chore: import upstream snapshot with attribution

server/node/drop_sequence.go

@@ -0,0 +1,129 @@
+// Copyright 2024 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 node
+
+import (
+	"context"
+
+	"github.com/cockroachdb/errors"
+	"github.com/dolthub/go-mysql-server/sql"
+	"github.com/dolthub/go-mysql-server/sql/plan"
+	vitess "github.com/dolthub/vitess/go/vt/sqlparser"
+
+	"github.com/dolthub/doltgresql/core"
+	"github.com/dolthub/doltgresql/core/id"
+)
+
+// DropSequence handles the DROP SEQUENCE statement.
+type DropSequence struct {
+	schema   string
+	sequence string
+	ifExists bool
+	cascade  bool
+}
+
+var _ sql.ExecSourceRel = (*DropSequence)(nil)
+var _ vitess.Injectable = (*DropSequence)(nil)
+
+// NewDropSequence returns a new *DropSequence.
+func NewDropSequence(ifExists bool, schema string, sequence string, cascade bool) *DropSequence {
+	return &DropSequence{
+		schema:   schema,
+		sequence: sequence,
+		ifExists: ifExists,
+		cascade:  cascade,
+	}
+}
+
+// Children implements the interface sql.ExecSourceRel.
+func (c *DropSequence) Children() []sql.Node {
+	return nil
+}
+
+// IsReadOnly implements the interface sql.ExecSourceRel.
+func (c *DropSequence) IsReadOnly() bool {
+	return false
+}
+
+// Resolved implements the interface sql.ExecSourceRel.
+func (c *DropSequence) Resolved() bool {
+	return true
+}
+
+// RowIter implements the interface sql.ExecSourceRel.
+func (c *DropSequence) RowIter(ctx *sql.Context, r sql.Row) (sql.RowIter, error) {
+	schema, err := core.GetSchemaName(ctx, nil, c.schema)
+	if err != nil {
+		return nil, err
+	}
+	relationType, err := core.GetRelationType(ctx, schema, c.sequence)
+	if err != nil {
+		return nil, err
+	}
+	if relationType == core.RelationType_DoesNotExist {
+		if c.ifExists {
+			// TODO: issue a notice
+			return sql.RowsToRowIter(), nil
+		}
+		return nil, errors.Errorf(`sequence "%s" does not exist`, c.sequence)
+	}
+	// TODO: we always use the current database for this operation, but it should also be possible drop a sequence in
+	//  a different DB (e.g. on a different branch)
+	collection, err := core.GetSequencesCollectionFromContext(ctx, ctx.GetCurrentDatabase())
+	if err != nil {
+		return nil, err
+	}
+	sequenceID := id.NewSequence(schema, c.sequence)
+	sequence, err := collection.GetSequence(ctx, sequenceID)
+	if err != nil {
+		return nil, err
+	}
+	if sequence.OwnerTable.IsValid() {
+		if c.cascade {
+			// TODO: if the sequence is referenced by the column's default value, then we also need to delete the default
+			return nil, errors.Errorf(`cascading sequence drops are not yet supported`)
+		} else {
+			// TODO: this error is only true if the sequence is referenced by the column's default value
+			return nil, errors.Errorf(`cannot drop sequence %s because other objects depend on it`, c.sequence)
+		}
+	}
+	if err = collection.DropSequence(ctx, sequenceID); err != nil {
+		return nil, err
+	}
+	return sql.RowsToRowIter(), nil
+}
+
+// Schema implements the interface sql.ExecSourceRel.
+func (c *DropSequence) Schema(ctx *sql.Context) sql.Schema {
+	return nil
+}
+
+// String implements the interface sql.ExecSourceRel.
+func (c *DropSequence) String() string {
+	return "DROP SEQUENCE"
+}
+
+// WithChildren implements the interface sql.ExecSourceRel.
+func (c *DropSequence) WithChildren(ctx *sql.Context, children ...sql.Node) (sql.Node, error) {
+	return plan.NillaryWithChildren(c, children...)
+}
+
+// WithResolvedChildren implements the interface vitess.Injectable.
+func (c *DropSequence) WithResolvedChildren(ctx context.Context, children []any) (any, error) {
+	if len(children) != 0 {
+		return nil, ErrVitessChildCount.New(0, len(children))
+	}
+	return c, nil
+}