Auto merge of #45791 - eddyb:quote-unquote, r=jseyfried
Prefer libproc_macro APIs to libsyntax ones in the quasi-quoter. The shift to using `proc_macro`'s own APIs in `proc_macro::quote`, both in the implementation of the quasi-quoter and the Rust code it generates to build `TokenStream`s at runtime, greatly reduces the dependency on `libsyntax`, with the generated runtime code being completely free of it. This is a prerequirement for introducing more abstraction/indirection between `proc_macro` and compiler implementation details (mainly those from `libsyntax`), which I want to attempt. cc @alexcrichton @jseyfried @nrc
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commit
563dc5171f
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@ -191,7 +191,7 @@ impl Default for Span {
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/// This is needed to implement a custom quoter.
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#[unstable(feature = "proc_macro", issue = "38356")]
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pub fn quote_span(span: Span) -> TokenStream {
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TokenStream(quote::Quote::quote(&span.0))
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quote::Quote::quote(span)
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}
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macro_rules! diagnostic_method {
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@ -728,7 +728,7 @@ impl TokenTree {
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#[unstable(feature = "proc_macro_internals", issue = "27812")]
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#[doc(hidden)]
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pub mod __internal {
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pub use quote::{Quoter, __rt};
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pub use quote::{LiteralKind, Quoter, unquote};
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use std::cell::Cell;
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@ -11,253 +11,255 @@
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//! # Quasiquoter
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//! This file contains the implementation internals of the quasiquoter provided by `quote!`.
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//! This quasiquoter uses macros 2.0 hygiene to reliably use items from `__rt`,
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//! including re-exported API `libsyntax`, to build a `syntax::tokenstream::TokenStream`
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//! and wrap it into a `proc_macro::TokenStream`.
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//! This quasiquoter uses macros 2.0 hygiene to reliably access
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//! items from `proc_macro`, to build a `proc_macro::TokenStream`.
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use {Delimiter, Literal, Spacing, Span, Term, TokenNode, TokenStream, TokenTree};
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use syntax::ast::Ident;
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use syntax::ext::base::{ExtCtxt, ProcMacro};
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use syntax::parse::token::{self, Token, Lit};
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use syntax::symbol::Symbol;
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use syntax::tokenstream::{Delimited, TokenTree, TokenStream, TokenStreamBuilder};
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use syntax_pos::{DUMMY_SP, Span};
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use syntax_pos::hygiene::SyntaxContext;
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use syntax::parse::token;
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use syntax::tokenstream;
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pub struct Quoter;
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pub mod __rt {
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pub use syntax::ast::Ident;
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pub use syntax::parse::token;
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pub use syntax::symbol::Symbol;
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pub use syntax::tokenstream::{TokenStream, TokenStreamBuilder, TokenTree, Delimited};
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pub use super::{ctxt, span};
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pub fn unquote<T: Into<::TokenStream> + Clone>(tokens: &T) -> TokenStream {
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T::into(tokens.clone()).0
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}
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}
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pub fn ctxt() -> SyntaxContext {
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::__internal::with_sess(|(_, mark)| SyntaxContext::empty().apply_mark(mark))
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}
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pub fn span() -> Span {
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::Span::default().0
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pub fn unquote<T: Into<TokenStream> + Clone>(tokens: &T) -> TokenStream {
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T::into(tokens.clone())
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}
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pub trait Quote {
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fn quote(&self) -> TokenStream;
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fn quote(self) -> TokenStream;
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}
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macro_rules! quote_tok {
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(,) => { Token::Comma };
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(.) => { Token::Dot };
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(:) => { Token::Colon };
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(::) => { Token::ModSep };
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(!) => { Token::Not };
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(<) => { Token::Lt };
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(>) => { Token::Gt };
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(_) => { Token::Underscore };
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(0) => { Token::Literal(token::Lit::Integer(Symbol::intern("0")), None) };
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(&) => { Token::BinOp(token::And) };
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($i:ident) => { Token::Ident(Ident { name: Symbol::intern(stringify!($i)), ctxt: ctxt() }) };
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(,) => { TokenNode::Op(',', Spacing::Alone) };
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(.) => { TokenNode::Op('.', Spacing::Alone) };
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(:) => { TokenNode::Op(':', Spacing::Alone) };
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(::) => {
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[
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TokenNode::Op(':', Spacing::Joint),
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TokenNode::Op(':', Spacing::Alone)
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].iter().cloned().collect::<TokenStream>()
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};
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(!) => { TokenNode::Op('!', Spacing::Alone) };
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(<) => { TokenNode::Op('<', Spacing::Alone) };
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(>) => { TokenNode::Op('>', Spacing::Alone) };
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(_) => { TokenNode::Op('_', Spacing::Alone) };
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(0) => { TokenNode::Literal(::Literal::integer(0)) };
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(&) => { TokenNode::Op('&', Spacing::Alone) };
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($i:ident) => { TokenNode::Term(Term::intern(stringify!($i))) };
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}
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macro_rules! quote_tree {
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((unquote $($t:tt)*)) => { TokenStream::from($($t)*) };
