---

yaml
---
r: 153828
b: refs/heads/try2
c: e0d10bb
h: refs/heads/master
v: v3

Author: bors

[refs]

@@ -5,7 +5,7 @@ refs/heads/snap-stage3: 78a7676898d9f80ab540c6df5d4c9ce35bb50463
 refs/heads/try: 519addf6277dbafccbb4159db4b710c37eaa2ec5
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b
-refs/heads/try2: c05cfab7f979f72a25821060576a2aaea4c61ef9
+refs/heads/try2: e0d10bb69ab04ab041b39c71f7537d8c63ef9669
 refs/heads/dist-snap: ba4081a5a8573875fed17545846f6f6902c8ba8d
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596
 refs/tags/release-0.3: b5f0d0f648d9a6153664837026ba1be43d3e2503

branches/try2/src/etc/licenseck.py

@@ -44,6 +44,7 @@
     "libsync/mpsc_intrusive.rs", # BSD
     "test/bench/shootout-binarytrees.rs", # BSD
     "test/bench/shootout-fannkuch-redux.rs", # BSD
+    "test/bench/shootout-k-nucleotide.rs", # BSD
     "test/bench/shootout-mandelbrot.rs", # BSD
     "test/bench/shootout-meteor.rs", # BSD
     "test/bench/shootout-pidigits.rs", # BSD

branches/try2/src/grammar/raw-string-literal-ambiguity.md

@@ -1,7 +1,11 @@
 Rust's lexical grammar is not context-free. Raw string literals are the source
 of the problem. Informally, a raw string literal is an `r`, followed by `N`
 hashes (where N can be zero), a quote, any characters, then a quote followed
-by `N` hashes. This grammar describes this as best possible:
+by `N` hashes. Critically, once inside the first pair of quotes,
+another quote cannot be followed by `N` consecutive hashes. e.g.
+`r###""###"###` is invalid.
+
+This grammar describes this as best possible:
 
     R -> 'r' S
     S -> '"' B '"'
@@ -22,8 +26,39 @@ accepted as one by the above grammar, using the derivation:
 (Where `T : U` means the rule `T` is applied, and `U` is the remainder of the
 string.) The difficulty arises from the fact that it is fundamentally
 context-sensitive. In particular, the context needed is the number of hashes.
-I know of no way to resolve this, but also have not come up with a proof that
-it is not context sensitive. Such a proof would probably use the pumping lemma
-for context-free languages, but I (cmr) could not come up with a proof after
-spending a few hours on it, and decided my time best spent elsewhere. Pull
-request welcome!
+
+To prove that Rust's string literals are not context-free, we will use
+the fact that context-free languages are closed under intersection with
+regular languages, and the
+[pumping lemma for context-free languages](https://en.wikipedia.org/wiki/Pumping_lemma_for_context-free_languages).
+
+Consider the regular language `R = r#+""#*"#+`. If Rust's raw string literals are
+context-free, then their intersection with `R`, `R'`, should also be context-free.
+Therefore, to prove that raw string literals are not context-free,
+it is sufficient to prove that `R'` is not context-free.
+
+The language `R'` is `{r#^n""#^m"#^n | m < n}`.
+
+Assume `R'` *is* context-free. Then `R'` has some pumping length `p > 0` for which
+the pumping lemma applies. Consider the following string `s` in `R'`:
+
+`r#^p""#^{p-1}"#^p`
+
+e.g. for `p = 2`: `s = r##""#"##`
+
+Then `s = uvwxy` for some choice of `uvwxy` such that `vx` is non-empty,
+`|vwx| < p+1`, and `uv^iwx^iy` is in `R'` for all `i >= 0`.
+
+Neither `v` nor `x` can contain a `"` or `r`, as the number of these characters
+in any string in `R'` is fixed. So `v` and `x` contain only hashes.
+Consequently, of the three sequences of hashes, `v` and `x` combined
+can only pump two of them.
+If we ever choose the central sequence of hashes, then one of the outer sequences
+will not grow when we pump, leading to an imbalance between the outer sequences.
+Therefore, we must pump both outer sequences of hashes. However,
+there are `p+2` characters between these two sequences of hashes, and `|vwx|` must
+be less than `p+1`. Therefore we have a contradiction, and `R'` must not be
+context-free.
+
+Since `R'` is not context-free, it follows that the Rust's raw string literals
+must not be context-free.

