/// <summary>
/// 加载参数，并写入条件转移指令
/// </summary>
/// <param name="op"></param>
/// <param name="target"></param>
private void GoToIf(LogicOperator op, ILabel target)
{
for (int i = 0; i < op.ArgumentCount; ++i)
{
// 参与验证的项
_evalStack.Pop();
}
op.WriteBranch(_writer, target);
}
/// <summary>
/// 比较操作
/// </summary>
/// <param name="op"></param>
public void Compare(LogicOperator op)
{
for (int i = 0; i < op.ArgumentCount; ++i)
{
// todo validate better
_evalStack.Pop();
}
op.WriteCompare(_writer);
_evalStack.Push(typeof(bool));
}
static LogicOperator()
{
var op1 = new LogicOperator
{
//从堆栈中弹出value；如果 value 为 true、非空或非零，则将控制转移到目标指令l
_branchWriter = (w, l) => w.Emit(OpCodes.Brtrue, l),
_compareWriter = w => { },//计算堆栈顶部的值，如果是true，那就是true，因此不需要额外的判断
ArgumentCount = 1
};
var op2 = new LogicOperator
{
//如果 value 为 false、空引用或零，则将控制转移到目标指令l
_branchWriter = (w, l) => w.Emit(OpCodes.Brfalse, l),
//求补（取反）
_compareWriter = w => { NotBoolean(w); },
ArgumentCount = 1
};
SetOpposites(op1, op2);
IsTrue = op1;
IsFalse = IsNull = op2;
op1 = new LogicOperator
{
//从堆栈中弹出 value2 和 value1；如果 value1 等于 value2，则执行分支操作l
_branchWriter = (w, l) => w.Emit(OpCodes.Beq, l),
//从堆栈中弹出值2和值1，值1值2相比。
//如果值1等于值2，被压入堆栈，否则为0压入堆栈。
_compareWriter = w => w.Emit(OpCodes.Ceq),
ArgumentCount = 2
};
op2 = new LogicOperator
{
//將 value2 和 value1 自堆栈取出，如果 value1 不等于 value2，则会执行分支操作l
_branchWriter = (wde, l) => wde.Emit(OpCodes.Bne_Un, l),
//不等于的比较
_compareWriter = w => { w.Emit(OpCodes.Ceq); NotBoolean(w); },
ArgumentCount = 2
};
SetOpposites(op1, op2);
AreEqual = op1;
AreNotEqual = op2;
// 大于
op1 = new LogicOperator
{
//大于
_branchWriter = (wde, l) => wde.Emit(OpCodes.Bgt, l),
_compareWriter = w => w.Emit(OpCodes.Cgt),
ArgumentCount = 2
};
op2 = new LogicOperator
{
//小于等于
_branchWriter = (wde, l) => wde.Emit(OpCodes.Ble, l),
//小于
_compareWriter = w => w.Emit(OpCodes.Clt),
ArgumentCount = 2
};
SetOpposites(op1, op2);
GreaterThan = op1;
LessThanOrEqualTo = op2;
op1 = new LogicOperator
{
//大于等于
_branchWriter = (wde, l) => wde.Emit(OpCodes.Bge, l),
//大于等于的比较
_compareWriter = w => { w.Emit(OpCodes.Clt); NotBoolean(w); },
ArgumentCount = 2
};
op2 = new LogicOperator
{
//小于的分支
_branchWriter = (wde, l) => wde.Emit(OpCodes.Blt, l),
//小于的比较
_compareWriter = w => { w.Emit(OpCodes.Cgt); NotBoolean(w); },
ArgumentCount = 2
};
SetOpposites(op1, op2);
GreaterThanOrEqualTo = op1;
LessThan = op2;
}
/// <summary>
/// <para>设置op1的相反IL操作为op2</para>
/// <para>设置op2的相反IL操作为op1</para>
/// </summary>
/// <param name="op1"></param>
/// <param name="op2"></param>
private static void SetOpposites(LogicOperator op1, LogicOperator op2)
{
op1._opposite = op2;
op2._opposite = op1;
}