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((unquote $($t:tt)*)) => { $($t)* };
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((quote $($t:tt)*)) => { ($($t)*).quote() };
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(($($t:tt)*)) => { delimit(token::Paren, quote!($($t)*)) };
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([$($t:tt)*]) => { delimit(token::Bracket, quote!($($t)*)) };
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({$($t:tt)*}) => { delimit(token::Brace, quote!($($t)*)) };
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(rt) => { quote!(::__internal::__rt) };
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($t:tt) => { TokenStream::from(TokenTree::Token(span(), quote_tok!($t))) };
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}
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fn delimit(delim: token::DelimToken, stream: TokenStream) -> TokenStream {
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TokenTree::Delimited(span(), Delimited { delim: delim, tts: stream.into() }).into()
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(($($t:tt)*)) => { TokenNode::Group(Delimiter::Parenthesis, quote!($($t)*)) };
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([$($t:tt)*]) => { TokenNode::Group(Delimiter::Bracket, quote!($($t)*)) };
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({$($t:tt)*}) => { TokenNode::Group(Delimiter::Brace, quote!($($t)*)) };
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($t:tt) => { quote_tok!($t) };
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}
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macro_rules! quote {
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() => { TokenStream::empty() };
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($($t:tt)*) => { [ $( quote_tree!($t), )* ].iter().cloned().collect::<TokenStream>() };
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($($t:tt)*) => {
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[
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$(TokenStream::from(quote_tree!($t)),)*
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].iter().cloned().collect::<TokenStream>()
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};
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}
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impl ProcMacro for Quoter {
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fn expand<'cx>(&self, cx: &'cx mut ExtCtxt, _: Span, stream: TokenStream) -> TokenStream {
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fn expand<'cx>(&self, cx: &'cx mut ExtCtxt,
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_: ::syntax_pos::Span,
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stream: tokenstream::TokenStream)
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-> tokenstream::TokenStream {
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let mut info = cx.current_expansion.mark.expn_info().unwrap();
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info.callee.allow_internal_unstable = true;
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cx.current_expansion.mark.set_expn_info(info);
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::__internal::set_sess(cx, || quote!(::TokenStream { 0: (quote stream) }))
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::__internal::set_sess(cx, || TokenStream(stream).quote().0)
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}
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}
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impl<T: Quote> Quote for Option<T> {
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fn quote(&self) -> TokenStream {
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match *self {
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Some(ref t) => quote!(Some((quote t))),
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fn quote(self) -> TokenStream {
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match self {
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Some(t) => quote!(Some((quote t))),
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None => quote!(None),
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}
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}
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}
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impl Quote for TokenStream {
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fn quote(&self) -> TokenStream {
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let mut builder = TokenStreamBuilder::new();
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builder.push(quote!(rt::TokenStreamBuilder::new()));
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let mut trees = self.trees();
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loop {
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let (mut tree, mut is_joint) = match trees.next_as_stream() {
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Some(next) => next.as_tree(),
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None => return builder.add(quote!(.build())).build(),
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};
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if let TokenTree::Token(_, Token::Dollar) = tree {
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let (next_tree, next_is_joint) = match trees.next_as_stream() {
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Some(next) => next.as_tree(),
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None => panic!("unexpected trailing `$` in `quote!`"),
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};
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match next_tree {
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TokenTree::Token(_, Token::Ident(..)) => {
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builder.push(quote!(.add(rt::unquote(&(unquote next_tree)))));
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continue
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}
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TokenTree::Token(_, Token::Dollar) => {
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tree = next_tree;
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is_joint = next_is_joint;
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fn quote(self) -> TokenStream {
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if self.is_empty() {
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return quote!(::TokenStream::empty());
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}
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let mut after_dollar = false;
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let tokens = self.into_iter().filter_map(|tree| {
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if after_dollar {
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after_dollar = false;
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match tree.kind {
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TokenNode::Term(_) => {
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return Some(quote!(::__internal::unquote(&(unquote tree)),));
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}
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TokenNode::Op('$', _) => {}
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_ => panic!("`$` must be followed by an ident or `$` in `quote!`"),
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}
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} else if let TokenNode::Op('$', _) = tree.kind {
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after_dollar = true;
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return None;
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}
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builder.push(match is_joint {
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true => quote!(.add((quote tree).joint())),
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false => quote!(.add(rt::TokenStream::from((quote tree)))),
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});
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Some(quote!(::TokenStream::from((quote tree)),))
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}).collect::<TokenStream>();
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if after_dollar {
