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
An "interner" is a data structure that associates values with usize tags and allows bidirectional lookup; i.e., given a value, one can easily find the type, and vice versa.
A byte offset. Keep this small (currently 32-bits), as AST contains a lot of them.
A character offset. Because of multibyte UTF-8 characters, a byte offset
is not equivalent to a character offset. The
Extra information for tracking spans of macro and syntax sugar expansion
A source code location used for error reporting.
Identifies an offset of a multi-byte character in a
A collection of spans. Spans have two orthogonal attributes:
A FileLoader that uses std::fs to load real files.
A single source in the
A compressed span.
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
The source of expansion.
The state of the lazy external source loading mechanism of a
Differentiates between real files and common virtual files.
Identifies an offset of a non-narrow character in a
Dummy span, both position and length are zero, syntax context is zero as well.
An abstraction over the fs operations used by the Parser.
Returns the span itself if it doesn't come from a macro expansion,
otherwise return the call site span up to the