private static MethodCallExpression GetJoin(Expression outerSource, Expression innerSource, IEdmNavigationProperty navigationProperty)
{
Type innerType = OeExpressionHelper.GetCollectionItemType(innerSource.Type);
var joinBuilder = new OeJoinBuilder(new OeQueryNodeVisitor(Expression.Parameter(typeof(Object))));
(LambdaExpression outerKeySelector, LambdaExpression innerKeySelector) =
joinBuilder.GetJoinKeySelector(outerSource.Type, innerType, Array.Empty <IEdmNavigationProperty>(), navigationProperty);
var replaceParameterVisitor = new ReplaceParameterVisitor(outerSource, outerKeySelector.Parameters[0]);
Expression outerKeyExpression = replaceParameterVisitor.Visit(outerKeySelector.Body);
IReadOnlyList <MemberExpression> outerKeyProperties;
IReadOnlyList <MemberExpression> innerKeyProperties;
if (OeExpressionHelper.IsTupleType(outerKeySelector.ReturnType))
{
outerKeyProperties = OeExpressionHelper.GetPropertyExpressions(outerKeyExpression);
innerKeyProperties = OeExpressionHelper.GetPropertyExpressions(innerKeySelector.Body);
}
else
{
outerKeyProperties = new MemberExpression[] { (MemberExpression)outerKeyExpression };
innerKeyProperties = new MemberExpression[] { (MemberExpression)innerKeySelector.Body };
}
BinaryExpression?joinExpression = null;
for (int i = 0; i < outerKeyProperties.Count; i++)
{
if (joinExpression == null)
{
joinExpression = Expression.MakeBinary(ExpressionType.Equal, outerKeyProperties[i], innerKeyProperties[i]);
}
else
{
BinaryExpression equal = Expression.MakeBinary(ExpressionType.Equal, outerKeyProperties[i], innerKeyProperties[i]);
joinExpression = Expression.MakeBinary(ExpressionType.AndAlso, joinExpression, equal);
}
}
MethodInfo firstMethodInfo = OeMethodInfoHelper.GetFirstMethodInfo(innerType);
LambdaExpression joinLambda = Expression.Lambda(joinExpression !, innerKeySelector.Parameters);
return(Expression.Call(firstMethodInfo, innerSource, joinLambda));
}