The CodeMap tracks all the source code used within a single crate, mapping from integer byte positions to the original source code location. Each bit of source parsed during crate parsing (typically files, in-memory strings, or various bits of macro expansion) cover a continuous range of bytes in the CodeMap and are represented by FileMaps. Byte positions are stored in spans and used pervasively in the compiler. They are absolute positions within the CodeMap, which upon request can be converted to line and column information, source code snippets, etc.

The main parser interface