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Issue 258 #280

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Issue 258 #280

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60f5caf
Added default activation dictionary
jarrettmeyer Feb 13, 2012
b88e23f
Added dictionary for method names for DbDataReader GetXXX
jarrettmeyer Feb 13, 2012
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62 changes: 51 additions & 11 deletions SubSonic.Core/Linq/Structure/ExecutionBuilder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,10 @@ namespace SubSonic.Linq.Structure
/// </summary>
public class ExecutionBuilder : DbExpressionVisitor
{
private static readonly IDictionary<Type, Expression> defaultValueActiviationDictionary = new Dictionary<Type, Expression>();
private static readonly IDictionary<Type, ConstantExpression> nonNullableTypeExpressionDictionary = new Dictionary<Type, ConstantExpression>();
private static readonly IDictionary<Type, string> readerGetValue;

private readonly List<Expression> initializers = new List<Expression>();
private readonly QueryPolicy policy;
private readonly Expression provider;
Expand All @@ -30,6 +34,22 @@ public class ExecutionBuilder : DbExpressionVisitor
private MemberInfo receivingMember;
private Scope scope;

static ExecutionBuilder()
{
readerGetValue = new Dictionary<Type, string>();
readerGetValue.Add(typeof(Boolean), "GetBoolean");
readerGetValue.Add(typeof(Byte), "GetByte");
readerGetValue.Add(typeof(DateTime), "GetDateTime");
readerGetValue.Add(typeof(Decimal), "GetDecimal");
readerGetValue.Add(typeof(Double), "GetDouble");
readerGetValue.Add(typeof(Single), "GetFloat");
readerGetValue.Add(typeof(Guid), "GetGuid");
readerGetValue.Add(typeof(Int16), "GetInt16");
readerGetValue.Add(typeof(Int32), "GetInt32");
readerGetValue.Add(typeof(Int64), "GetInt64");
readerGetValue.Add(typeof(String), "GetString");
}

private ExecutionBuilder(QueryPolicy policy, Expression provider)
{
this.policy = policy;
Expand Down Expand Up @@ -298,19 +318,39 @@ protected override Expression VisitColumn(ColumnExpression column)
}
else
{
defvalue = Expression.Constant(Activator.CreateInstance(column.Type), column.Type);
// Using a dictionary to cache default types increases performance 4 - 5%
if (!defaultValueActiviationDictionary.TryGetValue(column.Type, out defvalue))
{
defvalue = Expression.Constant(Activator.CreateInstance(column.Type), column.Type);
defaultValueActiviationDictionary.Add(column.Type, defvalue);
}
}

// this sucks, but since we don't track true SQL types through the query, and ADO throws exception if you
// call the wrong accessor, the best we can do is call GetValue and Convert.ChangeType
Expression value = Expression.Convert(
Expression.Call(typeof (Convert), "ChangeType", null,
Expression.Call(reader, "GetValue", null, Expression.Constant(iOrdinal)),
Expression.Constant(TypeHelper.GetNonNullableType(column.Type), typeof(Type))
),
column.Type
);

// If we know what method to call on DbDataReader (as defined by the dictionary),
// then use that method. (Int32 => GetInt32, String => GetString, etc.) If we don't
// know the type, then default to our original code.
Expression value;
string methodName;
if (readerGetValue.TryGetValue(column.Type, out methodName))
{
value = Expression.Call(reader, methodName, null, Expression.Constant(iOrdinal));
}
else
{
ConstantExpression typeConstantExpression;
if (!nonNullableTypeExpressionDictionary.TryGetValue(column.Type, out typeConstantExpression))
{
typeConstantExpression = Expression.Constant(TypeHelper.GetNonNullableType(column.Type), typeof(Type));
nonNullableTypeExpressionDictionary.Add(column.Type, typeConstantExpression);
}
value = Expression.Convert(
Expression.Call(typeof(Convert), "ChangeType", null,
Expression.Call(reader, "GetValue", null, Expression.Constant(iOrdinal)),
typeConstantExpression
),
column.Type
);
}
return Expression.Condition(
Expression.Call(reader, "IsDBNull", null, Expression.Constant(iOrdinal)),
defvalue, value
Expand Down