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use.go
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use.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 plan
import (
"fmt"
"github.com/Sndav/go-mysql-server/sql"
)
// Use changes the current database.
type Use struct {
db sql.Database
Catalog *sql.Catalog
}
// NewUse creates a new Use node.
func NewUse(db sql.Database) *Use {
return &Use{db: db}
}
var _ sql.Node = (*Use)(nil)
var _ sql.Databaser = (*Use)(nil)
// Database implements the sql.Databaser interface.
func (u *Use) Database() sql.Database {
return u.db
}
// WithDatabase implements the sql.Databaser interface.
func (u *Use) WithDatabase(db sql.Database) (sql.Node, error) {
nc := *u
nc.db = db
return &nc, nil
}
// Children implements the sql.Node interface.
func (Use) Children() []sql.Node { return nil }
// Resolved implements the sql.Node interface.
func (u *Use) Resolved() bool {
_, ok := u.db.(sql.UnresolvedDatabase)
return !ok
}
// Schema implements the sql.Node interface.
func (Use) Schema() sql.Schema { return nil }
// RowIter implements the sql.Node interface.
func (u *Use) RowIter(ctx *sql.Context, row sql.Row) (sql.RowIter, error) {
dbName := u.db.Name()
_, err := u.Catalog.Database(dbName)
if err != nil {
return nil, err
}
ctx.SetCurrentDatabase(dbName)
return sql.RowsToRowIter(), nil
}
// WithChildren implements the Node interface.
func (u *Use) WithChildren(children ...sql.Node) (sql.Node, error) {
if len(children) != 0 {
return nil, sql.ErrInvalidChildrenNumber.New(u, len(children), 1)
}
return u, nil
}
// String implements the sql.Node interface.
func (u *Use) String() string {
return fmt.Sprintf("USE(%s)", u.db.Name())
}