/// <summary>
/// <para>如果栈顶部是值对象，那么该方法可以将顶部的对象拆箱成<paramref name="type"/>对应的值类型</para>
/// <para>如果栈顶部是引用对象，那么该方法可以顶部的对象转换成<paramref name="type"/>对应的引用类型</para>
/// <para>转换后的值会被存储在堆栈上</para>
/// </summary>
public MethodGenerator UnboxAny(Type type)
{
if (type == null)
{
throw new ArgumentNullException("type");
}
var item = _evalStack.Pop();
StackAssert.IsAssignable(item, new StackItem(typeof(object), LoadOptions.BoxValues), false);
_writer.Emit(OpCodes.Unbox_Any, type);
_evalStack.Push(type);
return(this);
}
/// <summary>
/// 封装了返回指令
/// </summary>
public void Return()
{
if (_header.ReturnType != typeof(void))
{
StackAssert.IsAssignable(_evalStack.Pop(), new StackItem(_header.ReturnType, LoadOptions.Default), true);
}
if (_evalStack.Count > 0)
{
throw new InvalidOperationException("在返回代码执行之前，计算堆栈上的所有数据应该已被移除.");
}
_writer.Emit(OpCodes.Ret);
}
public override void Open()
{
var item = Owner._evalStack.Peek();
StackAssert.AreEqual(item, new StackItem(item.Type, LoadOptions.Default));
_targetDisposeMethod = UsingTarget.Type.GetBestCallableOverride(_disposeMethod);
UsingTarget = Owner.Declare(item.Type);
Owner.Store(UsingTarget);
base.Open();
Owner._writer.BeginTry();
}
/// <summary>
/// 三元运算
/// </summary>
/// <param name="type"></param>
/// <param name="options"></param>
/// <param name="condition"></param>
/// <param name="trueValue"></param>
/// <param name="falseValue"></param>
public void Ternary(Type type, LoadOptions options, Func <LogicOperator> condition, Action trueValue, Action falseValue)
{
if (condition == null)
{
throw new ArgumentNullException("condition");
}
if (trueValue == null)
{
throw new ArgumentNullException("trueValue");
}
if (falseValue == null)
{
throw new ArgumentNullException("falseValue");
}
var trueLabel = _writer.DefineLabel();
var doneLabel = _writer.DefineLabel();
var c = condition();
GoToIf(c, trueLabel);
int count = _evalStack.Count;
falseValue();
if (_evalStack.Count != count + 1)
{
throw new StackValidationException("The ternary operator expects exactly one more item on the evaluation stack after falseValue completes");
}
var falseResult = _evalStack.Pop();
StackAssert.IsAssignable(falseResult, new StackItem(type, options), true);
_writer.Emit(OpCodes.Br, doneLabel);
trueLabel.Mark();
count = _evalStack.Count();
trueValue();
if (_evalStack.Count != count + 1)
{
throw new StackValidationException("The ternary operator expects exactly one more item on the evaluation stack after trueValue completes");
}
var trueResult = _evalStack.Pop();
StackAssert.IsAssignable(trueResult, new StackItem(type, options), true);
doneLabel.Mark();
_evalStack.Push(type, options);
}
/// <summary>
/// 检查参数合法性，并从模拟计算堆栈中弹出参数
/// </summary>
/// <param name="method"></param>
private void PopAndValidateParams(MethodBase method)
{
var parameters = method.GetParameters();
for (int i = parameters.Length - 1; i >= 0; --i)
{
// 验证参数是否合法
StackAssert.IsAssignable(_evalStack.Pop(), new StackItem(parameters[i].ParameterType, LoadOptions.Default), true);
}
if (!method.IsStatic && !method.IsConstructor)
{
//如果不是静态方法或者构造方法，那么当前栈顶的数据，应该是this
//即：方法所声明的类型
StackAssert.IsAssignable(_evalStack.Pop(), new StackItem(method.DeclaringType, LoadOptions.ValueAsAddress), false);
