Modernize structural pattern matching

[ojeda-e]

Part of #1927

This PR includes changes to modernize type hints and structural pattern matching in:

• src/llmcompressor/pipelines/cache.py - Cache system with recursive types
• src/llmcompressor/modifiers/quantization/gptq/gptq_quantize.py - GPTQ logic
• src/llmcompressor/modifiers/pruning/sparsegpt/sgpt_base.py - SparseGPT logic

make test, make style and pytest tests -m smoke passing locally.

Please correct me if I am wrong here, but IMO TYPE_CHECKING is not necessary in any of these files. Since all imports are runtime required (torch, transformers, etc), TYPE_CHECKING would only add runtime overhead.

Added some comments to clarify why case _: is necessary in src/llmcompressor/pipelines/cache.py.

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[gemini-code-assist]

Summary of Changes

Hello @ojeda-e, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on modernizing the Python codebase by adopting contemporary language features. The primary changes involve updating type hints to the more recent | syntax and refactoring conditional logic that checks for object types into structural pattern matching statements. These updates enhance code readability and maintainability by leveraging newer Python capabilities.

Highlights

• Type Hint Modernization: Updated type hints across multiple files to use the more concise X | Y syntax instead of Union[X, Y] and Optional[X].
• Structural Pattern Matching Adoption: Replaced numerous isinstance checks with Python's structural pattern matching (match/case statements) for improved readability and conciseness, particularly in handling different data types and module types.
• Unnecessary Import Removal: Removed TYPE_CHECKING imports, as the author noted they are not necessary given all imports are runtime required.
• Code Clarity: Added comments to clarify the necessity and usage of case _: in src/llmcompressor/pipelines/cache.py.

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[gemini-code-assist]

Code Review

This pull request effectively modernizes the codebase by replacing older type hint syntax with the newer | operator for unions and if/isinstance chains with structural pattern matching (match...case). The changes are applied consistently across the modified files, leading to more readable and modern Python code. My review includes one suggestion to correct a misplaced comment in src/llmcompressor/pipelines/cache.py to improve code clarity and maintainability.

[brian-dellabetta]

Thanks for the contribution! Few change requests but looks good for the most part

[ojeda-e]

Thanks @brian-dellabetta I addressed your comments in the last commit.

[kylesayrs]

Looks good, thanks!