/
quote.rs
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/
quote.rs
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// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! # Quasiquoter
//! This file contains the implementation internals of the quasiquoter provided by `quote!`.
//! This quasiquoter uses macros 2.0 hygiene to reliably use items from `__rt`,
//! including re-exported API `libsyntax`, to build a `syntax::tokenstream::TokenStream`
//! and wrap it into a `proc_macro::TokenStream`.
use syntax::ast::Ident;
use syntax::ext::base::{ExtCtxt, ProcMacro};
use syntax::parse::token::{self, Token, Lit};
use syntax::symbol::Symbol;
use syntax::tokenstream::{Delimited, TokenTree, TokenStream, TokenStreamBuilder};
use syntax_pos::{DUMMY_SP, Span};
use syntax_pos::hygiene::SyntaxContext;
pub struct Quoter;
pub mod __rt {
pub use syntax::ast::Ident;
pub use syntax::parse::token;
pub use syntax::symbol::Symbol;
pub use syntax::tokenstream::{TokenStream, TokenStreamBuilder, TokenTree, Delimited};
pub use super::{ctxt, span};
pub fn unquote<T: Into<::TokenStream> + Clone>(tokens: &T) -> TokenStream {
T::into(tokens.clone()).0
}
}
pub fn ctxt() -> SyntaxContext {
::__internal::with_sess(|(_, mark)| SyntaxContext::empty().apply_mark(mark))
}
pub fn span() -> Span {
::Span::default().0
}
pub trait Quote {
fn quote(&self) -> TokenStream;
}
macro_rules! quote_tok {
(,) => { Token::Comma };
(.) => { Token::Dot };
(:) => { Token::Colon };
(::) => { Token::ModSep };
(!) => { Token::Not };
(<) => { Token::Lt };
(>) => { Token::Gt };
(_) => { Token::Underscore };
(0) => { Token::Literal(token::Lit::Integer(Symbol::intern("0")), None) };
(&) => { Token::BinOp(token::And) };
($i:ident) => { Token::Ident(Ident { name: Symbol::intern(stringify!($i)), ctxt: ctxt() }) };
}
macro_rules! quote_tree {
((unquote $($t:tt)*)) => { TokenStream::from($($t)*) };
((quote $($t:tt)*)) => { ($($t)*).quote() };
(($($t:tt)*)) => { delimit(token::Paren, quote!($($t)*)) };
([$($t:tt)*]) => { delimit(token::Bracket, quote!($($t)*)) };
({$($t:tt)*}) => { delimit(token::Brace, quote!($($t)*)) };
(rt) => { quote!(::__internal::__rt) };
($t:tt) => { TokenStream::from(TokenTree::Token(span(), quote_tok!($t))) };
}
fn delimit(delim: token::DelimToken, stream: TokenStream) -> TokenStream {
TokenTree::Delimited(span(), Delimited { delim: delim, tts: stream.into() }).into()
}
macro_rules! quote {
() => { TokenStream::empty() };
($($t:tt)*) => { [ $( quote_tree!($t), )* ].iter().cloned().collect::<TokenStream>() };
}
impl ProcMacro for Quoter {
fn expand<'cx>(&self, cx: &'cx mut ExtCtxt, _: Span, stream: TokenStream) -> TokenStream {
let mut info = cx.current_expansion.mark.expn_info().unwrap();
info.callee.allow_internal_unstable = true;
cx.current_expansion.mark.set_expn_info(info);
::__internal::set_sess(cx, || quote!(::TokenStream((quote stream))))
}
}
impl<T: Quote> Quote for Option<T> {
fn quote(&self) -> TokenStream {
match *self {
Some(ref t) => quote!(Some((quote t))),
None => quote!(None),
}
}
}
impl Quote for TokenStream {
fn quote(&self) -> TokenStream {
let mut builder = TokenStreamBuilder::new();
builder.push(quote!(rt::TokenStreamBuilder::new()));
let mut trees = self.trees();
loop {
let (mut tree, mut is_joint) = match trees.next_as_stream() {
Some(next) => next.as_tree(),
None => return builder.add(quote!(.build())).build(),
};
if let TokenTree::Token(_, Token::Dollar) = tree {
let (next_tree, next_is_joint) = match trees.next_as_stream() {
