ConstantPool.java

/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.utility.classfile;

import java.io.IOException;
import java.io.StringWriter;

import org.eclipse.persistence.tools.workbench.utility.ClassTools;
import org.eclipse.persistence.tools.workbench.utility.classfile.tools.ClassFileDataInputStream;
import org.eclipse.persistence.tools.workbench.utility.io.IndentingPrintWriter;


/**
 * This class models a class file constant pool:
 *     u2 constant_pool_count;
 *     cp_info[constant_pool_count-1] constant_pool;
 *
 * See "The Java Virtual Machine Specification" Chapter 4.
 */
public class ConstantPool {
    private short count;
    private Constant[] constants;


    /**
     * Construct a class file constant pool from the specified stream
     * of byte codes.
     */
    ConstantPool(ClassFileDataInputStream stream) throws IOException {
        super();
        this.initialize(stream);
    }

    private void initialize(ClassFileDataInputStream stream) throws IOException {
        this.count = stream.readU2();
        short cnt = this.count;
        this.constants = new Constant[cnt];
        Constant[] localConstants = this.constants;
        // start at 1 - the first entry is not present in the .class file...
        localConstants[0] = Constant.nullConstant(this, stream);
        for (short i = 1; i < cnt; i++) {
            Constant constant = Constant.buildConstant(this, stream);
            localConstants[i] = constant;
            if (constant.consumesTwoPoolEntries()) {
                i++;
                localConstants[i] = Constant.nullConstant(this, stream);
            }
        }
    }

    public String displayString() {
        StringWriter sw = new StringWriter(1000);
        IndentingPrintWriter writer = new IndentingPrintWriter(sw);
        this.displayStringOn(writer);
        return sw.toString();
    }

    public void displayStringOn(IndentingPrintWriter writer) {
        short cnt = this.count;
        Constant[] localConstants = this.constants;
        writer.print("Constant Pool (count: ");
        writer.print(cnt);
        writer.println(')');
        writer.indent();
        for (short i = 0; i < cnt; i++) {
            writer.print(i);
            writer.print(": ");
            localConstants[i].displayStringOn(writer);
        }
        writer.undent();
    }

    public void accept(Visitor visitor) {
        visitor.visit(this);
        short cnt = this.count;
        Constant[] localConstants = this.constants;
        for (short i = 0; i < cnt; i++) {
            localConstants[i].accept(visitor);
        }
    }

    public short getCount() {
        return this.count;
    }

    public Constant get(short index) {
        return this.constants[index];
    }

    public ClassConstant getClassConstant(short index) {
        return (ClassConstant) this.constants[index];
    }

    public DoubleConstant getDoubleConstant(short index) {
        return (DoubleConstant) this.constants[index];
    }

    public FloatConstant getFloatConstant(short index) {
        return (FloatConstant) this.constants[index];
    }

    public IntegerConstant getIntegerConstant(short index) {
        return (IntegerConstant) this.constants[index];
    }

    public LongConstant getLongConstant(short index) {
        return (LongConstant) this.constants[index];
    }

    public NameAndTypeConstant getNameAndTypeConstant(short index) {
        return (NameAndTypeConstant) this.constants[index];
    }

    public FieldRefConstant getFieldRefConstant(short index) {
        return (FieldRefConstant) this.constants[index];
    }

    public InterfaceMethodRefConstant getInterfaceMethodRefConstant(short index) {
        return (InterfaceMethodRefConstant) this.constants[index];
    }

    public MethodRefConstant getMethodRefConstant(short index) {
        return (MethodRefConstant) this.constants[index];
    }

    public StringConstant getStringConstant(short index) {
        return (StringConstant) this.constants[index];
    }

    public UTF8Constant getUTF8Constant(short index) {
        return (UTF8Constant) this.constants[index];
    }

    public String getUTF8String(short index) {
        return this.getUTF8Constant(index).string();
    }

    public String toString() {
        return ClassTools.shortClassNameForObject(this) + '(' + this.count + " constant(s))";
    }

}