}
}
public void Convert(Type toType, bool withOverflowCheck)
{
var item = _evalStack.Pop();
StackAssert.IsPrimitive(item);
OpCode conversionCode;
if (_conversions.TryGetValue(new ConversionKey(toType, withOverflowCheck), out conversionCode))
{
_writer.Emit(conversionCode);
_evalStack.Push(toType);
return;
}
throw new ArgumentException("不能转换类型 " + toType.Name, "toType");
}
/// <summary>
/// <para>开始加载数组元素</para>
/// <para>请在执行该方法之后，加载索引：</para>
/// <code>
/// g.BeginLoadElement();
/// {
/// g.Load(i);
/// }
/// g.EndLoadElement();
/// </code>
/// </summary>
private void BeginLoadElement()
{
_delayedInstructions.Push(() =>
{
//需要加载的成员的索引值
var item = _evalStack.Pop();
StackAssert.IsAssignable(item, new StackItem(typeof(int)), false);//检查索引值是否为int型
//目标数组
//此处是模拟弹出，用于效验
item = _evalStack.Pop();
StackAssert.IsAssignable(item, new StackItem(typeof(Array)), false);//检查弹出的项是否为array
//var elementType = item.Type.GetElementType();
var elementType = item.Type.ResolveElementType();
_writer.EmitLdelem(elementType);//将指定数组索引中的元素加载到计算堆栈的顶部。
_evalStack.Push(elementType);
});
}
/// <summary>
/// <para>开始创建新的数组</para>
/// <para>请在此方法时候，调用加载数组长度的方法，例如：</para>
/// <code>
/// g.BeginNewArray(_elementType);
/// {
/// g.Load(count);
/// }
/// g.EndNewArray();
/// </code>
/// </summary>
/// <param name="elementType">数组的成员类型</param>
/// <param name="rank">维数</param>
private void BeginNewArray(Type elementType, int rank)
{
if (elementType == null)
{
throw new ArgumentNullException("elementType");
}
if (rank < 1)
{
throw new ArgumentOutOfRangeException("rank", "数组维度不能小于1");
}
var arrayType = rank == 1 ? elementType.MakeArrayType() : elementType.MakeArrayType(rank);
_delayedInstructions.Push(() =>
{
for (int i = 0; i < rank; ++i)
{
StackAssert.AreEqual(_evalStack.Pop(), typeof(int));
}
if (rank == 1)
{
//创建一维数组
//将对新的从零开始的一维数组（其元素属于特定类型）的对象引用推送到计算堆栈上
_writer.Emit(OpCodes.Newarr, elementType);
}
else
{
var paramTypes = new Type[rank];
for (int i = 0; i < paramTypes.Length; ++i)
{
paramTypes[i] = typeof(int);
}
//创建多维数组
//利用多维数组的构造函数，创建多维数组对象
_writer.Emit(OpCodes.Newobj, arrayType.GetConstructor(paramTypes));
}
_evalStack.Push(arrayType);
});
}
/// <summary>
/// <para>开始将值存入数组指定的索引处</para>
/// <para>示例代码：</para>
/// <code>
/// g.Load(context.Member);
/// g.BeginStoreElement();
/// {
/// g.Load(i);
/// g.Load(element);
/// }
/// g.EndStoreElement();
/// </code>
/// </summary>
/// <remarks>
/// 注意：由于BeginStoreElement前后，分为三步：
/// 1.将对数组 array 的对象引用推送到堆栈上。
/// 2.将 array 中元素的索引值 index 推送到堆栈上。
/// 3.将指令中指定类型的值推送到堆栈上。
/// 因此，以下代码，要反向验证，即：堆栈顶部的数据为：
/// 1.需要存储的值
/// 2.索引值 index
/// 3.数组 array 的对象引用
/// </remarks>
private void BeginStoreElement()
{
_delayedInstructions.Push(() =>
{
//需要存储的值
var valueItem = _evalStack.Pop();
//验证索引值为int型
StackAssert.IsAssignable(_evalStack.Pop(), typeof(int), false);
//将对数组 array 的对象引用推送到堆栈上。
var arrayItem = _evalStack.Pop();
//检查是否为array类型
StackAssert.IsAssignable(arrayItem, typeof(Array), false);
Debug.Assert(arrayItem.Type.IsArray, "项必须存储在数组类型上");
var elementType = arrayItem.Type.GetElementType();
StackAssert.IsAssignable(valueItem, new StackItem(elementType, LoadOptions.Default), true);
_writer.EmitStelem(elementType);
});
}