forked from pingcap/tidb
/
unary.go
250 lines (229 loc) · 5.27 KB
/
unary.go
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// Copyright 2015 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package expressions
import (
"fmt"
"github.com/juju/errors"
"github.com/pingcap/tidb/context"
"github.com/pingcap/tidb/expression"
mysql "github.com/pingcap/tidb/mysqldef"
"github.com/pingcap/tidb/parser/opcode"
"github.com/pingcap/tidb/util/types"
)
var (
_ expression.Expression = (*UnaryOperation)(nil)
)
// UnaryOperation is the expression for unary operator.
type UnaryOperation struct {
// Op is the operator opcode.
Op opcode.Op
// V is the unary expression.
V expression.Expression
}
// NewUnaryOperation creates an unary expression.
func NewUnaryOperation(op opcode.Op, l expression.Expression) expression.Expression {
// extract expression in parenthese, e.g, ((expr)) -> expr
for {
pe, ok := l.(*PExpr)
if ok {
l = pe.Expr
continue
}
break
}
// if op is Not and l is relational comparison expression,
// we can invert relational operator.
if op == opcode.Not {
b, ok := l.(*BinaryOperation)
if ok {
switch b.Op {
case opcode.EQ:
b.Op = opcode.NE
return b
case opcode.NE:
b.Op = opcode.EQ
return b
case opcode.GT:
b.Op = opcode.LE
return b
case opcode.GE:
b.Op = opcode.LT
return b
case opcode.LT:
b.Op = opcode.GE
return b
case opcode.LE:
b.Op = opcode.GT
return b
}
}
u, ok := l.(*UnaryOperation)
if ok && u.Op == opcode.Not { // !!x: x
return u.V
}
}
return &UnaryOperation{op, l}
}
// Clone implements the Expression Clone interface.
func (u *UnaryOperation) Clone() (expression.Expression, error) {
v, err := u.V.Clone()
if err != nil {
return nil, err
}
return &UnaryOperation{Op: u.Op, V: v}, nil
}
// IsStatic implements the Expression IsStatic interface.
func (u *UnaryOperation) IsStatic() bool {
return u.V.IsStatic()
}
// String implements the Expression String interface.
func (u *UnaryOperation) String() string {
switch u.V.(type) {
case *BinaryOperation:
return fmt.Sprintf("%s(%s)", u.Op, u.V)
default:
switch u.Op {
case opcode.Not:
// we must handle not oeprator, e.g
// if not using (), "not null is null" will output "!null is null".
// the ! and not's precedences are not equal
// "not null is null" will returns 0, but "!null is null" will return 1
return fmt.Sprintf("%s(%s)", u.Op, u.V)
default:
return fmt.Sprintf("%s%s", u.Op, u.V)
}
}
}
// Eval implements the Expression Eval interface.
func (u *UnaryOperation) Eval(ctx context.Context, args map[interface{}]interface{}) (r interface{}, err error) {
defer func() {
if e := recover(); e != nil {
r, err = nil, errors.Errorf("%v", e)
}
}()
switch op := u.Op; op {
case opcode.Not:
a := Eval(u.V, ctx, args)
if a == nil {
return
}
n, err := types.ToBool(a)
if err != nil {
return types.UndOp(a, op)
} else if n == 0 {
return int8(1), nil
}
return int8(0), nil
case opcode.BitNeg:
a := Eval(u.V, ctx, args)
if a == nil {
return
}
// for bit operation, we will use int64 first, then return uint64
n, err := types.ToInt64(a)
if err != nil {
return types.UndOp(a, op)
}
return uint64(^n), nil
case opcode.Plus:
a := Eval(u.V, ctx, args)
switch x := a.(type) {
case nil:
return nil, nil
case float32:
return +x, nil
case float64:
return +x, nil
case int:
return +x, nil
case int8:
return +x, nil
case int16:
return +x, nil
case int32:
return +x, nil
case int64:
return +x, nil
case uint:
return +x, nil
case uint8:
return +x, nil
case uint16:
return +x, nil
case uint32:
return +x, nil
case uint64:
return +x, nil
case mysql.Duration:
return x, nil
case mysql.Time:
return x, nil
case string:
return x, nil
case mysql.Decimal:
return x, nil
case []byte:
return x, nil
default:
return types.UndOp(a, op)
}
case opcode.Minus:
a := Eval(u.V, ctx, args)
switch x := a.(type) {
case nil:
return nil, nil
case float32:
return -x, nil
case float64:
return -x, nil
case int:
return -x, nil
case int8:
return -x, nil
case int16:
return -x, nil
case int32:
return -x, nil
case int64:
return -x, nil
case uint:
return -int64(x), nil
case uint8:
return -int64(x), nil
case uint16:
return -int64(x), nil
case uint32:
return -int64(x), nil
case uint64:
// TODO: check overflow and do more test for unsigned type
return -int64(x), nil
case mysql.Duration:
return mysql.ZeroDecimal.Sub(x.ToNumber()), nil
case mysql.Time:
return mysql.ZeroDecimal.Sub(x.ToNumber()), nil
case string:
f, err := types.StrToFloat(x)
return -f, err
case mysql.Decimal:
f, _ := x.Float64()
return mysql.NewDecimalFromFloat(-f), nil
case []byte:
f, err := types.StrToFloat(string(x))
return -f, err
default:
return types.UndOp(a, op)
}
default:
panic("should never happen")
}
}