src/libsyntax/attr.rs - rust - Git at Google

 // Copyright 2012-2014 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.

 // Functions dealing with attributes and meta items

 pub use self::StabilityLevel::*;
 pub use self::ReprAttr::*;
 pub use self::IntType::*;

 use ast;
 use ast::{AttrId, Attribute, Attribute_, MetaItem, MetaWord, MetaNameValue, MetaList};
 use codemap::{Span, Spanned, spanned, dummy_spanned};
 use codemap::BytePos;
 use diagnostic::SpanHandler;
 use parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
 use parse::token::{InternedString, intern_and_get_ident};
 use parse::token;
 use ptr::P;

 use std::cell::{RefCell, Cell};
 use std::collections::BitSet;
 use std::collections::HashSet;
 use std::fmt;

 thread_local! { static USED_ATTRS: RefCell<BitSet> = RefCell::new(BitSet::new()) }

 pub fn mark_used(attr: &Attribute) {
     let AttrId(id) = attr.node.id;
     USED_ATTRS.with(|slot| slot.borrow_mut().insert(id));
 }

 pub fn is_used(attr: &Attribute) -> bool {
     let AttrId(id) = attr.node.id;
     USED_ATTRS.with(|slot| slot.borrow().contains(&id))
 }

 pub trait AttrMetaMethods {
     fn check_name(&self, name: &str) -> bool {
         name == &self.name()[..]
     }

     /// Retrieve the name of the meta item, e.g. `foo` in `#[foo]`,
     /// `#[foo="bar"]` and `#[foo(bar)]`
     fn name(&self) -> InternedString;

     /// Gets the string value if self is a MetaNameValue variant
     /// containing a string, otherwise None.
     fn value_str(&self) -> Option<InternedString>;
     /// Gets a list of inner meta items from a list MetaItem type.
     fn meta_item_list<'a>(&'a self) -> Option<&'a [P<MetaItem>]>;

     fn span(&self) -> Span;
 }

 impl AttrMetaMethods for Attribute {
     fn check_name(&self, name: &str) -> bool {
         let matches = name == &self.name()[..];
         if matches {
             mark_used(self);
         }
         matches
     }
     fn name(&self) -> InternedString { self.meta().name() }
     fn value_str(&self) -> Option<InternedString> {
         self.meta().value_str()
     }
     fn meta_item_list<'a>(&'a self) -> Option<&'a [P<MetaItem>]> {
         self.node.value.meta_item_list()
     }
     fn span(&self) -> Span { self.meta().span }
 }

 impl AttrMetaMethods for MetaItem {
     fn name(&self) -> InternedString {
         match self.node {
             MetaWord(ref n) => (*n).clone(),
             MetaNameValue(ref n, _) => (*n).clone(),
             MetaList(ref n, _) => (*n).clone(),
         }
     }

     fn value_str(&self) -> Option<InternedString> {
         match self.node {
             MetaNameValue(_, ref v) => {
                 match v.node {
                     ast::LitStr(ref s, _) => Some((*s).clone()),
                     _ => None,
                 }
             },
             _ => None
         }
     }

     fn meta_item_list<'a>(&'a self) -> Option<&'a [P<MetaItem>]> {
         match self.node {
             MetaList(_, ref l) => Some(&l[..]),
             _ => None
         }
     }
     fn span(&self) -> Span { self.span }
 }

 // Annoying, but required to get test_cfg to work
 impl AttrMetaMethods for P<MetaItem> {
     fn name(&self) -> InternedString { (**self).name() }
     fn value_str(&self) -> Option<InternedString> { (**self).value_str() }
     fn meta_item_list<'a>(&'a self) -> Option<&'a [P<MetaItem>]> {
         (**self).meta_item_list()
     }
     fn span(&self) -> Span { (**self).span() }
 }


 pub trait AttributeMethods {
     fn meta<'a>(&'a self) -> &'a MetaItem;
     fn with_desugared_doc<T, F>(&self, f: F) -> T where
         F: FnOnce(&Attribute) -> T;
 }

 impl AttributeMethods for Attribute {
     /// Extract the MetaItem from inside this Attribute.
     fn meta<'a>(&'a self) -> &'a MetaItem {
         &*self.node.value
     }

     /// Convert self to a normal #[doc="foo"] comment, if it is a
     /// comment like `///` or `/** */`. (Returns self unchanged for
     /// non-sugared doc attributes.)
     fn with_desugared_doc<T, F>(&self, f: F) -> T where
         F: FnOnce(&Attribute) -> T,
     {
         if self.node.is_sugared_doc {
             let comment = self.value_str().unwrap();
             let meta = mk_name_value_item_str(
                 InternedString::new("doc"),
                 token::intern_and_get_ident(&strip_doc_comment_decoration(
                         &comment)));
             if self.node.style == ast::AttrOuter {
                 f(&mk_attr_outer(self.node.id, meta))
             } else {
                 f(&mk_attr_inner(self.node.id, meta))
             }
         } else {
             f(self)
         }
     }
 }

