fixed can_feed() logic

[ehwan]

No description provided.

[Copilot]

Pull Request Overview

This PR fixes the can_feed() logic by refactoring the implementation to handle stack operations more accurately. The changes improve the parser's ability to determine whether it can accept a given terminal symbol by properly managing state and precedence stacks during lookahead operations.

Key changes include:

• Refactored can_feed_impl to use separate extra stacks instead of cloning existing stacks
• Added proper handling of reduce operations in nondeterministic parsing with multiple reduction paths
• Improved stack length tracking and precedence calculation logic

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
rusty_lr_core/src/parser/nondeterministic/context.rs	Major refactoring of can_feed_impl to handle multiple reduce paths and use extra stacks for simulation
rusty_lr_core/src/parser/deterministic/context.rs	Updated can_feed_impl to use extra stacks and improved stack length tracking

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}