Optimize input handling with the lookup table

[tatsuhiro-t]

No description provided.

[gemini-code-assist]

Summary of Changes

Hello @tatsuhiro-t, 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 significantly optimizes the URL parsing mechanism by transitioning from traditional switch-case based character validation to a lookup table approach. This refactoring aims to enhance both the readability and performance of the URL parsing functions by providing a more direct and efficient way to classify input characters, ensuring robust and faster URL processing.

Highlights

• Refactored Character Validation: Replaced extensive switch-case statements for character classification within URL parsing functions with efficient lookup tables. This change impacts scheme, path, userinfo, host, IPv6 host, and port parsing.
• Introduced Lookup Tables: New uint8_t arrays like scheme_chars, path_chars, userinfo_chars, host_chars, ipv6_host_chars, ipv6_zone_chars, port_chars, and extra_chars have been added to quickly determine character types.
• Improved Readability and Performance: The use of lookup tables simplifies the parsing logic, making the code more concise and potentially improving performance by reducing branch mispredictions compared to long switch statements.
• Added Test Case: A new test case was added to urlparse_test.c to verify that an invalid character (*) in the scheme part of a URL is correctly rejected by the parser.

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[gemini-code-assist]

Code Review

This pull request introduces a significant performance optimization by replacing large switch statements with lookup tables for character validation during URL parsing. The approach is sound and should improve parsing speed. However, I've identified a recurring critical issue across all the new lookup table usages: casting a char to size_t for array indexing can lead to out-of-bounds memory access if char is signed. This must be fixed by casting to unsigned char instead. Additionally, the new test case added in urlparse_test.c appears to expose a pre-existing logic bug in how malformed URLs are handled, which I've detailed in a comment.

[tatsuhiro-t]

/gemini review

[gemini-code-assist]

Code Review

This pull request optimizes input handling by replacing large switch statements with lookup tables. This is a great performance improvement and simplifies the parsing logic in many functions. The changes are well-implemented, and the addition of new test cases to cover edge cases like invalid characters in the scheme is much appreciated. My main suggestion is to replace the magic numbers used in the lookup tables and switch statements with named constants (e.g., using an enum) to improve code readability and maintainability.