SquirrelJME/SquirrelJME

// -*- Mode: Java; indent-tabs-mode: t; tab-width: 4 -*-
// ---------------------------------------------------------------------------
// SquirrelJME
//     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
// ---------------------------------------------------------------------------
// SquirrelJME is under the Mozilla Public License Version 2.0.
// See license.mkd for licensing and copyright information.
// ---------------------------------------------------------------------------

package net.multiphasicapps.classfile;

import java.lang.ref.Reference;
import java.lang.ref.WeakReference;

/**
 * This represents a branch or jump target that may be used by instructions.
 *
 * @since 2018/09/15
 */
public final class InstructionJumpTarget
    implements Comparable<InstructionJumpTarget>
{
    /** Does this have a key? */
    protected final boolean hasKey;
    
    /** The key. */
    protected final int key;
    
    /** The value. */
    protected final int target;
    
    /** String representation. */
    private Reference<String> _string;
    
    /**
     * Initializes the jump target.
     *
     * @param __t The target.
     * @throws IllegalArgumentException If the target is negative.
     * @since 2018/09/15
     */
    public InstructionJumpTarget(int __t)
        throws IllegalArgumentException
    {
        /* {@squirreljme.error JC3b Jump target is negative. (The target)} */
        if (__t < 0)
            throw new IllegalArgumentException(String.format("JC3b %d", __t));
        
        this.target = __t;
        this.hasKey = false;
        this.key = -1;
    }
    
    /**
     * Initializes the jump target.
     *
     * @param __t The target.
     * @param __key The key value.
     * @throws IllegalArgumentException If the target is negative.
     * @since 2023/07/04
     */
    public InstructionJumpTarget(int __t, int __key)
        throws IllegalArgumentException
    {
        /* {@squirreljme.error JC3m Jump target is negative. (The target)} */
        if (__t < 0)
            throw new IllegalArgumentException(String.format("JC3m %d", __t));
        
        this.target = __t;
        this.hasKey = true;
        this.key = __key;
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/09/15
     */
    @Override
    public final int compareTo(InstructionJumpTarget __o)
        throws NullPointerException
    {
        if (__o == null)
            throw new NullPointerException("NARG");
        
        // Sort ones that have keys after, so "default" branches are lower
        if (this.hasKey != __o.hasKey)
            return (this.hasKey ? 1 : -1);
        
        // Sort by key values first
        if (this.hasKey)
        {
            int diff = this.key - __o.key;
            if (diff != 0)
                return diff;
        }
        
        // Sort by target last
        return this.target - __o.target;
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/09/15
     */
    @Override
    public final boolean equals(Object __o)
    {
        if (__o == this)
            return true;
        
        if (!(__o instanceof InstructionJumpTarget))
            return false;
        
        InstructionJumpTarget o = (InstructionJumpTarget)__o;
        return this.target == o.target &&
            this.hasKey == o.hasKey &&
            this.key == o.key;
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/09/15
     */
    @Override
    public final int hashCode()
    {
        return this.target;
    }
    
    /**
     * Returns the jump target key, if there is one.
     * 
     * @return The key for the jump target.
     * @throws IllegalStateException If there is no key.
     * @since 2023/07/04
     */
    public int key()
        throws IllegalStateException
    {
        /* {@squirreljme.error JC06 Jump target has no key.} */
        if (!this.hasKey)
            throw new IllegalStateException("JC06");
        
        return this.key;
    }
    
    /**
     * Returns the target address of the jump.
     *
     * @return The jump target address.
     * @since 2018/09/15
     */
    public final int target()
    {
        return this.target;
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/09/15
     */
    @Override
    public final String toString()
    {
        Reference<String> ref = this._string;
        String rv;
        
        if (ref == null || null == (rv = ref.get()))
            this._string = new WeakReference<>(
                (rv = String.format("->@%d", this.target)));
        
        return rv;
    }
}