com.feilong.lib.javassist.bytecode.MethodParametersAttribute Maven / Gradle / Ivy

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package com.feilong.lib.javassist.bytecode;

import java.io.DataInputStream;
import java.io.IOException;
import java.util.Map;

/**
 * MethodParameters_attribute.
 */
public class MethodParametersAttribute extends AttributeInfo{

    /**
     * The name of this attribute "MethodParameters".
     */
    public static final String tag = "MethodParameters";

    MethodParametersAttribute(ConstPool cp, int n, DataInputStream in) throws IOException{
        super(cp, n, in);
    }

    /**
     * Constructs an attribute.
     *
     * @param cp
     *            a constant pool table.
     * @param names
     *            an array of parameter names.
     *            The i-th element is the name of the i-th parameter.
     * @param flags
     *            an array of parameter access flags.
     */
    public MethodParametersAttribute(ConstPool cp, String[] names, int[] flags){
        super(cp, tag);
        byte[] data = new byte[names.length * 4 + 1];
        data[0] = (byte) names.length;
        for (int i = 0; i < names.length; i++){
            ByteArray.write16bit(cp.addUtf8Info(names[i]), data, i * 4 + 1);
            ByteArray.write16bit(flags[i], data, i * 4 + 3);
        }

        set(data);
    }

    /**
     * Returns parameters_count, which is the number of
     * parameters.
     */
    public int size(){
        return info[0] & 0xff;
    }

    /**
     * Returns the value of name_index of the i-th element of parameters.
     *
     * @param i
     *            the position of the parameter.
     */
    public int name(int i){
        return ByteArray.readU16bit(info, i * 4 + 1);
    }

    /**
     * Returns the value of access_flags of the i-th element of parameters.
     *
     * @param i
     *            the position of the parameter.
     * @see AccessFlag
     */
    public int accessFlags(int i){
        return ByteArray.readU16bit(info, i * 4 + 3);
    }

    /**
     * Makes a copy.
     *
     * @param newCp
     *            the constant pool table used by the new copy.
     * @param classnames
     *            ignored.
     */
    @Override
    public AttributeInfo copy(ConstPool newCp,Map classnames){
        int s = size();
        ConstPool cp = getConstPool();
        String[] names = new String[s];
        int[] flags = new int[s];
        for (int i = 0; i < s; i++){
            names[i] = cp.getUtf8Info(name(i));
            flags[i] = accessFlags(i);
        }

        return new MethodParametersAttribute(newCp, names, flags);
    }
}