In the first place why I'm doing this. I work on Rewrite Tool and it's main functionality bases on replacing nodes in AST. Plus it works with sourceIntervals of nodes. Untill now my solution was:

if I replace node, I reparse tree to get intervals updated

However this solution brought new problems.

Second reason is, that I think it makes sense to update interval of all AST if you replace one node.

For example, we have:

obj1 foo + obj2 bar

and we replace obj1 with myObject.

The interval of ast was 1 to: 19, and now it should be 1 to: 23.

Mark

2014-10-28 14:00 GMT+02:00 Thierry Goubier <thierry.goubier@gmail.com>:

Le 28/10/2014 12:45, Mark Rizun a ��crit :

Yes, because they are wrong. Here is an issue:
https://pharo.fogbugz.com/f/cases/14254/AST-method-replaceWith-does-not-change-source-interval

I would say that they are correct.

When I write source to source compilers, I admit that anything that I change in the AST (via replaceWith equivalent) has no valid source interval (since it does not exist in the original source). However, all unmodified nodes should keep their 'non-modified' source interval (since I may need it to fetch the relevant text from the source).

If I want my modification to the AST to have valid source intervals, then, I need to regenerate the source from the modified AST. And only then they are valid.

You may want to update the source interval when you do a replaceWith, but the only thing we will get with what you want to do is that, after a replaceWith, no source interval can be trusted since it may end up past the end of the original source string length.

Thierry

2014-10-28 13:32 GMT+02:00 Thierry Goubier <thierry.goubier@gmail.com
<mailto:thierry.goubier@gmail.com>>:

�� Le 28/10/2014 12:12, Mark Rizun a ��crit :

�� Well, not really.

�� Technically, tokens are used to drive a parser from a scanner.

�� If an AST node knows how to relate itself to its original
�� source
�� code chunk and is able to print itself correctly, then
�� tokens are
�� redundant.

�� In short, if you work with parsers, you'd better know what
�� tokens
�� are. If you're only working with the AST, tokens are
�� redundant and
�� noise (i.e. they often have a type (or more than one) which
�� is only
�� understood by the parser).

�� I'm working with ASTs sourceInterval. Trying to calculate it after
�� method replaceWith:.
�� You see, my proble was that each node of AST doesn't hold its
�� start and
�� stop position in same place. So I thought that token is such a
�� place,
�� however, eventually I understood that RBValueNodes don't have
�� tokens:)

�� Do you mean you're trying to do a replace and update the positions
�� of all the nodes ?

�� Thierry