IUnboundExpr IPatternVisitor <IUnboundExpr> .Visit(VariablePattern expr)
{
// bind the variable
mVariables[expr.Name] = mValue;
// always succeed
return(new BoolExpr(expr.Position, true));
}
bool IPatternVisitor <bool> .Visit(VariablePattern expr)
{
// make sure the pattern is linear
if (mUsedVariables.ContainsKey(expr.Name))
{
throw new CompileException(
expr.Position, "The variable \"" + expr.Name + "\" cannot appear more than once in a single pattern.");
}
mUsedVariables[expr.Name] = true;
// a variable pattern matches any type
return(true);
}
bool IPatternVisitor <bool> .Visit(VariablePattern expr)
{
FullyCovered = true;
return(false);
}