/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2007 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package alterrs.asm.commons;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import alterrs.asm.ClassVisitor;
import alterrs.asm.Label;
import alterrs.asm.MethodVisitor;
import alterrs.asm.Opcodes;
import alterrs.asm.Type;

/**
 * A {@link alterrs.asm.MethodAdapter} with convenient methods to generate code.
 * For example, using this adapter, the class below
 * <p/>
 * 
 * <pre>
 * public class Example {
 * 	public static void main(String[] args) {
 * 		System.out.println(&quot;Hello world!&quot;);
 * 	}
 * }
 * </pre>
 * <p/>
 * can be generated as follows:
 * <p/>
 * 
 * <pre>
 * ClassWriter cw = new ClassWriter(true);
 * cw.visit(V1_1, ACC_PUBLIC, &quot;Example&quot;, null, &quot;java/lang/Object&quot;, null);
 * 
 * Method m = Method.getMethod(&quot;void &lt;init&gt; ()&quot;);
 * GeneratorAdapter mg = new GeneratorAdapter(ACC_PUBLIC, m, null, null, cw);
 * mg.loadThis();
 * mg.invokeConstructor(Type.getType(Object.class), m);
 * mg.returnValue();
 * mg.endMethod();
 * 
 * m = Method.getMethod(&quot;void main (String[])&quot;);
 * mg = new GeneratorAdapter(ACC_PUBLIC + ACC_STATIC, m, null, null, cw);
 * mg.getStatic(Type.getType(System.class), &quot;out&quot;, Type.getType(PrintStream.class));
 * mg.push(&quot;Hello world!&quot;);
 * mg.invokeVirtual(Type.getType(PrintStream.class),
 * 		Method.getMethod(&quot;void println (String)&quot;));
 * mg.returnValue();
 * mg.endMethod();
 * 
 * cw.visitEnd();
 * </pre>
 * 
 * @author Juozas Baliuka
 * @author Chris Nokleberg
 * @author Eric Bruneton
 */
public class GeneratorAdapter extends LocalVariablesSorter {

	private static final String CLDESC = "Ljava/lang/Class;";

	private static final Type BYTE_TYPE = Type.getObjectType("java/lang/Byte");

	private static final Type BOOLEAN_TYPE = Type
			.getObjectType("java/lang/Boolean");

	private static final Type SHORT_TYPE = Type
			.getObjectType("java/lang/Short");

	private static final Type CHARACTER_TYPE = Type
			.getObjectType("java/lang/Character");

	private static final Type INTEGER_TYPE = Type
			.getObjectType("java/lang/Integer");

	private static final Type FLOAT_TYPE = Type
			.getObjectType("java/lang/Float");

	private static final Type LONG_TYPE = Type.getObjectType("java/lang/Long");

	private static final Type DOUBLE_TYPE = Type
			.getObjectType("java/lang/Double");

	private static final Type NUMBER_TYPE = Type
			.getObjectType("java/lang/Number");

	private static final Type OBJECT_TYPE = Type
			.getObjectType("java/lang/Object");

	private static final Method BOOLEAN_VALUE = Method
			.getMethod("boolean booleanValue()");

	private static final Method CHAR_VALUE = Method
			.getMethod("char charValue()");

	private static final Method INT_VALUE = Method.getMethod("int intValue()");

	private static final Method FLOAT_VALUE = Method
			.getMethod("float floatValue()");

	private static final Method LONG_VALUE = Method
			.getMethod("long longValue()");

	private static final Method DOUBLE_VALUE = Method
			.getMethod("double doubleValue()");

	/**
	 * Constant for the {@link #math math} method.
	 */
	public static final int ADD = Opcodes.IADD;

	/**
	 * Constant for the {@link #math math} method.
	 */
	public static final int SUB = Opcodes.ISUB;

	/**
	 * Constant for the {@link #math math} method.
	 */
	public static final int MUL = Opcodes.IMUL;

	/**
	 * Constant for the {@link #math math} method.
	 */
	public static final int DIV = Opcodes.IDIV;

	/**
	 * Constant for the {@link #math math} method.
	 */
	public static final int REM = Opcodes.IREM;

	/**
	 * Constant for the {@link #math math} method.
	 */
	public static final int NEG = Opcodes.INEG;

	/**
	 * Constant for the {@link #math math} method.
	 */
	public static final int SHL = Opcodes.ISHL;

	/**
	 * Constant for the {@link #math math} method.
	 */
	public static final int SHR = Opcodes.ISHR;

	/**
	 * Constant for the {@link #math math} method.
	 */
	public static final int USHR = Opcodes.IUSHR;

	/**
	 * Constant for the {@link #math math} method.
	 */
	public static final int AND = Opcodes.IAND;

	/**
	 * Constant for the {@link #math math} method.
	 */
	public static final int OR = Opcodes.IOR;

	/**
	 * Constant for the {@link #math math} method.
	 */
	public static final int XOR = Opcodes.IXOR;

	/**
	 * Constant for the {@link #ifCmp ifCmp} method.
	 */
	public static final int EQ = Opcodes.IFEQ;

	/**
	 * Constant for the {@link #ifCmp ifCmp} method.
	 */
	public static final int NE = Opcodes.IFNE;

	/**
	 * Constant for the {@link #ifCmp ifCmp} method.
	 */
	public static final int LT = Opcodes.IFLT;

