syntax: modernise attribute handling in syntax::attr.

This does a number of things, but especially dramatically reduce the
number of allocations performed for operations involving attributes/
meta items:

- Converts ast::meta_item & ast::attribute and other associated enums
  to CamelCase.
- Converts several standalone functions in syntax::attr into methods,
  defined on two traits AttrMetaMethods & AttributeMethods. The former
  is common to both MetaItem and Attribute since the latter is a thin
  wrapper around the former.
- Deletes functions that are unnecessary due to iterators.
- Converts other standalone functions to use iterators and the generic
  AttrMetaMethods rather than allocating a lot of new vectors (e.g. the
  old code would have to allocate a new vector to use functions that
  operated on &[meta_item] on &[attribute].)
- Moves the core algorithm of the #[cfg] matching to syntax::attr,
  similar to find_inline_attr and find_linkage_metas.

This doesn't have much of an effect on the speed of #[cfg] stripping,
despite hugely reducing the number of allocations performed; presumably
most of the time is spent in the ast folder rather than doing attribute
checks.

Also fixes the Eq instance of MetaItem_ to correctly ignore spaces, so
that `rustc --cfg 'foo(bar)'` now works.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/libsyntax/parse/obsolete.rs b/src/libsyntax/parse/obsolete.rs
index b014c5668b6..6d7fd3390fa 100644
--- a/src/libsyntax/parse/obsolete.rs
+++ b/src/libsyntax/parse/obsolete.rs
@@ -17,7 +17,7 @@ Obsolete syntax that becomes too hard to parse can be
 removed.
 */
 
-use ast::{expr, expr_lit, lit_nil, attribute};
+use ast::{expr, expr_lit, lit_nil, Attribute};
 use ast;
 use codemap::{span, respan};
 use parse::parser::Parser;
@@ -88,7 +88,7 @@ pub trait ParserObsoleteMethods {
     fn eat_obsolete_ident(&self, ident: &str) -> bool;
     fn try_parse_obsolete_struct_ctor(&self) -> bool;
     fn try_parse_obsolete_with(&self) -> bool;
-    fn try_parse_obsolete_priv_section(&self, attrs: &[attribute]) -> bool;
+    fn try_parse_obsolete_priv_section(&self, attrs: &[Attribute]) -> bool;
 }
 
 impl ParserObsoleteMethods for Parser {
@@ -322,7 +322,7 @@ impl ParserObsoleteMethods for Parser {
         }
     }
 
-    pub fn try_parse_obsolete_priv_section(&self, attrs: &[attribute])
+    pub fn try_parse_obsolete_priv_section(&self, attrs: &[Attribute])
                                            -> bool {
         if self.is_keyword(keywords::Priv) &&
                 self.look_ahead(1, |t| *t == token::LBRACE) {