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.
• GuardedStr
  #"abc"#, ##"a" (fewer closing), or even #"a (unterminated).
• 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
  Enum representing the literal types supported by the lexer.
• RawStrError
• TokenKind
  Enum representing common lexeme types.

Constants

• UNICODE_XID_VERSION
  The version of Unicode that this version of unicode-xid is based on.

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.