private static void AutoCastSystemOperator(FunctionExpression exp, IList<Expression> parameters, List<SqlType> paramTypes)
{
SqlType t1 = paramTypes[0];
SqlType t2 = paramTypes[1];
// If both the types are identical, we good to go,
if (!t1.IsComparableTo(t2))
throw InvalidTypes(t1, t2, exp);
// Types are compatible,
// If they are numeric,
if (t1.IsNumeric) {
// The encoding is different, so now we do a static check
if (!t1.Equals(t2)) {
// TODO: We should do a check on each parameter by walking the tree
// to determine if it's static or not.
Expression exp1 = parameters[0];
Expression exp2 = parameters[1];
int staticop;
int varop;
// If the left or right is FETCHSTATIC,
if (exp1 is FetchStaticExpression) {
staticop = 0;
varop = 1;
} else if (exp2 is FetchStaticExpression) {
staticop = 1;
varop = 0;
} else {
// Neither static, so report error,
throw InvalidTypes(t1, t2, exp);
}
// The type of the variable and static sides,
SqlType varType = paramTypes[varop];
SqlObject castType = new SqlObject(varType.ToString());
FetchStaticExpression castExp = new FetchStaticExpression(castType);
castExp.ReturnType = SqlType.GetSqlType(typeof(string));
// Cast the static type to the variable type,
FunctionExpression newStaticExp = new FunctionExpression("@cast", new Expression[] {parameters[staticop], castExp});
newStaticExp.ReturnType = varType;
exp.Parameters[staticop] = newStaticExp;
}
}
}
private SqlObject[] EvaluateExpression(Expression expression)
{
if (expression is FetchStaticExpression)
return ((FetchStaticExpression)expression).Values;
if (expression is FunctionExpression) {
FunctionExpression functionExp = (FunctionExpression) expression;
// Check all the parameters are static
int sz = functionExp.Parameters.Count;
Expression[] functionArgs = new Expression[sz];
for (int i = 0; i < sz; ++i) {
object ob = functionExp.Parameters[i];
if (ob != null) {
if (ob is Expression) {
// Try and evaluate it
SqlObject[] result = EvaluateExpression((Expression)ob);
if (result == null)
return null;
functionArgs[i] = new FetchStaticExpression(result);
}
}
}
// Go ahead an evaluate the function,
string functionName = functionExp.Name;
if (IsSimpleEvaluable(functionName)) {
// Evaluate the simple function and return the result
ITable result = transaction.FunctionManager.Evaluate(functionName, simpleProcessor, functionArgs);
return QueryProcessor.Result(result);
}
// Not a simple evaluatable function, so return null
return null;
}
return null;
}