branches/try2/src/liballoc/arc.rs

@@ -8,10 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-/*!
- * Concurrency-enabled mechanisms for sharing mutable and/or immutable state
- * between tasks.
- */
+#![stable]
+
+//! Concurrency-enabled mechanisms for sharing mutable and/or immutable state
+//! between tasks.
 
 use core::atomics;
 use core::clone::Clone;
@@ -51,6 +51,7 @@ use heap::deallocate;
 /// }
 /// ```
 #[unsafe_no_drop_flag]
+#[stable]
 pub struct Arc<T> {
     // FIXME #12808: strange name to try to avoid interfering with
     // field accesses of the contained type via Deref
@@ -62,6 +63,7 @@ pub struct Arc<T> {
 /// Weak pointers will not keep the data inside of the `Arc` alive, and can be
 /// used to break cycles between `Arc` pointers.
 #[unsafe_no_drop_flag]
+#[experimental = "Weak pointers may not belong in this module."]
 pub struct Weak<T> {
     // FIXME #12808: strange name to try to avoid interfering with
     // field accesses of the contained type via Deref
@@ -77,6 +79,7 @@ struct ArcInner<T> {
 impl<T: Share + Send> Arc<T> {
     /// Create an atomically reference counted wrapper.
     #[inline]
+    #[stable]
     pub fn new(data: T) -> Arc<T> {
         // Start the weak pointer count as 1 which is the weak pointer that's
         // held by all the strong pointers (kinda), see std/rc.rs for more info
@@ -103,14 +106,15 @@ impl<T: Share + Send> Arc<T> {
     /// Weak pointers will not keep the data alive. Once all strong references
     /// to the underlying data have been dropped, the data itself will be
     /// destroyed.
+    #[experimental = "Weak pointers may not belong in this module."]
     pub fn downgrade(&self) -> Weak<T> {
         // See the clone() impl for why this is relaxed
         self.inner().weak.fetch_add(1, atomics::Relaxed);
         Weak { _ptr: self._ptr }
     }
 }
 
-#[unstable]
+#[unstable = "waiting on stability of Clone"]
 impl<T: Share + Send> Clone for Arc<T> {
     /// Duplicate an atomically reference counted wrapper.
     ///
@@ -135,6 +139,7 @@ impl<T: Share + Send> Clone for Arc<T> {
     }
 }
 
+#[experimental = "Deref is experimental."]
 impl<T: Send + Share> Deref<T> for Arc<T> {
     #[inline]
     fn deref<'a>(&'a self) -> &'a T {
@@ -169,6 +174,7 @@ impl<T: Send + Share + Clone> Arc<T> {
 }
 
 #[unsafe_destructor]
+#[experimental = "waiting on stability of Drop"]
 impl<T: Share + Send> Drop for Arc<T> {
     fn drop(&mut self) {
         // This structure has #[unsafe_no_drop_flag], so this drop glue may run
@@ -212,6 +218,7 @@ impl<T: Share + Send> Drop for Arc<T> {
     }
 }
 
+#[experimental = "Weak pointers may not belong in this module."]
 impl<T: Share + Send> Weak<T> {
     /// Attempts to upgrade this weak reference to a strong reference.
     ///
@@ -237,7 +244,7 @@ impl<T: Share + Send> Weak<T> {
     }
 }
 
-#[unstable]
+#[experimental = "Weak pointers may not belong in this module."]
 impl<T: Share + Send> Clone for Weak<T> {
     #[inline]
     fn clone(&self) -> Weak<T> {
@@ -248,6 +255,7 @@ impl<T: Share + Send> Clone for Weak<T> {
 }
 
 #[unsafe_destructor]
+#[experimental = "Weak pointers may not belong in this module."]
 impl<T: Share + Send> Drop for Weak<T> {
     fn drop(&mut self) {
         // see comments above for why this check is here

branches/try2/src/liballoc/boxed.rs

@@ -87,10 +87,12 @@ impl<T: Ord> Ord for Box<T> {
 impl<T: Eq> Eq for Box<T> {}
 
 /// Extension methods for an owning `Any` trait object
-#[unstable = "post-DST, the signature of `downcast` will change to take `Box<Self>`"]
+#[unstable = "post-DST and coherence changes, this will not be a trait but \
+              rather a direct `impl` on `Box<Any>`"]
 pub trait BoxAny {
     /// Returns the boxed value if it is of type `T`, or
     /// `Err(Self)` if it isn't.
+    #[unstable = "naming conventions around accessing innards may change"]
     fn downcast<T: 'static>(self) -> Result<Box<T>, Self>;
 
