Bug 131011 Support running query based on report document data
Data Engine should support running a query based on data set and expression data stored in a report document. This bugzilla entry serves as a repository for design docs and notes related to this feature.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/document/viewing/ExprMetaUtil.java
int size = exprMetaList.size( );
			IOUtil.writeInt( dos, size );
			for ( int i = 0; i < size; i++ )
			{
				ExprMetaInfo exprMeta = (ExprMetaInfo) exprMetaList.get( i );
				IOUtil.writeString( dos, exprMeta.getName( ) );
				IOUtil.writeInt( dos, exprMeta.getGroupLevel( ) );
				IOUtil.writeInt( dos, exprMeta.getDataType( ) );
				IOUtil.writeInt( dos, exprMeta.getType( ) );
				IOUtil.writeString( dos, exprMeta.getJSText( ) );
			}
			dos.close( );
		}
		catch ( IOException e )
		{
			throw new DataException( ResourceConstants.RD_SAVE_ERROR,
					"expression metadata" );
		}
	}
	
	/**
	 * Extract the expression information from query definition
	 * 
	 * @return queryDefn
	 */
	private List prepareQueryDefn( IBaseQueryDefinition queryDefn )
	{
		List exprMetaList = new ArrayList( );
		List groups = queryDefn.getGroups( );
		IBaseTransform groupDefn = null;