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The SourceMap 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 SourceMap and are represented by SourceFiles. Byte positions are stored in spans and used pervasively in the compiler. They are absolute positions within the SourceMap, which upon request can be converted to line and column information, source code snippets, etc.


Machinery for hygienic macros, inspired by the MTWT[1] paper.


An archived Span

A byte offset. Keep this small (currently 32-bits), as AST contains a lot of them.

The resolver for an archived BytePos

A character offset. Because of multibyte utf8 characters, a byte offset is not equivalent to a character offset. The SourceMap will convert BytePos values to CharPos values as necessary.

Used to create a .map file.

A source code location used for error reporting

A source code location used as the result of lookup_char_pos_adj

A mark is a unique id associated with a macro expansion.

Identifies an offset of a multi-byte character in a SourceFile

A collection of spans. Spans have two orthogonal attributes:

A FileLoader that uses std::fs to load real files.

A single source in the SourceMap.

The interner for spans.

Spans represent a region of code, used for error reporting. Positions in spans are absolute positions from the beginning of the source_map, not positions relative to SourceFiles. Methods on the SourceMap can be used to relate spans back to the original source. You must be careful if the span crosses more than one file - you will not be able to use many of the functions on spans in source_map and you cannot assume that the length of the span = hi - lo; there may be space in the BytePos range between files.

The resolver for an archived Span

A SyntaxContext represents a chain of macro expansions (represented by marks).


Differentiates between real files and common virtual files.

Identifies an offset of a non-narrow character in a SourceFile


Dummy span, both position and length are zero, syntax context is zero as well.


Storage for span hygiene data.


An abstraction over the fs operations used by the Parser.

Type Definitions