 /* Constructors */

 pub fn mk_name_value_item_str(name: InternedString, value: InternedString)
                               -> P<MetaItem> {
     let value_lit = dummy_spanned(ast::LitStr(value, ast::CookedStr));
     mk_name_value_item(name, value_lit)
 }

 pub fn mk_name_value_item(name: InternedString, value: ast::Lit)
                           -> P<MetaItem> {
     P(dummy_spanned(MetaNameValue(name, value)))
 }

 pub fn mk_list_item(name: InternedString, items: Vec<P<MetaItem>>) -> P<MetaItem> {
     P(dummy_spanned(MetaList(name, items)))
 }

 pub fn mk_word_item(name: InternedString) -> P<MetaItem> {
     P(dummy_spanned(MetaWord(name)))
 }

 thread_local! { static NEXT_ATTR_ID: Cell<usize> = Cell::new(0) }

 pub fn mk_attr_id() -> AttrId {
     let id = NEXT_ATTR_ID.with(|slot| {
         let r = slot.get();
         slot.set(r + 1);
         r
     });
     AttrId(id)
 }

 /// Returns an inner attribute with the given value.
 pub fn mk_attr_inner(id: AttrId, item: P<MetaItem>) -> Attribute {
     dummy_spanned(Attribute_ {
         id: id,
         style: ast::AttrInner,
         value: item,
         is_sugared_doc: false,
     })
 }

 /// Returns an outer attribute with the given value.
 pub fn mk_attr_outer(id: AttrId, item: P<MetaItem>) -> Attribute {
     dummy_spanned(Attribute_ {
         id: id,
         style: ast::AttrOuter,
         value: item,
         is_sugared_doc: false,
     })
 }

 pub fn mk_sugared_doc_attr(id: AttrId, text: InternedString, lo: BytePos,
                            hi: BytePos)
                            -> Attribute {
     let style = doc_comment_style(&text);
     let lit = spanned(lo, hi, ast::LitStr(text, ast::CookedStr));
     let attr = Attribute_ {
         id: id,
         style: style,
         value: P(spanned(lo, hi, MetaNameValue(InternedString::new("doc"),
                                                lit))),
         is_sugared_doc: true
     };
     spanned(lo, hi, attr)
 }

 /* Searching */
 /// Check if `needle` occurs in `haystack` by a structural
 /// comparison. This is slightly subtle, and relies on ignoring the
 /// span included in the `==` comparison a plain MetaItem.
 pub fn contains(haystack: &[P<MetaItem>], needle: &MetaItem) -> bool {
     debug!("attr::contains (name={})", needle.name());
     haystack.iter().any(|item| {
         debug!("  testing: {}", item.name());
         item.node == needle.node
     })
 }

 pub fn contains_name<AM: AttrMetaMethods>(metas: &[AM], name: &str) -> bool {
     debug!("attr::contains_name (name={})", name);
     metas.iter().any(|item| {
         debug!("  testing: {}", item.name());
         item.check_name(name)
     })
 }

 pub fn first_attr_value_str_by_name(attrs: &[Attribute], name: &str)
                                  -> Option<InternedString> {
     attrs.iter()
         .find(|at| at.check_name(name))
         .and_then(|at| at.value_str())
 }

 pub fn last_meta_item_value_str_by_name(items: &[P<MetaItem>], name: &str)
                                      -> Option<InternedString> {
     items.iter()
          .rev()
          .find(|mi| mi.check_name(name))
          .and_then(|i| i.value_str())
 }

 /* Higher-level applications */

 pub fn sort_meta_items(items: Vec<P<MetaItem>>) -> Vec<P<MetaItem>> {
     // This is sort of stupid here, but we need to sort by
     // human-readable strings.
     let mut v = items.into_iter()
         .map(|mi| (mi.name(), mi))
         .collect::<Vec<(InternedString, P<MetaItem>)>>();

     v.sort_by(|&(ref a, _), &(ref b, _)| a.cmp(b));

     // There doesn't seem to be a more optimal way to do this
     v.into_iter().map(|(_, m)| m.map(|Spanned {node, span}| {
         Spanned {
             node: match node {
                 MetaList(n, mis) => MetaList(n, sort_meta_items(mis)),
                 _ => node
             },
             span: span
         }
     })).collect()
 }

 pub fn find_crate_name(attrs: &[Attribute]) -> Option<InternedString> {
     first_attr_value_str_by_name(attrs, "crate_name")
 }

 /// Find the value of #[export_name=*] attribute and check its validity.
 pub fn find_export_name_attr(diag: &SpanHandler, attrs: &[Attribute]) -> Option<InternedString> {
     attrs.iter().fold(None, |ia,attr| {
         if attr.check_name("export_name") {
             if let s@Some(_) = attr.value_str() {
                 s
             } else {
                 diag.span_err(attr.span, "export_name attribute has invalid format");
                 diag.handler.help("use #[export_name=\"*\"]");
                 None
             }
         } else {
             ia
         }
     })
 }

 #[derive(Copy, Clone, PartialEq)]
 pub enum InlineAttr {
     None,
     Hint,
     Always,
     Never,
 }

