[Cython] When to run tree transformations

[Robert Bradshaw]

On Mar 15, 2008, at 3:34 AM, Stefan Behnel wrote:

> Hi,
>
> as I suggested before, I think it would be helpful if plugins could  
> tell the
> compiler directly when they were to run (without the current -T  
> option). I
> think there would at least be an analysis step in addition to the  
> existing
> tree processing step for the plugin lifecycle, but the plugin might  
> also need
> to run at different times of the compiler lifecycle, and treat  
> different
> syntax structures. I see the following lifecycle hooks here:
>
> - pre analyse types
> - post analyse types

- post type conversion phase?

> - pre generate code
> - post generate code

What would happen in this last one?

> I would suggest mapping these to method names in the plugins. You  
> could then write
>
>     class MyTransform(Transform):
>          def pre_analyse_types(self, node, name):
>              ...
>
> instead of the current "process_node()" method.

I think process_node offers more flexibility of phases, which may  
change/become more granular later on. Some transforms may need to  
know what the current phase is though.

> I could also imagine keeping a set of node types in the plugin that  
> would be
> used for selecting appropriate transformations for the current  
> node. In the
> transformation example, there is this line
>
>     if isinstance(node, Nodes.ForInStatNode) ...
>
> that determines when to run the plugin. If the plugin provided a  
> set of
> interesting nodes instead, the infrastructure could store them in a  
> dict
> (mapping node types to a list of plugins) and directly select the
> transformations that can run on that node. Question in that case:  
> how to deal
> with subtypes? Would they be expected to match? Or should the  
> plugin just
> specify all node types, including their expected subtypes?

Perhaps. One would have to come up with a reasonable way to filter  
things. The current approach seems the simplest way to get something  
up and running.

- Robert

- Robert