Function scan_expr

impl/src/scan_expr.rs:192–264

(input: ParseStream)

];

pub(crate) fn scan_expr(input: ParseStream) -> Result<()> {
    let mut state = INIT.as_slice();
    let mut depth = 0usize;
    'table: loop {
        for rule in state {
            if match rule.0 {
                Input::Keyword(expected) => input.step(|cursor| match cursor.ident() {
                    Some((ident, rest)) if ident == expected => Ok((true, rest)),
                    _ => Ok((false, *cursor)),
                })?,
                Input::Punct(expected) => input.step(|cursor| {
                    let begin = *cursor;
                    let mut cursor = begin;
                    for (i, ch) in expected.chars().enumerate() {
                        match cursor.punct() {
                            Some((punct, _)) if punct.as_char() != ch => break,
                            Some((_, rest)) if i == expected.len() - 1 => {
                                return Ok((true, rest));
                            }
                            Some((punct, rest)) if punct.spacing() == Spacing::Joint => {
                                cursor = rest;
                            }
                            _ => break,
                        }
                    }
                    Ok((false, begin))
                })?,
                Input::ConsumeAny => input.parse::<Option<TokenTree>>()?.is_some(),
                Input::ConsumeBinOp => input.parse::<BinOp>().is_ok(),
                Input::ConsumeBrace | Input::ConsumeNestedBrace => {
                    (matches!(rule.0, Input::ConsumeBrace) || depth > 0)
                        && input.step(|cursor| match cursor.group(Delimiter::Brace) {
                            Some((_inside, _span, rest)) => Ok((true, rest)),
                            None => Ok((false, *cursor)),
                        })?
                }
                Input::ConsumeDelimiter => input.step(|cursor| match cursor.any_group() {
                    Some((_inside, _delimiter, _span, rest)) => Ok((true, rest)),
                    None => Ok((false, *cursor)),
                })?,
                Input::ConsumeIdent => input.parse::<Option<Ident>>()?.is_some(),
                Input::ConsumeLifetime => input.parse::<Option<Lifetime>>()?.is_some(),
                Input::ConsumeLiteral => input.parse::<Option<Lit>>()?.is_some(),
                Input::ExpectPath => {
                    input.parse::<ExprPath>()?;
                    true
                }
                Input::ExpectTurbofish => {
                    if input.peek(Token![::]) {
                        input.parse::<AngleBracketedGenericArguments>()?;
                    }
                    true
                }
                Input::ExpectType => {
                    Type::without_plus(input)?;
                    true
                }
                Input::CanBeginExpr => Expr::peek(input),