Some(next) => next.as_tree(),
None => panic!("unexpected trailing `$` in `quote!`"),
};
match next_tree {
TokenTree::Token(_, Token::Ident(..)) => {
builder.push(quote!(.add(rt::unquote(&(unquote next_tree)))));
continue
}
TokenTree::Token(_, Token::Dollar) => {
tree = next_tree;
is_joint = next_is_joint;
}
_ => panic!("`$` must be followed by an ident or `$` in `quote!`"),
}
}
builder.push(match is_joint {
true => quote!(.add((quote tree).joint())),
false => quote!(.add(rt::TokenStream::from((quote tree)))),
});
}
}
}
impl Quote for TokenTree {
fn quote(&self) -> TokenStream {
match *self {
TokenTree::Token(span, ref token) => quote! {
rt::TokenTree::Token((quote span), (quote token))
},
TokenTree::Delimited(span, ref delimited) => quote! {
rt::TokenTree::Delimited((quote span), (quote delimited))
},
}
}
}
impl Quote for Delimited {
fn quote(&self) -> TokenStream {
quote!(rt::Delimited { delim: (quote self.delim), tts: (quote self.stream()).into() })
}
}
impl<'a> Quote for &'a str {
fn quote(&self) -> TokenStream {
TokenTree::Token(span(), Token::Literal(token::Lit::Str_(Symbol::intern(self)), None))
.into()
}
}
impl Quote for usize {
fn quote(&self) -> TokenStream {
let integer_symbol = Symbol::intern(&self.to_string());
TokenTree::Token(DUMMY_SP, Token::Literal(token::Lit::Integer(integer_symbol), None))
.into()
}
}
impl Quote for Ident {
fn quote(&self) -> TokenStream {
quote!(rt::Ident { name: (quote self.name), ctxt: rt::ctxt() })
}
}
impl Quote for Symbol {
fn quote(&self) -> TokenStream {
quote!(rt::Symbol::intern((quote &*self.as_str())))
}
}
impl Quote for Span {
fn quote(&self) -> TokenStream {
quote!(rt::span())
}
}
impl Quote for Token {
fn quote(&self) -> TokenStream {
macro_rules! gen_match {
($($i:ident),*; $($t:tt)*) => {
match *self {
$( Token::$i => quote!(rt::token::$i), )*
$( $t )*
}
}
}
gen_match! {
Eq, Lt, Le, EqEq, Ne, Ge, Gt, AndAnd, OrOr, Not, Tilde, At, Dot, DotDot, DotDotDot,
Comma, Semi, Colon, ModSep, RArrow, LArrow, FatArrow, Pound, Dollar, Question,
Underscore;
Token::OpenDelim(delim) => quote!(rt::token::OpenDelim((quote delim))),
Token::CloseDelim(delim) => quote!(rt::token::CloseDelim((quote delim))),
Token::BinOp(tok) => quote!(rt::token::BinOp((quote tok))),
Token::BinOpEq(tok) => quote!(rt::token::BinOpEq((quote tok))),
Token::Ident(ident) => quote!(rt::token::Ident((quote ident))),
Token::Lifetime(ident) => quote!(rt::token::Lifetime((quote ident))),
Token::Literal(lit, sfx) => quote!(rt::token::Literal((quote lit), (quote sfx))),
_ => panic!("Unhandled case!"),
}
}
}
impl Quote for token::BinOpToken {
fn quote(&self) -> TokenStream {
macro_rules! gen_match {
($($i:ident),*) => {
match *self {
$( token::BinOpToken::$i => quote!(rt::token::BinOpToken::$i), )*
}
}
}
gen_match!(Plus, Minus, Star, Slash, Percent, Caret, And, Or, Shl, Shr)
}
}
impl Quote for Lit {
fn quote(&self) -> TokenStream {
macro_rules! gen_match {
($($i:ident),*; $($raw:ident),*) => {
match *self {
$( Lit::$i(lit) => quote!(rt::token::Lit::$i((quote lit))), )*
$( Lit::$raw(lit, n) => {
quote!(::syntax::parse::token::Lit::$raw((quote lit), (quote n)))
})*
}
}
}
gen_match!(Byte, Char, Float, Str_, Integer, ByteStr; StrRaw, ByteStrRaw)
}
}
impl Quote for token::DelimToken {
fn quote(&self) -> TokenStream {
macro_rules! gen_match {
($($i:ident),*) => {
match *self {
$(token::DelimToken::$i => { quote!(rt::token::DelimToken::$i) })*
}
}
}
gen_match!(Paren, Bracket, Brace, NoDelim)
}
}