[boost] Is output formatting like Spirit? Was: Re: Formal review of "Output Formatters" library begins today

From: Hartmut Kaiser (hartmutkaiser_at_[hidden])
Date: 2004-09-23 01:01:30

Jonathan Turkanis wrote:

> >    I see the library as the inverse of Spirit. Spirit takes 
> a linear 
> > text and builds complex objects, while the output 
> formatting library 
> > takes complex objects and renders them as linear text. Just as an 
> > abstract syntax tree does not preserve all the information in the 
> > input text, in many cases it will be desirable to loose information 
> > when an object is formatted using the present library. For example, 
> > sometime you might want a dog to be formatted as follows

I 100% agree with that. Moreover I have a first experimental implementation
of such a library here, which is able to do formatted output controlled by a
structure, which is very much similar to the Spirit grammar DSL. BTW, the
name of this library is Tirips (reversed Spirit) :-).

For instance you could write:

    generate(str("abc") << char('d'), someoutputiter);

Which will simply output "abcd". The different generator objects are
parametrizable with lazy constructs:

    char const *str = "abc";
    char ch = 'd';
    generate(
        str[phoenix::const_(str)] << char_[phoenix::const_(ch)], 
        someoutputiter);

Would output "abcd" as well.

More sophisticated constructs like the list_ would help in outputting
container structures:

    vector<int> v = ...;
    generate(list_(',', int_)[phoenix::const_(v)], someoutputiter);

outputs a comma separeted list of integers, and so on.

I'm currently at the early stages of such a library so there isn't very much
code to show, but if anybody is interested I'm happy to collaborate on
discussing and implementing this.

Regards Hartmut