 /// Determine what `#[inline]` attribute is present in `attrs`, if any.
 pub fn find_inline_attr(diagnostic: Option<&SpanHandler>, attrs: &[Attribute]) -> InlineAttr {
     // FIXME (#2809)---validate the usage of #[inline] and #[inline]
     attrs.iter().fold(InlineAttr::None, |ia,attr| {
         match attr.node.value.node {
             MetaWord(ref n) if *n == "inline" => {
                 mark_used(attr);
                 InlineAttr::Hint
             }
             MetaList(ref n, ref items) if *n == "inline" => {
                 mark_used(attr);
                 if items.len() != 1 {
                     diagnostic.map(|d|{ d.span_err(attr.span, "expected one argument"); });
                     InlineAttr::None
                 } else if contains_name(&items[..], "always") {
                     InlineAttr::Always
                 } else if contains_name(&items[..], "never") {
                     InlineAttr::Never
                 } else {
                     diagnostic.map(|d|{ d.span_err((*items[0]).span, "invalid argument"); });
                     InlineAttr::None
                 }
             }
             _ => ia
         }
     })
 }

 /// True if `#[inline]` or `#[inline(always)]` is present in `attrs`.
 pub fn requests_inline(attrs: &[Attribute]) -> bool {
     match find_inline_attr(None, attrs) {
         InlineAttr::Hint | InlineAttr::Always => true,
         InlineAttr::None | InlineAttr::Never => false,
     }
 }

 /// Tests if a cfg-pattern matches the cfg set
 pub fn cfg_matches(diagnostic: &SpanHandler, cfgs: &[P<MetaItem>], cfg: &ast::MetaItem) -> bool {
     match cfg.node {
         ast::MetaList(ref pred, ref mis) if &pred[..] == "any" =>
             mis.iter().any(|mi| cfg_matches(diagnostic, cfgs, &**mi)),
         ast::MetaList(ref pred, ref mis) if &pred[..] == "all" =>
             mis.iter().all(|mi| cfg_matches(diagnostic, cfgs, &**mi)),
         ast::MetaList(ref pred, ref mis) if &pred[..] == "not" => {
             if mis.len() != 1 {
                 diagnostic.span_err(cfg.span, "expected 1 cfg-pattern");
                 return false;
             }
             !cfg_matches(diagnostic, cfgs, &*mis[0])
         }
         ast::MetaList(ref pred, _) => {
             diagnostic.span_err(cfg.span, &format!("invalid predicate `{}`", pred));
             false
         },
         ast::MetaWord(_) | ast::MetaNameValue(..) => contains(cfgs, cfg),
     }
 }

 /// Represents the #[deprecated] and friends attributes.
 #[derive(RustcEncodable,RustcDecodable,Clone,Debug)]
 pub struct Stability {
     pub level: StabilityLevel,
     pub feature: InternedString,
     pub since: Option<InternedString>,
     pub deprecated_since: Option<InternedString>,
     // The reason for the current stability level. If deprecated, the
     // reason for deprecation.
     pub reason: Option<InternedString>,
 }

 /// The available stability levels.
 #[derive(RustcEncodable,RustcDecodable,PartialEq,PartialOrd,Clone,Debug,Copy)]
 pub enum StabilityLevel {
     Unstable,
     Stable,
 }

 impl fmt::Display for StabilityLevel {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         fmt::Debug::fmt(self, f)
     }
 }

 fn find_stability_generic<'a,
                               AM: AttrMetaMethods,
                               I: Iterator<Item=&'a AM>>
                              (diagnostic: &SpanHandler, attrs: I, item_sp: Span)
                              -> (Option<Stability>, Vec<&'a AM>) {

     let mut stab: Option<Stability> = None;
     let mut deprecated: Option<(InternedString, Option<InternedString>)> = None;
     let mut used_attrs: Vec<&'a AM> = vec![];

     'outer: for attr in attrs {
         let tag = attr.name();
         let tag = &tag[..];
         if tag != "deprecated" && tag != "unstable" && tag != "stable" {
             continue // not a stability level
         }

         used_attrs.push(attr);

         let (feature, since, reason) = match attr.meta_item_list() {
             Some(metas) => {
                 let mut feature = None;
                 let mut since = None;
                 let mut reason = None;
                 for meta in metas.iter() {
                     if meta.name() == "feature" {
                         match meta.value_str() {
                             Some(v) => feature = Some(v),
                             None => {
                                 diagnostic.span_err(meta.span, "incorrect meta item");
                                 continue 'outer;
                             }
                         }
                     }
                     if &meta.name()[..] == "since" {
                         match meta.value_str() {
                             Some(v) => since = Some(v),
                             None => {
                                 diagnostic.span_err(meta.span, "incorrect meta item");
                                 continue 'outer;
                             }
                         }
                     }
                     if &meta.name()[..] == "reason" {
                         match meta.value_str() {
                             Some(v) => reason = Some(v),
                             None => {
                                 diagnostic.span_err(meta.span, "incorrect meta item");
                                 continue 'outer;
                             }
                         }
                     }
                 }
                 (feature, since, reason)
             }
             None => {
                 diagnostic.span_err(attr.span(), "incorrect stability attribute type");
                 continue
             }
         };

         // Deprecated tags don't require feature names
         if feature == None && tag != "deprecated" {
             diagnostic.span_err(attr.span(), "missing 'feature'");
         }

