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binary_operator.go
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/
binary_operator.go
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// Copyright (c) 2013 Couchbase, 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, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
// either express or implied. See the License for the specific language governing permissions
// and limitations under the License.
package ast
import (
"fmt"
"github.com/couchbaselabs/dparval"
)
type BinaryOperator struct {
operator string
Left Expression `json:"left"`
Right Expression `json:"right"`
}
func (this *BinaryOperator) compare(context *dparval.Value) (*dparval.Value, error) {
lv, rv, err := this.EvaluateBoth(context)
if err != nil {
return nil, err
}
// if either side is NULL, the result is NULL
if lv.Type() == dparval.NULL || rv.Type() == dparval.NULL {
return nil, nil
}
lvalue := lv.Value()
rvalue := rv.Value()
// if we got this far, we evaluated both sides
// there were no errors, and neither side was NULL or MISSING
// now check types (types must be the same)
ltype := collationType(lvalue)
rtype := collationType(rvalue)
// ugly fixups for boolean (returns different values for true/false)
if ltype == 2 {
// fixup for boolean type
ltype = 1
}
if rtype == 2 {
rtype = 1
}
if ltype != rtype {
return nil, &TypeMismatch{ltype, rtype}
}
return dparval.NewValue(float64(CollateJSON(lvalue, rvalue))), nil
}
func (this *BinaryOperator) Dependencies() ExpressionList {
rv := ExpressionList{this.Left, this.Right}
return rv
}
func (this *BinaryOperator) GetLeft() Expression {
return this.Left
}
func (this *BinaryOperator) GetRight() Expression {
return this.Right
}
func (this *BinaryOperator) SetLeft(left Expression) {
this.Left = left
}
func (this *BinaryOperator) SetRight(right Expression) {
this.Right = right
}
func (this *BinaryOperator) Operator() string {
return this.operator
}
func (this *BinaryOperator) String() string {
return fmt.Sprintf("%v %s %v", this.Left, this.operator, this.Right)
}
func (this *BinaryOperator) EquivalentTo(t Expression) bool {
// another binary operator?
that, ok := t.(BinaryOperatorExpression)
if !ok {
return false
}
// same type of operator?
if this.operator != that.Operator() {
return false
}
// same operands?
if this.Left.EquivalentTo(that.GetLeft()) &&
this.Right.EquivalentTo(that.GetRight()) {
return true
}
return false
}
func (this *BinaryOperator) EvaluateBoth(context *dparval.Value) (*dparval.Value, *dparval.Value, error) {
lv, err := this.Left.Evaluate(context)
if err != nil {
return nil, nil, err
}
rv, err := this.Right.Evaluate(context)
if err != nil {
return nil, nil, err
}
return lv, rv, nil
}
func (this *BinaryOperator) EvaluateBothRequireNumber(context *dparval.Value) (float64, float64, bool, error) {
lv, rv, err := this.EvaluateBoth(context)
if err != nil {
return 0.0, 0.0, true, err
}
if lv.Type() == rv.Type() && rv.Type() == dparval.NUMBER {
lvalue := lv.Value()
rvalue := rv.Value()
switch lvalue := lvalue.(type) {
case float64:
switch rvalue := rvalue.(type) {
case float64:
return lvalue, rvalue, true, nil
}
}
}
return 0.0, 0.0, false, nil
}
func (this *BinaryOperator) EvaluateBothRequireString(context *dparval.Value) (string, string, bool, error) {
lv, rv, err := this.EvaluateBoth(context)
if err != nil {
return "", "", true, err
}
if lv.Type() == rv.Type() && rv.Type() == dparval.STRING {
lvalue := lv.Value()
rvalue := rv.Value()
switch lvalue := lvalue.(type) {
case string:
switch rvalue := rvalue.(type) {
case string:
return lvalue, rvalue, true, nil
}
}
}
return "", "", false, nil
}