Crate rustc_lexer

Low-level Rust lexer.

The idea with rustc_lexer is to make a reusable library, by separating out pure lexing and rustc-specific concerns, like spans, error reporting, and interning. So, rustc_lexer operates directly on &str, produces simple tokens which are a pair of type-tag and a bit of original text, and does not report errors, instead storing them as flags on the token.

Tokens produced by this lexer are not yet ready for parsing the Rust syntax. For that see rustc_parse::lexer, which converts this basic token stream into wide tokens used by actual parser.

The purpose of this crate is to convert raw sources into a labeled sequence of well-known token types, so building an actual Rust token stream will be easier.

The main entity of this crate is the TokenKind enum which represents common lexeme types.

Modules

cursor 🔒

unescape

Utilities for validating string and char literals and turning them into values they represent.

Structs

Cursor

Peekable iterator over a char sequence.

Token

Parsed token. It doesn’t contain information about data that has been parsed, only the type of the token and its size.

Enums

Base

Base of numeric literal encoding according to its prefix.

DocStyle

LiteralKind

RawStrError

TokenKind

Enum representing common lexeme types.

Functions

is_id_continue

True if c is valid as a non-first character of an identifier. See Rust language reference for a formal definition of valid identifier name.

is_id_start

True if c is valid as a first character of an identifier. See Rust language reference for a formal definition of valid identifier name.

is_ident

The passed string is lexically an identifier.

is_whitespace

True if c is considered a whitespace according to Rust language definition. See Rust language reference for definitions of these classes.

strip_shebang

rustc allows files to have a shebang, e.g. “#!/usr/bin/rustrun”, but shebang isn’t a part of rust syntax.

tokenize

Creates an iterator that produces tokens from the input string.

validate_raw_str

Validates a raw string literal. Used for getting more information about a problem with a RawStr/RawByteStr with a None field.