public static IDisposable ForEachLoop(this ILGenerator il, Type elementType, LocalBuilder collection, out LocalBuilder currentElement)
{
Label lMoveNext = il.DefineLabel();
Label lWork = il.DefineLabel();
currentElement = il.DeclareLocal(elementType);
//get collection enumerator
LocalBuilder enumerator = il.DeclareLocal(typeof(IEnumerator));
#if DEBUG
il.EmitWriteLine("foreach-begin");
#endif
il.Emit(Ldloc, collection.LocalIndex);
il.Emit(Callvirt, getEnumeratorMethod);
il.Emit(Stloc, enumerator.LocalIndex);
//immediately move to "move next" to start enumeration
il.Emit(Br, lMoveNext);
//iteration work block
il.MarkLabel(lWork);
#if DEBUG
il.EmitWriteLine(" foreach-loop");
#endif
//get current element
il.Emit(Ldloc, enumerator.LocalIndex);
il.Emit(Callvirt, getCurrentMethod);
il.Emit(Unbox_Any, elementType);
il.Emit(Stloc, currentElement.LocalIndex);
return(il.After(() =>
{
//"move next" block
il.MarkLabel(lMoveNext);
il.Emit(Ldloc, enumerator.LocalIndex); //load enumerator as an argument
il.Emit(Callvirt, moveNextMethod);
il.Emit(Brtrue, lWork); //if result is true, go to lWork
//otherwise, dispose enumerator and exit
//il.Emit(Ldloc, enumerator.LocalIndex);
//il.Emit(Callvirt, disposeMethod);
#if DEBUG
il.EmitWriteLine("foreach-end");
#endif
}));
}
public static IDisposable ForLoop(this ILGenerator il, LocalBuilder max, out LocalBuilder loopCounter)
{
loopCounter = il.DeclareLocal(typeof(int)); //loop counter
#if DEBUG
il.EmitWriteLine("for-begin");
#endif
il.Emit(Ldc_I4_0);
il.Emit(Stloc, loopCounter.LocalIndex);
Label lBody = il.DefineLabel(); //loop body start
Label lExit = il.DefineLabel(); //final and return
il.MarkLabel(lBody); //loop body starts here
//load counter and max and compare them
il.Emit(Ldloc, loopCounter.LocalIndex);
il.Emit(Ldloc, max.LocalIndex);
//il.Emit(Ldc_I4_3);
il.Emit(Clt); //1 - less, 0 - equal or more (exit)
il.Emit(Brfalse, lExit); //jump on 1
#if DEBUG
il.EmitWriteLine(" for-loop");
#endif
// loop body executes here
LocalBuilder loopCounterAfter = loopCounter;
return(il.After(() =>
{
//increment loop counter
il.Increment(loopCounterAfter);
//loop again
il.Emit(Br, lBody);
il.MarkLabel(lExit);
#if DEBUG
il.EmitWriteLine("for-end");
#endif
}));
}