public ResultDelegate <TSearch, TResult> CreateResultDelegate(LinkedList <CompositPropertyVertex> vertices,
SearchStrategy <TSearch, TResult> strategy)
{
var delegateMap = new Dictionary <CompositPropertyVertex, ProxyDelegate <TSearch, TResult> >();
var delegates = new ProxyDelegate <TSearch, TResult> [vertices.Count];
var index = 0;
vertices.ForEach(
node =>
{
CreateDelegate(node.Value, delegateMap, strategy);
delegates[index++] = delegateMap[node.Value];
});
var rootDelegate = new RootProxyDelegate <TSearch, TResult>(delegates, strategy);
rootDelegate.BuildExecuteChildrenDelegate();
return(rootDelegate.Execute);
}
private static void CreateDelegate(CompositPropertyVertex vertex,
Dictionary <CompositPropertyVertex, ProxyDelegate <TSearch, TResult> > delegateMap,
SearchStrategy <TSearch, TResult> strategy)
{
if (vertex.PropertyList.First == null)
{
throw new NullReferenceException();
}
if (delegateMap.ContainsKey(vertex))
{
return;
}
var propertyGetters = new Func <object, object> [vertex.PropertyList.Count];
var parameter = Expression.Parameter(typeof(object), "obj");
var nullConst = Expression.Constant(null);
var hasCollection = false;
var index = 0;
vertex.PropertyList.ForEach(
node =>
{
if (typeof(ICollection).IsAssignableFrom(node.Value.PropertyType))
{
hasCollection = true;
}
var resultVariable = Expression.Variable(typeof(object), "result");
var castVariable = Expression.Variable(node.Value.DeclaringType, "value");
var castAs = Expression.TypeAs(parameter, node.Value.DeclaringType);
var castAssign = Expression.Assign(castVariable, castAs);
var checkNotNull = Expression.NotEqual(castVariable, nullConst);
var memberAccess = Expression.Convert(Expression.MakeMemberAccess(castVariable, node.Value),
typeof(object));
var conditionalMemberAccess = Expression.Condition(checkNotNull, memberAccess, nullConst);
var resultAssign = Expression.Assign(resultVariable, conditionalMemberAccess);
var returnTarget = Expression.Label(typeof(object));
var returnLabel = Expression.Label(returnTarget, nullConst);
var returnExpr = Expression.Return(returnTarget, resultVariable);
var block = Expression.Block(typeof(object), new[] { castVariable, resultVariable }, castAssign,
resultAssign, returnExpr, returnLabel);
var deleg = Expression.Lambda <Func <object, object> >(block, parameter).Compile();
propertyGetters[index++] = deleg;
});
var childDelegates = new ProxyDelegate <TSearch, TResult> [vertex.Children.Count];
delegateMap[vertex] = new ProxyDelegate <TSearch, TResult>(propertyGetters, childDelegates, strategy,
hasCollection);
index = 0;
vertex.Children.ForEach(
node =>
{
CreateDelegate(node.Value, delegateMap, strategy);
childDelegates[index++] = delegateMap[node.Value];
});
}