/// Parses the arguments from the given list of tokens, returning None
/// if there's a parse error so we can continue parsing other format!
/// expressions.
///
/// If parsing succeeds, the return value is:
/// ```ignore
/// Some((fmtstr, parsed arguments, index map for named arguments))
/// ```
Parses the arguments from the given list of tokens, returning None
if there's a parse error so we can continue parsing other format.
expressions.


Parses the arguments from the given list of tokens returning None if there ' s a parse error so we can continue parsing other format . expressions .
fn parse_args(ecx: &mut ExtCtxt, sp: Span, tts: &[tokenstream::TokenTree])
              -> Option<(P<ast::Expr>, Vec<P<ast::Expr>>, HashMap<String, usize>)> {
    let mut args = Vec::<P<ast::Expr>>::new();
    let mut names = HashMap::<String, usize>::new();
    let mut p = ecx.new_parser_from_tts(tts);
    if p.token == token::Eof {
        ecx.span_err(sp, "requires at least a format string argument");
        return None;
    }
    let fmtstr = panictry!(p.parse_expr());
    let mut named = false;
    while p.token != token::Eof {
        if !p.eat(&token::Comma) {
            ecx.span_err(sp, "expected token: `,`");
            return None;
        }
        if p.token == token::Eof { break } // accept trailing commas
        if named || (p.token.is_ident() && p.look_ahead(1, |t| *t == token::Eq)) {
            named = true;
            let ident = match p.token {
                token::Ident(i) => {
                    p.bump();
                    i
                }
                _ if named => {
                    ecx.span_err(p.span,
                                 "expected ident, positional arguments \
                                 cannot follow named arguments");
                    return None;
                }
                _ => {
                    ecx.span_err(p.span,
                                 &format!("expected ident for named argument, found `{}`",
                                         p.this_token_to_string()));
                    return None;
                }
            };
            let name: &str = &ident.name.as_str();
            panictry!(p.expect(&token::Eq));
            let e = panictry!(p.parse_expr());
            if let Some(prev) = names.get(name) {
                ecx.struct_span_err(e.span,
                                    &format!("duplicate argument named `{}`",
                                             name))
                    .span_note(args[*prev].span, "previously here")
                    .emit();
                continue;
            }
            // Resolve names into slots early.
            // Since all the positional args are already seen at this point
            // if the input is valid, we can simply append to the positional
            // args. And remember the names.
            let slot = args.len();
            names.insert(name.to_string(), slot);
            args.push(e);
        } else {
            args.push(panictry!(p.parse_expr()));
        }
    }
    Some((fmtstr, args, names))
}
fn parse_args ( ecx : & mut ExtCtxt , sp : Span , tts : & [ tokenstream :: TokenTree ] ) -> Option < ( P < ast :: Expr > , Vec < P < ast :: Expr > > , HashMap < String , usize > ) > { let mut args = Vec :: < P < ast :: Expr > > :: new ( ) ; let mut names = HashMap :: < String , usize > :: new ( ) ; let mut p = ecx . new_parser_from_tts ( tts ) ; if p . token == token :: Eof { ecx . span_err ( sp , " " ) ; return None ; } let fmtstr = panictry ! ( p parse_expr ( ) ) ; let mut named = false ; while p . token != token :: Eof { if ! p . eat ( & token :: Comma ) { ecx . span_err ( sp , " " ) ; return None ; } if p . token == token :: Eof { break } // accept trailing commas if named || ( p . token . is_ident ( ) && p . look_ahead ( 1 , | t | * t == token :: Eq ) ) { named = true ; let ident = match p . token { token :: Ident ( i ) => { p . bump ( ) ; i } _ if named => { ecx . span_err ( p . span , " \
 " ) ; return None ; } _ => { ecx . span_err ( p . span , & format ! ( " " p this_token_to_string ( ) ) ) ; return None ; } } ; let name : & str = & ident . name . as_str ( ) ; panictry ! ( p expect ( token Eq ) ) ; let e = panictry ! ( p parse_expr ( ) ) ; if let Some ( prev ) = names . get ( name ) { ecx . struct_span_err ( e . span , & format ! ( " " name ) ) . span_note ( args [ * prev ] . span , " " ) . emit ( ) ; continue ; } // Resolve names into slots early. // Since all the positional args are already seen at this point // if the input is valid, we can simply append to the positional // args. And remember the names. let slot = args . len ( ) ; names . insert ( name . to_string ( ) , slot ) ; args . push ( e ) ; } else { args . push ( panictry ! ( p parse_expr ( ) ) ) ; } } Some ( ( fmtstr , args , names ) ) }
Parses the arguments from the given list of tokens, returning None
if there's a parse error so we can continue parsing other format!
Parses the arguments from the given list of tokens returning None if there ' s a parse error so we can continue parsing other format!
ecx
&mut ExtCtxt
sp
Span
tts
&[tokenstream::TokenTree]