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point.go
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point.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 spatial
import (
"fmt"
"github.com/gabereiser/go-mysql-server/sql"
"github.com/gabereiser/go-mysql-server/sql/types"
)
// Point is a function that returns a point type containing values Y and Y.
type Point struct {
X sql.Expression
Y sql.Expression
}
var _ sql.FunctionExpression = (*Point)(nil)
// NewPoint creates a new point expression.
func NewPoint(e1, e2 sql.Expression) sql.Expression {
return &Point{e1, e2}
}
// FunctionName implements sql.FunctionExpression
func (p *Point) FunctionName() string {
return "point"
}
// Description implements sql.FunctionExpression
func (p *Point) Description() string {
return "returns a new point."
}
// Children implements the sql.Expression interface.
func (p *Point) Children() []sql.Expression {
return []sql.Expression{p.X, p.Y}
}
// Resolved implements the sql.Expression interface.
func (p *Point) Resolved() bool {
return p.X.Resolved() && p.Y.Resolved()
}
// IsNullable implements the sql.Expression interface.
func (p *Point) IsNullable() bool {
return p.X.IsNullable() || p.Y.IsNullable()
}
// Type implements the sql.Expression interface.
func (p *Point) Type() sql.Type {
return types.PointType{}
}
func (p *Point) String() string {
return fmt.Sprintf("%s(%s,%s)", p.FunctionName(), p.X.String(), p.Y.String())
}
// WithChildren implements the Expression interface.
func (p *Point) WithChildren(children ...sql.Expression) (sql.Expression, error) {
if len(children) != 2 {
return nil, sql.ErrInvalidChildrenNumber.New(p, len(children), 2)
}
return NewPoint(children[0], children[1]), nil
}
// Eval implements the sql.Expression interface.
func (p *Point) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
// Evaluate X
x, err := p.X.Eval(ctx, row)
if err != nil {
return nil, err
}
if x == nil {
return nil, nil
}
// Convert to float64
_x, err := types.Float64.Convert(x)
if err != nil {
return nil, err
}
// Evaluate Y
y, err := p.Y.Eval(ctx, row)
if err != nil {
return nil, err
}
if y == nil {
return nil, nil
}
// Convert to float64
_y, err := types.Float64.Convert(y)
if err != nil {
return nil, err
}
return types.Point{X: _x.(float64), Y: _y.(float64)}, nil
}