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This module connects Table/SQL API and runtime. It is responsible for translating and optimizing a table program into a Flink pipeline. The module can access all resources that are required during pre-flight and runtime phase for planning.

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/*
 * 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.sql.validate;

import org.apache.flink.annotation.Internal;

import org.apache.calcite.rel.type.RelDataType;
import org.apache.calcite.sql.SqlCall;
import org.apache.calcite.sql.SqlCallBinding;
import org.apache.calcite.sql.SqlKind;
import org.apache.calcite.sql.SqlNode;
import org.apache.calcite.sql.SqlOperator;
import org.apache.calcite.sql.SqlTableFunction;
import org.apache.calcite.sql.SqlUtil;
import org.apache.calcite.sql.type.SqlReturnTypeInference;
import org.apache.calcite.sql.type.SqlTypeName;

/**
 * Namespace whose contents are defined by the result of a call to a user-defined procedure.
 *
 * Note: Compared to Calcite, this class implements custom logic for dealing with collection
 * tables like {@code TABLE(function(...))} procedures. Compared to the SQL standard, Flink's table
 * functions can return arbitrary types that are wrapped into a ROW type if necessary. We don't
 * interpret ARRAY or MULTISET types as it would be standard.
 */
@Internal
public final class ProcedureNamespace extends AbstractNamespace {

    private final SqlValidatorScope scope;

    private final SqlCall call;

    ProcedureNamespace(
            SqlValidatorImpl validator,
            SqlValidatorScope scope,
            SqlCall call,
            SqlNode enclosingNode) {
        super(validator, enclosingNode);
        this.scope = scope;
        this.call = call;
    }

    public RelDataType validateImpl(RelDataType targetRowType) {
        validator.inferUnknownTypes(validator.unknownType, scope, call);
        final RelDataType type = validator.deriveTypeImpl(scope, call);
        final SqlOperator operator = call.getOperator();
        final SqlCallBinding callBinding = new SqlCallBinding(validator, scope, call);
        if (operator instanceof SqlTableFunction) {
            final SqlTableFunction tableFunction = (SqlTableFunction) operator;
            if (type.getSqlTypeName() != SqlTypeName.CURSOR) {
                throw new IllegalArgumentException(
                        "Table function should have CURSOR " + "type, not " + type);
            }
            final SqlReturnTypeInference rowTypeInference = tableFunction.getRowTypeInference();
            RelDataType retType = rowTypeInference.inferReturnType(callBinding);
            return validator.getTypeFactory().createTypeWithNullability(retType, false);
        }

        // special handling of collection tables TABLE(function(...))
        if (SqlUtil.stripAs(enclosingNode).getKind() == SqlKind.COLLECTION_TABLE) {
            return toStruct(type, getNode());
        }
        return type;
    }

    /** Converts a type to a struct if it is not already. */
    protected RelDataType toStruct(RelDataType type, SqlNode unnest) {
        if (type.isStruct()) {
            return validator.getTypeFactory().createTypeWithNullability(type, false);
        }
        return validator
                .getTypeFactory()
                .builder()
                .kind(type.getStructKind())
                .add(validator.deriveAlias(unnest, 0), type)
                .build();
    }

    public SqlNode getNode() {
        return call;
    }
}