Module lexer 

Tokenizer for PDDL S-expressions.

Converts raw PDDL source text into a flat vector of Tokens, each carrying a TokenKind and a Span for error reporting.

Token conventions:

• : prefix → TokenKind::Keyword (e.g. :requirements, :typing)
• ? prefix → TokenKind::Variable (e.g. ?x, ?duration)
• ; → line comment (skipped entirely)
• All symbols and keywords are lowercased during tokenization.

Structs

Token

A single token produced by the lexer, pairing a TokenKind with its source Span.

Enums

TokenKind

The kind of a lexed PDDL token.

Functions

tokenize

Tokenize a PDDL source string into a flat vector of Tokens.