public static ZilResult PROG([NotNull] Context ctx,
[CanBeNull][Optional] ZilAtom activationAtom,
BindingParams.BindingList bindings,
[CanBeNull][Optional] ZilDecl bodyDecl,
[NotNull][Required] ZilObject[] body)
{
return(PerformProg(ctx, activationAtom, bindings, bodyDecl, body, "PROG", false, true));
}
static ZilResult PerformProg([NotNull][ProvidesContext] Context ctx, [CanBeNull] ZilAtom activationAtom,
BindingParams.BindingList bindings, [CanBeNull] ZilDecl bodyDecl, [ItemNotNull][NotNull] ZilObject[] body,
[NotNull] string name, bool repeat, bool catchy)
{
using (var activation = new ZilActivation(ctx.GetStdAtom(StdAtom.PROG)))
{
using (var innerEnv = ctx.PushEnvironment())
{
if (activationAtom != null)
{
innerEnv.Rebind(activationAtom, activation);
}
var bodyAtomDecls = bodyDecl?.GetAtomDeclPairs().ToLookup(p => p.Key, p => p.Value);
foreach (var b in bindings.Bindings)
{
var atom = b.Atom;
var initializer = b.Initializer;
ZilObject value;
if (initializer != null)
{
var initResult = initializer.Eval(ctx);
if (initResult.ShouldPass(activation, ref initResult))
{
return(initResult);
}
value = (ZilObject)initResult;
}
else
{
value = null;
}
var previousDecl = b.Decl;
var firstBodyDecl = bodyAtomDecls?[atom].FirstOrDefault();
if (firstBodyDecl != null && (previousDecl != null || bodyAtomDecls[atom].Skip(1).Any()))
{
throw new InterpreterError(InterpreterMessages._0_Conflicting_DECLs_For_Atom_1, name, atom);
}
var decl = previousDecl ?? firstBodyDecl;
if (value != null)
{
ctx.MaybeCheckDecl(initializer, value, decl, "LVAL of {0}", atom);
}
innerEnv.Rebind(atom, value, decl);
}
if (catchy)
{
innerEnv.Rebind(ctx.EnclosingProgActivationAtom, activation);
}
// evaluate body
ZilResult result = null;
bool again;
do
{
again = false;
foreach (var expr in body)
{
result = expr.Eval(ctx);
if (result.IsAgain(activation))
{
again = true;
}
else if (result.ShouldPass(activation, ref result))
{
return(result);
}
}
} while (repeat || again);
return(result);
}
}
}