         // Unstable tags don't require a version
         if since == None && tag != "unstable" {
             diagnostic.span_err(attr.span(), "missing 'since'");
         }

         if tag == "unstable" || tag == "stable" {
             if stab.is_some() {
                 diagnostic.span_err(item_sp, "multiple stability levels");
             }

             let level = match tag {
                 "unstable" => Unstable,
                 "stable" => Stable,
                 _ => unreachable!()
             };

             stab = Some(Stability {
                 level: level,
                 feature: feature.unwrap_or(intern_and_get_ident("bogus")),
                 since: since,
                 deprecated_since: None,
                 reason: reason
             });
         } else { // "deprecated"
             if deprecated.is_some() {
                 diagnostic.span_err(item_sp, "multiple deprecated attributes");
             }

             deprecated = Some((since.unwrap_or(intern_and_get_ident("bogus")), reason));
         }
     }

     // Merge the deprecation info into the stability info
     if deprecated.is_some() {
         match stab {
             Some(ref mut s) => {
                 let (since, reason) = deprecated.unwrap();
                 s.deprecated_since = Some(since);
                 s.reason = reason;
             }
             None => {
                 diagnostic.span_err(item_sp, "deprecated attribute must be paired with \
                                               either stable or unstable attribute");
             }
         }
     }

     (stab, used_attrs)
 }

 /// Find the first stability attribute. `None` if none exists.
 pub fn find_stability(diagnostic: &SpanHandler, attrs: &[Attribute],
                       item_sp: Span) -> Option<Stability> {
     let (s, used) = find_stability_generic(diagnostic, attrs.iter(), item_sp);
     for used in used { mark_used(used) }
     return s;
 }

 pub fn require_unique_names(diagnostic: &SpanHandler, metas: &[P<MetaItem>]) {
     let mut set = HashSet::new();
     for meta in metas {
         let name = meta.name();

         if !set.insert(name.clone()) {
             panic!(diagnostic.span_fatal(meta.span,
                                   &format!("duplicate meta item `{}`", name)));
         }
     }
 }


 /// Parse #[repr(...)] forms.
 ///
 /// Valid repr contents: any of the primitive integral type names (see
 /// `int_type_of_word`, below) to specify enum discriminant type; `C`, to use
 /// the same discriminant size that the corresponding C enum would or C
 /// structure layout, and `packed` to remove padding.
 pub fn find_repr_attrs(diagnostic: &SpanHandler, attr: &Attribute) -> Vec<ReprAttr> {
     let mut acc = Vec::new();
     match attr.node.value.node {
         ast::MetaList(ref s, ref items) if *s == "repr" => {
             mark_used(attr);
             for item in items {
                 match item.node {
                     ast::MetaWord(ref word) => {
                         let hint = match &word[..] {
                             // Can't use "extern" because it's not a lexical identifier.
                             "C" => Some(ReprExtern),
                             "packed" => Some(ReprPacked),
                             _ => match int_type_of_word(&word) {
                                 Some(ity) => Some(ReprInt(item.span, ity)),
                                 None => {
                                     // Not a word we recognize
                                     diagnostic.span_err(item.span,
                                                         "unrecognized representation hint");
                                     None
                                 }
                             }
                         };

                         match hint {
                             Some(h) => acc.push(h),
                             None => { }
                         }
                     }
                     // Not a word:
                     _ => diagnostic.span_err(item.span, "unrecognized enum representation hint")
                 }
             }
         }
         // Not a "repr" hint: ignore.
         _ => { }
     }
     acc
 }

 fn int_type_of_word(s: &str) -> Option<IntType> {
     match s {
         "i8" => Some(SignedInt(ast::TyI8)),
         "u8" => Some(UnsignedInt(ast::TyU8)),
         "i16" => Some(SignedInt(ast::TyI16)),
         "u16" => Some(UnsignedInt(ast::TyU16)),
         "i32" => Some(SignedInt(ast::TyI32)),
         "u32" => Some(UnsignedInt(ast::TyU32)),
         "i64" => Some(SignedInt(ast::TyI64)),
         "u64" => Some(UnsignedInt(ast::TyU64)),
         "isize" => Some(SignedInt(ast::TyIs)),
         "usize" => Some(UnsignedInt(ast::TyUs)),
         _ => None
     }
 }

 #[derive(PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, Clone)]
 pub enum ReprAttr {
     ReprAny,
     ReprInt(Span, IntType),
     ReprExtern,
     ReprPacked,
 }

 impl ReprAttr {
     pub fn is_ffi_safe(&self) -> bool {
         match *self {
             ReprAny => false,
             ReprInt(_sp, ity) => ity.is_ffi_safe(),
             ReprExtern => true,
             ReprPacked => false
         }
     }
 }

 #[derive(Eq, Hash, PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, Clone)]
 pub enum IntType {
     SignedInt(ast::IntTy),
     UnsignedInt(ast::UintTy)
 }

 impl IntType {
     #[inline]
     pub fn is_signed(self) -> bool {
         match self {
             SignedInt(..) => true,
             UnsignedInt(..) => false
         }
     }
     fn is_ffi_safe(self) -> bool {
         match self {
             SignedInt(ast::TyI8) | UnsignedInt(ast::TyU8) |
             SignedInt(ast::TyI16) | UnsignedInt(ast::TyU16) |
             SignedInt(ast::TyI32) | UnsignedInt(ast::TyU32) |
             SignedInt(ast::TyI64) | UnsignedInt(ast::TyU64) => true,
             SignedInt(ast::TyIs) | UnsignedInt(ast::TyUs) => false
         }
     }
 }
	// Copyright 2012-2014 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.