	/**
	 * Constant for the {@link #ifCmp ifCmp} method.
	 */
	public static final int GE = Opcodes.IFGE;

	/**
	 * Constant for the {@link #ifCmp ifCmp} method.
	 */
	public static final int GT = Opcodes.IFGT;

	/**
	 * Constant for the {@link #ifCmp ifCmp} method.
	 */
	public static final int LE = Opcodes.IFLE;

	/**
	 * Access flags of the method visited by this adapter.
	 */
	private final int access;

	/**
	 * Return type of the method visited by this adapter.
	 */
	private final Type returnType;

	/**
	 * Argument types of the method visited by this adapter.
	 */
	private final Type[] argumentTypes;

	/**
	 * Types of the local variables of the method visited by this adapter.
	 */
	private final List localTypes = new ArrayList();

	/**
	 * Creates a new {@link GeneratorAdapter}.
	 * 
	 * @param mv
	 *            the method visitor to which this adapter delegates calls.
	 * @param access
	 *            the method's access flags (see {@link Opcodes}).
	 * @param name
	 *            the method's name.
	 * @param desc
	 *            the method's descriptor (see {@link Type Type}).
	 */
	public GeneratorAdapter(final MethodVisitor mv, final int access,
			final String name, final String desc) {
		super(access, desc, mv);
		this.access = access;
		this.returnType = Type.getReturnType(desc);
		this.argumentTypes = Type.getArgumentTypes(desc);
	}

	/**
	 * Creates a new {@link GeneratorAdapter}.
	 * 
	 * @param access
	 *            access flags of the adapted method.
	 * @param method
	 *            the adapted method.
	 * @param mv
	 *            the method visitor to which this adapter delegates calls.
	 */
	public GeneratorAdapter(final int access, final Method method,
			final MethodVisitor mv) {
		super(access, method.getDescriptor(), mv);
		this.access = access;
		this.returnType = method.getReturnType();
		this.argumentTypes = method.getArgumentTypes();
	}

	/**
	 * Creates a new {@link GeneratorAdapter}.
	 * 
	 * @param access
	 *            access flags of the adapted method.
	 * @param method
	 *            the adapted method.
	 * @param signature
	 *            the signature of the adapted method (may be <tt>null</tt>).
	 * @param exceptions
	 *            the exceptions thrown by the adapted method (may be
	 *            <tt>null</tt>).
	 * @param cv
	 *            the class visitor to which this adapter delegates calls.
	 */
	public GeneratorAdapter(final int access, final Method method,
			final String signature, final Type[] exceptions,
			final ClassVisitor cv) {
		this(access, method, cv
				.visitMethod(access, method.getName(), method.getDescriptor(),
						signature, getInternalNames(exceptions)));
	}

	/**
	 * Returns the internal names of the given types.
	 * 
	 * @param types
	 *            a set of types.
	 * @return the internal names of the given types.
	 */
	private static String[] getInternalNames(final Type[] types) {
		if (types == null) {
			return null;
		}
		String[] names = new String[types.length];
		for (int i = 0; i < names.length; ++i) {
			names[i] = types[i].getInternalName();
		}
		return names;
	}

	// ------------------------------------------------------------------------
	// Instructions to push constants on the stack
	// ------------------------------------------------------------------------

	/**
	 * Generates the instruction to push the given value on the stack.
	 * 
	 * @param value
	 *            the value to be pushed on the stack.
	 */
	public void push(final boolean value) {
		push(value ? 1 : 0);
	}

	/**
	 * Generates the instruction to push the given value on the stack.
	 * 
	 * @param value
	 *            the value to be pushed on the stack.
	 */
	public void push(final int value) {
		if (value >= -1 && value <= 5) {
			mv.visitInsn(Opcodes.ICONST_0 + value);
		} else if (value >= Byte.MIN_VALUE && value <= Byte.MAX_VALUE) {
			mv.visitIntInsn(Opcodes.BIPUSH, value);
		} else if (value >= Short.MIN_VALUE && value <= Short.MAX_VALUE) {
			mv.visitIntInsn(Opcodes.SIPUSH, value);
		} else {
			mv.visitLdcInsn(new Integer(value));
		}
	}

	/**
	 * Generates the instruction to push the given value on the stack.
	 * 
	 * @param value
	 *            the value to be pushed on the stack.
	 */
	public void push(final long value) {
		if (value == 0L || value == 1L) {
			mv.visitInsn(Opcodes.LCONST_0 + (int) value);
		} else {
			mv.visitLdcInsn(new Long(value));
		}
	}

	/**
	 * Generates the instruction to push the given value on the stack.
	 * 
	 * @param value
	 *            the value to be pushed on the stack.
	 */
	public void push(final float value) {
		int bits = Float.floatToIntBits(value);
		if (bits == 0L || bits == 0x3f800000 || bits == 0x40000000) { // 0..2
			mv.visitInsn(Opcodes.FCONST_0 + (int) value);
		} else {
			mv.visitLdcInsn(new Float(value));
		}
	}

	/**
	 * Generates the instruction to push the given value on the stack.
	 * 
	 * @param value
	 *            the value to be pushed on the stack.
	 */
	public void push(final double value) {
		long bits = Double.doubleToLongBits(value);
		if (bits == 0L || bits == 0x3ff0000000000000L) { // +0.0d and 1.0d
			mv.visitInsn(Opcodes.DCONST_0 + (int) value);
		} else {
			mv.visitLdcInsn(new Double(value));
		}
	}

