virtual public void VisitFromClause(Linq.FromClause x)
{
foreach (Linq.Generator g in x.Generators)
{
VisitElement(g);
}
}
public LinqExpression(Position p, FromClause/*!*/ from, QueryBody/*!*/ body)
: base(p)
{
Debug.Assert(from != null && body != null);
body.FromWhere.Insert(0, from);
this.body = body;
}
private void FromWhereToGenerators(List <Generator> /*!*/ generators)
{
// query is the inner-most query - it will be converted to OpChain //
int i = 0;
for (; ;)
{
// convert from clauses to generators if there are any;
// (the query can start with where-clause if there was an into-clause):
while (i < fromWhere.Count && fromWhere[i].IsFromClause)
{
FromClause f = (FromClause)fromWhere[i];
// each from-clause contains at least one generator:
Debug.Assert(f.Generators.Count > 0);
// adds generators contained in the from clause (Rule #2):
foreach (Generator generator in f.Generators)
{
generators.Add(generator);
}
i++;
}
// no more clauses:
if (i == fromWhere.Count)
{
break;
}
// where-clause follows; at least one generator has been added:
Debug.Assert(fromWhere[i].IsWhereClause && generators.Count > 0);
Generator last_generator = generators[generators.Count - 1];
DirectVarUse x_key = last_generator.KeyVar;
DirectVarUse x_value = last_generator.ValueVar;
LinqOpChain chain = null;
LinqOp last_op = null;
// embeds where-clauses imediately preceded by a from-clause to
// the last generator of the from-clause (Rule #3):
do
{
LinqOp.Where where_op = new LinqOp.Where(x_key, x_value, ((WhereClause)fromWhere[i]).Expression);
if (last_op == null)
{
chain = new LinqOpChain(last_generator.Expression, where_op);
}
else
{
last_op.Next = where_op;
}
last_op = where_op;
i++;
}while (i < fromWhere.Count && fromWhere[i].IsWhereClause);
Debug.Assert(chain != null);
last_generator.Expression = chain;
// no more clauses:
if (i == fromWhere.Count)
{
break;
}
}
}