Define Grammar AST types explicitly, refine EBNF-based terminals to avoid synthetic capturing groups #1966
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…icated AST type `TerminalElement` * updated grammar
… to RegExp now avoiding unnecessary capturing groups '(...)' * added 'paranthesized' flag to type TerminalElement * marked required synthetic groups as non-capturing '(?:...)' * updated tests * updated example languages
sailingKieler
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sailingKieler
changed the title
spoenemann
reviewed
Jun 25, 2025
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| type AbstractRule = InfixRule | ParserRule | TerminalRule; | |||
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Please add the copyright header with Copyright 2025
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| interface AbstractElement { | ||
| cardinality?: "*" | "+" | "?"; | ||
| // parenthesized: boolean; |
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Let's remove it instead of leaving it commented out.
| return reflection.isInstance(item, TerminalElement.$type); | ||
| } | ||
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| export interface CharacterRange extends TerminalElement { |
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It looks like we're not sorting the types properly prior to generating them – the order shouldn't change after switching to declared types.
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This PR introduces
langium-types.langiumdefining all the AST types of Langium's grammar language.As an initial customization it contributes interface
TerminalElement extends AbstractElement, andAbstractElement#lookaheadis moved toTerminalElement.The second commit refines the synthesis of RegExps representing the terminals s.t. synthetic pairs of parentheses that are added to the RegExp are marked as non-capturing groups
(?:...), while parentheses being present in the terminal definition are transferred as capturing groups(...). To enable that an additional flagTerminalElement#parenthesizedis introduced for capturing the information wether a sub terminal is enclosed in parenthesizes.This gives adopters more control over the capturing groups within the RegExp, which is relevant when re-using the generated RegExps e.g. for value conversion, like