[PoC] Support Token Categories #551
Draft
Conversation
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
I considered introducing **Token Categories** into Lrama, inspired by Chevrotain's Token Categories. This mechanism allows multiple token types to be logically grouped together so they can be matched collectively in grammar rules. Reference: [Chevrotain Token Categories](https://chevrotain.io/docs/features/token_categories.html) For example, in `parse.y`, we currently define grammar rules like this: ```yacc p_cases : opt_else | p_case_body ; ``` This rule matches two token types: `opt_else` and `p_case_body`. If we introduce a **Token Category** named `p_cases` to group these token types, we could define the rule more concisely: ```yacc %token-categories <node> p_cases: opt_else p_case_body ``` By grouping multiple token types into a single category, grammar rules only need to consume the category, simplifying rule definitions. In Chevrotain, tokens can belong to multiple categories by specifying categories in their definitions. However, this approach makes it difficult to see which tokens belong to a given category at a glance. To address this, Lrama explicitly lists token members in the category definition.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
I considered introducing Token Categories into Lrama, inspired by Chevrotain's Token Categories. This mechanism allows multiple token types to be logically grouped together so they can be matched collectively in grammar rules.
Reference: Chevrotain Token Categories
For example, in
parse.y, we currently define grammar rules like this:This rule matches two token types:
opt_elseandp_case_body. If we introduce a Token Category namedp_casesto group these token types, we could define the rule more concisely:By grouping multiple token types into a single category, grammar rules only need to consume the category, simplifying rule definitions.
In Chevrotain, tokens can belong to multiple categories by specifying categories in their definitions. However, this approach makes it difficult to see which tokens belong to a given category at a glance. To address this, Lrama explicitly lists token members in the category definition.