Re: Simple Components (Generic_Directed_Graph)

[Victor Porton <porton@narod.ru>]

Dmitry A. Kazakov wrote:

> On 2017-10-30 11:41, Victor Porton wrote:
> 
>> I do not understand your logic in Generic_Directed_Graph:
>> 
>> The procedures like
>> 
>> procedure Disconnect (Parent : Node; Child : Node);
>> 
>> do not take "Graph" argument.
> 
> A graph consists of connected nodes. Each node is in and a graph.
> 
>> Does it mean that there exists just one graph (per instantiation)?
> 
> No. If two nodes are mutually unreachable you have two graphs.
> 
>> This looks wrong for me. First it is using global variables.
> 
> It uses referential semantics. Node is an access type to the type you
> pass to the package when you instantiate it. E.g. if you want a graph of
> Strings you instantiate the package with String. Then Node is a pointer
> to string.
> 
> The notion of scope does not really applied to the structures like
> graph. You can scope the pool you pass to the instance. You can scope
> nodes with some logic attached when a node leaves its scope. But
> otherwise it makes little sense to talk about the scope of a graph.

Oh, I've finally realized that Node_Type and Node are not the same type. Now 
your logic seems clear.

But how to solve my particular problem?

I have two objects (URI1 and URI2) of URI_Type type each (or for simplicity 
both could be two strings). I need to check if there exists a path from URI1 
to URI2. How to do this?

My current idea is to use Ada standard "map" container which could map from 
"access URI_Type" to "URI_Type" (for all URIs in the considered finite set) 
before asking your generic package for existence of a path.

The same problem appears when I insert new edges: An edge should be 
identified by two values of type URI_Type but you require two accesses to 
URI_Type instead. Should I convert URI_Type to "access URI_Type" using a 
standard map before inserting into the graph?

-- 
Victor Porton - http://portonvictor.org