	// Functions dealing with attributes and meta items

	pub use self::StabilityLevel::*;
	pub use self::ReprAttr::*;
	pub use self::IntType::*;

	use ast;
	use ast::{AttrId, Attribute, Attribute_, MetaItem, MetaWord, MetaNameValue, MetaList};
	use codemap::{Span, Spanned, spanned, dummy_spanned};
	use codemap::BytePos;
	use diagnostic::SpanHandler;
	use parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
	use parse::token::{InternedString, intern_and_get_ident};
	use parse::token;
	use ptr::P;

	use std::cell::{RefCell, Cell};
	use std::collections::BitSet;
	use std::collections::HashSet;
	use std::fmt;

	thread_local! { static USED_ATTRS: RefCell<BitSet> = RefCell::new(BitSet::new()) }

	pub fn mark_used(attr: &Attribute) {
	let AttrId(id) = attr.node.id;
	USED_ATTRS.with(\|slot\| slot.borrow_mut().insert(id));
	}

	pub fn is_used(attr: &Attribute) -> bool {
	let AttrId(id) = attr.node.id;
	USED_ATTRS.with(\|slot\| slot.borrow().contains(&id))
	}

	pub trait AttrMetaMethods {
	fn check_name(&self, name: &str) -> bool {
	name == &self.name()[..]
	}

	/// Retrieve the name of the meta item, e.g. `foo` in `#[foo]`,
	/// `#[foo="bar"]` and `#[foo(bar)]`
	fn name(&self) -> InternedString;

	/// Gets the string value if self is a MetaNameValue variant
	/// containing a string, otherwise None.
	fn value_str(&self) -> Option<InternedString>;
	/// Gets a list of inner meta items from a list MetaItem type.
	fn meta_item_list<'a>(&'a self) -> Option<&'a [P<MetaItem>]>;

	fn span(&self) -> Span;
	}

	impl AttrMetaMethods for Attribute {
	fn check_name(&self, name: &str) -> bool {
	let matches = name == &self.name()[..];
	if matches {
	mark_used(self);
	}
	matches
	}
	fn name(&self) -> InternedString { self.meta().name() }
	fn value_str(&self) -> Option<InternedString> {
	self.meta().value_str()
	}
	fn meta_item_list<'a>(&'a self) -> Option<&'a [P<MetaItem>]> {
	self.node.value.meta_item_list()
	}
	fn span(&self) -> Span { self.meta().span }
	}

	impl AttrMetaMethods for MetaItem {
	fn name(&self) -> InternedString {
	match self.node {
	MetaWord(ref n) => (*n).clone(),
	MetaNameValue(ref n, _) => (*n).clone(),
	MetaList(ref n, _) => (*n).clone(),
	}
	}

	fn value_str(&self) -> Option<InternedString> {
	match self.node {
	MetaNameValue(_, ref v) => {
	match v.node {
	ast::LitStr(ref s, _) => Some((*s).clone()),
	_ => None,
	}
	},
	_ => None
	}
	}

	fn meta_item_list<'a>(&'a self) -> Option<&'a [P<MetaItem>]> {
	match self.node {
	MetaList(_, ref l) => Some(&l[..]),
	_ => None
	}
	}
	fn span(&self) -> Span { self.span }
	}

	// Annoying, but required to get test_cfg to work
	impl AttrMetaMethods for P<MetaItem> {
	fn name(&self) -> InternedString { (**self).name() }
	fn value_str(&self) -> Option<InternedString> { (**self).value_str() }
	fn meta_item_list<'a>(&'a self) -> Option<&'a [P<MetaItem>]> {
	(**self).meta_item_list()
	}
	fn span(&self) -> Span { (**self).span() }
	}


	pub trait AttributeMethods {
	fn meta<'a>(&'a self) -> &'a MetaItem;
	fn with_desugared_doc<T, F>(&self, f: F) -> T where
	F: FnOnce(&Attribute) -> T;
	}

	impl AttributeMethods for Attribute {
	/// Extract the MetaItem from inside this Attribute.
	fn meta<'a>(&'a self) -> &'a MetaItem {
	&*self.node.value
	}

	/// Convert self to a normal #[doc="foo"] comment, if it is a
	/// comment like `///` or `/** */`. (Returns self unchanged for
	/// non-sugared doc attributes.)
	fn with_desugared_doc<T, F>(&self, f: F) -> T where
	F: FnOnce(&Attribute) -> T,
	{
	if self.node.is_sugared_doc {
	let comment = self.value_str().unwrap();
	let meta = mk_name_value_item_str(
	InternedString::new("doc"),
	token::intern_and_get_ident(&strip_doc_comment_decoration(
	&comment)));
	if self.node.style == ast::AttrOuter {
	f(&mk_attr_outer(self.node.id, meta))
	} else {
	f(&mk_attr_inner(self.node.id, meta))
	}
	} else {
	f(self)
	}
	}
	}

