This emacs package provides a utility for deducing the repository root directory for a given file, based on predefined or user provided matching criteria. It is specifically designed to be useful in a heterogeneous environment, where the developer is using several source control tools and types of projects. Once the repository root directory is deduced, it is cached (per buffer) for future reference in subsequent calls to repository-root. In itself this library isn't that useful - it's meant to be used by other libraries that may benefit from knowing where the repository root directory resides (e.g for limiting search effort). Nested/embedded repositories (e.g git with submodules) are also supported.