carbon-lang/docs/design/lexical_conventions

Lexical conventions

Table of contents

• Lexical elements

Lexical elements

The first stage of processing a source file is the division of the source file into lexical elements.

A lexical element is one of the following:

• a maximal sequence of whitespace characters
• a word

• a literal:

  • a numeric literal
  • a string literal

• a comment

• a symbolic token

The sequence of lexical elements is formed by repeatedly removing the longest initial sequence of characters that forms a valid lexical element, with the following exception:

• When a numeric literal immediately follows a . or -> token, with no intervening whitespace, a real literal is never formed. Instead, the token will end no later than the next . character. For example, tuple.1.2 is five tokens, tuple . 1 . 2, not three tokens, tuple . 1.2. However, tuple . 1.2 is lexed as three tokens.