private DelayedTupleExpression LiftVariable(ParameterExpression param)
{
DelayedTupleExpression res;
if (!_vars.TryGetValue(param, out res))
{
_vars[param] = res = new DelayedTupleExpression(_vars.Count, _tupleExpr, _tupleType, param.Type);
_orderedVars.Add(new KeyValuePair <ParameterExpression, DelayedTupleExpression>(param, res));
}
return(res);
}
internal Expression Reduce(bool shouldInterpret, bool emitDebugSymbols, int compilationThreshold,
IList <ParameterExpression> parameters, Func <Expression <Func <MutableTuple, object> >,
Expression <Func <MutableTuple, object> > > bodyConverter)
{
_state = LiftVariable(Expression.Parameter(typeof(int), "state"));
_current = LiftVariable(Expression.Parameter(typeof(object), "current"));
// lift the parameters into the tuple
foreach (ParameterExpression pe in parameters)
{
LiftVariable(pe);
}
DelayedTupleExpression liftedGen = LiftVariable(_generatorParam);
// Visit body
Expression body = Visit(_body);
Debug.Assert(_returnLabels.Count == 1);
// Add the switch statement to the body
int count = _yields.Count;
var cases = new SwitchCase[count + 1];
for (int i = 0; i < count; i++)
{
cases[i] = Expression.SwitchCase(Expression.Goto(_yields[i].Label), AstUtils.Constant(_yields[i].State));
}
cases[count] = Expression.SwitchCase(Expression.Goto(_returnLabels.Peek()), AstUtils.Constant(Finished));
// Create the lambda for the PythonGeneratorNext, hoisting variables
// into a tuple outside the lambda
Expression[] tupleExprs = new Expression[_vars.Count];
foreach (var variable in _orderedVars)
{
// first 2 are our state & out var
if (variable.Value.Index >= 2 && variable.Value.Index < (parameters.Count + 2))
{
tupleExprs[variable.Value.Index] = parameters[variable.Value.Index - 2];
}
else
{
tupleExprs[variable.Value.Index] = Expression.Default(variable.Key.Type);
}
}
Expression newTuple = MutableTuple.Create(tupleExprs);
Type tupleType = _tupleType.Value = newTuple.Type;
ParameterExpression tupleExpr = _tupleExpr.Value = Expression.Parameter(tupleType, "tuple");
ParameterExpression tupleArg = Expression.Parameter(typeof(MutableTuple), "tupleArg");
_temps.Add(_gotoRouter);
_temps.Add(tupleExpr);
// temps for the outer lambda
ParameterExpression tupleTmp = Expression.Parameter(tupleType, "tuple");
ParameterExpression ret = Expression.Parameter(typeof(PythonGenerator), "ret");
var innerLambda = Expression.Lambda <Func <MutableTuple, object> >(
Expression.Block(
_temps.ToArray(),
Expression.Assign(
tupleExpr,
Expression.Convert(
tupleArg,
tupleType
)
),
Expression.Switch(Expression.Assign(_gotoRouter, _state), cases),
body,
MakeAssign(_state, AstUtils.Constant(Finished)),
Expression.Label(_returnLabels.Peek()),
_current
),
_name,
new ParameterExpression[] { tupleArg }
);
// Generate a call to PythonOps.MakeGeneratorClosure(Tuple data, object generatorCode)
return(Expression.Block(
new[] { tupleTmp, ret },
Expression.Assign(
ret,
Expression.Call(
typeof(PythonOps).GetMethod("MakeGenerator"),
parameters[0],
Expression.Assign(tupleTmp, newTuple),
emitDebugSymbols ?
(Expression)bodyConverter(innerLambda) :
(Expression)Expression.Constant(
new LazyCode <Func <MutableTuple, object> >(
bodyConverter(innerLambda),
shouldInterpret,
compilationThreshold
),
typeof(object)
)
)
),
new DelayedTupleAssign(
new DelayedTupleExpression(liftedGen.Index, new StrongBox <ParameterExpression>(tupleTmp), _tupleType, typeof(PythonGenerator)),
ret
),
ret
));
}
