public override Expression Visit(
[NotNull] Expression expression)
{
var currentExpression = expression;
var inExpressionOptimized =
new EqualityPredicateInExpressionOptimizer().Visit(currentExpression);
currentExpression = inExpressionOptimized;
var negationOptimized1 =
new PredicateNegationExpressionOptimizer()
.Visit(currentExpression);
currentExpression = negationOptimized1;
var equalityExpanded =
new EqualityPredicateExpandingVisitor().Visit(currentExpression);
currentExpression = equalityExpanded;
var negationOptimized2 =
new PredicateNegationExpressionOptimizer()
.Visit(currentExpression);
currentExpression = negationOptimized2;
var parameterDectector = new ParameterExpressionDetectingVisitor();
parameterDectector.Visit(currentExpression);
if (!parameterDectector.ContainsParameters
&& !_useRelationalNullSemantics)
{
var optimizedNullExpansionVisitor = new NullSemanticsOptimizedExpandingVisitor();
var nullSemanticsExpandedOptimized = optimizedNullExpansionVisitor.Visit(currentExpression);
if (optimizedNullExpansionVisitor.OptimizedExpansionPossible)
{
currentExpression = nullSemanticsExpandedOptimized;
}
else
{
currentExpression = new NullSemanticsExpandingVisitor()
.Visit(currentExpression);
}
}
if (_useRelationalNullSemantics)
{
currentExpression = new NotNullableExpression(currentExpression);
}
var negationOptimized3 =
new PredicateNegationExpressionOptimizer()
.Visit(currentExpression);
currentExpression = negationOptimized3;
return currentExpression;
}
public virtual Expression VisitSelect(SelectExpression selectExpression)
{
Check.NotNull(selectExpression, nameof(selectExpression));
IDisposable subQueryIndent = null;
if (selectExpression.Alias != null)
{
_sql.AppendLine("(");
subQueryIndent = _sql.Indent();
}
_sql.Append("SELECT ");
if (selectExpression.IsDistinct)
{
_sql.Append("DISTINCT ");
}
GenerateTop(selectExpression);
if (selectExpression.Projection.Any())
{
VisitJoin(selectExpression.Projection);
}
else if (selectExpression.IsProjectStar)
{
_sql.Append(DelimitIdentifier(selectExpression.Tables.Single().Alias))
.Append(".*");
}
else
{
_sql.Append("1");
}
if (selectExpression.Tables.Any())
{
_sql.AppendLine()
.Append("FROM ");
VisitJoin(selectExpression.Tables, sql => sql.AppendLine());
}
if (selectExpression.Predicate != null)
{
_sql.AppendLine()
.Append("WHERE ");
var constantExpression = selectExpression.Predicate as ConstantExpression;
if (constantExpression != null)
{
_sql.Append((bool)constantExpression.Value ? "1 = 1" : "1 = 0");
}
else
{
var predicate
= new NullComparisonTransformingVisitor(_parameterValues)
.Visit(selectExpression.Predicate);
// we have to optimize out comparisons to null-valued parameters before we can expand null semantics
if (_parameterValues.Count > 0)
{
var optimizedNullExpansionVisitor = new NullSemanticsOptimizedExpandingVisitor();
var nullSemanticsExpandedOptimized = optimizedNullExpansionVisitor.Visit(predicate);
if (optimizedNullExpansionVisitor.OptimizedExpansionPossible)
{
predicate = nullSemanticsExpandedOptimized;
}
else
{
predicate = new NullSemanticsExpandingVisitor()
.Visit(predicate);
}
}
predicate = new ReducingExpressionVisitor().Visit(predicate);
Visit(predicate);
if (selectExpression.Predicate is ParameterExpression ||
selectExpression.Predicate.IsAliasWithColumnExpression() ||
selectExpression.Predicate is SelectExpression)
{
_sql.Append(" = ");
_sql.Append(TrueLiteral);
}
}
}
if (selectExpression.OrderBy.Any())
{
_sql.AppendLine()
.Append("ORDER BY ");
VisitJoin(selectExpression.OrderBy, t =>
{
var aliasExpression = t.Expression as AliasExpression;
if (aliasExpression != null)
{
if (aliasExpression.Alias != null)
{
var columnExpression = aliasExpression.TryGetColumnExpression();
if (columnExpression != null)
{
_sql.Append(DelimitIdentifier(columnExpression.TableAlias))
.Append(".");
}
_sql.Append(DelimitIdentifier(aliasExpression.Alias));
}
else
{
Visit(aliasExpression.Expression);
}
}
else
{
Visit(t.Expression);
}
if (t.OrderingDirection == OrderingDirection.Desc)
{
_sql.Append(" DESC");
}
});
}
GenerateLimitOffset(selectExpression);
if (subQueryIndent != null)
{
subQueryIndent.Dispose();
_sql.AppendLine()
.Append(")");
if (selectExpression.Alias.Length > 0)
{
_sql.Append(" AS ")
.Append(DelimitIdentifier(selectExpression.Alias));
}
}
return(selectExpression);
}
