/*

 * Copyright (c) 2017, 2021, Oracle and/or its affiliates. All rights reserved.

 */

/*

 * 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 com.sun.org.apache.bcel.internal.generic;

import java.io.DataOutputStream;

import java.io.IOException;

import com.sun.org.apache.bcel.internal.ExceptionConst;

import com.sun.org.apache.bcel.internal.util.ByteSequence;

/**

 * LDC - Push item from constant pool.

 *

 * <PRE>Stack: ... -&gt; ..., item</PRE>

 *

 * @LastModified: May 2021

 */

public class LDC extends CPInstruction implements PushInstruction, ExceptionThrower {

    /**

     * Empty constructor needed for Instruction.readInstruction.

     * Not to be used otherwise.

     */

    LDC() {

    }

    public LDC(final int index) {

        super(com.sun.org.apache.bcel.internal.Const.LDC_W, index);

        setSize();

    }

    // Adjust to proper size

    protected final void setSize() {

        if (super.getIndex() <= com.sun.org.apache.bcel.internal.Const.MAX_BYTE) { // Fits in one byte?

            super.setOpcode(com.sun.org.apache.bcel.internal.Const.LDC);

            super.setLength(2);

        } else {

            super.setOpcode(com.sun.org.apache.bcel.internal.Const.LDC_W);

            super.setLength(3);

        }

    }

    /**

     * Dump instruction as byte code to stream out.

     * @param out Output stream

     */

    @Override

    public void dump( final DataOutputStream out ) throws IOException {

        out.writeByte(super.getOpcode());

        if (super.getLength() == 2) { // TODO useless check?

            out.writeByte(super.getIndex());

        } else {

            out.writeShort(super.getIndex());

        }

    }

    /**

     * Set the index to constant pool and adjust size.

     */

    @Override

    public final void setIndex( final int index ) {

        super.setIndex(index);

        setSize();

    }

    /**

     * Read needed data (e.g. index) from file.

     */

    @Override

    protected void initFromFile( final ByteSequence bytes, final boolean wide ) throws IOException {

        super.setLength(2);

        super.setIndex(bytes.readUnsignedByte());

    }

    public Object getValue( final ConstantPoolGen cpg ) {

        com.sun.org.apache.bcel.internal.classfile.Constant c = cpg.getConstantPool().getConstant(super.getIndex());

        switch (c.getTag()) {

            case com.sun.org.apache.bcel.internal.Const.CONSTANT_String:

                final int i = ((com.sun.org.apache.bcel.internal.classfile.ConstantString) c).getStringIndex();

                c = cpg.getConstantPool().getConstant(i);

                return ((com.sun.org.apache.bcel.internal.classfile.ConstantUtf8) c).getBytes();

            case com.sun.org.apache.bcel.internal.Const.CONSTANT_Float:

                return ((com.sun.org.apache.bcel.internal.classfile.ConstantFloat) c).getBytes();

            case com.sun.org.apache.bcel.internal.Const.CONSTANT_Integer:

                return ((com.sun.org.apache.bcel.internal.classfile.ConstantInteger) c).getBytes();

            case com.sun.org.apache.bcel.internal.Const.CONSTANT_Class:

                final int nameIndex = ((com.sun.org.apache.bcel.internal.classfile.ConstantClass) c).getNameIndex();

                c = cpg.getConstantPool().getConstant(nameIndex);

                return new ObjectType(((com.sun.org.apache.bcel.internal.classfile.ConstantUtf8) c).getBytes());

            default: // Never reached

                throw new IllegalArgumentException("Unknown or invalid constant type at " + super.getIndex());

        }

    }

    @Override

    public Type getType( final ConstantPoolGen cpg ) {

        switch (cpg.getConstantPool().getConstant(super.getIndex()).getTag()) {

            case com.sun.org.apache.bcel.internal.Const.CONSTANT_String:

                return Type.STRING;

            case com.sun.org.apache.bcel.internal.Const.CONSTANT_Float:

                return Type.FLOAT;

            case com.sun.org.apache.bcel.internal.Const.CONSTANT_Integer:

                return Type.INT;

            case com.sun.org.apache.bcel.internal.Const.CONSTANT_Class:

                return Type.CLASS;

            default: // Never reached

                throw new IllegalArgumentException("Unknown or invalid constant type at " + super.getIndex());

        }

    }

    @Override

    public Class<?>[] getExceptions() {

        return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_STRING_RESOLUTION);

    }

    /**

     * Call corresponding visitor method(s). The order is:

     * Call visitor methods of implemented interfaces first, then

     * call methods according to the class hierarchy in descending order,

     * i.e., the most specific visitXXX() call comes last.

     *

     * @param v Visitor object

     */

    @Override

    public void accept( final Visitor v ) {

        v.visitStackProducer(this);

        v.visitPushInstruction(this);

        v.visitExceptionThrower(this);

        v.visitTypedInstruction(this);

        v.visitCPInstruction(this);

        v.visitLDC(this);

    }

}