Emmet is a mature, production-grade library that expands CSS-selector-like abbreviations into HTML markup and CSS property declarations. The repository is a monorepo housing the core `emmet` package (which handles full abbreviation expansion, snippet resolution, and formatting for HTML, Pug, HAML, Slim, and CSS) alongside three smaller, independently usable subpackages: `@emmetio/scanner` (a character-by-character string reader), `@emmetio/abbreviation` (tokenizer and parser for markup abbreviations), and `@emmetio/css-abbreviation` (tokenizer and parser for stylesheet abbreviations). The architecture is modular, with clean separation of tokenization, parsing, transformation, and output formatting. The codebase demonstrates strong software engineering practices: clear TypeScript types, exhaustive tests, and a plugin-like configuration system. It is the engine behind the Emmet feature in many code editors, serving millions of developers daily.
coc-snippets is a Neovim/Vim plugin that provides snippet completion and expansion for the coc.nvim completion framework. It supports multiple snippet formats including UltiSnips, snipmate, and VSCode snippets, allowing users to load snippets from various sources and use them as completion items in their code editing workflow. The extension follows a modular architecture where each snippet format is handled by a dedicated provider (e.g., UltiSnipsProvider, SnipmateProvider, TextmateProvider). A provider manager aggregates results from all active providers, filters and sorts them, and presents them as completion options. When a snippet is selected, it is expanded in the buffer with support for placeholders and tab stops. Key features include asynchronous loading of snippets to avoid blocking the UI, support for snippet context conditions (via UltiSnips context), and integration with coc.nvim's completion system. The extension also provides commands for editing snippets and listing available snippets. While the core functionality is well-implemented, the extension is tightly coupled to the coc.nvim API, which limits the reusability of individual components outside of the Neovim/Vim ecosystem. However, the utility module (src/util.ts) contains a collection of reusable functions for string manipulation, collections, and cryptographic operations that can be extracted with minimal modification.