zabetak commented on a change in pull request #1020: [CALCITE-2812] Add algebraic operators to allow expressing recursive queries (Ruben Quesada Lopez) URL: https://github.com/apache/calcite/pull/1020#discussion_r276286371
########## File path: core/src/main/java/org/apache/calcite/schema/impl/TransientTable.java ########## @@ -0,0 +1,142 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to you 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 org.apache.calcite.schema.impl; + +import org.apache.calcite.DataContext; +import org.apache.calcite.adapter.java.AbstractQueryableTable; +import org.apache.calcite.linq4j.AbstractEnumerable; +import org.apache.calcite.linq4j.Enumerable; +import org.apache.calcite.linq4j.Enumerator; +import org.apache.calcite.linq4j.Linq4j; +import org.apache.calcite.linq4j.QueryProvider; +import org.apache.calcite.linq4j.Queryable; +import org.apache.calcite.linq4j.function.Experimental; +import org.apache.calcite.linq4j.tree.Expression; +import org.apache.calcite.plan.RelOptCluster; +import org.apache.calcite.plan.RelOptTable; +import org.apache.calcite.prepare.Prepare; +import org.apache.calcite.rel.RelNode; +import org.apache.calcite.rel.core.TableModify; +import org.apache.calcite.rel.logical.LogicalTableModify; +import org.apache.calcite.rel.type.RelDataType; +import org.apache.calcite.rel.type.RelDataTypeFactory; +import org.apache.calcite.rex.RexNode; +import org.apache.calcite.schema.ModifiableTable; +import org.apache.calcite.schema.ScannableTable; +import org.apache.calcite.schema.SchemaPlus; +import org.apache.calcite.schema.Schemas; + +import java.lang.reflect.Type; +import java.util.ArrayList; +import java.util.Collection; +import java.util.List; + +/** + * Simple modifiable table backed by a Java list. + * It can be used, for example, in a repeat union to accumulate all intermediate results. + * + * <p>NOTE: The current API is experimental and subject to change without notice.</p> + */ +@Experimental +public class TransientTable extends AbstractQueryableTable + implements ModifiableTable, ScannableTable { + private static final Type TYPE = Object[].class; + private final List rows = new ArrayList(); + private final String name; + private final RelDataType rowType; + + public TransientTable(String name, RelDataType rowType) { + super(TYPE); + this.name = name; + this.rowType = rowType; + } + + @Override public TableModify toModificationRel( + RelOptCluster cluster, + RelOptTable table, + Prepare.CatalogReader catalogReader, + RelNode child, + TableModify.Operation operation, + List<String> updateColumnList, + List<RexNode> sourceExpressionList, + boolean flattened) { + return LogicalTableModify.create(table, catalogReader, child, operation, + updateColumnList, sourceExpressionList, flattened); + } + + @Override public Collection getModifiableCollection() { + return rows; + } + + @Override public Enumerable<Object[]> scan(DataContext root) { + // add the table into the schema, so that it is accessible by any potential operator + root.getRootSchema().add(name, this); + + return new AbstractEnumerable<Object[]>() { + public Enumerator<Object[]> enumerator() { + return new Enumerator<Object[]>() { + private final List list = rows; + private int i = -1; + + // TODO cleaner way to handle non-array objects? + @Override public Object[] current() { + Object current = list.get(i); + return current.getClass().isArray() + ? (Object[]) current + : new Object[]{current}; + } + + @Override public boolean moveNext() { + return ++i < list.size(); + } + + @Override public void reset() { + i = -1; + } + + @Override public void close() { + } + }; + } + }; + } + + public Expression getExpression(SchemaPlus schema, String tableName, + Class clazz) { + return Schemas.tableExpression(schema, elementType, tableName, clazz); + } + + @Override public <T> Queryable<T> asQueryable(QueryProvider queryProvider, + SchemaPlus schema, String tableName) { + return new AbstractTableQueryable<T>(queryProvider, schema, this, tableName) { + public Enumerator<T> enumerator() { + //noinspection unchecked + return (Enumerator<T>) Linq4j.enumerator(rows); + } + }; + } + + @Override public RelDataType getRowType(RelDataTypeFactory typeFactory) { + return rowType; Review comment: Replace with `return typeFactory.copy(rowType);` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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