	/**
	 * Generates the instruction to push the given value on the stack.
	 * 
	 * @param value
	 *            the value to be pushed on the stack. May be <tt>null</tt>.
	 */
	public void push(final String value) {
		if (value == null) {
			mv.visitInsn(Opcodes.ACONST_NULL);
		} else {
			mv.visitLdcInsn(value);
		}
	}

	/**
	 * Generates the instruction to push the given value on the stack.
	 * 
	 * @param value
	 *            the value to be pushed on the stack.
	 */
	public void push(final Type value) {
		if (value == null) {
			mv.visitInsn(Opcodes.ACONST_NULL);
		} else {
			switch (value.getSort()) {
			case Type.BOOLEAN:
				mv.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/Boolean",
						"TYPE", CLDESC);
				break;
			case Type.CHAR:
				mv.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/Character",
						"TYPE", CLDESC);
				break;
			case Type.BYTE:
				mv.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/Byte", "TYPE",
						CLDESC);
				break;
			case Type.SHORT:
				mv.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/Short", "TYPE",
						CLDESC);
				break;
			case Type.INT:
				mv.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/Integer",
						"TYPE", CLDESC);
				break;
			case Type.FLOAT:
				mv.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/Float", "TYPE",
						CLDESC);
				break;
			case Type.LONG:
				mv.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/Long", "TYPE",
						CLDESC);
				break;
			case Type.DOUBLE:
				mv.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/Double",
						"TYPE", CLDESC);
				break;
			default:
				mv.visitLdcInsn(value);
			}
		}
	}

	// ------------------------------------------------------------------------
	// Instructions to load and store method arguments
	// ------------------------------------------------------------------------

	/**
	 * Returns the index of the given method argument in the frame's local
	 * variables array.
	 * 
	 * @param arg
	 *            the index of a method argument.
	 * @return the index of the given method argument in the frame's local
	 *         variables array.
	 */
	private int getArgIndex(final int arg) {
		int index = (access & Opcodes.ACC_STATIC) == 0 ? 1 : 0;
		for (int i = 0; i < arg; i++) {
			index += argumentTypes[i].getSize();
		}
		return index;
	}

	/**
	 * Generates the instruction to push a local variable on the stack.
	 * 
	 * @param type
	 *            the type of the local variable to be loaded.
	 * @param index
	 *            an index in the frame's local variables array.
	 */
	private void loadInsn(final Type type, final int index) {
		mv.visitVarInsn(type.getOpcode(Opcodes.ILOAD), index);
	}

	/**
	 * Generates the instruction to store the top stack value in a local
	 * variable.
	 * 
	 * @param type
	 *            the type of the local variable to be stored.
	 * @param index
	 *            an index in the frame's local variables array.
	 */
	private void storeInsn(final Type type, final int index) {
		mv.visitVarInsn(type.getOpcode(Opcodes.ISTORE), index);
	}

	/**
	 * Generates the instruction to load 'this' on the stack.
	 */
	public void loadThis() {
		if ((access & Opcodes.ACC_STATIC) != 0) {
			throw new IllegalStateException(
					"no 'this' pointer within static method");
		}
		mv.visitVarInsn(Opcodes.ALOAD, 0);
	}

	/**
	 * Generates the instruction to load the given method argument on the stack.
	 * 
	 * @param arg
	 *            the index of a method argument.
	 */
	public void loadArg(final int arg) {
		loadInsn(argumentTypes[arg], getArgIndex(arg));
	}

	/**
	 * Generates the instructions to load the given method arguments on the
	 * stack.
	 * 
	 * @param arg
	 *            the index of the first method argument to be loaded.
	 * @param count
	 *            the number of method arguments to be loaded.
	 */
	public void loadArgs(final int arg, final int count) {
		int index = getArgIndex(arg);
		for (int i = 0; i < count; ++i) {
			Type t = argumentTypes[arg + i];
			loadInsn(t, index);
			index += t.getSize();
		}
	}

	/**
	 * Generates the instructions to load all the method arguments on the stack.
	 */
	public void loadArgs() {
		loadArgs(0, argumentTypes.length);
	}

	/**
	 * Generates the instructions to load all the method arguments on the stack,
	 * as a single object array.
	 */
	public void loadArgArray() {
		push(argumentTypes.length);
		newArray(OBJECT_TYPE);
		for (int i = 0; i < argumentTypes.length; i++) {
			dup();
			push(i);
			loadArg(i);
			box(argumentTypes[i]);
			arrayStore(OBJECT_TYPE);
		}
	}

	/**
	 * Generates the instruction to store the top stack value in the given
	 * method argument.
	 * 
	 * @param arg
	 *            the index of a method argument.
	 */
	public void storeArg(final int arg) {
		storeInsn(argumentTypes[arg], getArgIndex(arg));
	}

	// ------------------------------------------------------------------------
	// Instructions to load and store local variables
	// ------------------------------------------------------------------------

	/**
	 * Returns the type of the given local variable.
	 * 
	 * @param local
	 *            a local variable identifier, as returned by
	 *            {@link LocalVariablesSorter#newLocal(Type) newLocal()}.
	 * @return the type of the given local variable.
	 */
	public Type getLocalType(final int local) {
		return (Type) localTypes.get(local - firstLocal);
	}

	protected void setLocalType(final int local, final Type type) {
		int index = local - firstLocal;
		while (localTypes.size() < index + 1) {
			localTypes.add(null);
		}
		localTypes.set(index, type);
	}

