chore: import upstream snapshot with attribution

server/tables/handler.go

@@ -0,0 +1,48 @@
+// 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 tables
+
+import "github.com/dolthub/go-mysql-server/sql"
+
+// Handler is an interface that controls how data is represented for some table.
+type Handler interface {
+	// Name returns the name of the table.
+	Name() string
+	// RowIter returns a sql.RowIter that returns the rows of the table.
+	RowIter(ctx *sql.Context, partition sql.Partition) (sql.RowIter, error)
+	// PkSchema returns the table's schema.
+	PkSchema() sql.PrimaryKeySchema
+}
+
+type IndexedTableHandler interface {
+	Handler
+	// Indexes returns the table's indexes.
+	Indexes() ([]sql.Index, error)
+	// LookupPartitions returns a sql.PartitionIter that can be used to look up rows in the table using the given lookup
+	LookupPartitions(context *sql.Context, lookup sql.IndexLookup) (sql.PartitionIter, error)
+}
+
+// handlers is a map from the schema name, to the table name, to the handler.
+var handlers = map[string]map[string]Handler{}
+
+// AddHandler adds the given handler to the handler set.
+func AddHandler(schemaName string, tableName string, handler Handler) {
+	tableMap, ok := handlers[schemaName]
+	if !ok {
+		tableMap = make(map[string]Handler)
+		handlers[schemaName] = tableMap
+	}
+	tableMap[tableName] = handler
+}