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GitHub Flavored Markdown Specification and Implementation

1 post · Mar 2017

What this trail covers

This feature thread tracks the evolution of GitHub Flavored Markdown (GFM), focusing on formalizing its syntax and improving its parsing and rendering implementation. Initially, GFM was built on Sundown with custom extensions. This post details the creation of a formal GFM specification based on CommonMark, the migration of the backend to `cmark` (the CommonMark reference implementation), and the implementation of GFM-specific extensions on top of `cmark`. It also covers the normalization of existing user content to ensure a smooth transition and the eventual application of the new standard to content within Git repositories.

All GitHub trails
  1. A formal spec for GitHub Flavored MarkdownThis post introduces the formal specification for GitHub Flavored Markdown (GFM), based on CommonMark, and details the migration of GitHub's backend Markdown parsing to `cmark`, the CommonMark reference implementation. It covers the implementation of GFM-specific extensions (tables, strikethrough, autolinks, task lists) on top of `cmark`, performance and security contributions to the upstream `cmark` project, and a pragmatic migration strategy involving normalization of existing user content to ensure visual consistency and data integrity. The new system generates an Abstract Syntax Tree (AST) for more robust processing.