fn paren(iter: &mut Peekable<Iter<Token>>) -> Result<Code, Code> {
    let mut tokens = Vec::new();

    match iter.peek() {
        Some(Token::Symbol(Symbol::LParen)) => { iter.next(); }
        // if the first token is not `(`, then it is what we want, return Err.
        _ => return Err(Code { tokens })
    }

    let mut n = 0;
    loop {
        match iter.next() {
            Some(Token::Symbol(Symbol::RParen)) if n == 0 => {
                return Ok(Code { tokens });
            }
            Some(Token::Symbol(Symbol::LParen)) => {
                n += 1;
                tokens.push(Token::Symbol(Symbol::LParen));
            }
            Some(Token::Symbol(Symbol::RParen)) => {
                n -= 1;
                tokens.push(Token::Symbol(Symbol::RParen));
            }
            Some(token) => {
                tokens.push(token.clone())
            }
            None => {
                // no right parenthesis found, return the code it has read, should
                // add the left side parenthesis at the front.
                tokens.insert(0, Token::Symbol(Symbol::LParen));
                return Err(Code { tokens });
            }
        }
    }
}
/// Find code in parenthesis, returning code without parenthesis if success,
/// and if it can't find any right side parenthesis, then it would return the
/// code it has read.
Find code in parenthesis, returning code without parenthesis if success,
and if it can't find any right side parenthesis, then it would return the
code it has read.
Find code in parenthesis returning code without parenthesis if success and if it can ' t find any right side parenthesis then it would return the code it has read .
fn paren(iter: &mut Peekable<Iter<Token>>) -> Result<Code, Code> {
    let mut tokens = Vec::new();
    match iter.peek() {
        Some(Token::Symbol(Symbol::LParen)) => { iter.next(); }
        // if the first token is not `(`, then it is what we want, return Err.
        _ => return Err(Code { tokens })
    }
    let mut n = 0;
    loop {
        match iter.next() {
            Some(Token::Symbol(Symbol::RParen)) if n == 0 => {
                return Ok(Code { tokens });
            }
            Some(Token::Symbol(Symbol::LParen)) => {
                n += 1;
                tokens.push(Token::Symbol(Symbol::LParen));
            }
            Some(Token::Symbol(Symbol::RParen)) => {
                n -= 1;
                tokens.push(Token::Symbol(Symbol::RParen));
            }
            Some(token) => {
                tokens.push(token.clone())
            }
            None => {
                // no right parenthesis found, return the code it has read, should
                // add the left side parenthesis at the front.
                tokens.insert(0, Token::Symbol(Symbol::LParen));
                return Err(Code { tokens });
            }
        }
    }
}
fn paren ( iter : & mut Peekable < Iter < Token > > ) -> Result < Code , Code > { let mut tokens = Vec :: new ( ) ; match iter . peek ( ) { Some ( Token :: Symbol ( Symbol :: LParen ) ) => { iter . next ( ) ; } // if the first token is not `(`, then it is what we want, return Err. _ => return Err ( Code { tokens } ) } let mut n = 0 ; loop { match iter . next ( ) { Some ( Token :: Symbol ( Symbol :: RParen ) ) if n == 0 => { return Ok ( Code { tokens } ) ; } Some ( Token :: Symbol ( Symbol :: LParen ) ) => { n += 1 ; tokens . push ( Token :: Symbol ( Symbol :: LParen ) ) ; } Some ( Token :: Symbol ( Symbol :: RParen ) ) => { n -= 1 ; tokens . push ( Token :: Symbol ( Symbol :: RParen ) ) ; } Some ( token ) => { tokens . push ( token . clone ( ) ) } None => { // no right parenthesis found, return the code it has read, should // add the left side parenthesis at the front. tokens . insert ( 0 , Token :: Symbol ( Symbol :: LParen ) ) ; return Err ( Code { tokens } ) ; } } } }
Find code in parenthesis, returning code without parenthesis if success,
and if it can't find any right side parenthesis, then it would return the
code it has read.
Find code in parenthesis returning code without parenthesis if success and if it can ' t find any right side parenthesis then it would return the code it has read .
iter
&mut Peekable<Iter<Token>>
iter
&mut Peekable<Iter<Token>>