNull {
		// if no matched but we got null in In, return null
		// e.g 1 in (null, 2, 3) returns null
		return nil, nil
	}

	return not, nil
}

// comparison function that takes minNotNullVal and maxVal into account.
func indexCompare(a interface{}, b interface{}) int {
	if a == nil && b == nil {
		return 0
	} else if b == nil {
		return 1
	} else if b == nil {
		return -1
	}
	// a and b both not nil
	if a == minNotNullVal && b == minNotNullVal {
		return 0
	} else if b == minNotNullVal {
		return 1
	} else if a == minNotNullVal {
		return -1
	}

	// a and b both not min value
	if a == maxVal && b == maxVal {
		return 0
	} else if a == maxVal {
		return 1
	} else if b == maxVal {
		return -1
	}

	n, err := types.Compare(a, b)
	if err != nil {
		// Old compare panics if err, so here we do the same thing now.
		// TODO: return err instead of panic.
		panic(fmt.Sprintf("should never happend %v", err))
	}
	return n
}

// operator: >=, >, <=, <, !=, <>, = <=>, etc.
// see https://dev.mysql.com/doc/refman/5.7/en/comparison-operators.html
func (o *BinaryOperation) evalComparisonOp(ctx context.Context, args map[interface{}]interface{}) (interface{}, error) {
	//TODO: support <=> later
	a, b, err := o.get2(ctx, args)
	if err != nil {
		return nil, err
	}

	if a == nil || b == nil {
		// TODO: for <=>, if a and b are both nil, return true
		return nil, nil
	}

	n, err := types.Compare(a, b)
	if err != nil {
		return nil, o.traceErr(err)
	}

	switch o.Op {
	case opcode.LT:
		return n < 0, nil
	case opcode.LE:
		return n <= 0, nil
	case opcode.GE:
		return n >= 0, nil
	case opcode.GT:
		return n > 0, nil
	case opcode.EQ:
		return n == 0, nil
	case opcode.NE:
		return n != 0, nil
	default:
		return nil, o.errorf("invalid op %v in comparision operation", o.Op)
	}
}

func (n *PatternIn) checkInList(in interface{}, list []interface{}) (interface{}, error) {
	hasNull := false
	for _, v := range list {
		if types.IsNil(v) {
			hasNull = true
			continue
		}

		r, err := types.Compare(in, v)
		if err != nil {
			return nil, err
		}

		if r == 0 {
			return !n.Not, nil
		}
	}

	if hasNull {
		// if no matched but we got null in In, return null
		// e.g 1 in (null, 2, 3) returns null
		return nil, nil
	}

	return n.Not, nil
}

// operator: >=, >, <=, <, !=, <>, = <=>, etc.
// see https://dev.mysql.com/doc/refman/5.7/en/comparison-operators.html
func (o *BinaryOperation) evalComparisonOp(ctx context.Context, args map[interface{}]interface{}) (interface{}, error) {
	//TODO: support <=> later
	a, b, err := o.get2(ctx, args)
	if err != nil {
		return nil, err
	}

	if a == nil || b == nil {
		// for <=>, if a and b are both nil, return true.
		// if a or b is nil, return false.
		if o.Op == opcode.NullEQ {
			return a == b, nil
		}

		return nil, nil
	}

	n, err := types.Compare(a, b)
	if err != nil {
		return nil, o.traceErr(err)
	}

	r, err := getCompResult(o.Op, n)
	if err != nil {
		return nil, o.errorf(err.Error())
	}

	return r, nil
}

func (n *AggregateFuncExpr) updateMaxMin(max bool) error {
	ctx := n.GetContext()
	if len(n.Args) != 1 {
		return errors.New("Wrong number of args for AggFuncFirstRow")
	}
	v := n.Args[0].GetValue()
	if !ctx.evaluated {
		ctx.Value = v
		ctx.evaluated = true
		return nil
	}
	c, err := types.Compare(ctx.Value, v)
	if err != nil {
		return errors.Trace(err)
	}
	if max {
		if c == -1 {
			ctx.Value = v
		}
	} else {
		if c == 1 {
			ctx.Value = v
		}

	}
	return nil
}

func (e *Evaluator) patternIn(n *ast.PatternInExpr) bool {
	lhs := n.Expr.GetValue()
	if types.IsNil(lhs) {
		n.SetValue(nil)
		return true
	}
	hasNull := false
	for _, v := range n.List {
		if types.IsNil(v.GetValue()) {
			hasNull = true
			continue
		}
		r, err := types.Compare(n.Expr.GetValue(), v.GetValue())
		if err != nil {
			e.err = errors.Trace(err)
			return false
		}
		if r == 0 {
			n.SetValue(boolToInt64(!n.Not))
			return true
		}
	}
	if hasNull {
		// if no matched but we got null in In, return null
		// e.g 1 in (null, 2, 3) returns null
		n.SetValue(nil)
		return true
	}
	n.SetValue(boolToInt64(n.Not))
	return true
}

// comparison function that takes minNotNullVal and maxVal into account.
func indexCompare(a interface{}, b interface{}) int {
	if a == nil && b == nil {
		return 0
	} else if b == nil {
		return 1
	} else if b == nil {
		return -1
	}
	// a and b both not nil
	if a == minNotNullVal && b == minNotNullVal {
		return 0
	} else if b == minNotNullVal {
		return 1
	} else if a == minNotNullVal {
		return -1
	}

	// a and b both not min value
	if a == maxVal && b == maxVal {
		return 0
	} else if a == maxVal {
		return 1
	} else if b == maxVal {
		return -1
	}

	return types.Compare(a, b)
}

// comparison function that takes minNotNullVal and maxVal into account.
func indexColumnCompare(a interface{}, b interface{}) (int, error) {
	if a == nil && b == nil {
		return 0, nil
	} else if b == nil {
		return 1, nil
	} else if a == nil {
		return -1, nil
	}

	// a and b both not nil
	if a == plan.MinNotNullVal && b == plan.MinNotNullVal {
		return 0, nil
	} else if b == plan.MinNotNullVal {
		return 1, nil
	} else if a == plan.MinNotNullVal {
		return -1, nil
	}

	// a and b both not min value
	if a == plan.MaxVal && b == plan.MaxVal {
		return 0, nil
	} else if a == plan.MaxVal {
		return 1, nil
	} else if b == plan.MaxVal {
		return -1, nil
	}

	n, err := types.Compare(a, b)
	if err != nil {
		return 0, errors.Trace(err)
	}
	return n, nil
}

// Update implements AggregationFunction interface.
func (mmf *maxMinFunction) Update(row []types.Datum, groupKey []byte, ectx context.Context) error {
	ctx := mmf.getContext(groupKey)
	if len(mmf.Args) != 1 {
		return errors.New("Wrong number of args for AggFuncMaxMin")
	}
	a := mmf.Args[0]
	value, err := a.Eval(row, ectx)
	if err != nil {
		return errors.Trace(err)
	}
	if !ctx.Evaluated {
		ctx.Value = value.GetValue()
	}
	if value.GetValue() == nil {
		return nil
	}
	var c int
	c, err = types.Compare(ctx.Value, value.GetValue())
	if err != nil {
		return errors.Trace(err)
	}
	if (mmf.isMax && c == -1) || (!mmf.isMax && c == 1) {
		ctx.Value = value.GetValue()
	}
	ctx.Evaluated = true
	return nil
}