column.java

jboss规则引擎

package org.drools.rule;

/*
 * Copyright 2005 JBoss 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.
 */

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import org.drools.spi.ColumnExtractor;
import org.drools.spi.Extractor;
import org.drools.spi.FieldConstraint;
import org.drools.spi.ObjectType;

public class Column
    implements
    Serializable {
    /**
     * 
     */
    private static final long serialVersionUID = 9167552040211010022L;
    private final ObjectType  objectType;
    private List              constraints      = Collections.EMPTY_LIST;
    final Declaration         declaration;
    private final int         index;

    // this is the negative offset of the related fact inside a tuple. i.e:
    // tuple_fact_index = column_index + offset; 
    private int               offset;

    public Column(final int index,
                  final ObjectType objectType) {
        this( index,
              0,
              objectType,
              null );
    }

    public Column(final int index,
                  final ObjectType objectType,
                  final String identifier) {
        this( index,
              0,
              objectType,
              identifier );
    }

    public Column(final int index,
                  final int offset,
                  final ObjectType objectType,
                  final String identifier) {
        this.index = index;
        this.offset = offset;
        this.objectType = objectType;
        if ( identifier != null ) {
            this.declaration = new Declaration( identifier,
                                                new ColumnExtractor( objectType ),
                                                this.getFactIndex() );
        } else {
            this.declaration = null;
        }
    }

    public ObjectType getObjectType() {
        return this.objectType;
    }

    public List getConstraints() {
        return Collections.unmodifiableList( this.constraints );
    }

    public void addConstraint(final FieldConstraint constraint) {
        if ( this.constraints == Collections.EMPTY_LIST ) {
            this.constraints = new ArrayList( 1 );
        }
        this.constraints.add( constraint );
    }

    public Declaration addDeclaration(final String identifier,
                                      final Extractor extractor) {
        if ( this.constraints == Collections.EMPTY_LIST ) {
            this.constraints = new ArrayList( 1 );
        }
        final Declaration declaration = new Declaration( identifier,
                                                         extractor,
                                                         this.getFactIndex() );
        this.constraints.add( declaration );
        return declaration;

    }

    public boolean isBound() {
        return (this.declaration != null);
    }

    public Declaration getDeclaration() {
        return this.declaration;
    }

    public int getIndex() {
        return this.index;
    }

    /**
     * @return the offset
     */
    public int getOffset() {
        return this.offset;
    }

    public int getFactIndex() {
        return this.index + this.offset;
    }

    /**
     * A simple method to adjust offset of all declarations using the specified value
     * @param adjust
     */
    public void adjustOffset(final int adjust) {
        this.offset += adjust;

        if ( this.declaration != null ) {
            this.declaration.setColumn( this.getFactIndex() );
        }
        for ( final Iterator i = this.constraints.iterator(); i.hasNext(); ) {
            final Object constr = i.next();
            if ( constr instanceof Declaration ) {
                ((Declaration) constr).setColumn( this.getFactIndex() );
            }
        }
    }

    public String toString() {
        return "Column type='" + this.objectType + "', index='" + this.index + "', offset='" + this.getOffset() + "', identifer='" + this.declaration.getIdentifier() + "'";
    }

}