	/* Constructors */

	pub fn mk_name_value_item_str(name: InternedString, value: InternedString)
	-> P<MetaItem> {
	let value_lit = dummy_spanned(ast::LitStr(value, ast::CookedStr));
	mk_name_value_item(name, value_lit)
	}

	pub fn mk_name_value_item(name: InternedString, value: ast::Lit)
	-> P<MetaItem> {
	P(dummy_spanned(MetaNameValue(name, value)))
	}

	pub fn mk_list_item(name: InternedString, items: Vec<P<MetaItem>>) -> P<MetaItem> {
	P(dummy_spanned(MetaList(name, items)))
	}

	pub fn mk_word_item(name: InternedString) -> P<MetaItem> {
	P(dummy_spanned(MetaWord(name)))
	}

	thread_local! { static NEXT_ATTR_ID: Cell<usize> = Cell::new(0) }

	pub fn mk_attr_id() -> AttrId {
	let id = NEXT_ATTR_ID.with(\|slot\| {
	let r = slot.get();
	slot.set(r + 1);
	r
	});
	AttrId(id)
	}

	/// Returns an inner attribute with the given value.
	pub fn mk_attr_inner(id: AttrId, item: P<MetaItem>) -> Attribute {
	dummy_spanned(Attribute_ {
	id: id,
	style: ast::AttrInner,
	value: item,
	is_sugared_doc: false,
	})
	}

	/// Returns an outer attribute with the given value.
	pub fn mk_attr_outer(id: AttrId, item: P<MetaItem>) -> Attribute {
	dummy_spanned(Attribute_ {
	id: id,
	style: ast::AttrOuter,
	value: item,
	is_sugared_doc: false,
	})
	}

	pub fn mk_sugared_doc_attr(id: AttrId, text: InternedString, lo: BytePos,
	hi: BytePos)
	-> Attribute {
	let style = doc_comment_style(&text);
	let lit = spanned(lo, hi, ast::LitStr(text, ast::CookedStr));
	let attr = Attribute_ {
	id: id,
	style: style,
	value: P(spanned(lo, hi, MetaNameValue(InternedString::new("doc"),
	lit))),
	is_sugared_doc: true
	};
	spanned(lo, hi, attr)
	}

	/* Searching */
	/// Check if `needle` occurs in `haystack` by a structural
	/// comparison. This is slightly subtle, and relies on ignoring the
	/// span included in the `==` comparison a plain MetaItem.
	pub fn contains(haystack: &[P<MetaItem>], needle: &MetaItem) -> bool {
	debug!("attr::contains (name={})", needle.name());
	haystack.iter().any(\|item\| {
	debug!(" testing: {}", item.name());
	item.node == needle.node
	})
	}

	pub fn contains_name<AM: AttrMetaMethods>(metas: &[AM], name: &str) -> bool {
	debug!("attr::contains_name (name={})", name);
	metas.iter().any(\|item\| {
	debug!(" testing: {}", item.name());
	item.check_name(name)
	})
	}

	pub fn first_attr_value_str_by_name(attrs: &[Attribute], name: &str)
	-> Option<InternedString> {
	attrs.iter()
	.find(\|at\| at.check_name(name))
	.and_then(\|at\| at.value_str())
	}

	pub fn last_meta_item_value_str_by_name(items: &[P<MetaItem>], name: &str)
	-> Option<InternedString> {
	items.iter()
	.rev()
	.find(\|mi\| mi.check_name(name))
	.and_then(\|i\| i.value_str())
	}

	/* Higher-level applications */

	pub fn sort_meta_items(items: Vec<P<MetaItem>>) -> Vec<P<MetaItem>> {
	// This is sort of stupid here, but we need to sort by
	// human-readable strings.
	let mut v = items.into_iter()
	.map(\|mi\| (mi.name(), mi))
	.collect::<Vec<(InternedString, P<MetaItem>)>>();

	v.sort_by(\|&(ref a, _), &(ref b, _)\| a.cmp(b));

	// There doesn't seem to be a more optimal way to do this
	v.into_iter().map(\|(_, m)\| m.map(\|Spanned {node, span}\| {
	Spanned {
	node: match node {
	MetaList(n, mis) => MetaList(n, sort_meta_items(mis)),
	_ => node
	},
	span: span
	}
	})).collect()
	}

	pub fn find_crate_name(attrs: &[Attribute]) -> Option<InternedString> {
	first_attr_value_str_by_name(attrs, "crate_name")
	}

	/// Find the value of #[export_name=*] attribute and check its validity.
	pub fn find_export_name_attr(diag: &SpanHandler, attrs: &[Attribute]) -> Option<InternedString> {
	attrs.iter().fold(None, \|ia,attr\| {
	if attr.check_name("export_name") {
	if let s@Some(_) = attr.value_str() {
	s
	} else {
	diag.span_err(attr.span, "export_name attribute has invalid format");
	diag.handler.help("use #[export_name=\"*\"]");
	None
	}
	} else {
	ia
	}
	})
	}

	#[derive(Copy, Clone, PartialEq)]
	pub enum InlineAttr {
	None,
	Hint,
	Always,
	Never,
	}

