public void RevertContextualsIn(FrameScope fs, CodeGen cg)
{
foreach (var varname in MangledContextuals.Values)
{
if (fs.AssignedContextuals.Contains(varname))
{
if (cg.This().Type.Name != "TopLevelFrame")
{
cg.If(cg.This().Field("_assigned_" + fs.ID + "_" + varname) > 0);
{
cg.Assign(cg.This().Field("TopLevelFrame").Field("_ctxl_" + varname), cg.This().Field("TopLevelFrame").Field("_stack_" + varname).Invoke("Pop"));
cg.Assign(cg.This().Field("_assigned_" + fs.ID + "_" + varname), 0);
}
cg.End();
}
else
{
cg.If(cg.This().Field("_assigned_" + fs.ID + "_" + varname) > 0);
{
cg.Assign(cg.This().Field("_ctxl_" + varname), cg.This().Field("_stack_" + varname).Invoke("Pop"));
cg.Assign(cg.This().Field("_assigned_" + fs.ID + "_" + varname), 0);
}
cg.End();
}
}
}
}
// this routine runs at parser-runtime (not parser-compiletime nor program-runtime)
public string GetMangledContextual(TypeGen currentFrameBuilder, FrameScope currentScope, FrameScope topLevelScope, string varname)
{
string mangledName;
if (!MangledContextuals.TryGetValue(varname, out mangledName))
{
throw new InvalidOperationException("you must declare the contextual " + varname + ", including its type annotation");
}
return(GetMangledContextual(currentFrameBuilder, currentScope, topLevelScope, topLevelScope[varname].Type, varname));
}
// generates code that resets the lexical slots in the enclosing frame for re-entering
// a block (such as in a loop). Effectively emulates a parameterless closure.
public void RevertLexicalsIn(FrameScope fs, CodeGen cg)
{
foreach (var varname in fs.OwnKeysList)
{
if (fs[varname].Type.IsValueType)
{
cg.This().Field(fs[varname].MangledName).ForceEmitAddress(cg);
cg.IL.Emit(OpCodes.Initobj, fs[varname].Type);
}
else
{
cg.Assign(cg.This().Field(fs[varname].MangledName), null);
}
}
}
// this routine runs at parser-runtime (not parser-compiletime nor program-runtime)
public string GetMangledContextual(TypeGen currentFrameBuilder, FrameScope currentScope, FrameScope topLevelScope, Type type, string varname)
{
string mangledName;
if (!MangledContextuals.TryGetValue(varname, out mangledName))
{
var frameLocal = new FrameLocal(varname, type, topLevelScope);
topLevelScope.AddHere(varname, frameLocal);
currentFrameBuilder.FrameGen.MangledContextuals.Add(varname, mangledName = frameLocal.MangledName);
// create a field in the toplevel frame class for the current contextual value
Public.Field(type, "_ctxl_" + mangledName);
// and create a runtime type representing the type of the Stack<TypeOfThisContextual>
var stack_type = typeof(Stack <>).MakeGenericType(type);
// create a field in the toplevel frame class for the stack of previously assigned dynamic
// values of the contextual variable.
Public.Field(stack_type, "_stack_" + mangledName);
// push a closure that will run (parser-runtime) at the end of the toplevel routine declaration
// (but at program-runtime will run as a prologue to the program) that initializes this stack
PrologueEvents.Add((CodeGen cg) => {
if (cg.This().Type.Name == "TopLevelFrame")
{
cg.Assign(cg.This().Field("_stack_" + mangledName), Exp.New(stack_type));
}
else
{
cg.Assign(cg.This().Field("TopLevelFrame").Field("_stack_" + mangledName), Exp.New(stack_type));
}
});
}
// if we haven't already added a flag assigned slot for this contextual-scope tuple in this frame,
if (!currentScope.AssignedContextuals.Contains(mangledName))
{
// record that we've done so,
currentScope.AssignedContextuals.Add(mangledName);
// and create a field in the current frame class for a flag representing whether to pop the
// contextual stack upon leaving this scope,
currentFrameBuilder.FrameGen.Public.Field(typeof(int), "_assigned_" + currentScope.ID + "_" + mangledName);
}
return(mangledName);
}
