Implement Ord trait for Timespec

doc/tutorial.md

@@ -863,11 +863,34 @@ allocating memory and indirecting through a pointer. But for big structs, or
 those with mutable fields, it can be useful to have a single copy on
 the stack or on the heap, and refer to that through a pointer.
 
-Rust supports several types of pointers. The safe pointer types are
-`@T`, for managed boxes allocated on the local heap, `~T`, for
-uniquely-owned boxes allocated on the exchange heap, and `&T`, for
-borrowed pointers, which may point to any memory, and whose lifetimes
-are governed by the call stack.
+Whenever memory is allocated on the heap, the program needs a strategy to
+dispose of the memory when no longer needed. Most languages, such as Java or
+Python, use *garbage collection* for this, a strategy in which the program
+periodically searches for allocations that are no longer reachable in order
+to dispose of them. Other languages, such as C, use *manual memory
+management*, which relies on the programmer to specify when memory should be
+reclaimed.
+
+Rust is in a different position. It differs from the garbage-collected
+environments in that allows the programmer to choose the disposal
+strategy on an object-by-object basis. Not only does this have benefits for
+performance, but we will later see that this model has benefits for
+concurrency as well, by making it possible for the Rust compiler to detect
+data races at compile time. Rust also differs from the manually managed
+languages in that it is *safe*—it uses a [pointer lifetime
+analysis][borrow] to ensure that manual memory management cannot cause memory
+errors at runtime.
+
+[borrow]: tutorial-borrowed-ptr.html
+
+The cornerstone of Rust's memory management is the concept of a *smart
+pointer*—a pointer type that indicates the lifetime of the object it points
+to. This solution is familiar to C++ programmers; Rust differs from C++,
+however, in that a small set of smart pointers are built into the language.
+The safe pointer types are `@T`, for *managed* boxes allocated on the *local
+heap*, `~T`, for *uniquely-owned* boxes allocated on the *exchange
+heap*, and `&T`, for *borrowed* pointers, which may point to any memory, and
+whose lifetimes are governed by the call stack.
 
 All pointer types can be dereferenced with the `*` unary operator.
 
@@ -919,7 +942,17 @@ node2.next = SomeNode(node3);
 node3.prev = SomeNode(node2);
 ~~~
 
-Managed boxes never cross task boundaries.
+Managed boxes never cross task boundaries. This has several benefits for
+performance:
+
+* The Rust garbage collector does not need to stop multiple threads in order
+  to collect garbage.
+
+* You can separate your application into "real-time" tasks that do not use
+  the garbage collector and "non-real-time" tasks that do, and the real-time
+  tasks will not be interrupted by the non-real-time tasks.
+
+C++ programmers will recognize `@T` as similar to `std::shared_ptr<T>`.
 
 > ***Note:*** Currently, the Rust compiler generates code to reclaim
 > managed boxes through reference counting and a cycle collector, but
@@ -956,10 +989,19 @@ let z = *x + *y;
 assert z == 20;
 ~~~~
 
-Owned boxes, when they do not contain any managed boxes, can be sent
-to other tasks. The sending task will give up ownership of the box,
+When they do not contain any managed boxes, owned boxes can be sent
+to other tasks. The sending task will give up ownership of the box
 and won't be able to access it afterwards. The receiving task will
-become the sole owner of the box.
+become the sole owner of the box. This prevents *data races*—errors
+that could otherwise result from multiple tasks working on the same
+data without synchronization.
+
+When an owned pointer goes out of scope or is overwritten, the object
+it points to is immediately freed. Effective use of owned boxes can
+therefore be an efficient alternative to garbage collection.
+
+C++ programmers will recognize `~T` as similar to `std::unique_ptr<T>`
+(or `std::auto_ptr<T>` in C++03 and below).
 
 ## Borrowed pointers
 

src/librustc/front/test.rs

@@ -145,19 +145,17 @@ fn fold_item(cx: test_ctxt, &&i: @ast::item, fld: fold::ast_fold) ->
 }
 
 fn is_test_fn(i: @ast::item) -> bool {
-    let has_test_attr =
-        vec::len(attr::find_attrs_by_name(i.attrs, ~"test")) > 0u;
+    let has_test_attr = attr::find_attrs_by_name(i.attrs,
+                                                 ~"test").is_not_empty();
 