	/// Determine what `#[inline]` attribute is present in `attrs`, if any.
	pub fn find_inline_attr(diagnostic: Option<&SpanHandler>, attrs: &[Attribute]) -> InlineAttr {
	// FIXME (#2809)---validate the usage of #[inline] and #[inline]
	attrs.iter().fold(InlineAttr::None, \|ia,attr\| {
	match attr.node.value.node {
	MetaWord(ref n) if *n == "inline" => {
	mark_used(attr);
	InlineAttr::Hint
	}
	MetaList(ref n, ref items) if *n == "inline" => {
	mark_used(attr);
	if items.len() != 1 {
	diagnostic.map(\|d\|{ d.span_err(attr.span, "expected one argument"); });
	InlineAttr::None
	} else if contains_name(&items[..], "always") {
	InlineAttr::Always
	} else if contains_name(&items[..], "never") {
	InlineAttr::Never
	} else {
	diagnostic.map(\|d\|{ d.span_err((*items[0]).span, "invalid argument"); });
	InlineAttr::None
	}
	}
	_ => ia
	}
	})
	}

	/// True if `#[inline]` or `#[inline(always)]` is present in `attrs`.
	pub fn requests_inline(attrs: &[Attribute]) -> bool {
	match find_inline_attr(None, attrs) {
	InlineAttr::Hint \| InlineAttr::Always => true,
	InlineAttr::None \| InlineAttr::Never => false,
	}
	}

	/// Tests if a cfg-pattern matches the cfg set
	pub fn cfg_matches(diagnostic: &SpanHandler, cfgs: &[P<MetaItem>], cfg: &ast::MetaItem) -> bool {
	match cfg.node {
	ast::MetaList(ref pred, ref mis) if &pred[..] == "any" =>
	mis.iter().any(\|mi\| cfg_matches(diagnostic, cfgs, &**mi)),
	ast::MetaList(ref pred, ref mis) if &pred[..] == "all" =>
	mis.iter().all(\|mi\| cfg_matches(diagnostic, cfgs, &**mi)),
	ast::MetaList(ref pred, ref mis) if &pred[..] == "not" => {
	if mis.len() != 1 {
	diagnostic.span_err(cfg.span, "expected 1 cfg-pattern");
	return false;
	}
	!cfg_matches(diagnostic, cfgs, &*mis[0])
	}
	ast::MetaList(ref pred, _) => {
	diagnostic.span_err(cfg.span, &format!("invalid predicate `{}`", pred));
	false
	},
	ast::MetaWord(_) \| ast::MetaNameValue(..) => contains(cfgs, cfg),
	}
	}

	/// Represents the #[deprecated] and friends attributes.
	#[derive(RustcEncodable,RustcDecodable,Clone,Debug)]
	pub struct Stability {
	pub level: StabilityLevel,
	pub feature: InternedString,
	pub since: Option<InternedString>,
	pub deprecated_since: Option<InternedString>,
	// The reason for the current stability level. If deprecated, the
	// reason for deprecation.
	pub reason: Option<InternedString>,
	}

	/// The available stability levels.
	#[derive(RustcEncodable,RustcDecodable,PartialEq,PartialOrd,Clone,Debug,Copy)]
	pub enum StabilityLevel {
	Unstable,
	Stable,
	}

	impl fmt::Display for StabilityLevel {
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
	fmt::Debug::fmt(self, f)
	}
	}

	fn find_stability_generic<'a,
	AM: AttrMetaMethods,
	I: Iterator<Item=&'a AM>>
	(diagnostic: &SpanHandler, attrs: I, item_sp: Span)
	-> (Option<Stability>, Vec<&'a AM>) {

	let mut stab: Option<Stability> = None;
	let mut deprecated: Option<(InternedString, Option<InternedString>)> = None;
	let mut used_attrs: Vec<&'a AM> = vec![];

	'outer: for attr in attrs {
	let tag = attr.name();
	let tag = &tag[..];
	if tag != "deprecated" && tag != "unstable" && tag != "stable" {
	continue // not a stability level
	}

	used_attrs.push(attr);

	let (feature, since, reason) = match attr.meta_item_list() {
	Some(metas) => {
	let mut feature = None;
	let mut since = None;
	let mut reason = None;
	for meta in metas.iter() {
	if meta.name() == "feature" {
	match meta.value_str() {
	Some(v) => feature = Some(v),
	None => {
	diagnostic.span_err(meta.span, "incorrect meta item");
	continue 'outer;
	}
	}
	}
	if &meta.name()[..] == "since" {
	match meta.value_str() {
	Some(v) => since = Some(v),
	None => {
	diagnostic.span_err(meta.span, "incorrect meta item");
	continue 'outer;
	}
	}
	}
	if &meta.name()[..] == "reason" {
	match meta.value_str() {
	Some(v) => reason = Some(v),
	None => {
	diagnostic.span_err(meta.span, "incorrect meta item");
	continue 'outer;
	}
	}
	}
	}
	(feature, since, reason)
	}
	None => {
	diagnostic.span_err(attr.span(), "incorrect stability attribute type");
	continue
	}
	};

	// Deprecated tags don't require feature names
	if feature == None && tag != "deprecated" {
	diagnostic.span_err(attr.span(), "missing 'feature'");
	}

