IUnboundExpr IPatternVisitor <IUnboundExpr> .Visit(TuplePattern expr)
{
var tupleDecl = (BoundTupleType)mDecl;
// match each field
var match = (IUnboundExpr)null;
for (int i = 0; i < tupleDecl.Fields.Count; i++)
{
mC.SetPosition(expr.Fields[i].Position);
// create an expression to pull out the tuple field
var fieldValue = mC.Call(mC.Int(i), mValue);
// match it
var matchField = Match(mContext, tupleDecl.Fields[i], expr.Fields[i],
fieldValue, mVariables);
if (match == null)
{
match = matchField;
}
else
{
// combine with the previous matches
match = mC.Op(match, "&", matchField);
}
}
return(match);
}
bool IPatternVisitor <bool> .Visit(TuplePattern expr)
{
var tuple = mType as BoundTupleType;
// it must be a tuple
if (tuple == null)
{
throw new CompileException(expr.Position,
String.Format("A tuple pattern cannot be used to match against a value of type {0}.", mType));
}
// if must be the right length
if (tuple.Fields.Count != expr.Fields.Count)
{
throw new CompileException(expr.Position,
String.Format("The tuple pattern has {0} fields when {1} are expected.", expr.Fields.Count, tuple.Fields.Count));
}
// the fields must match for
for (int i = 0; i < expr.Fields.Count; i++)
{
expr.Fields[i].Accept(new ShapeChecker(tuple.Fields[i], mUsedVariables));
}
return(true);
}
bool IPatternVisitor <bool> .Visit(TuplePattern expr)
{
//### bob: coverage for tuples is not supported yet
// so this just does nothing
return(false);
}