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panic!("unexpected trailing `$` in `quote!`");
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}
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quote!([(unquote tokens)].iter().cloned().collect::<::TokenStream>())
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}
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}
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impl Quote for TokenTree {
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fn quote(&self) -> TokenStream {
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match *self {
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TokenTree::Token(span, ref token) => quote! {
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rt::TokenTree::Token((quote span), (quote token))
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},
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TokenTree::Delimited(span, ref delimited) => quote! {
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rt::TokenTree::Delimited((quote span), (quote delimited))
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},
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}
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fn quote(self) -> TokenStream {
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quote!(::TokenTree { span: (quote self.span), kind: (quote self.kind) })
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}
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}
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impl Quote for Delimited {
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fn quote(&self) -> TokenStream {
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quote!(rt::Delimited { delim: (quote self.delim), tts: (quote self.stream()).into() })
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impl Quote for TokenNode {
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fn quote(self) -> TokenStream {
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macro_rules! gen_match {
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($($i:ident($($arg:ident),+)),*) => {
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match self {
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$(TokenNode::$i($($arg),+) => quote! {
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::TokenNode::$i($((quote $arg)),+)
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},)*
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}
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}
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}
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gen_match! { Op(op, kind), Group(delim, tokens), Term(term), Literal(lit) }
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}
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}
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impl Quote for char {
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fn quote(self) -> TokenStream {
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TokenNode::Literal(Literal::character(self)).into()
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}
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}
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impl<'a> Quote for &'a str {
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fn quote(&self) -> TokenStream {
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TokenTree::Token(span(), Token::Literal(token::Lit::Str_(Symbol::intern(self)), None))
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.into()
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fn quote(self) -> TokenStream {
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TokenNode::Literal(Literal::string(self)).into()
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}
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}
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impl Quote for usize {
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fn quote(&self) -> TokenStream {
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let integer_symbol = Symbol::intern(&self.to_string());
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TokenTree::Token(DUMMY_SP, Token::Literal(token::Lit::Integer(integer_symbol), None))
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.into()
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fn quote(self) -> TokenStream {
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TokenNode::Literal(Literal::integer(self as i128)).into()
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}
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}
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impl Quote for Ident {
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fn quote(&self) -> TokenStream {
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quote!(rt::Ident { name: (quote self.name), ctxt: rt::ctxt() })
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}
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}
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impl Quote for Symbol {
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fn quote(&self) -> TokenStream {
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quote!(rt::Symbol::intern((quote &*self.as_str())))
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impl Quote for Term {
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fn quote(self) -> TokenStream {
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quote!(::Term::intern((quote self.as_str())))
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}
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}
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impl Quote for Span {
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fn quote(&self) -> TokenStream {
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quote!(rt::span())
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fn quote(self) -> TokenStream {
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quote!(::Span::default())
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}
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}
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impl Quote for Token {
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fn quote(&self) -> TokenStream {
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macro_rules! gen_match {
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($($i:ident),*; $($t:tt)*) => {
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match *self {
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$( Token::$i => quote!(rt::token::$i), )*
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$( $t )*
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}
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}
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macro_rules! literals {
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($($i:ident),*; $($raw:ident),*) => {
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pub enum LiteralKind {
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$($i,)*
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$($raw(usize),)*
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}
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gen_match! {
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Eq, Lt, Le, EqEq, Ne, Ge, Gt, AndAnd, OrOr, Not, Tilde, At, Dot, DotDot, DotDotDot,
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DotDotEq, Comma, Semi, Colon, ModSep, RArrow, LArrow, FatArrow, Pound, Dollar,
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Question, Underscore;
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Token::OpenDelim(delim) => quote!(rt::token::OpenDelim((quote delim))),
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Token::CloseDelim(delim) => quote!(rt::token::CloseDelim((quote delim))),
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Token::BinOp(tok) => quote!(rt::token::BinOp((quote tok))),
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Token::BinOpEq(tok) => quote!(rt::token::BinOpEq((quote tok))),
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Token::Ident(ident) => quote!(rt::token::Ident((quote ident))),
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Token::Lifetime(ident) => quote!(rt::token::Lifetime((quote ident))),
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Token::Literal(lit, sfx) => quote!(rt::token::Literal((quote lit), (quote sfx))),
