---

yaml
---
r: 153836
b: refs/heads/try2
c: 79e9f14
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: d7993153a49cf849cd41c259037f2d50ec2ab67c
+refs/heads/try2: 79e9f14abf50eecb7d3c53f10ad900615bb2d397
 refs/heads/dist-snap: ba4081a5a8573875fed17545846f6f6902c8ba8d
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596
 refs/tags/release-0.3: b5f0d0f648d9a6153664837026ba1be43d3e2503

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/libcollections/ringbuf.rs

@@ -19,6 +19,8 @@ use core::cmp;
 use core::default::Default;
 use core::fmt;
 use core::iter::RandomAccessIterator;
+use core::iter;
+use std::hash::{Writer, Hash};
 
 use {Deque, Collection, Mutable, MutableSeq};
 use vec::Vec;
@@ -450,6 +452,21 @@ impl<A: PartialEq> PartialEq for RingBuf<A> {
     }
 }
 
+impl<A: PartialOrd> PartialOrd for RingBuf<A> {
+    fn partial_cmp(&self, other: &RingBuf<A>) -> Option<Ordering> {
+        iter::order::partial_cmp(self.iter(), other.iter())
+    }
+}
+
+impl<S: Writer, A: Hash<S>> Hash<S> for RingBuf<A> {
+    fn hash(&self, state: &mut S) {
+        self.len().hash(state);
+        for elt in self.iter() {
+            elt.hash(state);
+        }
+    }
+}
+
 impl<A> FromIterator<A> for RingBuf<A> {
     fn from_iter<T: Iterator<A>>(iterator: T) -> RingBuf<A> {
         let (lower, _) = iterator.size_hint();
@@ -485,6 +502,7 @@ mod tests {
     use std::fmt::Show;
     use std::prelude::*;
     use std::gc::{GC, Gc};
+    use std::hash;
     use test::Bencher;
     use test;
 
@@ -912,6 +930,37 @@ mod tests {
         assert!(e == RingBuf::new());
     }
 
+    #[test]
+    fn test_hash() {
+      let mut x = RingBuf::new();
+      let mut y = RingBuf::new();
+
+      x.push(1i);
+      x.push(2);
+      x.push(3);
+
+      y.push(0i);
+      y.push(1i);
+      y.pop_front();
+      y.push(2);
+      y.push(3);
+
+      assert!(hash::hash(&x) == hash::hash(&y));
+    }
+
+    #[test]
+    fn test_ord() {
+        let x = RingBuf::new();
+        let mut y = RingBuf::new();
+        y.push(1i);
+        y.push(2);
+        y.push(3);
+        assert!(x < y);
+        assert!(y > x);
+        assert!(x <= x);
+        assert!(x >= x);
+    }
+
     #[test]
     fn test_show() {
         let ringbuf: RingBuf<int> = range(0i, 10).collect();

branches/try2/src/librustdoc/html/render.rs

@@ -845,8 +845,12 @@ impl DocFolder for Cache {
                     }
                     _ => (None, Some(self.stack.as_slice()))
                 };
+                let hidden_field = match item.inner {
+                    clean::StructFieldItem(clean::HiddenStructField) => true,
+                    _ => false
+                };
                 match parent {
-                    (parent, Some(path)) if !self.privmod => {
+                    (parent, Some(path)) if !self.privmod && !hidden_field => {
                         self.search_index.push(IndexItem {
                             ty: shortty(&item),
                             name: s.to_string(),

branches/try2/src/libstd/collections/hashmap.rs

@@ -1850,6 +1850,7 @@ impl<T: Hash + Eq> HashSet<T, RandomSipHasher> {
     ///
     /// # Example
     ///
+    /// ```
     /// use std::collections::HashSet;
     /// let mut set: HashSet<int> = HashSet::new();
     /// ```
@@ -1863,6 +1864,7 @@ impl<T: Hash + Eq> HashSet<T, RandomSipHasher> {
     ///
     /// # Example
     ///
+    /// ```
     /// use std::collections::HashSet;
     /// let mut set: HashSet<int> = HashSet::with_capacity(10);
     /// ```
@@ -1920,6 +1922,7 @@ impl<T: Eq + Hash<S>, S, H: Hasher<S>> HashSet<T, H> {
     ///
     /// # Example
     ///
+    /// ```
     /// use std::collections::HashSet;
     /// let mut set: HashSet<int> = HashSet::new();
     /// set.reserve(10);