auto merge of #9062 : blake2-ppc/rust/vec-iterator, r=alexcrichton

Visit the free functions of std::vec and reimplement or remove some. Most prominently, remove `each_permutation` and replace with two iterators, ElementSwaps and Permutations.

Replace unzip, unzip_slice with an updated `unzip` that works with an iterator argument.

Replace each_permutation with a Permutation iterator. The new permutation iterator is more efficient since it uses an algorithm that produces permutations in an order where each is only one element swap apart, including swapping back to the original state with one swap at the end.

Unify the seldomly used functions `build`, `build_sized`, `build_sized_opt` into just one function `build`.

Remove `equal_sizes`

Author: bors

src/libextra/base64.rs

@@ -315,11 +315,8 @@ mod test {
         use std::vec;
 
         do 1000.times {
-            let v: ~[u8] = do vec::build |push| {
-                do task_rng().gen_uint_range(1, 100).times {
-                    push(random());
-                }
-            };
+            let times = task_rng().gen_uint_range(1, 100);
+            let v = vec::from_fn(times, |_| random::<u8>());
             assert_eq!(v.to_base64(STANDARD).from_base64().unwrap(), v);
         }
     }

src/librustc/middle/typeck/infer/combine.rs

@@ -61,7 +61,6 @@ use middle::typeck::infer::{TypeTrace};
 use util::common::indent;
 
 use std::result;
-use std::vec;
 use syntax::ast::{Onceness, purity};
 use syntax::ast;
 use syntax::opt_vec;
@@ -88,7 +87,7 @@ pub trait Combine {
         // future we could allow type parameters to declare a
         // variance.
 
-        if vec::same_length(as_, bs) {
+        if as_.len() == bs.len() {
             result::fold_(as_.iter().zip(bs.iter())
                           .map(|(a, b)| eq_tys(self, *a, *b)))
                 .then(|| Ok(as_.to_owned()))
@@ -419,7 +418,7 @@ pub fn super_fn_sigs<C:Combine>(
     this: &C, a: &ty::FnSig, b: &ty::FnSig) -> cres<ty::FnSig> {
 
     fn argvecs<C:Combine>(this: &C, a_args: &[ty::t], b_args: &[ty::t]) -> cres<~[ty::t]> {
-        if vec::same_length(a_args, b_args) {
+        if a_args.len() == b_args.len() {
             result::collect(a_args.iter().zip(b_args.iter())
                             .map(|(a, b)| this.args(*a, *b)))
         } else {

src/librustc/middle/typeck/infer/region_inference/mod.rs

@@ -373,14 +373,12 @@ impl RegionVarBindings {
 
     pub fn vars_created_since_snapshot(&mut self, snapshot: uint)
                                        -> ~[RegionVid] {
-        do vec::build |push| {
-            for &elt in self.undo_log.slice_from(snapshot).iter() {
-                match elt {
-                    AddVar(vid) => push(vid),
-                    _ => ()
-                }
-            }
-        }
+        self.undo_log.slice_from(snapshot).iter()
+            .filter_map(|&elt| match elt {
+                AddVar(vid) => Some(vid),
+                _ => None
+            })
+            .collect()
     }
 
     pub fn tainted(&mut self, snapshot: uint, r0: Region) -> ~[Region] {

src/librustdoc/config.rs

@@ -112,7 +112,7 @@ pub fn parse_config_(
     process_output: Process
 ) -> Result<Config, ~str> {
     let args = args.tail();
-    let opts = vec::unzip(opts()).first();
+    let opts = vec::unzip(opts().move_iter()).first();
     match getopts::getopts(args, opts) {
         Ok(matches) => {
             if matches.free.len() == 1 {

src/libstd/at_vec.rs

@@ -33,62 +33,30 @@ pub fn capacity<T>(v: @[T]) -> uint {
 /**
  * Builds a vector by calling a provided function with an argument
  * function that pushes an element to the back of a vector.
- * This version takes an initial size for the vector.
+ * The initial size for the vector may optionally be specified
  *
  * # Arguments
  *
- * * size - An initial size of the vector to reserve
+ * * size - An option, maybe containing initial size of the vector to reserve
  * * builder - A function that will construct the vector. It receives
  *             as an argument a function that will push an element
  *             onto the vector being constructed.
  */
 #[inline]
-pub fn build_sized<A>(size: uint, builder: &fn(push: &fn(v: A))) -> @[A] {
+pub fn build<A>(size: Option<uint>, builder: &fn(push: &fn(v: A))) -> @[A] {
     let mut vec = @[];
-    unsafe { raw::reserve(&mut vec, size); }
+    unsafe { raw::reserve(&mut vec, size.unwrap_or_default(4)); }
     builder(|x| unsafe { raw::push(&mut vec, x) });
     vec
 }
 
-/**
- * Builds a vector by calling a provided function with an argument
- * function that pushes an element to the back of a vector.
- *
- * # Arguments
- *
- * * builder - A function that will construct the vector. It receives
- *             as an argument a function that will push an element
- *             onto the vector being constructed.
- */
-#[inline]
-pub fn build<A>(builder: &fn(push: &fn(v: A))) -> @[A] {
-    build_sized(4, builder)
-}
-
-/**
- * Builds a vector by calling a provided function with an argument
- * function that pushes an element to the back of a vector.
- * This version takes an initial size for the vector.
- *
- * # Arguments
- *
- * * size - An option, maybe containing initial size of the vector to reserve
- * * builder - A function that will construct the vector. It receives
- *             as an argument a function that will push an element
- *             onto the vector being constructed.
- */
-#[inline]
-pub fn build_sized_opt<A>(size: Option<uint>, builder: &fn(push: &fn(v: A))) -> @[A] {
-    build_sized(size.unwrap_or_default(4), builder)
-}
-
 // Appending
 
