Support parser generation without %union directive (Bison compatibility) #765
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## 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
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| # @rbs () -> bool | ||
| def union_not_defined? |
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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?
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Thank you. I push the following commit. Is my understanding correct?
…ying on tag presence
yui-knk
approved these changes
Jan 23, 2026
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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: