Re: [Boost-users] Translating an absolute path to a path relative to the current directory

From: Simon Buchan (simon_at_[hidden])
Date: 2005-11-03 03:03:29

Hermann Rodrigues wrote:
> Hi,
> 
> I am running into the following problem these days:
> 
> I need to translate an absolute path to a path relative to the current
> directory on Windows. The translation process need to include all
> required ".." directory specifiers in the path to make sure it can be
> accessed from the current directory.
> 

Try this...

path relative_to_current(path p)
{
        path current = current_path();

        // Trivial case
        if(equivalent(current, p)) return p;

        // Doesn't share a root
        if(!equivalent(current.root_path(), p.root_path()))
                return p;

        // We don't care about the root anymore
        // (and makes the rest easier)
        current = current.relative_path();
        p = p.relative_path();

        path final(".", native);
        
        path::iterator pit = p.begin(),
                       cit = current.begin();
        // Find the shared directory
        for(;pit != p.end() && cit != current.end(); ++pit, ++cit)
                if(*pit != *cit) // May not be right
                        break;
        
        // Put needed parent dirs in
        while(cit != current.end())
        {
                final = ".." / final;
                ++cit;
        }

        // Add the path from shared
        while(pit != p.end())
                // Gah! Why doesn't *path::iterator return paths?
                final /= path(*pit++, native);

        // .normalize()?
        return final;
}

Haven't tested it too extensively, but it seems to work. Probably better 
as relative_path(path from, path to), but hey.

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