	// Unstable tags don't require a version
	if since == None && tag != "unstable" {
	diagnostic.span_err(attr.span(), "missing 'since'");
	}

	if tag == "unstable" \|\| tag == "stable" {
	if stab.is_some() {
	diagnostic.span_err(item_sp, "multiple stability levels");
	}

	let level = match tag {
	"unstable" => Unstable,
	"stable" => Stable,
	_ => unreachable!()
	};

	stab = Some(Stability {
	level: level,
	feature: feature.unwrap_or(intern_and_get_ident("bogus")),
	since: since,
	deprecated_since: None,
	reason: reason
	});
	} else { // "deprecated"
	if deprecated.is_some() {
	diagnostic.span_err(item_sp, "multiple deprecated attributes");
	}

	deprecated = Some((since.unwrap_or(intern_and_get_ident("bogus")), reason));
	}
	}

	// Merge the deprecation info into the stability info
	if deprecated.is_some() {
	match stab {
	Some(ref mut s) => {
	let (since, reason) = deprecated.unwrap();
	s.deprecated_since = Some(since);
	s.reason = reason;
	}
	None => {
	diagnostic.span_err(item_sp, "deprecated attribute must be paired with \
	either stable or unstable attribute");
	}
	}
	}

	(stab, used_attrs)
	}

	/// Find the first stability attribute. `None` if none exists.
	pub fn find_stability(diagnostic: &SpanHandler, attrs: &[Attribute],
	item_sp: Span) -> Option<Stability> {
	let (s, used) = find_stability_generic(diagnostic, attrs.iter(), item_sp);
	for used in used { mark_used(used) }
	return s;
	}

	pub fn require_unique_names(diagnostic: &SpanHandler, metas: &[P<MetaItem>]) {
	let mut set = HashSet::new();
	for meta in metas {
	let name = meta.name();

	if !set.insert(name.clone()) {
	panic!(diagnostic.span_fatal(meta.span,
	&format!("duplicate meta item `{}`", name)));
	}
	}
	}


	/// Parse #[repr(...)] forms.
	///
	/// Valid repr contents: any of the primitive integral type names (see
	/// `int_type_of_word`, below) to specify enum discriminant type; `C`, to use
	/// the same discriminant size that the corresponding C enum would or C
	/// structure layout, and `packed` to remove padding.
	pub fn find_repr_attrs(diagnostic: &SpanHandler, attr: &Attribute) -> Vec<ReprAttr> {
	let mut acc = Vec::new();
	match attr.node.value.node {
	ast::MetaList(ref s, ref items) if *s == "repr" => {
	mark_used(attr);
	for item in items {
	match item.node {
	ast::MetaWord(ref word) => {
	let hint = match &word[..] {
	// Can't use "extern" because it's not a lexical identifier.
	"C" => Some(ReprExtern),
	"packed" => Some(ReprPacked),
	_ => match int_type_of_word(&word) {
	Some(ity) => Some(ReprInt(item.span, ity)),
	None => {
	// Not a word we recognize
	diagnostic.span_err(item.span,
	"unrecognized representation hint");
	None
	}
	}
	};

	match hint {
	Some(h) => acc.push(h),
	None => { }
	}
	}
	// Not a word:
	_ => diagnostic.span_err(item.span, "unrecognized enum representation hint")
	}
	}
	}
	// Not a "repr" hint: ignore.
	_ => { }
	}
	acc
	}

	fn int_type_of_word(s: &str) -> Option<IntType> {
	match s {
	"i8" => Some(SignedInt(ast::TyI8)),
	"u8" => Some(UnsignedInt(ast::TyU8)),
	"i16" => Some(SignedInt(ast::TyI16)),
	"u16" => Some(UnsignedInt(ast::TyU16)),
	"i32" => Some(SignedInt(ast::TyI32)),
	"u32" => Some(UnsignedInt(ast::TyU32)),
	"i64" => Some(SignedInt(ast::TyI64)),
	"u64" => Some(UnsignedInt(ast::TyU64)),
	"isize" => Some(SignedInt(ast::TyIs)),
	"usize" => Some(UnsignedInt(ast::TyUs)),
	_ => None
	}
	}

	#[derive(PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, Clone)]
	pub enum ReprAttr {
	ReprAny,
	ReprInt(Span, IntType),
	ReprExtern,
	ReprPacked,
	}

	impl ReprAttr {
	pub fn is_ffi_safe(&self) -> bool {
	match *self {
	ReprAny => false,
	ReprInt(_sp, ity) => ity.is_ffi_safe(),
	ReprExtern => true,
	ReprPacked => false
	}
	}
	}

	#[derive(Eq, Hash, PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, Clone)]
	pub enum IntType {
	SignedInt(ast::IntTy),
	UnsignedInt(ast::UintTy)
	}

	impl IntType {
	#[inline]
	pub fn is_signed(self) -> bool {
	match self {
	SignedInt(..) => true,
	UnsignedInt(..) => false
	}
	}
	fn is_ffi_safe(self) -> bool {
	match self {
	SignedInt(ast::TyI8) \| UnsignedInt(ast::TyU8) \|
	SignedInt(ast::TyI16) \| UnsignedInt(ast::TyU16) \|
	SignedInt(ast::TyI32) \| UnsignedInt(ast::TyU32) \|
	SignedInt(ast::TyI64) \| UnsignedInt(ast::TyU64) => true,
	SignedInt(ast::TyIs) \| UnsignedInt(ast::TyUs) => false
	}
	}
	}