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, 2 insertions, 2 deletions

diff --git a/src/libsyntax/ext/auto_encode.rs b/src/libsyntax/ext/auto_encode.rs
index 64d2644b383..4ada7f7479b 100644
--- a/src/libsyntax/ext/auto_encode.rs
+++ b/src/libsyntax/ext/auto_encode.rs
@@ -17,7 +17,7 @@ use ext::base::*;
 pub fn expand_auto_encode(
     cx: @ExtCtxt,
     span: span,
-    _mitem: @ast::meta_item,
+    _mitem: @ast::MetaItem,
     in_items: ~[@ast::item]
 ) -> ~[@ast::item] {
     cx.span_err(span, "`#[auto_encode]` is deprecated, use `#[deriving(Encodable)]` instead");
@@ -27,7 +27,7 @@ pub fn expand_auto_encode(
 pub fn expand_auto_decode(
     cx: @ExtCtxt,
     span: span,
-    _mitem: @ast::meta_item,
+    _mitem: @ast::MetaItem,
     in_items: ~[@ast::item]
 ) -> ~[@ast::item] {
     cx.span_err(span, "`#[auto_decode]` is deprecated, use `#[deriving(Decodable)]` instead");