Bug in phoenix docs and example code

[Eric Niebler]

The example here is leading people astray. It is not recursively applying the transformation for node types other than plus, minus, multiplies and divides. If the top-most node is not one of those, no transformation happens.

The default case shown is:

struct invert_actions
{
    template <typename Rule>
    struct when
        : proto::_ // the default is proto::_
    {};
};

I think it should be:

struct invert_actions
{
    template <typename Rule>
    struct when
      : proto::nary_expr<
            proto::_,
            proto::vararg<
                proto::when<proto::_, evaluator(proto::_, _context)>
            >
        >
    {};
};

I'm actually not quite sure how this works, but it seems to. Note that the problem would also need to be fixed here.

See ​http://stackoverflow.com/questions/15077637/transforming-a-boost-c-phoenix-expression-tree for a discussion.

[Kohei Takahashi]

Yes, you are right.

[Kohei Takahashi]

Fixed ​https://github.com/boostorg/phoenix/pull/56