	/**
	 * Generates the instruction to load the given local variable on the stack.
	 * 
	 * @param local
	 *            a local variable identifier, as returned by
	 *            {@link LocalVariablesSorter#newLocal(Type) newLocal()}.
	 */
	public void loadLocal(final int local) {
		loadInsn(getLocalType(local), local);
	}

	/**
	 * Generates the instruction to load the given local variable on the stack.
	 * 
	 * @param local
	 *            a local variable identifier, as returned by
	 *            {@link LocalVariablesSorter#newLocal(Type) newLocal()}.
	 * @param type
	 *            the type of this local variable.
	 */
	public void loadLocal(final int local, final Type type) {
		setLocalType(local, type);
		loadInsn(type, local);
	}

	/**
	 * Generates the instruction to store the top stack value in the given local
	 * variable.
	 * 
	 * @param local
	 *            a local variable identifier, as returned by
	 *            {@link LocalVariablesSorter#newLocal(Type) newLocal()}.
	 */
	public void storeLocal(final int local) {
		storeInsn(getLocalType(local), local);
	}

	/**
	 * Generates the instruction to store the top stack value in the given local
	 * variable.
	 * 
	 * @param local
	 *            a local variable identifier, as returned by
	 *            {@link LocalVariablesSorter#newLocal(Type) newLocal()}.
	 * @param type
	 *            the type of this local variable.
	 */
	public void storeLocal(final int local, final Type type) {
		setLocalType(local, type);
		storeInsn(type, local);
	}

	/**
	 * Generates the instruction to load an element from an array.
	 * 
	 * @param type
	 *            the type of the array element to be loaded.
	 */
	public void arrayLoad(final Type type) {
		mv.visitInsn(type.getOpcode(Opcodes.IALOAD));
	}

	/**
	 * Generates the instruction to store an element in an array.
	 * 
	 * @param type
	 *            the type of the array element to be stored.
	 */
	public void arrayStore(final Type type) {
		mv.visitInsn(type.getOpcode(Opcodes.IASTORE));
	}

	// ------------------------------------------------------------------------
	// Instructions to manage the stack
	// ------------------------------------------------------------------------

	/**
	 * Generates a POP instruction.
	 */
	public void pop() {
		mv.visitInsn(Opcodes.POP);
	}

	/**
	 * Generates a POP2 instruction.
	 */
	public void pop2() {
		mv.visitInsn(Opcodes.POP2);
	}

	/**
	 * Generates a DUP instruction.
	 */
	public void dup() {
		mv.visitInsn(Opcodes.DUP);
	}

	/**
	 * Generates a DUP2 instruction.
	 */
	public void dup2() {
		mv.visitInsn(Opcodes.DUP2);
	}

	/**
	 * Generates a DUP_X1 instruction.
	 */
	public void dupX1() {
		mv.visitInsn(Opcodes.DUP_X1);
	}

	/**
	 * Generates a DUP_X2 instruction.
	 */
	public void dupX2() {
		mv.visitInsn(Opcodes.DUP_X2);
	}

	/**
	 * Generates a DUP2_X1 instruction.
	 */
	public void dup2X1() {
		mv.visitInsn(Opcodes.DUP2_X1);
	}

	/**
	 * Generates a DUP2_X2 instruction.
	 */
	public void dup2X2() {
		mv.visitInsn(Opcodes.DUP2_X2);
	}

	/**
	 * Generates a SWAP instruction.
	 */
	public void swap() {
		mv.visitInsn(Opcodes.SWAP);
	}

	/**
	 * Generates the instructions to swap the top two stack values.
	 * 
	 * @param prev
	 *            type of the top - 1 stack value.
	 * @param type
	 *            type of the top stack value.
	 */
	public void swap(final Type prev, final Type type) {
		if (type.getSize() == 1) {
			if (prev.getSize() == 1) {
				swap(); // same as dupX1(), pop();
			} else {
				dupX2();
				pop();
			}
		} else {
			if (prev.getSize() == 1) {
				dup2X1();
				pop2();
			} else {
				dup2X2();
				pop2();
			}
		}
	}

	// ------------------------------------------------------------------------
	// Instructions to do mathematical and logical operations
	// ------------------------------------------------------------------------

	/**
	 * Generates the instruction to do the specified mathematical or logical
	 * operation.
	 * 
	 * @param op
	 *            a mathematical or logical operation. Must be one of ADD, SUB,
	 *            MUL, DIV, REM, NEG, SHL, SHR, USHR, AND, OR, XOR.
	 * @param type
	 *            the type of the operand(s) for this operation.
	 */
	public void math(final int op, final Type type) {
		mv.visitInsn(type.getOpcode(op));
	}

	/**
	 * Generates the instructions to compute the bitwise negation of the top
	 * stack value.
	 */
	public void not() {
		mv.visitInsn(Opcodes.ICONST_1);
		mv.visitInsn(Opcodes.IXOR);
	}

	/**
	 * Generates the instruction to increment the given local variable.
	 * 
	 * @param local
	 *            the local variable to be incremented.
	 * @param amount
	 *            the amount by which the local variable must be incremented.
	 */
	public void iinc(final int local, final int amount) {
		mv.visitIincInsn(local, amount);
	}

