Struct Parser 

pub struct Parser<'a> { /* private fields */ }

A cursor over tokens. Shared by the expression parser (this task) and the section parser (Task 4).

Implementations

impl<'a> Parser<'a>

pub fn new(toks: &'a [Token]) -> Self

A parser positioned at the first token.

Panics

If toks is empty; lex always appends Tok::Eof, so this cannot happen for tokens it produced.

pub fn peek(&self) -> &Tok

The current token without consuming it.

pub fn peek2(&self) -> &Tok

The token after the current one.

pub fn peek_at(&self, n: usize) -> &Tok

The token n positions ahead of the cursor; peek_at(0) is Parser::peek. Clamped to the trailing Eof, like peek and peek2.

pub fn span(&self) -> Span

The current token’s span.

pub fn prev_span(&self) -> Span

Span of the token just consumed, or of the current one at the start of input.

Expr::span() cannot serve here: a parenthesised expression carries the span of its contents, so !(a | b) ends before the closing parens. This gives the real end of whatever was last read, which is what quoting a construct back to the author needs.

pub fn bump(&mut self) -> Token

Consumes and returns the current token.

pub fn eat(&mut self, want: &Tok) -> bool

Consumes the current token if it matches, reporting whether it did.

pub fn expect( &mut self, want: &Tok, what: &str, diags: &mut Diagnostics, ) -> bool

Consumes the current token if it matches, otherwise records a diagnostic.

pub fn at_eof(&self) -> bool

Whether input is exhausted.

pub fn parse_expr(&mut self, diags: &mut Diagnostics) -> Expr

Parses a formula.