Adela Vais - SAOC Milestone 4 Update 4 - Dlang GLR Parser for GNU Bison

[Adela Vais]

On Saturday, 16 January 2021 at 22:09:04 UTC, Adela Vais wrote:
>>>>>>>>[...]

Hello!

- I worked with Akim Demaille (one of my mentors, Bison 
co-maintainer) on adding the '%define api.value.type union'. He 
provided me with a WIP based on my work on the token 
constructors, and I continued it with the D code needed. Unlike 
C++, D allows structs, classes, etc. to be union members, so 
there is no need for D to implement '%define api.value.type 
variant'. [1]

- I worked on token-constructors. In C++, this directive works 
only with '%define api.value.type variant'. In D, I managed to 
add this feature for the default parser, which uses %union, too. 
For this change, I had to rewrite the Symbol's constructors. I 
wrote them in D, but they became too complex. In the near future, 
I want to rewrite them in M4, which will also make them easier to 
maintain. [1]

- I almost finished the push-parser. After this change, the 
backend will support 3 different options for this directive: pull 
(by default), push (which I implemented in the past month), and 
both (which means that the user has access to both parse 
functions, and the pull-parse method is a wrapper around the push 
one). I integrated it into the backend and it is going to be 
reviewed soon. [2]


Future plans:

- In the near future I will finish my work on the LALR1, which 
means that I will add the token-constructors and push-parser 
features to the backend. I also need to rewrite the Symbol's 
constructors in M4 and to complete the documentation.
- During the next few months I will be working on the GLR. It 
will not be a wrapper around the C's GLR, as initially planned, 
but a stand-alone parser. The difference between a user's code of 
a LALR1 and GLR parser is only the presence of the '%glr-parser' 
declaration, otherwise, the user's code is identical. Given that 
the user APIs are the same, a lot of my work on the LALR1 will be 
used by the GLR, too.

[1]: https://github.com/adelavais/bison/tree/tok-constr
[2]: https://github.com/adelavais/bison/tree/push-parser