	/**
	 * Generates the instructions to cast a numerical value from one type to
	 * another.
	 * 
	 * @param from
	 *            the type of the top stack value
	 * @param to
	 *            the type into which this value must be cast.
	 */
	public void cast(final Type from, final Type to) {
		if (from != to) {
			if (from == Type.DOUBLE_TYPE) {
				if (to == Type.FLOAT_TYPE) {
					mv.visitInsn(Opcodes.D2F);
				} else if (to == Type.LONG_TYPE) {
					mv.visitInsn(Opcodes.D2L);
				} else {
					mv.visitInsn(Opcodes.D2I);
					cast(Type.INT_TYPE, to);
				}
			} else if (from == Type.FLOAT_TYPE) {
				if (to == Type.DOUBLE_TYPE) {
					mv.visitInsn(Opcodes.F2D);
				} else if (to == Type.LONG_TYPE) {
					mv.visitInsn(Opcodes.F2L);
				} else {
					mv.visitInsn(Opcodes.F2I);
					cast(Type.INT_TYPE, to);
				}
			} else if (from == Type.LONG_TYPE) {
				if (to == Type.DOUBLE_TYPE) {
					mv.visitInsn(Opcodes.L2D);
				} else if (to == Type.FLOAT_TYPE) {
					mv.visitInsn(Opcodes.L2F);
				} else {
					mv.visitInsn(Opcodes.L2I);
					cast(Type.INT_TYPE, to);
				}
			} else {
				if (to == Type.BYTE_TYPE) {
					mv.visitInsn(Opcodes.I2B);
				} else if (to == Type.CHAR_TYPE) {
					mv.visitInsn(Opcodes.I2C);
				} else if (to == Type.DOUBLE_TYPE) {
					mv.visitInsn(Opcodes.I2D);
				} else if (to == Type.FLOAT_TYPE) {
					mv.visitInsn(Opcodes.I2F);
				} else if (to == Type.LONG_TYPE) {
					mv.visitInsn(Opcodes.I2L);
				} else if (to == Type.SHORT_TYPE) {
					mv.visitInsn(Opcodes.I2S);
				}
			}
		}
	}

	// ------------------------------------------------------------------------
	// Instructions to do boxing and unboxing operations
	// ------------------------------------------------------------------------

	private static Type getBoxedType(final Type type) {
		switch (type.getSort()) {
		case Type.BYTE:
			return BYTE_TYPE;
		case Type.BOOLEAN:
			return BOOLEAN_TYPE;
		case Type.SHORT:
			return SHORT_TYPE;
		case Type.CHAR:
			return CHARACTER_TYPE;
		case Type.INT:
			return INTEGER_TYPE;
		case Type.FLOAT:
			return FLOAT_TYPE;
		case Type.LONG:
			return LONG_TYPE;
		case Type.DOUBLE:
			return DOUBLE_TYPE;
		}
		return type;
	}

	/**
	 * Generates the instructions to box the top stack value. This value is
	 * replaced by its boxed equivalent on top of the stack.
	 * 
	 * @param type
	 *            the type of the top stack value.
	 */
	public void box(final Type type) {
		if (type.getSort() == Type.OBJECT || type.getSort() == Type.ARRAY) {
			return;
		}
		if (type == Type.VOID_TYPE) {
			push((String) null);
		} else {
			Type boxed = getBoxedType(type);
			newInstance(boxed);
			if (type.getSize() == 2) {
				// Pp -> Ppo -> oPpo -> ooPpo -> ooPp -> o
				dupX2();
				dupX2();
				pop();
			} else {
				// p -> po -> opo -> oop -> o
				dupX1();
				swap();
			}
			invokeConstructor(boxed, new Method("<init>", Type.VOID_TYPE,
					new Type[] { type }));
		}
	}

	/**
	 * Generates the instructions to box the top stack value using Java 5's
	 * valueOf() method. This value is replaced by its boxed equivalent on top
	 * of the stack.
	 * 
	 * @param type
	 *            the type of the top stack value.
	 * @author Prashant Deva
	 */
	public void valueOf(final Type type) {
		if (type.getSort() == Type.OBJECT || type.getSort() == Type.ARRAY) {
			return;
		}
		if (type == Type.VOID_TYPE) {
			push((String) null);
		} else {
			Type boxed = getBoxedType(type);
			invokeStatic(boxed, new Method("valueOf", boxed,
					new Type[] { type }));
		}
	}

	/**
	 * Generates the instructions to unbox the top stack value. This value is
	 * replaced by its unboxed equivalent on top of the stack.
	 * 
	 * @param type
	 *            the type of the top stack value.
	 */
	public void unbox(final Type type) {
		Type t = NUMBER_TYPE;
		Method sig = null;
		switch (type.getSort()) {
		case Type.VOID:
			return;
		case Type.CHAR:
			t = CHARACTER_TYPE;
			sig = CHAR_VALUE;
			break;
		case Type.BOOLEAN:
			t = BOOLEAN_TYPE;
			sig = BOOLEAN_VALUE;
			break;
		case Type.DOUBLE:
			sig = DOUBLE_VALUE;
			break;
		case Type.FLOAT:
			sig = FLOAT_VALUE;
			break;
		case Type.LONG:
			sig = LONG_VALUE;
			break;
		case Type.INT:
		case Type.SHORT:
		case Type.BYTE:
			sig = INT_VALUE;
		}
		if (sig == null) {
			checkCast(type);
		} else {
			checkCast(t);
			invokeVirtual(t, sig);
		}
	}

