Support parser generation without %union directive (Bison compatibility)#765
Merged
ydah merged 2 commits intoruby:masterfrom Jan 23, 2026
Merged
Support parser generation without %union directive (Bison compatibility)#765ydah merged 2 commits intoruby:masterfrom
ydah merged 2 commits intoruby:masterfrom
Conversation
## Motivation When writing simple parser samples or prototypes, defining `%union` can be cumbersome and unnecessary. Bison allows users to generate parsers without the `%union` directive, defaulting `YYSTYPE` to `int`. This PR brings the same convenience to lrama for better Bison compatibility. ## How it works When %union is not defined: 1. YYSTYPE defaults to int (same as Bison) 2. Semantic value references are generated without union member access 3. The parser works exactly like Bison-generated parsers
yui-knk
reviewed
Jan 22, 2026
| end | ||
|
|
||
| # @rbs () -> bool | ||
| def union_not_defined? |
Collaborator
There was a problem hiding this comment.
I think it's more straightforward to check if %union is used in the input grammar file (by checking @grammar.union), what do you think about it?
Member
Author
There was a problem hiding this comment.
Thank you. I push the following commit. Is my understanding correct?
…ying on tag presence
yui-knk
approved these changes
Jan 23, 2026
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Motivation
When writing simple parser samples or prototypes, defining
%unioncan be cumbersome and unnecessary. Bison allows users to generate parsers without the%uniondirective, defaultingYYSTYPEtoint. This PR brings the same convenience to lrama for better Bison compatibility.How it works
When %union is not defined: