Struct Parser 

pub struct Parser<'t> { /* private fields */ }

the parser state.

tokens is the lexer’s output (assumed to end in TokenKind::Eof, which lexer::Lexer::tokenize guarantees). pos indexes into it. depth counts active recursive productions for the stack-overflow guard. open_delims stacks the still-open opener tokens and their spans: on a delimiter mismatch the innermost (top) is blamed – its span is the error’s span, per the “blame the opener” rule.

Implementations

impl<'t> Parser<'t>

pub fn parse(tokens: &'t [Token]) -> Result<Ast, QalaError>

parse a token stream into an untyped Ast, or return the first syntax error.

the input is expected to be a well-formed token stream ending in TokenKind::Eof (what crate::lexer::Lexer::tokenize produces). an empty program (just [Eof]) parses to an empty item list with no error. fail-fast: the first parse error stops the parse and is returned; later errors are not collected.

pub fn parse_expr(&mut self) -> Result<Expr, QalaError>

parse a single expression at the loosest precedence. a thin alias for expr_bp(0, ExprCtx::Normal); statements call this to read the leaves of the grammar.