// Restore stack to match given machine state. Stack should currently be empty.
public bool Restore(MachineState stateAfterRestore, int skip)
{
if (skip > stateAfterRestore.Depth)
{
return(Failed(false, "underflow in restore"));
}
if (Depth != 0)
{
return(Failed(false, "cannot restore into non-empty stack"));
}
for (var i = 0; i < stateAfterRestore.Depth - skip; i++)
{
var id = stateAfterRestore.PeekId(stateAfterRestore.Depth - skip - 1 - i, gensym);
var cell = new VariableCell(id);
// Ok if already added as temporary
compEnv.AddVariable
(id, ArgLocal.Local, false, true, compEnv.SubstituteType(stateAfterRestore.PeekType(stateAfterRestore.Depth - skip - 1 - i)));
stack.Add(new ExpressionStackEntry(cell.Read(), bottom));
}
return(true);
}
private bool Dump(ISeq <Statement> statements, MachineState state, int skip, int i)
{
if (statements == null)
{
return(Failed(false, "eval in flush"));
}
var id = state.PeekId(stack.Count - (1 + skip) - i, gensym);
var cell = new VariableCell(id);
var read = stack[i].Expression as ReadExpression;
if (read == null || !read.Address.Equals(cell.AddressOf()))
{
// Ok if id already added as temporary
compEnv.AddVariable(id, ArgLocal.Local, false, true, compEnv.SubstituteType(state.PeekType(stack.Count - (1 + skip) - i)));
statements.Add(new ExpressionStatement(cell.Write(stack[i].Expression.CloneIfStruct(compEnv))));
}
// else: stack entry has not changed, so no need to save it
return(true);
}