add retain and extract_if

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[Copilot]

Pull Request Overview

This PR adds retain and extract_if methods to WordVec, along with comprehensive test coverage. These methods allow in-place filtering of vector elements with different semantics: retain keeps elements matching a predicate, while extract_if returns an iterator that extracts (removes and yields) matching elements.

• Implements retain method that removes elements not matching a predicate
• Implements extract_if method that returns an iterator extracting matching elements
• Adds a new retain module with the core filtering logic and ExtractIf iterator

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 7 comments.

File	Description
src/lib.rs	Added public retain and extract_if API methods and imported the retain module
src/retain.rs	New module implementing the Retain helper struct and ExtractIf iterator with memory-safe element manipulation
src/tests.rs	Added comprehensive test suite covering empty, full, partial, panic, and early-drop scenarios for both methods

Comments suppressed due to low confidence (2)

src/lib.rs:1

• The documentation references retain_mut, but this method does not exist in WordVec. The correct reference should be to retain. Change both occurrences of retain_mut to retain.

//! A [thin][thinvec] and [small][smallvec] vector

src/lib.rs:1

• The 'Panics' section states 'If range is out of bounds', but extract_if does not accept a range parameter and cannot panic for this reason. This section should be removed.

//! A [thin][thinvec] and [small][smallvec] vector

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[Copilot]

Pull Request Overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

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