Re: [Vxl-users] vgl_point_3d input stream feature request

[Ian S. <ian...@st...>]

Peter Vanroose wrote:
> David Doria wrote:
>> Can "1,2,3" and "(1,2,3)" type input handling be added?
> 
> Good idea; only... I don't know what would be the correct way to implement this using istream; the current implementation is:
> 
>     Type x, y, z; is >> x >> y >> z; p.set(x,y,z); return is;
> 
> We would need something like 
> 1) "peek()" to see whether a "(" is coming up and if so, gobble it;
> 2) is >> x;
> 3) "peek()" again to see wheter a "," comes up and gobble it;
> (etc.)
> Not to speak of gobbling optional whitespace; or is this always automatic, also with peek()?
> 
> Anybody did something similar before and can provide a working & robust implementation?
> 
> --      Peter.
> 


There is an implementation of operator>>(istream, complex) in 
Stroustrup, 3rd Ed p 621 - "Input of User Defined Types".  It handles 
the default real-only case, but it should be easy* to modify appropriately.

* - Easy compared to writing other parsers. It is usually quite 
difficult to get the case-analysis and error-handling correct.

Ian.