src/org/apache/pig/impl/logicalLayer/LogicalOperator.java

/*
 * 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.pig.impl.logicalLayer;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import org.apache.pig.impl.logicalLayer.schema.TupleSchema;

import org.apache.pig.backend.executionengine.ExecScopedLogicalOperator;


abstract public class LogicalOperator implements Serializable, ExecScopedLogicalOperator {
    public String alias = null;

    public static final int FIXED = 1;
    public static final int MONOTONE = 2;
    public static final int UPDATABLE = 3;      // Reserved for future use
    public static final int AMENDABLE = 4;

    protected int requestedParallelism = -1;
    protected TupleSchema schema = null;
    protected List<OperatorKey> inputs;

    protected Map<OperatorKey, LogicalOperator> opTable;

    protected String scope;
    protected long id;
    
    protected LogicalOperator(Map<OperatorKey, LogicalOperator> opTable,
                              String scope, 
                              long id) {
        this.inputs = new ArrayList<OperatorKey> ();
        this.opTable = opTable;
        this.scope = scope;
        this.id = id;

        opTable.put(getOperatorKey(), this);
    } 
    
    protected LogicalOperator(Map<OperatorKey, LogicalOperator> opTable, 
                              String scope, 
                              long id, 
                              List<OperatorKey> inputs) {
        this.opTable = opTable;
        this.inputs = inputs;
        this.scope = scope;
        this.id = id;
        
        opTable.put(getOperatorKey(), this);
    }

    protected LogicalOperator(Map<OperatorKey, LogicalOperator> opTable,
                              String scope, 
                              long id, 
                              OperatorKey input) {
        this.opTable = opTable;
        this.inputs = new ArrayList<OperatorKey> ();
        inputs.add(input);
        this.scope = scope;
        this.id = id;

        opTable.put(getOperatorKey(), this);
    }
    
    public OperatorKey getOperatorKey() {
        return new OperatorKey(scope, id);
    }
    
    public String getScope() {
        return this.scope;
    }
    
    public long getId() {
        return this.id;
    }
    
    public String getAlias() {
        return alias;
    }

    public void setAlias(String newAlias) {
        alias = newAlias;
    }

    public int getRequestedParallelism() {
        return requestedParallelism;
    }

    public void setRequestedParallelism(int newRequestedParallelism) {
        requestedParallelism = newRequestedParallelism;
    }

    @Override public String toString() {
        StringBuilder result = new StringBuilder(super.toString());
        result.append(" (alias: ");
        result.append(alias);
        result.append(", requestedParallelism: ");
        result.append(requestedParallelism);
        result.append(')');
        return result.toString();
    }

    public abstract TupleSchema outputSchema();

    public String name() {
        StringBuilder sb = new StringBuilder();
        sb.append("ROOT ");
        sb.append(scope);
        sb.append("-");
        sb.append(id);
        return sb.toString();
    }

    public List<OperatorKey> getInputs() {
        return inputs;
    }

    public Map<OperatorKey, LogicalOperator> getOpTable() {
        return opTable;
    }
    
    public String arguments() {
        return "";
    }

    public List<String> getFuncs() {
        List<String> funcs = new LinkedList<String>();
        for (int i = 0; i < inputs.size(); i++) {
            funcs.addAll(opTable.get(inputs.get(i)).getFuncs());
        }
        return funcs;
    }

    public abstract int getOutputType();

    public void setSchema(TupleSchema schema) {
        this.schema = schema;
    }

    /**
     * Visit all of the logical operators in a tree, starting with this
     * one.  
     * @param v LOVisitor to visit this logical plan with.
     */
    public abstract void visit(LOVisitor v);
}