protected override void EmitRead(ProtoBuf.Compiler.CompilerContext ctx, ProtoBuf.Compiler.Local valueFrom)
{
/* This looks more complex than it is. Look at the non-compiled Read to
* see what it is trying to do, but note that it needs to cope with a
* few more scenarios. Note that it picks the **most specific** Add,
* unlike the runtime version that uses IList when possible. The core
* is just a "do {list.Add(readValue())} while {thereIsMore}"
*
* The complexity is due to:
* - value types vs reference types (boxing etc)
* - initialization if we need to pass in a value to the tail
* - handling whether or not the tail *returns* the value vs updates the input
*/
bool returnList = ReturnList;
using (Compiler.Local list = AppendToCollection ? ctx.GetLocalWithValue(ExpectedType, valueFrom) : new Compiler.Local(ctx, declaredType))
using (Compiler.Local origlist = (returnList && AppendToCollection) ? new Compiler.Local(ctx, ExpectedType) : null)
{
if (!AppendToCollection)
{ // always new
ctx.LoadNullRef();
ctx.StoreValue(list);
}
else if (returnList)
{ // need a copy
ctx.LoadValue(list);
ctx.StoreValue(origlist);
}
if (concreteType != null)
{
ctx.LoadValue(list);
Compiler.CodeLabel notNull = ctx.DefineLabel();
ctx.BranchIfTrue(notNull, true);
ctx.EmitCtor(concreteType);
ctx.StoreValue(list);
ctx.MarkLabel(notNull);
}
EmitReadList(ctx, list, Tail, add, packedWireType);
if (returnList)
{
if (AppendToCollection)
{
// remember ^^^^ we had a spare copy of the list on the stack; now we'll compare
ctx.LoadValue(origlist);
ctx.LoadValue(list); // [orig] [new-value]
Compiler.CodeLabel sameList = ctx.DefineLabel(), allDone = ctx.DefineLabel();
ctx.BranchIfEqual(sameList, true);
ctx.LoadValue(list);
ctx.Branch(allDone, true);
ctx.MarkLabel(sameList);
ctx.LoadNullRef();
ctx.MarkLabel(allDone);
}
else
{
ctx.LoadValue(list);
}
}
}
}