[Structured Output][Refactor] Move apply_grammar_bitmask() method from ModelRunner to structured output utils

[shen-shanshan]

Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.

Purpose

Currently, the feature structured output is closely coupled with the model_runner, and we need to implement duplicate apply_grammar_bitmask() method in different model_runner of each platform, e.g., gpu_model_runner, npu_model_runner. Once there are changes have made in this method, we need to update the method in all kinds of model_runner to sync these changes.

Thus, maybe it's better to move these structured output related code in model_runner to the structured_output module to make it clearer and more extensible.

Test Plan

Test Result

(Optional) Documentation Update

[gemini-code-assist]

Code Review

This pull request removes a redundant null check for grammar_bitmask. This is a good code cleanup that improves maintainability by removing unnecessary code. The change is straightforward and relies on the caller performing the null check, as stated in the PR description.

[shen-shanshan]

CC: @russellb

[github-actions]

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[russellb]

The StructuredOutputManager isn't an object used by the model runner right now. How about just making it a utility function somewhere instead of hanging it off of that class? Maybe here https://github.com/vllm-project/vllm/blob/main/vllm/v1/structured_output/utils.py

[shen-shanshan]

The StructuredOutputManager isn't an object used by the model runner right now. How about just making it a utility function somewhere instead of hanging it off of that class? Maybe here https://github.com/vllm-project/vllm/blob/main/vllm/v1/structured_output/utils.py

Thanks for your suggestion! I will modify it later~

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @shen-shanshan.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[russellb]

I'm good with this in general, but it will need to be updated one more time.

It's in conflict with main. Before fixing it though, there are a few bug fix PRs that I'd like to merge first. Once they go in, if you can incorporate them into your change, I think we'll be good.

1. [FIXBUG] Correctly Apply Grammar Bitmask in Mixed Batches #22896
2. Upgrade xgrammar to 0.1.23 #22988
3. [Structured Outputs] [Bug] Fix misalignment in apply_grammar_bitmask causing unintended masking and NaN logits #22963

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @shen-shanshan.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[shen-shanshan]

I'm good with this in general, but it will need to be updated one more time.

It's in conflict with main. Before fixing it though, there are a few bug fix PRs that I'd like to merge first. Once they go in, if you can incorporate them into your change, I think we'll be good.

1. [FIXBUG] Correctly Apply Grammar Bitmask in Mixed Batches #22896
2. Upgrade xgrammar to 0.1.23 #22988
3. [Structured Outputs] [Bug] Fix misalignment in apply_grammar_bitmask causing unintended masking and NaN logits #22963

OK, no problem. After these fix PR have been merged, I will update this soon.

[shen-shanshan]

@russellb Hello, all the fix PRs you mentioned have already been merged, and I have rebased on the latest code. 😃

[russellb]

lgtm, thanks!

[shen-shanshan]

@russellb The CI run failed due to #24366, and I have rebased once again. Now the CI has all passed.

[benchislett]

LGTM

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @shen-shanshan.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork