src/mac.rs

use super::*;

/// Represents a macro invocation. The Path indicates which macro
/// is being invoked, and the vector of token-trees contains the source
/// of the macro invocation.
///
/// NB: the additional ident for a `macro_rules`-style macro is actually
/// stored in the enclosing item. Oog.
#[derive(Debug, Clone, Eq, PartialEq, Hash)]
pub struct Mac {
    pub path: Path,
    pub tts: Vec<TokenTree>,
}

/// When the main rust parser encounters a syntax-extension invocation, it
/// parses the arguments to the invocation as a token-tree. This is a very
/// loose structure, such that all sorts of different AST-fragments can
/// be passed to syntax extensions using a uniform type.
///
/// If the syntax extension is an MBE macro, it will attempt to match its
/// LHS token tree against the provided token tree, and if it finds a
/// match, will transcribe the RHS token tree, splicing in any captured
/// `macro_parser::matched_nonterminals` into the `SubstNt`s it finds.
///
/// The RHS of an MBE macro is the only place `SubstNt`s are substituted.
/// Nothing special happens to misnamed or misplaced `SubstNt`s.
#[derive(Debug, Clone, Eq, PartialEq, Hash)]
pub enum TokenTree {
    /// A single token
    Token(Token),
    /// A delimited sequence of token trees
    Delimited(Delimited),
}

#[derive(Debug, Clone, Eq, PartialEq, Hash)]
pub struct Delimited {
    /// The type of delimiter
    pub delim: DelimToken,
    /// The delimited sequence of token trees
    pub tts: Vec<TokenTree>,
}

#[derive(Debug, Clone, Eq, PartialEq, Hash)]
pub enum Token {
    // Expression-operator symbols.
    Eq,
    Lt,
    Le,
    EqEq,
    Ne,
    Ge,
    Gt,
    AndAnd,
    OrOr,
    Not,
    Tilde,
    BinOp(BinOpToken),
    BinOpEq(BinOpToken),

    // Structural symbols
    At,
    Dot,
    DotDot,
    DotDotDot,
    Comma,
    Semi,
    Colon,
    ModSep,
    RArrow,
    LArrow,
    FatArrow,
    Pound,
    Dollar,
    Question,

    // Literals
    Literal(Lit),

    // Name components
    Ident(Ident),
    Underscore,
    Lifetime(Ident),

    DocComment(String),
}

#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
pub enum BinOpToken {
    Plus,
    Minus,
    Star,
    Slash,
    Percent,
    Caret,
    And,
    Or,
    Shl,
    Shr,
}

/// A delimiter token
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
pub enum DelimToken {
    /// A round parenthesis: `(` or `)`
    Paren,
    /// A square bracket: `[` or `]`
    Bracket,
    /// A curly brace: `{` or `}`
    Brace,
}

#[cfg(feature = "parsing")]
pub mod parsing {
    use super::*;
    use Lifetime;
    use generics::parsing::lifetime;
    use ident::parsing::word;
    use lit::parsing::lit;
    use ty::parsing::path;
    use attr::parsing::{inner_doc_comment, outer_doc_comment};

    named!(pub mac -> Mac, do_parse!(
        what: path >>
        punct!("!") >>
        body: delimited >>
        (Mac {
            path: what,
            tts: vec![TokenTree::Delimited(body)],
        })
    ));

    named!(pub token_trees -> Vec<TokenTree>, many0!(token_tree));

    named!(pub delimited -> Delimited, alt!(
        delim!(
            Parenthesis,
            token_trees
        ) => { |tts| Delimited { delim: DelimToken::Paren, tts: tts } }
        |
        delim!(
            Bracket,
            token_trees
        ) => { |tts| Delimited { delim: DelimToken::Bracket, tts: tts } }
        |
        delim!(
            Brace,
            token_trees
        ) => { |tts| Delimited { delim: DelimToken::Brace, tts: tts } }
    ));

    named!(pub token_tree -> TokenTree, alt!(
        map!(token, TokenTree::Token)
        |
        map!(delimited, TokenTree::Delimited)
    ));

    named!(token -> Token, alt!(
        keyword!("_") => { |_| Token::Underscore }
        |
        punct!("&&") => { |_| Token::AndAnd } // must be before BinOp
        |
        punct!("||") => { |_| Token::OrOr } // must be before BinOp
        |
        punct!("->") => { |_| Token::RArrow } // must be before BinOp
        |
        punct!("<-") => { |_| Token::LArrow } // must be before Lt
        |
        punct!("=>") => { |_| Token::FatArrow } // must be before Eq
        |
        punct!("...") => { |_| Token::DotDotDot } // must be before DotDot
        |
        punct!("..") => { |_| Token::DotDot } // must be before Dot
        |
        punct!(".") => { |_| Token::Dot }
        |
        map!(doc_comment, Token::DocComment) // must be before bin_op
        |
        map!(bin_op_eq, Token::BinOpEq) // must be before bin_op
        |
        map!(bin_op, Token::BinOp)
        |
        map!(lit, Token::Literal)
        |
        map!(word, Token::Ident)
        |
        map!(lifetime, |lt: Lifetime| Token::Lifetime(lt.ident))
        |
        punct!("<=") => { |_| Token::Le }
        |
        punct!("==") => { |_| Token::EqEq }
        |
        punct!("!=") => { |_| Token::Ne }
        |
        punct!(">=") => { |_| Token::Ge }
        |
        punct!("::") => { |_| Token::ModSep }
        |
        punct!("=") => { |_| Token::Eq }
        |
        punct!("<") => { |_| Token::Lt }
        |
        punct!(">") => { |_| Token::Gt }
        |
        punct!("!") => { |_| Token::Not }
        |
        punct!("~") => { |_| Token::Tilde }
        |
        punct!("@") => { |_| Token::At }
        |
        punct!(",") => { |_| Token::Comma }
        |
        punct!(";") => { |_| Token::Semi }
        |
        punct!(":") => { |_| Token::Colon }
        |
        punct!("#") => { |_| Token::Pound }
        |
        punct!("$") => { |_| Token::Dollar }
        |
        punct!("?") => { |_| Token::Question }
    ));

    named!(bin_op -> BinOpToken, alt!(
        punct!("+") => { |_| BinOpToken::Plus }
        |
        punct!("-") => { |_| BinOpToken::Minus }
        |
        punct!("*") => { |_| BinOpToken::Star }
        |
        punct!("/") => { |_| BinOpToken::Slash }
        |
        punct!("%") => { |_| BinOpToken::Percent }
        |
        punct!("^") => { |_| BinOpToken::Caret }
        |
        punct!("&") => { |_| BinOpToken::And }
        |
        punct!("|") => { |_| BinOpToken::Or }
        |
        punct!("<<") => { |_| BinOpToken::Shl }
        |
        punct!(">>") => { |_| BinOpToken::Shr }
    ));

    named!(bin_op_eq -> BinOpToken, alt!(
        punct!("+=") => { |_| BinOpToken::Plus }
        |
        punct!("-=") => { |_| BinOpToken::Minus }
        |
        punct!("*=") => { |_| BinOpToken::Star }
        |
        punct!("/=") => { |_| BinOpToken::Slash }
        |
        punct!("%=") => { |_| BinOpToken::Percent }
        |
        punct!("^=") => { |_| BinOpToken::Caret }
        |
        punct!("&=") => { |_| BinOpToken::And }
        |
        punct!("|=") => { |_| BinOpToken::Or }
        |
        punct!("<<=") => { |_| BinOpToken::Shl }
        |
        punct!(">>=") => { |_| BinOpToken::Shr }
    ));

    named!(doc_comment -> String, alt!(
        inner_doc_comment
        |
        outer_doc_comment
    ));
}

#[cfg(feature = "printing")]
mod printing {
    use super::*;
    use quote::{Tokens, ToTokens};

    impl ToTokens for Mac {
        fn to_tokens(&self, tokens: &mut Tokens) {
            self.path.to_tokens(tokens);
            tokens.append("!");
            for tt in &self.tts {
                tt.to_tokens(tokens);
            }
        }
    }

    impl ToTokens for TokenTree {
        fn to_tokens(&self, tokens: &mut Tokens) {
            match *self {
                TokenTree::Token(ref token) => token.to_tokens(tokens),
                TokenTree::Delimited(ref delimited) => delimited.to_tokens(tokens),
            }
        }
    }

    impl DelimToken {
        fn open(&self) -> &'static str {
            match *self {
                DelimToken::Paren => "(",
                DelimToken::Bracket => "[",
                DelimToken::Brace => "{",
            }
        }

        fn close(&self) -> &'static str {
            match *self {
                DelimToken::Paren => ")",
                DelimToken::Bracket => "]",
                DelimToken::Brace => "}",
            }
        }
    }

    impl ToTokens for Delimited {
        fn to_tokens(&self, tokens: &mut Tokens) {
            tokens.append(self.delim.open());
            for tt in &self.tts {
                tt.to_tokens(tokens);
            }
            tokens.append(self.delim.close());
        }
    }

    impl ToTokens for Token {
        fn to_tokens(&self, tokens: &mut Tokens) {
            match *self {
                Token::Eq => tokens.append("="),
                Token::Lt => tokens.append("<"),
                Token::Le => tokens.append("<="),
                Token::EqEq => tokens.append("=="),
                Token::Ne => tokens.append("!="),
                Token::Ge => tokens.append(">="),
                Token::Gt => tokens.append(">"),
                Token::AndAnd => tokens.append("&&"),
                Token::OrOr => tokens.append("||"),
                Token::Not => tokens.append("!"),
                Token::Tilde => tokens.append("~"),
                Token::BinOp(binop) => tokens.append(binop.op()),
                Token::BinOpEq(binop) => tokens.append(binop.assign_op()),
                Token::At => tokens.append("@"),
                Token::Dot => tokens.append("."),
                Token::DotDot => tokens.append(".."),
                Token::DotDotDot => tokens.append("..."),
                Token::Comma => tokens.append(","),
                Token::Semi => tokens.append(";"),
                Token::Colon => tokens.append(":"),
                Token::ModSep => tokens.append("::"),
                Token::RArrow => tokens.append("->"),
                Token::LArrow => tokens.append("<-"),
                Token::FatArrow => tokens.append("=>"),
                Token::Pound => tokens.append("#"),
                Token::Dollar => tokens.append("$"),
                Token::Question => tokens.append("?"),
                Token::Literal(ref lit) => lit.to_tokens(tokens),
                Token::Ident(ref ident) |
                Token::Lifetime(ref ident) => ident.to_tokens(tokens),
                Token::Underscore => tokens.append("_"),
                Token::DocComment(ref com) => {
                    tokens.append(&format!("{}\n", com));
                }
            }
        }
    }

    impl BinOpToken {
        fn op(&self) -> &'static str {
            match *self {
                BinOpToken::Plus => "+",
                BinOpToken::Minus => "-",
                BinOpToken::Star => "*",
                BinOpToken::Slash => "/",
                BinOpToken::Percent => "%",
                BinOpToken::Caret => "^",
                BinOpToken::And => "&",
                BinOpToken::Or => "|",
                BinOpToken::Shl => "<<",
                BinOpToken::Shr => ">>",
            }
        }

        fn assign_op(&self) -> &'static str {
            match *self {
                BinOpToken::Plus => "+=",
                BinOpToken::Minus => "-=",
                BinOpToken::Star => "*=",
                BinOpToken::Slash => "/=",
                BinOpToken::Percent => "%=",
                BinOpToken::Caret => "^=",
                BinOpToken::And => "&=",
                BinOpToken::Or => "|=",
                BinOpToken::Shl => "<<=",
                BinOpToken::Shr => ">>=",
            }
        }
    }

    impl ToTokens for BinOpToken {
        fn to_tokens(&self, tokens: &mut Tokens) {
            tokens.append(self.op());
        }
    }
}