 /// Iterates over the `rhs` vector, copying each element and appending it to the
 /// `lhs`. Afterwards, the `lhs` is then returned for use again.
 #[inline]
 pub fn append<T:Clone>(lhs: @[T], rhs: &[T]) -> @[T] {
-    do build_sized(lhs.len() + rhs.len()) |push| {
+    do build(Some(lhs.len() + rhs.len())) |push| {
         for x in lhs.iter() {
             push((*x).clone());
         }
@@ -101,7 +69,7 @@ pub fn append<T:Clone>(lhs: @[T], rhs: &[T]) -> @[T] {
 
 /// Apply a function to each element of a vector and return the results
 pub fn map<T, U>(v: &[T], f: &fn(x: &T) -> U) -> @[U] {
-    do build_sized(v.len()) |push| {
+    do build(Some(v.len())) |push| {
         for elem in v.iter() {
             push(f(elem));
         }
@@ -115,7 +83,7 @@ pub fn map<T, U>(v: &[T], f: &fn(x: &T) -> U) -> @[U] {
  * to the value returned by the function `op`.
  */
 pub fn from_fn<T>(n_elts: uint, op: &fn(uint) -> T) -> @[T] {
-    do build_sized(n_elts) |push| {
+    do build(Some(n_elts)) |push| {
         let mut i: uint = 0u;
         while i < n_elts { push(op(i)); i += 1u; }
     }
@@ -128,7 +96,7 @@ pub fn from_fn<T>(n_elts: uint, op: &fn(uint) -> T) -> @[T] {
  * to the value `t`.
  */
 pub fn from_elem<T:Clone>(n_elts: uint, t: T) -> @[T] {
-    do build_sized(n_elts) |push| {
+    do build(Some(n_elts)) |push| {
         let mut i: uint = 0u;
         while i < n_elts {
             push(t.clone());
@@ -312,7 +280,7 @@ mod test {
     fn test() {
         // Some code that could use that, then:
         fn seq_range(lo: uint, hi: uint) -> @[uint] {
-            do build |push| {
+            do build(None) |push| {
                 for i in range(lo, hi) {
                     push(i);
                 }
@@ -359,15 +327,15 @@ mod test {
     fn bench_build_sized(b: &mut bh) {
         let len = 64;
         do b.iter {
-            build_sized(len, |push| for i in range(0, 1024) { push(i) });
+            build(Some(len), |push| for i in range(0, 1024) { push(i) });
         }
     }
 
     #[bench]
     fn bench_build(b: &mut bh) {
         do b.iter {
             for i in range(0, 95) {
-                build(|push| push(i));
+                build(None, |push| push(i));
             }
         }
     }

src/libstd/io.rs

@@ -777,7 +777,7 @@ impl<T:Reader> ReaderUtil for T {
     }
 
     fn read_lines(&self) -> ~[~str] {
-        do vec::build |push| {
+        do vec::build(None) |push| {
             do self.each_line |line| {
                 push(line.to_owned());
                 true

src/libstd/select.rs

@@ -148,7 +148,7 @@ mod test {
         // Unfortunately this does not actually test the block_on early-break
         // codepath in select -- racing between the sender and the receiver in
         // separate tasks is necessary to get around the optimistic check.
-        let (ports, chans) = unzip(from_fn(num_ports, |_| oneshot::<()>()));
+        let (ports, chans) = unzip(range(0, num_ports).map(|_| oneshot::<()>()));
         let mut dead_chans = ~[];
         let mut ports = ports;
         for (i, chan) in chans.move_iter().enumerate() {
@@ -165,7 +165,7 @@ mod test {
 
         // Same thing with streams instead.
         // FIXME(#7971): This should be in a macro but borrowck isn't smart enough.
-        let (ports, chans) = unzip(from_fn(num_ports, |_| stream::<()>()));
+        let (ports, chans) = unzip(range(0, num_ports).map(|_| stream::<()>()));
         let mut dead_chans = ~[];
         let mut ports = ports;
         for (i, chan) in chans.move_iter().enumerate() {
@@ -209,7 +209,7 @@ mod test {
         // Sends 10 buffered packets, and uses select to retrieve them all.
         // Puts the port in a different spot in the vector each time.
         do run_in_newsched_task {
-            let (ports, _) = unzip(from_fn(10, |_| stream()));
+            let (ports, _) = unzip(range(0u, 10).map(|_| stream::<int>()));
             let (port, chan) = stream();
             do 10.times { chan.send(31337); }
             let mut ports = ports;
@@ -327,7 +327,7 @@ mod test {
                     let (p,c) = oneshot();
                     let c = Cell::new(c);
                     do task::spawn {
-                        let (dead_ps, dead_cs) = unzip(from_fn(5, |_| oneshot::<()>()));
+                        let (dead_ps, dead_cs) = unzip(range(0u, 5).map(|_| oneshot::<()>()));
                         let mut ports = dead_ps;
                         select(ports); // should get killed; nothing should leak
                         c.take().send(()); // must not happen