Quadcap Embeddable Database

com/quadcap/sql/Column.java

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package com.quadcap.sql;

/* Copyright 1999 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

import java.util.Enumeration;
import java.util.Vector;

import java.sql.ResultSetMetaData;
import java.sql.SQLException;

import com.quadcap.sql.types.Type;

import com.quadcap.util.Debug;

/**
 * A column lives in a tuple, has a name, a type, and a default value.
 *
 * @author Stan Bailes
 */
public class Column implements Externalizable {
    transient Tuple             table;
    transient Vector            constraints     = null;

    String                      name;
    String                      shortName;
    int                         column;
    boolean                     joinColumn      = false;
    Type                        type;
    Expression                  defaultExpr;
    boolean                     isAutoIncr = false;
    int                         nullable
    =                                       ResultSetMetaData.columnNullable;

    /**
     * Default constructor
     */
    public Column() {}

    /**
     * Basic column construction: name + type
     */
    public Column(String name, Type type) {
        this.name = name;
        this.type = type;
    }

    /**
     * Copy (rename) column construction: name + old col
     */
    public Column(String name, Column col) {
        this.name = name;
        this.type = col.getType();
        this.isAutoIncr = col.isAutoIncr;
    }

    /**
     * Read me from a stream
     *
     * @exception IOException may be thrown
     */
    public void readExternal(ObjectInput in)
        throws IOException, ClassNotFoundException
    {
        name = (String)in.readObject();
        shortName = (String)in.readObject();
        type = (Type)in.readObject();
        column = in.readInt();
        defaultExpr = (Expression)in.readObject();
        nullable = in.readInt();
        isAutoIncr = (in.read() == 1);
    }

    /**
     * Write me to a stream
     *
     * @exception IOException may be thrown
     */
    public void writeExternal(ObjectOutput out) throws IOException {
        out.writeObject(name);
        out.writeObject(shortName);
        out.writeObject(type);
        out.writeInt(column);
        out.writeObject(defaultExpr);
        out.writeInt(nullable);
        out.write(isAutoIncr ?  1 : 0);
    }

    /**
     * Add a new column constraint.  Keep the constraints in order by
     * priority.
     */
    public void addConstraint(Constraint con) {
        if (con instanceof AutoNumberConstraint) {
            isAutoIncr = true;
        }
        
        con.setColumn(this);
        if (constraints == null) constraints = new Vector();
        boolean added = false;
        for (int i = 0; i < constraints.size(); i++) {
            Constraint c1 = (Constraint)constraints.elementAt(i);
            if (con.getPriority() < c1.getPriority()) {
                constraints.insertElementAt(con, i);
                added = true;
                break;
            }
        }
        if (!added) constraints.addElement(con);
    }

    /**
     * Return all of this column's constraints, as a vector
     */
    Vector getConstraints() {
        return constraints;
    }

    /**
     * Return this column's type
     */
    public Type getType() { return type; }

    /**
     * Set the column's type
     */
    void setType(Type type) { this.type = type; }

    /**
     * Set the column's position (one-based) in the table
     */
    void setColumn(int column) { this.column = column; }

    /**
     * Get the column's position (one-based) in the table
     */
    public int getColumn() { return column; }

    /**
     * Get the column's name
     */
    public String getName() { return name; }

    /**
     * Set the column's name
     */
    void setName(String name) { this.name = name; }

    /**
     * Set the column's short name
     */
    void setShortName(String name) { this.shortName = name; }

    /**
     * Get the column's short name
     */
    public String getShortName() {
        if (shortName == null) shortName = name;
        return shortName;
    }

    /**
     * Return true if this column has the 'joinColumn' flag set.
     */
    public boolean isJoinColumn() {
        return joinColumn;
    }

    /**
     * Set the 'joinColumn' flag.
     */
    public void setJoinColumn(boolean b) {
        joinColumn = b;
    }

    /**
     * Set the column's table
     */
    void setTable(Tuple table) { this.table = table; }

    /**
     * Get the tuple in which this column is contained.
     */
    public Tuple getRelation() { return table; }

    /**
     * Return the JDBC 'nullable' state of this column.
     */
    public int getNullable() {
        return nullable;
    }

    /**
     * Return true if this column allows nulls.
     */
    public boolean isNullable() {
        return nullable == ResultSetMetaData.columnNullable;
    }

    /**
     * Set the JDBC 'nullable' state of this column.
     */
    public void setNullable(int nullable) {
        this.nullable = nullable;
    }

    /**
     * Set the column's default value
     */
    public void setDefault(Expression expr) {
        defaultExpr = expr;
    }

    /**
     * Get the column's default value
     */
    public Expression getDefault() {
        return defaultExpr;
    }

    /**
     * Return <code><b>true</b></code> if this column is an auto-increment
     * type.
     */
    public boolean isAutoIncrement() {
        return isAutoIncr;
    }

    //#ifdef DEBUG
    /**
     * Return a string for debugging purposes
     */
    public String toString() {
        StringBuffer sb = new StringBuffer("Column ");
        if (joinColumn) sb.append("*");
        sb.append(name);
        sb.append(", type = ");
        sb.append(type);
        sb.append(", col = ");
        sb.append(column);
        if (isAutoIncr) sb.append(", with identity");
        return sb.toString();
    }
    //#endif
}