	// ------------------------------------------------------------------------
	// Instructions to jump to other instructions
	// ------------------------------------------------------------------------

	/**
	 * Creates a new {@link Label}.
	 * 
	 * @return a new {@link Label}.
	 */
	public Label newLabel() {
		return new Label();
	}

	/**
	 * Marks the current code position with the given label.
	 * 
	 * @param label
	 *            a label.
	 */
	public void mark(final Label label) {
		mv.visitLabel(label);
	}

	/**
	 * Marks the current code position with a new label.
	 * 
	 * @return the label that was created to mark the current code position.
	 */
	public Label mark() {
		Label label = new Label();
		mv.visitLabel(label);
		return label;
	}

	/**
	 * Generates the instructions to jump to a label based on the comparison of
	 * the top two stack values.
	 * 
	 * @param type
	 *            the type of the top two stack values.
	 * @param mode
	 *            how these values must be compared. One of EQ, NE, LT, GE, GT,
	 *            LE.
	 * @param label
	 *            where to jump if the comparison result is <tt>true</tt>.
	 */
	public void ifCmp(final Type type, final int mode, final Label label) {
		switch (type.getSort()) {
		case Type.LONG:
			mv.visitInsn(Opcodes.LCMP);
			break;
		case Type.DOUBLE:
			mv.visitInsn(mode == GE || mode == GT ? Opcodes.DCMPG
					: Opcodes.DCMPL);
			break;
		case Type.FLOAT:
			mv.visitInsn(mode == GE || mode == GT ? Opcodes.FCMPG
					: Opcodes.FCMPL);
			break;
		case Type.ARRAY:
		case Type.OBJECT:
			switch (mode) {
			case EQ:
				mv.visitJumpInsn(Opcodes.IF_ACMPEQ, label);
				return;
			case NE:
				mv.visitJumpInsn(Opcodes.IF_ACMPNE, label);
				return;
			}
			throw new IllegalArgumentException("Bad comparison for type "
					+ type);
		default:
			int intOp = -1;
			switch (mode) {
			case EQ:
				intOp = Opcodes.IF_ICMPEQ;
				break;
			case NE:
				intOp = Opcodes.IF_ICMPNE;
				break;
			case GE:
				intOp = Opcodes.IF_ICMPGE;
				break;
			case LT:
				intOp = Opcodes.IF_ICMPLT;
				break;
			case LE:
				intOp = Opcodes.IF_ICMPLE;
				break;
			case GT:
				intOp = Opcodes.IF_ICMPGT;
				break;
			}
			mv.visitJumpInsn(intOp, label);
			return;
		}
		mv.visitJumpInsn(mode, label);
	}

	/**
	 * Generates the instructions to jump to a label based on the comparison of
	 * the top two integer stack values.
	 * 
	 * @param mode
	 *            how these values must be compared. One of EQ, NE, LT, GE, GT,
	 *            LE.
	 * @param label
	 *            where to jump if the comparison result is <tt>true</tt>.
	 */
	public void ifICmp(final int mode, final Label label) {
		ifCmp(Type.INT_TYPE, mode, label);
	}

	/**
	 * Generates the instructions to jump to a label based on the comparison of
	 * the top integer stack value with zero.
	 * 
	 * @param mode
	 *            how these values must be compared. One of EQ, NE, LT, GE, GT,
	 *            LE.
	 * @param label
	 *            where to jump if the comparison result is <tt>true</tt>.
	 */
	public void ifZCmp(final int mode, final Label label) {
		mv.visitJumpInsn(mode, label);
	}

	/**
	 * Generates the instruction to jump to the given label if the top stack
	 * value is null.
	 * 
	 * @param label
	 *            where to jump if the condition is <tt>true</tt>.
	 */
	public void ifNull(final Label label) {
		mv.visitJumpInsn(Opcodes.IFNULL, label);
	}

	/**
	 * Generates the instruction to jump to the given label if the top stack
	 * value is not null.
	 * 
	 * @param label
	 *            where to jump if the condition is <tt>true</tt>.
	 */
	public void ifNonNull(final Label label) {
		mv.visitJumpInsn(Opcodes.IFNONNULL, label);
	}

	/**
	 * Generates the instruction to jump to the given label.
	 * 
	 * @param label
	 *            where to jump if the condition is <tt>true</tt>.
	 */
	public void goTo(final Label label) {
		mv.visitJumpInsn(Opcodes.GOTO, label);
	}

	/**
	 * Generates a RET instruction.
	 * 
	 * @param local
	 *            a local variable identifier, as returned by
	 *            {@link LocalVariablesSorter#newLocal(Type) newLocal()}.
	 */
	public void ret(final int local) {
		mv.visitVarInsn(Opcodes.RET, local);
	}

	/**
	 * Generates the instructions for a switch statement.
	 * 
	 * @param keys
	 *            the switch case keys.
	 * @param generator
	 *            a generator to generate the code for the switch cases.
	 */
	public void tableSwitch(final int[] keys,
			final TableSwitchGenerator generator) {
		float density;
		if (keys.length == 0) {
			density = 0;
		} else {
			density = (float) keys.length
					/ (keys[keys.length - 1] - keys[0] + 1);
		}
		tableSwitch(keys, generator, density >= 0.5f);
	}

