private static Action <Hashtable, Array, int> EmitCopyValues()
{
/*
* private void CopyValues(Hashtable hashtable, Array array, int arrayLength)
* {
* bucket[] buckets = hashtable.buckets;
* int length = buckets.Length;
* int arrayIndex = 0;
* while (--length >= 0)
* {
* object key = buckets[length].key;
* if ((key != null) && (key != hashtable.buckets))
* {
* if (arrayIndex >= arrayLength)
* return;
* array.SetValue(buckets[length].val, arrayIndex++);
* }
* }
* }
*/
var dynamicMethod = new DynamicMethod(
Guid.NewGuid().ToString(), typeof(void), new[] { typeof(Hashtable), typeof(Array), typeof(int) },
typeof(Hashtable), true);
var bucketsFieldInfo = typeof(Hashtable).GetField("buckets",
BindingFlags.Instance | BindingFlags.NonPublic);
var bucketType = typeof(Hashtable).GetNestedType("bucket", BindingFlags.NonPublic);
var bucketArrayType = bucketType.MakeArrayType();
var keyFieldInfo = bucketType.GetField("key", BindingFlags.Instance | BindingFlags.Public);
var valFieldInfo = bucketType.GetField("val", BindingFlags.Instance | BindingFlags.Public);
var setValueMethodInfo = typeof(Array).GetMethod("SetValue", new[] { typeof(object), typeof(int) });
using (var il = new GroboIL(dynamicMethod))
{
var buckets = il.DeclareLocal(bucketArrayType, "buckets");
var length = il.DeclareLocal(typeof(int), "length");
var arrayIndex = il.DeclareLocal(typeof(int), "arrayIndex");
var key = il.DeclareLocal(typeof(object), "key");
var cycleStartLabel = il.DefineLabel("cycleStart");
var cycleNextLabel = il.DefineLabel("cycleNext");
var endLabel = il.DefineLabel("end");
il.EmitSetIntToZero(arrayIndex);
il.Ldarg(0); // stack: hashtable
il.Ldfld(bucketsFieldInfo); // stack: hashtable::buckets
il.Stloc(buckets);
il.Ldloc(buckets); // stack: hashtable::buckets
il.Ldlen(); // stack: buckets.length
il.Conv <int>(); // stack: buckets.length (i4)
il.Stloc(length);
il.Br(cycleNextLabel); // jump(cycleNext)
il.MarkLabel(cycleStartLabel);
il.EmitLoadArrayItemRef(buckets, length, bucketType); // stack: *bucket[current]
il.Ldfld(keyFieldInfo); // stack: key
il.Stloc(key); // 2: key
il.Ldloc(key); // stack: key
il.Brfalse(cycleNextLabel); // jump(cycleNext) if key == null
il.Ldloc(key); // stack: key
il.Ldarg(0); // stack+: hashtable
il.Ldfld(bucketsFieldInfo); // stack: key, hashtable::buckets
il.Beq(cycleNextLabel);
// jump(cycleNext) if key == hashtable::buckets (какой-то хитрый хак hashtable-а)
il.Ldloc(arrayIndex); // stack: arrayIndex
il.Ldarg(2); // stack+: arrayLength
il.Bge(endLabel, false); // jump(end) if arrayIndex >= arrayLength
il.Ldarg(1); // stack: array (arg1)
il.EmitLoadArrayItemRef(buckets, length, bucketType); // stack: array (arg1), *bucket[current]
il.Ldfld(valFieldInfo); // stack: array (arg1), bucket[current].val
il.EmitXPlusPlus(arrayIndex); // stack: array (arg1), bucket[current].val, arrayIndex++
il.Call(setValueMethodInfo); // array.SetValue(bucket[current].val, old_arrayIndex);
il.MarkLabel(cycleNextLabel);
il.EmitMinusMinusX(length); // stack: --current
il.Ldc_I4(0); // stack+: 0
il.Bge(cycleStartLabel, false); // jump(cycleStart) if --current >= 0
il.MarkLabel(endLabel);
il.Ret();
}
return((Action <Hashtable, Array, int>)dynamicMethod.CreateDelegate(typeof(Action <Hashtable, Array, int>)));
}