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_ => panic!("Unhandled case!"),
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}
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}
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}
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impl Quote for token::BinOpToken {
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fn quote(&self) -> TokenStream {
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macro_rules! gen_match {
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($($i:ident),*) => {
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match *self {
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$( token::BinOpToken::$i => quote!(rt::token::BinOpToken::$i), )*
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}
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}
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}
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gen_match!(Plus, Minus, Star, Slash, Percent, Caret, And, Or, Shl, Shr)
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}
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}
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impl Quote for Lit {
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fn quote(&self) -> TokenStream {
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macro_rules! gen_match {
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($($i:ident),*; $($raw:ident),*) => {
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match *self {
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$( Lit::$i(lit) => quote!(rt::token::Lit::$i((quote lit))), )*
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$( Lit::$raw(lit, n) => {
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quote!(::syntax::parse::token::Lit::$raw((quote lit), (quote n)))
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impl LiteralKind {
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pub fn with_contents_and_suffix(self, contents: Term, suffix: Option<Term>)
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-> Literal {
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let contents = contents.0;
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let suffix = suffix.map(|t| t.0);
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match self {
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$(LiteralKind::$i => {
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Literal(token::Literal(token::Lit::$i(contents), suffix))
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})*
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$(LiteralKind::$raw(n) => {
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Literal(token::Literal(token::Lit::$raw(contents, n), suffix))
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})*
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}
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}
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}
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gen_match!(Byte, Char, Float, Str_, Integer, ByteStr; StrRaw, ByteStrRaw)
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}
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}
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impl Literal {
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fn kind_contents_and_suffix(self) -> (LiteralKind, Term, Option<Term>) {
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let (lit, suffix) = match self.0 {
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token::Literal(lit, suffix) => (lit, suffix),
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_ => panic!("unsupported literal {:?}", self.0),
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};
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impl Quote for token::DelimToken {
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fn quote(&self) -> TokenStream {
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macro_rules! gen_match {
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($($i:ident),*) => {
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match *self {
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$(token::DelimToken::$i => { quote!(rt::token::DelimToken::$i) })*
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let (kind, contents) = match lit {
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$(token::Lit::$i(contents) => (LiteralKind::$i, contents),)*
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$(token::Lit::$raw(contents, n) => (LiteralKind::$raw(n), contents),)*
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};
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(kind, Term(contents), suffix.map(Term))
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}
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}
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impl Quote for LiteralKind {
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fn quote(self) -> TokenStream {
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match self {
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$(LiteralKind::$i => quote! {
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::__internal::LiteralKind::$i
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},)*
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$(LiteralKind::$raw(n) => quote! {
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::__internal::LiteralKind::$raw((quote n))
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},)*
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}
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}
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}
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gen_match!(Paren, Bracket, Brace, NoDelim)
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impl Quote for Literal {
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fn quote(self) -> TokenStream {
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let (kind, contents, suffix) = self.kind_contents_and_suffix();
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quote! {
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(quote kind).with_contents_and_suffix((quote contents), (quote suffix))
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}
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}
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}
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}
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}
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literals!(Byte, Char, Float, Str_, Integer, ByteStr; StrRaw, ByteStrRaw);
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impl Quote for Delimiter {
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fn quote(self) -> TokenStream {
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macro_rules! gen_match {
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($($i:ident),*) => {
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match self {
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$(Delimiter::$i => { quote!(::Delimiter::$i) })*
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}
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}
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}
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gen_match!(Parenthesis, Brace, Bracket, None)
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}
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}
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impl Quote for Spacing {
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fn quote(self) -> TokenStream {
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macro_rules! gen_match {
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($($i:ident),*) => {
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match self {
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$(Spacing::$i => { quote!(::Spacing::$i) })*
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}
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}
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}
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gen_match!(Alone, Joint)
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}
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}
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