	/**
	 * Generates the instructions for a switch statement.
	 * 
	 * @param keys
	 *            the switch case keys.
	 * @param generator
	 *            a generator to generate the code for the switch cases.
	 * @param useTable
	 *            <tt>true</tt> to use a TABLESWITCH instruction, or
	 *            <tt>false</tt> to use a LOOKUPSWITCH instruction.
	 */
	public void tableSwitch(final int[] keys,
			final TableSwitchGenerator generator, final boolean useTable) {
		for (int i = 1; i < keys.length; ++i) {
			if (keys[i] < keys[i - 1]) {
				throw new IllegalArgumentException(
						"keys must be sorted ascending");
			}
		}
		Label def = newLabel();
		Label end = newLabel();
		if (keys.length > 0) {
			int len = keys.length;
			int min = keys[0];
			int max = keys[len - 1];
			int range = max - min + 1;
			if (useTable) {
				Label[] labels = new Label[range];
				Arrays.fill(labels, def);
				for (int i = 0; i < len; ++i) {
					labels[keys[i] - min] = newLabel();
				}
				mv.visitTableSwitchInsn(min, max, def, labels);
				for (int i = 0; i < range; ++i) {
					Label label = labels[i];
					if (label != def) {
						mark(label);
						generator.generateCase(i + min, end);
					}
				}
			} else {
				Label[] labels = new Label[len];
				for (int i = 0; i < len; ++i) {
					labels[i] = newLabel();
				}
				mv.visitLookupSwitchInsn(def, keys, labels);
				for (int i = 0; i < len; ++i) {
					mark(labels[i]);
					generator.generateCase(keys[i], end);
				}
			}
		}
		mark(def);
		generator.generateDefault();
		mark(end);
	}

	/**
	 * Generates the instruction to return the top stack value to the caller.
	 */
	public void returnValue() {
		mv.visitInsn(returnType.getOpcode(Opcodes.IRETURN));
	}

	// ------------------------------------------------------------------------
	// Instructions to load and store fields
	// ------------------------------------------------------------------------

	/**
	 * Generates a get field or set field instruction.
	 * 
	 * @param opcode
	 *            the instruction's opcode.
	 * @param ownerType
	 *            the class in which the field is defined.
	 * @param name
	 *            the name of the field.
	 * @param fieldType
	 *            the type of the field.
	 */
	private void fieldInsn(final int opcode, final Type ownerType,
			final String name, final Type fieldType) {
		mv.visitFieldInsn(opcode, ownerType.getInternalName(), name,
				fieldType.getDescriptor());
	}

	/**
	 * Generates the instruction to push the value of a static field on the
	 * stack.
	 * 
	 * @param owner
	 *            the class in which the field is defined.
	 * @param name
	 *            the name of the field.
	 * @param type
	 *            the type of the field.
	 */
	public void getStatic(final Type owner, final String name, final Type type) {
		fieldInsn(Opcodes.GETSTATIC, owner, name, type);
	}

	/**
	 * Generates the instruction to store the top stack value in a static field.
	 * 
	 * @param owner
	 *            the class in which the field is defined.
	 * @param name
	 *            the name of the field.
	 * @param type
	 *            the type of the field.
	 */
	public void putStatic(final Type owner, final String name, final Type type) {
		fieldInsn(Opcodes.PUTSTATIC, owner, name, type);
	}

	/**
	 * Generates the instruction to push the value of a non static field on the
	 * stack.
	 * 
	 * @param owner
	 *            the class in which the field is defined.
	 * @param name
	 *            the name of the field.
	 * @param type
	 *            the type of the field.
	 */
	public void getField(final Type owner, final String name, final Type type) {
		fieldInsn(Opcodes.GETFIELD, owner, name, type);
	}

	/**
	 * Generates the instruction to store the top stack value in a non static
	 * field.
	 * 
	 * @param owner
	 *            the class in which the field is defined.
	 * @param name
	 *            the name of the field.
	 * @param type
	 *            the type of the field.
	 */
	public void putField(final Type owner, final String name, final Type type) {
		fieldInsn(Opcodes.PUTFIELD, owner, name, type);
	}

	// ------------------------------------------------------------------------
	// Instructions to invoke methods
	// ------------------------------------------------------------------------

	/**
	 * Generates an invoke method instruction.
	 * 
	 * @param opcode
	 *            the instruction's opcode.
	 * @param type
	 *            the class in which the method is defined.
	 * @param method
	 *            the method to be invoked.
	 */
	private void invokeInsn(final int opcode, final Type type,
			final Method method) {
		String owner = type.getSort() == Type.ARRAY ? type.getDescriptor()
				: type.getInternalName();
		mv.visitMethodInsn(opcode, owner, method.getName(),
				method.getDescriptor());
	}

	/**
	 * Generates the instruction to invoke a normal method.
	 * 
	 * @param owner
	 *            the class in which the method is defined.
	 * @param method
	 *            the method to be invoked.
	 */
	public void invokeVirtual(final Type owner, final Method method) {
		invokeInsn(Opcodes.INVOKEVIRTUAL, owner, method);
	}

	/**
	 * Generates the instruction to invoke a constructor.
	 * 
	 * @param type
	 *            the class in which the constructor is defined.
	 * @param method
	 *            the constructor to be invoked.
	 */
	public void invokeConstructor(final Type type, final Method method) {
		invokeInsn(Opcodes.INVOKESPECIAL, type, method);
	}

