public override IScheminType Execute(Environment env, Evaluator eval, ScheminList args)
{
ScheminList conditions = (ScheminList) args;
ScheminList builtIf = new ScheminList();
builtIf.UnQuote();
ScheminList firstCondition = (ScheminList) conditions.Car();
if ((firstCondition.Car() as ScheminAtom) != null)
{
ScheminAtom atom = (ScheminAtom) firstCondition.Car();
if (atom.Name == "else")
{
ScheminList elseClause = firstCondition.Cdr();
elseClause.Cons(new ScheminPrimitive("begin"));
return elseClause;
}
}
builtIf.Append(new ScheminPrimitive("if"));
builtIf.Append(firstCondition.Car());
ScheminList beginExpression = firstCondition.Cdr();
beginExpression.Cons(new ScheminPrimitive("begin"));
builtIf.Append(beginExpression);
if (conditions.Cdr().Length > 0)
{
ScheminList nextConditions = conditions.Cdr();
nextConditions.Cons(new ScheminPrimitive("cond"));
builtIf.Append(nextConditions);
}
return builtIf;
}
public override IScheminType Execute(Environment env, Evaluator eval, ScheminList args)
{
IScheminType function = args.Car();
ScheminList argList = args.Cdr();
ScheminList toApply = (ScheminList) args.Cdr().Last();
ScheminList list = new ScheminList();
list.UnQuote();
foreach (IScheminType type in toApply)
{
list.Append(type);
}
foreach (IScheminType type in argList)
{
if (type != toApply)
list.Cons(type);
}
list.Cons(function);
return list;
}
private ScheminList CombineStackFrame(ScheminList before, ScheminList after, IScheminType result)
{
ScheminList complete = new ScheminList();
complete.UnQuote();
if (before != null && !before.Empty)
{
complete.Append(before.Head);
var restBefore = before.Rest;
while (restBefore != null)
{
complete.Append(restBefore.Head);
restBefore = restBefore.Rest;
}
}
if (result != null)
{
complete.Append(result);
}
if (after != null && !after.Empty)
{
complete.Append(after.Head);
var restAfter = after.Rest;
while (restAfter != null)
{
complete.Append(restAfter.Head);
restAfter = restAfter.Rest;
}
}
return complete;
}
public IScheminType EvaluateList(ScheminList list)
{
StackFrame start = new StackFrame();
start.WaitingOn = list;
start.CurrentEnv = this.GlobalEnv;
Stack.Clear();
Stack.Push(start);
StackStart:
while (Stack.Count > 0)
{
StackFrame current = Stack.Pop();
Environment CurrentEnv = current.CurrentEnv;
ScheminList before = current.Before;
ScheminList after = current.After;
IScheminType WaitingOn = current.WaitingOn;
if ((WaitingOn as ScheminList) == null || WaitingOn.Quoted() == true || IsEmptyList(WaitingOn))
{
StackFrame next = new StackFrame();
if (before == null && after == null)
{
if ((WaitingOn as ScheminAtom) != null && !WaitingOn.Quoted())
{
WaitingOn = EvalAtom(WaitingOn, CurrentEnv);
}
if (Stack.Count < 1)
{
return WaitingOn;
}
StackFrame previous = Stack.Pop();
if (previous.Before == null && previous.After == null)
{
next.WaitingOn = WaitingOn;
}
else
{
next.WaitingOn = CombineStackFrame(previous.Before, previous.After, WaitingOn);
}
// Use the previous environment in this case as well
if (Stack.Count > 0)
{
next.CurrentEnv = Stack.Peek().CurrentEnv;
}
else
{
next.CurrentEnv = previous.CurrentEnv;
}
Stack.Push(next);
continue;
}
// We need to use the PREVIOUS environment here, so peek it.. otherwise we're re-using the same environment for the previous context.
StackFrame peeked = Stack.Peek();
next.WaitingOn = CombineStackFrame(before, after, WaitingOn);
next.CurrentEnv = peeked.CurrentEnv;
Stack.Push(next);
continue;
}
StackFrame completeFrame = new StackFrame();
ScheminPrimitive currentPrimitive = null;
ScheminList rest = (ScheminList) WaitingOn;
ScheminList pendingBefore = new ScheminList();
pendingBefore.UnQuote();
if ((rest.Car() as ScheminPrimitive) != null)
{
if (rest.Car().Quoted() == false)
{
currentPrimitive = (ScheminPrimitive) rest.Car();
}
}
int currentArg = 0;
while (!rest.Empty)
{
IScheminType type = rest.Car();
if (currentPrimitive != null)
{
if (!EvaluateNextArg(currentPrimitive, currentArg, ((ScheminList) WaitingOn).Cdr()))
{
pendingBefore.Append(type);
rest = rest.Cdr();
currentArg++;
continue;
}
}
if ((type as ScheminAtom) != null)
{
if (type.Quoted())
{
pendingBefore.Append(type);
}
else
{
IScheminType atomResult = EvalAtom(type, CurrentEnv);
if ((atomResult as ScheminRewriter) != null)
{
// if we get a quoted rewriter here, we're going to apply it :(
pendingBefore.Append(atomResult);
QuoteAll(rest.Cdr());
}
else
{
pendingBefore.Append(atomResult);
}
}
}
else if ((type as ScheminList) != null)
{
ScheminList tempList = (ScheminList) type;
if (tempList.Quoted() || tempList.Empty)
{
pendingBefore.Append(type);
rest = rest.Cdr();
currentArg++;
continue;
}
StackFrame next = new StackFrame();
next.WaitingOn = type;
next.After = rest.Cdr();
next.Before = pendingBefore;
next.CurrentEnv = CurrentEnv;
Stack.Push(current);
Stack.Push(next);
goto StackStart;
}
else
{
pendingBefore.Append(type);
}
rest = rest.Cdr();
currentArg++;
}
IScheminType functionPosition = pendingBefore.Car();
ScheminList functionArgs = pendingBefore.Cdr();
if ((functionPosition as ScheminPrimitive) != null)
{
ScheminPrimitive prim = (ScheminPrimitive) functionPosition;
completeFrame.Before = before;
completeFrame.After = after;
// Need to pass push the previous frame back on so we can get access to the current continuation via the evaluator's Stack field.
