/
linestring.go
100 lines (84 loc) · 2.97 KB
/
linestring.go
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// Copyright 2020-2022 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"
"strings"
"github.com/dolthub/go-mysql-server/sql/expression"
"github.com/dolthub/go-mysql-server/sql/types"
"github.com/dolthub/go-mysql-server/sql"
)
// LineString is a function that returns a point type containing values Y and Y.
type LineString struct {
expression.NaryExpression
}
var _ sql.FunctionExpression = (*LineString)(nil)
var _ sql.CollationCoercible = (*LineString)(nil)
// NewLineString creates a new LineString.
func NewLineString(args ...sql.Expression) (sql.Expression, error) {
if len(args) < 2 {
return nil, sql.ErrInvalidArgumentNumber.New("LineString", "2 or more", len(args))
}
return &LineString{expression.NaryExpression{ChildExpressions: args}}, nil
}
// FunctionName implements sql.FunctionExpression
func (l *LineString) FunctionName() string {
return "linestring"
}
// Description implements sql.FunctionExpression
func (l *LineString) Description() string {
return "returns a new linestring."
}
// Type implements the sql.Expression interface.
func (l *LineString) Type() sql.Type {
return types.LineStringType{}
}
// CollationCoercibility implements the interface sql.CollationCoercible.
func (*LineString) CollationCoercibility(ctx *sql.Context) (collation sql.CollationID, coercibility byte) {
return sql.Collation_binary, 5
}
func (l *LineString) String() string {
var args = make([]string, len(l.ChildExpressions))
for i, arg := range l.ChildExpressions {
args[i] = arg.String()
}
return fmt.Sprintf("%s(%s)", l.FunctionName(), strings.Join(args, ","))
}
// WithChildren implements the Expression interface.
func (l *LineString) WithChildren(children ...sql.Expression) (sql.Expression, error) {
return NewLineString(children...)
}
// Eval implements the sql.Expression interface.
func (l *LineString) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
// Allocate array of points
var points = make([]types.Point, len(l.ChildExpressions))
// Go through each argument
for i, arg := range l.ChildExpressions {
// Evaluate argument
val, err := arg.Eval(ctx, row)
if err != nil {
return nil, err
}
// Must be of type point, throw error otherwise
switch v := val.(type) {
case types.Point:
points[i] = v
case types.GeometryValue:
return nil, sql.ErrInvalidArgumentDetails.New(l.FunctionName(), v)
default:
return nil, sql.ErrIllegalGISValue.New(v)
}
}
return types.LineString{Points: points}, nil
}