forked from dolthub/go-mysql-server
/
sqrt_power.go
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/
sqrt_power.go
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// Copyright 2020-2021 Dolthub, 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 function
import (
"fmt"
"math"
"github.com/gabereiser/go-mysql-server/sql"
"github.com/gabereiser/go-mysql-server/sql/expression"
"github.com/gabereiser/go-mysql-server/sql/types"
)
// Sqrt is a function that returns the square value of the number provided.
type Sqrt struct {
expression.UnaryExpression
}
var _ sql.FunctionExpression = (*Sqrt)(nil)
// NewSqrt creates a new Sqrt expression.
func NewSqrt(e sql.Expression) sql.Expression {
return &Sqrt{expression.UnaryExpression{Child: e}}
}
// FunctionName implements sql.FunctionExpression
func (s *Sqrt) FunctionName() string {
return "sqrt"
}
// Description implements sql.FunctionExpression
func (s *Sqrt) Description() string {
return "returns the square root of a nonnegative number X."
}
func (s *Sqrt) String() string {
return fmt.Sprintf("sqrt(%s)", s.Child.String())
}
// Type implements the Expression interface.
func (s *Sqrt) Type() sql.Type {
return types.Float64
}
// IsNullable implements the Expression interface.
func (s *Sqrt) IsNullable() bool {
return s.Child.IsNullable()
}
// WithChildren implements the Expression interface.
func (s *Sqrt) WithChildren(children ...sql.Expression) (sql.Expression, error) {
if len(children) != 1 {
return nil, sql.ErrInvalidChildrenNumber.New(s, len(children), 1)
}
return NewSqrt(children[0]), nil
}
// Eval implements the Expression interface.
func (s *Sqrt) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
child, err := s.Child.Eval(ctx, row)
if err != nil {
return nil, err
}
if child == nil {
return nil, nil
}
child, err = types.Float64.Convert(child)
if err != nil {
return nil, err
}
return math.Sqrt(child.(float64)), nil
}
// Power is a function that returns value of X raised to the power of Y.
type Power struct {
expression.BinaryExpression
}
var _ sql.FunctionExpression = (*Power)(nil)
// NewPower creates a new Power expression.
func NewPower(e1, e2 sql.Expression) sql.Expression {
return &Power{
expression.BinaryExpression{
Left: e1,
Right: e2,
},
}
}
// FunctionName implements sql.FunctionExpression
func (p *Power) FunctionName() string {
return "power"
}
// Description implements sql.FunctionExpression
func (p *Power) Description() string {
return "returns the value of X raised to the power of Y."
}
// Type implements the Expression interface.
func (p *Power) Type() sql.Type { return types.Float64 }
// IsNullable implements the Expression interface.
func (p *Power) IsNullable() bool { return p.Left.IsNullable() || p.Right.IsNullable() }
func (p *Power) String() string {
return fmt.Sprintf("power(%s, %s)", p.Left, p.Right)
}
// WithChildren implements the Expression interface.
func (p *Power) WithChildren(children ...sql.Expression) (sql.Expression, error) {
if len(children) != 2 {
return nil, sql.ErrInvalidChildrenNumber.New(p, len(children), 2)
}
return NewPower(children[0], children[1]), nil
}
// Eval implements the Expression interface.
func (p *Power) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
left, err := p.Left.Eval(ctx, row)
if err != nil {
return nil, err
}
if left == nil {
return nil, nil
}
left, err = types.Float64.Convert(left)
if err != nil {
return nil, err
}
right, err := p.Right.Eval(ctx, row)
if err != nil {
return nil, err
}
if right == nil {
return nil, nil
}
right, err = types.Float64.Convert(right)
if err != nil {
return nil, err
}
return math.Pow(left.(float64), right.(float64)), nil
}