std: Recreate a rand module

This commit shuffles around some of the `rand` code, along with some
reorganization. The new state of the world is as follows:

* The librand crate now only depends on libcore. This interface is experimental.
* The standard library has a new module, `std::rand`. This interface will
  eventually become stable.

Unfortunately, this entailed more of a breaking change than just shuffling some
names around. The following breaking changes were made to the rand library:

* Rng::gen_vec() was removed. This has been replaced with Rng::gen_iter() which
  will return an infinite stream of random values. Previous behavior can be
  regained with `rng.gen_iter().take(n).collect()`

* Rng::gen_ascii_str() was removed. This has been replaced with
  Rng::gen_ascii_chars() which will return an infinite stream of random ascii
  characters. Similarly to gen_iter(), previous behavior can be emulated with
  `rng.gen_ascii_chars().take(n).collect()`

* {IsaacRng, Isaac64Rng, XorShiftRng}::new() have all been removed. These all
  relied on being able to use an OSRng for seeding, but this is no longer
  available in librand (where these types are defined). To retain the same
  functionality, these types now implement the `Rand` trait so they can be
  generated with a random seed from another random number generator. This allows
  the stdlib to use an OSRng to create seeded instances of these RNGs.

* Rand implementations for `Box<T>` and `@T` were removed. These seemed to be
  pretty rare in the codebase, and it allows for librand to not depend on
  liballoc.  Additionally, other pointer types like Rc<T> and Arc<T> were not
  supported.  If this is undesirable, librand can depend on liballoc and regain
  these implementations.

* The WeightedChoice structure is no longer built with a `Vec<Weighted<T>>`,
  but rather a `&mut [Weighted<T>]`. This means that the WeightedChoice
  structure now has a lifetime associated with it.

* The `sample` method on `Rng` has been moved to a top-level function in the
  `rand` module due to its dependence on `Vec`.

cc #13851

[breaking-change]

Author: alexcrichton

mk/crates.mk

@@ -60,9 +60,9 @@ DEPS_core :=
 DEPS_rlibc :=
 DEPS_alloc := core libc native:jemalloc
 DEPS_debug := std
-DEPS_std := core libc alloc native:rustrt native:backtrace
+DEPS_std := core rand libc alloc native:rustrt native:backtrace
 DEPS_graphviz := std
-DEPS_green := std rand native:context_switch
+DEPS_green := std native:context_switch
 DEPS_rustuv := std native:uv native:uv_support
 DEPS_native := std
 DEPS_syntax := std term serialize collections log fmt_macros debug
@@ -77,16 +77,16 @@ DEPS_glob := std
 DEPS_serialize := std collections log
 DEPS_term := std collections log
 DEPS_semver := std
-DEPS_uuid := std serialize rand
+DEPS_uuid := std serialize
 DEPS_sync := std alloc
 DEPS_getopts := std
-DEPS_collections := std rand debug
+DEPS_collections := std debug
 DEPS_fourcc := syntax std
 DEPS_hexfloat := syntax std
-DEPS_num := std rand
+DEPS_num := std
 DEPS_test := std collections getopts serialize term time regex
 DEPS_time := std serialize sync
-DEPS_rand := std
+DEPS_rand := core
 DEPS_url := std collections
 DEPS_workcache := std serialize collections log
 DEPS_log := std sync
@@ -104,6 +104,7 @@ TOOL_SOURCE_rustc := $(S)src/driver/driver.rs
 ONLY_RLIB_core := 1
 ONLY_RLIB_rlibc := 1
 ONLY_RLIB_alloc := 1
+ONLY_RLIB_rand := 1
 
 ################################################################################
 # You should not need to edit below this line

src/doc/guide-tasks.md

@@ -329,10 +329,10 @@ Here is a small example showing how to use Arcs. We wish to run concurrently sev
 a single large vector of floats. Each task needs the full vector to perform its duty.
 
 ~~~
-extern crate rand;
 extern crate sync;
 
 use sync::Arc;
+use std::rand;
 
 fn pnorm(nums: &[f64], p: uint) -> f64 {
     nums.iter().fold(0.0, |a, b| a + b.powf(p as f64)).powf(1.0 / (p as f64))
@@ -358,7 +358,7 @@ created by the line
 
 ~~~
 # extern crate sync;
-# extern crate rand;
+# use std::rand;
 # use sync::Arc;
 # fn main() {
 # let numbers = Vec::from_fn(1000000, |_| rand::random::<f64>());
@@ -372,7 +372,7 @@ reference to the underlying vector as if it were local.
 
 ~~~
 # extern crate sync;
-# extern crate rand;
+# use std::rand;
 # use sync::Arc;
 # fn pnorm(nums: &[f64], p: uint) -> f64 { 4.0 }
 # fn main() {

src/libcollections/bitv.rs

@@ -980,8 +980,8 @@ mod tests {
     use bitv;
 
     use std::uint;
-    use rand;
-    use rand::Rng;
+    use std::rand;
+    use std::rand::Rng;
 
     static BENCH_BITS : uint = 1 << 14;
 

src/libcollections/deque.rs

@@ -44,8 +44,8 @@ pub mod bench {
     extern crate test;
     use self::test::Bencher;
     use std::container::MutableMap;
-    use rand;
-    use rand::Rng;
+    use std::rand;
+    use std::rand::Rng;
 
     pub fn insert_rand_n<M:MutableMap<uint,uint>>(n: uint,
                                                   map: &mut M,

src/libcollections/dlist.rs

@@ -610,7 +610,7 @@ mod tests {
     extern crate test;
     use self::test::Bencher;
     use deque::Deque;
-    use rand;
+    use std::rand;
     use super::{DList, Node, ListInsertion};
 
     pub fn check_links<T>(list: &DList<T>) {

src/libcollections/hashmap.rs

@@ -24,8 +24,8 @@ use std::iter::{range, range_inclusive};
 use std::mem::replace;
 use std::num;
 use std::option::{Option, Some, None};
-use rand;
-use rand::Rng;
+use std::rand;
+use std::rand::Rng;
 use std::result::{Ok, Err};
 use std::slice::ImmutableVector;
 

src/libcollections/lib.rs

@@ -24,7 +24,6 @@
 
 #![deny(deprecated_owned_vector)]
 
-extern crate rand;
 extern crate debug;
 
 #[cfg(test)] extern crate test;

src/libcollections/treemap.rs

@@ -1000,8 +1000,8 @@ impl<T: TotalOrd> Extendable<T> for TreeSet<T> {
 mod test_treemap {
     use super::{TreeMap, TreeNode};
 
-    use rand::Rng;
-    use rand;
+    use std::rand::Rng;
+    use std::rand;
 
     #[test]
     fn find_empty() {

src/libcollections/trie.rs

@@ -915,7 +915,7 @@ mod test_map {
 mod bench_map {
     extern crate test;
     use super::TrieMap;
-    use rand::{weak_rng, Rng};
+    use std::rand::{weak_rng, Rng};
     use self::test::Bencher;
 
     #[bench]

src/libcore/any.rs

@@ -119,7 +119,7 @@ mod tests {
     use prelude::*;
     use super::*;
     use realstd::owned::{Box, AnyOwnExt};
-    use realstd::str::{Str, StrAllocating};
+    use realstd::str::Str;
 
     #[deriving(Eq, Show)]
     struct Test;