auto merge of #8921 : huonw/rust/stability, r=brson

Significant progress on #6875, enough that I'll open new bugs and turn that into a metabug when this lands.

Description & example in the commit message.

2 files changed, 58 insertions, 0 deletions

diff --git a/src/libsyntax/ast_map.rs b/src/libsyntax/ast_map.rs
index ccaadcbad4d..e3023b919f8 100644
--- a/src/libsyntax/ast_map.rs
+++ b/src/libsyntax/ast_map.rs
@@ -80,6 +80,26 @@ pub enum ast_node {
     node_callee_scope(@Expr)
 }
 
+impl ast_node {
+    pub fn with_attrs<T>(&self, f: &fn(Option<&[Attribute]>) -> T) -> T {
+        let attrs = match *self {
+            node_item(i, _) => Some(i.attrs.as_slice()),
+            node_foreign_item(fi, _, _, _) => Some(fi.attrs.as_slice()),
+            node_trait_method(tm, _, _) => match *tm {
+                required(ref type_m) => Some(type_m.attrs.as_slice()),
+                provided(m) => Some(m.attrs.as_slice())
+            },
+            node_method(m, _, _) => Some(m.attrs.as_slice()),
+            node_variant(ref v, _, _) => Some(v.node.attrs.as_slice()),
+            // unit/tuple structs take the attributes straight from
+            // the struct definition.
+            node_struct_ctor(_, strct, _) => Some(strct.attrs.as_slice()),
+            _ => None
+        };
+        f(attrs)
+    }
+}
+
 pub type map = @mut HashMap<NodeId, ast_node>;
 
 pub struct Ctx {
diff --git a/src/libsyntax/attr.rs b/src/libsyntax/attr.rs
index 2ed03040fa1..fd0887de722 100644
--- a/src/libsyntax/attr.rs
+++ b/src/libsyntax/attr.rs
@@ -313,6 +313,44 @@ pub fn test_cfg<AM: AttrMetaMethods, It: Iterator<AM>>
     no_cfgs || some_cfg_matches
 }
 
+/// Represents the #[deprecated="foo"] (etc) attributes.
+pub struct Stability {
+    level: StabilityLevel,
+    text: Option<@str>
+}
+
+/// The available stability levels.
+#[deriving(Eq,Ord,Clone)]
+pub enum StabilityLevel {
+    Deprecated,
+    Experimental,
+    Unstable,
+    Stable,
+    Frozen,
+    Locked
+}
+
+/// Find the first stability attribute. `None` if none exists.
+pub fn find_stability<AM: AttrMetaMethods, It: Iterator<AM>>(mut metas: It) -> Option<Stability> {
+    for m in metas {
+        let level = match m.name().as_slice() {
+            "deprecated" => Deprecated,
+            "experimental" => Experimental,
+            "unstable" => Unstable,
+            "stable" => Stable,
+            "frozen" => Frozen,
+            "locked" => Locked,
+            _ => loop // not a stability level
+        };
+
+        return Some(Stability {
+                level: level,
+                text: m.value_str()
+            });
+    }
+    None
+}
+
 pub fn require_unique_names(diagnostic: @mut span_handler,
                             metas: &[@MetaItem]) {
     let mut set = HashSet::new();