Implements a generic LCS (Longest Common Subsequence) diff algorithm (Myers' algorithm) for computing minimal text differences. The `stringDiff` function accepts two strings and returns an array of `IDiffChange` objects describing insertions and deletions. This is a self-contained, well-tested algorithm that can be extracted and reused in any project requiring text diffing, not just ESLint. It includes methods for prettifying changes and merging overlapping changes, demonstrating non-obvious algorithmic skill.

Provides several independent utility functions: a `Semaphore` class for limiting concurrent async operations (e.g., migration locking), a `convert2RegExp` function that translates glob patterns (including `**`, `?`, `{alternatives}`, `[brackets]`) into regular expressions, and path conversion helpers (`toOSPath`, `toPosixPath`, `findEslint`). The semaphore and glob-to-regex converter are high-quality, well-documented components that can be reused in any JavaScript/TypeScript project without modification.

Contains a generic `LinkedMap` data structure (key-value pairs with O(1) insertion, deletion, and iteration order) and a `LRUCache` subclass that automatically trims to a size limit with a configurable ratio. The implementation supports touch operations (move to front/back), `first`/`last` access, and `shift` removal. This is a self-contained, reusable caching component suitable for any application needing an LRU cache with predictable iteration order.

Provides cross-platform path handling utilities: `normalizeDriveLetter` ensures Windows drive letters are uppercase (matching Node's default), `isUNC` detects Windows UNC paths, `getFileSystemPath` converts a URI to a file path with optional realpath resolution (casing normalization on Windows/macOS), and `normalizePath` converts backslashes to forward slashes on Windows. These functions handle subtle path inconsistencies that cause bugs in linting and are cleanly separated for reuse in any Node.js application that needs robust path manipulation.