Re: [boost] [gsoc-2013] proposal for approximate string matching

Subject: Re: [boost] [gsoc-2013] proposal for approximate string matching
From: Erik Erlandson (eje_at_[hidden])
Date: 2013-04-28 21:18:50

> 
> Part A, similarity metrics(use edit distance as an example):
> template....
> (1) (size_type or unsigned) edit_distance(const Range1T&, const Range2T&);
> (2) (size_type or unsigned) edit_distance(const Range1T&, const Range2T&,
> (size_type or unsigned) threshold);
> (3) (size_type or unsigned) edit_distance(const Range1T&, const Range2T&,
> equal_func);
> (4) (user-defined type) edit_distance(const Range1T&, const Range2T&, cost);
> 
> the cost struct may be like this:
> template<T, V>
> struct cost
> {
>    V substitution(const T&, const T&) const;
>    V insertion(const T &a) const;
>    V deletion(const T &a) const;
> }

This seems like a good approach to me.   

> 
> (5) pair<container of operations, edit_distance>
> edit_distance_with_operation(const Range1T&, const Range2T&);
> (6) pair<container of operations, edit_distance>
> edit_distance_with_operation(const Range1T&, const Range2T&, threshold);
> (7) pair<container of operations, edit_distance>
> edit_distance_with_operation(const Range1T&, const Range2T&, equal_func);
> (8) pair<container of operations, edit_distance>
> edit_distance_with_operation(const Range1T&, const Range2T&, cost);
> the "operation" may be a pair<"operator", "position">, where "operator" may
> be an enum of insertion, deletion and substitution, "position" is an
> unsigned value.

In the past, I would have said "returning a container on the stack will be an efficiency problem", however with the new "move" semantics, I *think* it will OK if it is implemented properly.

I have only read about the new "move" semantics, and not used them, so if I'm wrong about that somebody please set me straight  :)