// also adding the primitive's name to the exception if it gets thrown.
try
{
Stack.Push(current);
completeFrame.WaitingOn = prim.Evaluate(functionArgs, CurrentEnv, this);
Stack.Pop();
}
catch (BadArgumentsException ba)
{
Token sourceToken = prim.SourceToken;
string line = String.Empty;
if (sourceToken != null)
{
line = " line: " + sourceToken.LineNumber.ToString() + " col: " + sourceToken.ColNumber.ToString();
}
throw new BadArgumentsException(prim.ToString() + " " + ba.Message + line);
}
completeFrame.CurrentEnv = CurrentEnv;
Stack.Push(completeFrame);
continue;
}
else if ((functionPosition as ScheminLambda) != null)
{
ScheminLambda lam = (ScheminLambda) functionPosition;
completeFrame.Before = before;
completeFrame.After = after;
Environment args = lam.MakeEnvironment(functionArgs, this);
completeFrame.WaitingOn = lam.Definition;
completeFrame.CurrentEnv = args;
Stack.Push(completeFrame);
continue;
}
else if ((functionPosition as ScheminContinuation) != null)
{
ScheminContinuation con = (ScheminContinuation) functionPosition;
this.Stack = new Stack<StackFrame>(con.PreviousStack);
this.Stack.Peek().WaitingOn = functionArgs.Car();
continue;
}
else if ((functionPosition as ScheminRewriter) != null)
{
ScheminRewriter rewriter = (ScheminRewriter) functionPosition;
QuoteAll(functionArgs);
IScheminType result = rewriter.Rewrite(functionArgs);
completeFrame.Before = before;
completeFrame.After = after;
completeFrame.WaitingOn = result;
completeFrame.CurrentEnv = CurrentEnv;
this.Stack.Push(completeFrame);
continue;
}
else
{
throw new InvalidOperationException("Non-function in function position: " + functionPosition.ToString());
}
}
throw new InvalidOperationException("Control escaped list evaluator...");
}
public override IScheminType Execute(Environment env, Evaluator eval, ScheminList args)
{
bool isNamed = false;
if ((args.Car() as ScheminAtom) != null)
{
isNamed = true;
}
ScheminList bindings;
ScheminList expression;
if (!isNamed)
{
expression = args.Cdr();
bindings = (ScheminList) args.Car();
}
else
{
expression = args.Cdr().Cdr();
bindings = (ScheminList) args.Cdr().Car();
}
ScheminList letArgs = new ScheminList();
ScheminList argExps = new ScheminList();
letArgs.UnQuote();
argExps.UnQuote();
foreach (ScheminList bindingPair in bindings)
{
letArgs.Append(bindingPair.Car());
argExps.Append(bindingPair.Cdr().Car());
}
ScheminList lambdaDef = new ScheminList(letArgs);
lambdaDef.UnQuote();
foreach (IScheminType type in expression)
{
lambdaDef.Append(type);
}
Environment closure = env;
if (isNamed)
{
closure = new Environment();
closure.parent = env;
}
ScheminLambda lam = new ScheminLambda(lambdaDef, closure);
if (isNamed)
{
ScheminAtom name = (ScheminAtom) args.Car();
closure.AddBinding(name, lam);
}
ScheminList toEvaluate = new ScheminList(lam);
toEvaluate.UnQuote();
foreach (IScheminType arg in argExps)
{
toEvaluate.Append(arg);
}
return toEvaluate;
}
public override IScheminType Execute(Environment env, Evaluator eval, ScheminList args)
{
bool deffun = false;
if ((args.Car() as ScheminList) != null)
{
deffun = true;
}
if (!deffun)
{
ScheminAtom symbol = (ScheminAtom) args.Car();
IScheminType definition = args.Cdr().Car();
if (env.bindings.ContainsKey(symbol.Name))
{
env.RemoveBinding(symbol);
env.AddBinding(symbol, definition);
}
else
{
env.AddBinding(symbol, definition);
}
return new ScheminList(false);
}
else
{
ScheminList arguments = (ScheminList) args.Car();
ScheminList expression = args.Cdr();
ScheminAtom name = (ScheminAtom) arguments.Car();
ScheminList argSymbols = arguments.Cdr();
ScheminList lamArgs = new ScheminList(argSymbols, expression);
lamArgs.UnQuote();
ScheminLambda lam = new ScheminLambda(lamArgs, env);
if (env.bindings.ContainsKey(name.Name))
{
env.RemoveBinding(name);
env.AddBinding(name, lam);
}
else
{
env.AddBinding(name, lam);
}
return new ScheminList(false);
}
}