bjoernager/rust
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Interpolate AST nodes in quasiquote.

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This changes the `ToTokens` implementations for expressions, statements,
etc. with almost-trivial ones that produce `Interpolated(*Nt(...))`
pseudo-tokens. In this way, quasiquote now works the same way as macros
do: already-parsed AST fragments are used as-is, not reparsed.

The `ToSource` trait is removed. Quasiquote no longer involves
pretty-printing at all, which removes the need for the
`encode_with_hygiene` hack. All associated machinery is removed.

A new `Nonterminal` is added, NtArm, which the parser now interpolates.
This is just for quasiquote, not macros (although it could be in the
future).

`ToTokens` is no longer implemented for `Arg` (although this could be
added again) and `Generics` (which I don't think makes sense).

This breaks any compiler extensions that relied on the ability of
`ToTokens` to turn AST fragments back into inspectable token trees. For
this reason, this closes #16987.

As such, this is a [breaking-change].

Fixes #16472.
Fixes #15962.
Fixes #17397.
Fixes #16617.
This commit is contained in:
Geoffry Song 2015-03-05 15:06:49 -05:00
parent da623844a9
commit 2d9831dea5
9 changed files with 246 additions and 562 deletions
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7
src/libsyntax/parse/parser.rs
View file

@ -1152,7 +1152,8 @@ impl<'a> Parser<'a> {
&token::OpenDelim(token::Brace),
&token::CloseDelim(token::Brace),
seq_sep_none(),
|p| {
|p| -> PResult<P<TraitItem>> {
maybe_whole!(no_clone p, NtTraitItem);
let mut attrs = p.parse_outer_attributes();
let lo = p.span.lo;
@ -2943,6 +2944,8 @@ impl<'a> Parser<'a> {
}
pub fn parse_arm_nopanic(&mut self) -> PResult<Arm> {
maybe_whole!(no_clone self, NtArm);
let attrs = self.parse_outer_attributes();
let pats = try!(self.parse_pats());
let mut guard = None;
@ -4335,6 +4338,8 @@ impl<'a> Parser<'a> {
/// Parse an impl item.
pub fn parse_impl_item(&mut self) -> PResult<P<ImplItem>> {
maybe_whole!(no_clone self, NtImplItem);
let mut attrs = self.parse_outer_attributes();
let lo = self.span.lo;
let vis = try!(self.parse_visibility());