private ExpressionStackEntry Eval(ISeq <Statement> statements, ExpressionStackEntry entry)
{
if (statements == null)
{
throw new ArgumentNullException("statements");
}
// Eval the expression and save it in a temporary. If result is a structure, make the implied
// value semantics explicit by cloning the value.
var id = gensym();
var cell = new VariableCell(id);
compEnv.AddVariable(id, ArgLocal.Local, false, true, compEnv.SubstituteType(entry.Expression.Type(compEnv)));
statements.Add(new ExpressionStatement(cell.Write(entry.Expression.CloneIfStruct(compEnv))));
// We never re-write to temporaries, so this stack entry now has no effects, not even a 'read' effect.
// Also, the result's Expression.IsValue will be true.
return(new ExpressionStackEntry(cell.Read(), bottom));
}
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);
}