	/**
	 * Generates the instruction to invoke a static method.
	 * 
	 * @param owner
	 *            the class in which the method is defined.
	 * @param method
	 *            the method to be invoked.
	 */
	public void invokeStatic(final Type owner, final Method method) {
		invokeInsn(Opcodes.INVOKESTATIC, owner, method);
	}

	/**
	 * Generates the instruction to invoke an interface method.
	 * 
	 * @param owner
	 *            the class in which the method is defined.
	 * @param method
	 *            the method to be invoked.
	 */
	public void invokeInterface(final Type owner, final Method method) {
		invokeInsn(Opcodes.INVOKEINTERFACE, owner, method);
	}

	/**
	 * Generates the instruction to invoke a dynamic method.
	 * 
	 * @param method
	 *            the method to be invoked.
	 */
	public void invokeDynamic(final Method method) {
		invokeInsn(Opcodes.INVOKEDYNAMIC,
				Type.getObjectType(Opcodes.INVOKEDYNAMIC_OWNER), method);
	}

	// ------------------------------------------------------------------------
	// Instructions to create objects and arrays
	// ------------------------------------------------------------------------

	/**
	 * Generates a type dependent instruction.
	 * 
	 * @param opcode
	 *            the instruction's opcode.
	 * @param type
	 *            the instruction's operand.
	 */
	private void typeInsn(final int opcode, final Type type) {
		mv.visitTypeInsn(opcode, type.getInternalName());
	}

	/**
	 * Generates the instruction to create a new object.
	 * 
	 * @param type
	 *            the class of the object to be created.
	 */
	public void newInstance(final Type type) {
		typeInsn(Opcodes.NEW, type);
	}

	/**
	 * Generates the instruction to create a new array.
	 * 
	 * @param type
	 *            the type of the array elements.
	 */
	public void newArray(final Type type) {
		int typ;
		switch (type.getSort()) {
		case Type.BOOLEAN:
			typ = Opcodes.T_BOOLEAN;
			break;
		case Type.CHAR:
			typ = Opcodes.T_CHAR;
			break;
		case Type.BYTE:
			typ = Opcodes.T_BYTE;
			break;
		case Type.SHORT:
			typ = Opcodes.T_SHORT;
			break;
		case Type.INT:
			typ = Opcodes.T_INT;
			break;
		case Type.FLOAT:
			typ = Opcodes.T_FLOAT;
			break;
		case Type.LONG:
			typ = Opcodes.T_LONG;
			break;
		case Type.DOUBLE:
			typ = Opcodes.T_DOUBLE;
			break;
		default:
			typeInsn(Opcodes.ANEWARRAY, type);
			return;
		}
		mv.visitIntInsn(Opcodes.NEWARRAY, typ);
	}

	// ------------------------------------------------------------------------
	// Miscelaneous instructions
	// ------------------------------------------------------------------------

	/**
	 * Generates the instruction to compute the length of an array.
	 */
	public void arrayLength() {
		mv.visitInsn(Opcodes.ARRAYLENGTH);
	}

	/**
	 * Generates the instruction to throw an exception.
	 */
	public void throwException() {
		mv.visitInsn(Opcodes.ATHROW);
	}

	/**
	 * Generates the instructions to create and throw an exception. The
	 * exception class must have a constructor with a single String argument.
	 * 
	 * @param type
	 *            the class of the exception to be thrown.
	 * @param msg
	 *            the detailed message of the exception.
	 */
	public void throwException(final Type type, final String msg) {
		newInstance(type);
		dup();
		push(msg);
		invokeConstructor(type, Method.getMethod("void <init> (String)"));
		throwException();
	}

	/**
	 * Generates the instruction to check that the top stack value is of the
	 * given type.
	 * 
	 * @param type
	 *            a class or interface type.
	 */
	public void checkCast(final Type type) {
		if (!type.equals(OBJECT_TYPE)) {
			typeInsn(Opcodes.CHECKCAST, type);
		}
	}

	/**
	 * Generates the instruction to test if the top stack value is of the given
	 * type.
	 * 
	 * @param type
	 *            a class or interface type.
	 */
	public void instanceOf(final Type type) {
		typeInsn(Opcodes.INSTANCEOF, type);
	}

	/**
	 * Generates the instruction to get the monitor of the top stack value.
	 */
	public void monitorEnter() {
		mv.visitInsn(Opcodes.MONITORENTER);
	}

	/**
	 * Generates the instruction to release the monitor of the top stack value.
	 */
	public void monitorExit() {
		mv.visitInsn(Opcodes.MONITOREXIT);
	}

	// ------------------------------------------------------------------------
	// Non instructions
	// ------------------------------------------------------------------------

	/**
	 * Marks the end of the visited method.
	 */
	public void endMethod() {
		if ((access & Opcodes.ACC_ABSTRACT) == 0) {
			mv.visitMaxs(0, 0);
		}
		mv.visitEnd();
	}

	/**
	 * Marks the start of an exception handler.
	 * 
	 * @param start
	 *            beginning of the exception handler's scope (inclusive).
	 * @param end
	 *            end of the exception handler's scope (exclusive).
	 * @param exception
	 *            internal name of the type of exceptions handled by the
	 *            handler.
	 */
	public void catchException(final Label start, final Label end,
			final Type exception) {
		if (exception == null) {
			mv.visitTryCatchBlock(start, end, mark(), null);
		} else {
			mv.visitTryCatchBlock(start, end, mark(),
					exception.getInternalName());
		}
	}
}