     /// Deprecated; this method has been renamed to `downcast`.
@@ -100,6 +102,7 @@ pub trait BoxAny {
     }
 }
 
+#[stable]
 impl BoxAny for Box<Any> {
     #[inline]
     fn downcast<T: 'static>(self) -> Result<Box<T>, Box<Any>> {

branches/try2/src/liballoc/rc.rs

@@ -379,7 +379,6 @@ impl<T> Drop for Weak<T> {
     }
 }
 
-#[unstable]
 #[experimental = "Weak pointers may not belong in this module."]
 impl<T> Clone for Weak<T> {
     #[inline]

branches/try2/src/libcollections/ringbuf.rs

@@ -133,6 +133,18 @@ impl<T> RingBuf<T> {
     /// Retrieve an element in the RingBuf by index
     ///
     /// Fails if there is no element with the given index
+    ///
+    /// # Example
+    ///
+    /// ```rust
+    /// use std::collections::RingBuf;
+    ///
+    /// let mut buf = RingBuf::new();
+    /// buf.push(3i);
+    /// buf.push(4);
+    /// buf.push(5);
+    /// assert_eq!(buf.get(1), &4);
+    /// ```
     pub fn get<'a>(&'a self, i: uint) -> &'a T {
         let idx = self.raw_index(i);
         match *self.elts.get(idx) {
@@ -144,6 +156,19 @@ impl<T> RingBuf<T> {
     /// Retrieve an element in the RingBuf by index
     ///
     /// Fails if there is no element with the given index
+    ///
+    /// # Example
+    ///
+    /// ```rust
+    /// use std::collections::RingBuf;
+    ///
+    /// let mut buf = RingBuf::new();
+    /// buf.push(3i);
+    /// buf.push(4);
+    /// buf.push(5);
+    /// *buf.get_mut(1) = 7;
+    /// assert_eq!(buf.get(1), &7);
+    /// ```
     pub fn get_mut<'a>(&'a mut self, i: uint) -> &'a mut T {
         let idx = self.raw_index(i);
         match *self.elts.get_mut(idx) {
@@ -157,6 +182,20 @@ impl<T> RingBuf<T> {
     /// `i` and `j` may be equal.
     ///
     /// Fails if there is no element with the given index
+    ///
+    /// # Example
+    ///
+    /// ```rust
+    /// use std::collections::RingBuf;
+    ///
+    /// let mut buf = RingBuf::new();
+    /// buf.push(3i);
+    /// buf.push(4);
+    /// buf.push(5);
+    /// buf.swap(0, 2);
+    /// assert_eq!(buf.get(0), &5);
+    /// assert_eq!(buf.get(2), &3);
+    /// ```
     pub fn swap(&mut self, i: uint, j: uint) {
         assert!(i < self.len());
         assert!(j < self.len());
@@ -196,11 +235,38 @@ impl<T> RingBuf<T> {
     }
 
     /// Front-to-back iterator.
+    ///
+    /// # Example
+    ///
+    /// ```rust
+    /// use std::collections::RingBuf;
+    ///
+    /// let mut buf = RingBuf::new();
+    /// buf.push(5i);
+    /// buf.push(3);
+    /// buf.push(4);
+    /// assert_eq!(buf.iter().collect::<Vec<&int>>().as_slice(), &[&5, &3, &4]);
+    /// ```
     pub fn iter<'a>(&'a self) -> Items<'a, T> {
         Items{index: 0, rindex: self.nelts, lo: self.lo, elts: self.elts.as_slice()}
     }
 
     /// Front-to-back iterator which returns mutable values.
+    ///
+    /// # Example
+    ///
+    /// ```rust
+    /// use std::collections::RingBuf;
+    ///
+    /// let mut buf = RingBuf::new();
+    /// buf.push(5i);
+    /// buf.push(3);
+    /// buf.push(4);
+    /// for num in buf.mut_iter() {
+    ///     *num = *num - 2;
+    /// }
+    /// assert_eq!(buf.mut_iter().collect::<Vec<&mut int>>().as_slice(), &[&mut 3, &mut 1, &mut 2]);
+    /// ```
     pub fn mut_iter<'a>(&'a mut self) -> MutItems<'a, T> {
         let start_index = raw_index(self.lo, self.elts.len(), 0);
         let end_index = raw_index(self.lo, self.elts.len(), self.nelts);