public static Expression Parse(LambdaExpression expression, Expression keyExpr, InjectedExpression subquery, Func<Expression, TranslateResult> translator)
{
AggregateParser parser = new AggregateParser();
parser.map = expression.Parameters.Select((param, i) => new { param, i })
.ToDictionary(x => x.param, x => x.i == 0 ? keyExpr : subquery);
parser.translator = translator;
return parser.Visit(expression.Body);
}
protected override Expression VisitInjected(InjectedExpression node)
{
SqlExpression sqlExpr = node.TranslateResult.SqlExpression;
if (sqlExpr.NodeType == SqlExpressionType.Column)
{
ColumnExpression column = (ColumnExpression)sqlExpr;
ColumnExpression mapped;
if (this.map.TryGetValue(column, out mapped))
{
return new InjectedExpression(new TranslateResult(mapped), node.Type);
}
foreach (ColumnDeclaration existingColumn in this.columns)
{
ColumnExpression c = existingColumn.Expression as ColumnExpression;
if (c != null && c.TableAlias == column.TableAlias && c.ColumnName == column.ColumnName)
{
return new InjectedExpression(new TranslateResult(new ColumnExpression(this.newAlias, existingColumn.DeclaredName)), node.Type);
}
}
if (this.existingAliases.Contains(column.TableAlias))
{
string declaredName = this.GetUniqueColumnName(column.ColumnName);
this.columns.Add(new ColumnDeclaration(declaredName, column));
mapped = new ColumnExpression(this.newAlias, declaredName);
this.map.Add(column, mapped);
return new InjectedExpression(new TranslateResult(mapped), node.Type);
}
return node;
}
else
{
string declaredName = this.GetNextColumnName();
this.columns.Add(new ColumnDeclaration(declaredName, sqlExpr));
return new InjectedExpression(new TranslateResult(new ColumnExpression(this.newAlias, declaredName)), node.Type);
}
}
protected virtual Expression VisitInjected(InjectedExpression node)
{
return node;
}