public ConstructorMap( ObjectMap objectMap, ConstructorInfo constructorInfo, ColumnInfo columnInfo, object[] row )
{
this.objectMap = objectMap;
this.constructorInfo = constructorInfo;
this.columnInfo = columnInfo;
InitBitArrays( Math.Max( objectMap.Fields.Count, row.Length ) );
InitConstructorMap( row );
}
/// <summary>
/// Method to scan for and determine the least expensive constructor for a given array of
/// column names.
/// </summary>
/// <param name="columnNames">The column names of the result set</param>
/// <param name="row">A sample row used to determine if type conversion is needed</param>
/// <returns>A hash which can be used as constructor selector subsequently or 0 if no
/// valid constructor could be found for the given columns.</returns>
public int DetermineConstructor( string[] columnNames, object[] row )
{
int hash = GetFieldComboHashCode( columnNames );
// make a quick exit if we've already processed this column combination
if( constructorMaps.ContainsKey( hash ) )
{
return hash;
}
else
{
if( ! columnInfos.ContainsKey( hash ) )
{
columnInfos[ hash ] = new ColumnInfo( objectMap, columnNames );
}
ConstructorMap best = null;
foreach( ConstructorInfo ci in constructorInfos )
{
ConstructorMap cm = new ConstructorMap( objectMap, ci, columnInfos[ hash ] as ColumnInfo, row );
if( cm.IsValid )
{
if( best == null || cm.Cost < best.Cost )
{
best = cm;
}
}
}
if( best != null )
{
constructorMaps[ hash ] = best;
// warn user that code has non-optimal performance
if( best.Cost > 0 )
{
Check.LogInfo( LogCategories.Metadata, "Best available constructor for type {0} is non-optimal (cost {1}).", objectMap.Type, best.Cost );
Check.LogInfo( LogCategories.Metadata,
"See http://www.mertner.com/confluence/pages/viewpage.action?pageId=240 for additional information." );
}
}
else // no valid constructor found at all
{
StringBuilder sb = new StringBuilder();
for( int i = 0; i < columnNames.Length; i++ )
{
sb.AppendFormat( "{0}{1}={2}", i % 3 != 0 ? ", " : Environment.NewLine, i, columnNames[ i ] );
}
Check.Fail( Error.Unspecified, "No constructor found for type {0} using columns: {1}",
objectMap.Type, sb.ToString() );
}
return hash;
}
}