     fn has_test_signature(i: @ast::item) -> bool {
-        match /*bad*/copy i.node {
-          ast::item_fn(decl, _, tps, _) => {
-            let input_cnt = vec::len(decl.inputs);
+        match &i.node {
+          &ast::item_fn(ref decl, _, ref tps, _) => {
             let no_output = match decl.output.node {
                 ast::ty_nil => true,
                 _ => false
             };
-            let tparm_cnt = vec::len(tps);
-            input_cnt == 0u && no_output && tparm_cnt == 0u
+            decl.inputs.is_empty() && no_output && tps.is_empty()
           }
           _ => false
         }

src/librustc/middle/liveness.rs

@@ -1662,7 +1662,7 @@ fn check_fn(_fk: visit::fn_kind, _decl: fn_decl,
 enum ReadKind {
     PossiblyUninitializedVariable,
     PossiblyUninitializedField,
-    MovedVariable
+    MovedValue
 }
 
 impl @Liveness {
@@ -1815,7 +1815,7 @@ impl @Liveness {
                            lnk: LiveNodeKind,
                            var: Variable) {
 
-        // the only time that it is possible to have a moved variable
+        // the only time that it is possible to have a moved value
         // used by ExitNode would be arguments or fields in a ctor.
         // we give a slightly different error message in those cases.
         if lnk == ExitNode {
@@ -1837,7 +1837,7 @@ impl @Liveness {
             }
         }
 
-        self.report_illegal_read(move_span, lnk, var, MovedVariable);
+        self.report_illegal_read(move_span, lnk, var, MovedValue);
         self.tcx.sess.span_note(
             move_span, ~"move of variable occurred here");
 
@@ -1852,7 +1852,7 @@ impl @Liveness {
             ~"possibly uninitialized variable"
           }
           PossiblyUninitializedField => ~"possibly uninitialized field",
-          MovedVariable => ~"moved variable"
+          MovedValue => ~"moved value"
         };
         let name = (*self.ir).variable_name(var);
         match lnk {

src/libstd/time.rs

@@ -10,7 +10,7 @@
 
 #[forbid(deprecated_mode)];
 
-use core::cmp::Eq;
+use core::cmp::{Eq, Ord};
 use core::int;
 use core::libc::{c_char, c_int, c_long, size_t, time_t};
 use core::i32;
@@ -41,7 +41,7 @@ extern mod rustrt {
 pub struct Timespec { sec: i64, nsec: i32 }
 
 impl Timespec {
-    static fn new(sec: i64, nsec: i32) -> Timespec {
+    static pure fn new(sec: i64, nsec: i32) -> Timespec {
         Timespec { sec: sec, nsec: nsec }
     }
 }
@@ -53,6 +53,16 @@ impl Timespec : Eq {
     pure fn ne(&self, other: &Timespec) -> bool { !self.eq(other) }
 }
 
+impl Timespec : Ord {
+    pure fn lt(&self, other: &Timespec) -> bool {
+        self.sec < other.sec ||
+            (self.sec == other.sec && self.nsec < other.nsec)
+    }
+    pure fn le(&self, other: &Timespec) -> bool { !other.lt(self) }
+    pure fn ge(&self, other: &Timespec) -> bool { !self.lt(other) }
+    pure fn gt(&self, other: &Timespec) -> bool { !self.le(other) }
+}
+
 /**
  * Returns the current time as a `timespec` containing the seconds and
  * nanoseconds since 1970-01-01T00:00:00Z.
@@ -1247,4 +1257,38 @@ mod tests {
         assert utc.rfc822z() == ~"Fri, 13 Feb 2009 23:31:30 -0000";
         assert utc.rfc3339() == ~"2009-02-13T23:31:30Z";
     }
+
+    #[test]
+    fn test_timespec_eq_ord() {
+        use core::cmp::{eq, ge, gt, le, lt, ne};
+
+        let a = &Timespec::new(-2, 1);
+        let b = &Timespec::new(-1, 2);
+        let c = &Timespec::new(1, 2);
+        let d = &Timespec::new(2, 1);
+        let e = &Timespec::new(2, 1);
+
+        assert eq(d, e);
+        assert ne(c, e);
+
+        assert lt(a, b);
+        assert lt(b, c);
+        assert lt(c, d);
+
+        assert le(a, b);
+        assert le(b, c);
+        assert le(c, d);
+        assert le(d, e);
+        assert le(e, d);
+
+        assert ge(b, a);
+        assert ge(c, b);
+        assert ge(d, c);
+        assert ge(e, d);
+        assert ge(d, e);
+
+        assert gt(b, a);
+        assert gt(c, b);
+        assert gt(d, c);
+    }
 }

src/test/compile-fail/alt-vec-tail-move.rs

@@ -4,5 +4,5 @@ fn main() {
         [1, 2, ..move tail] => tail,
         _ => core::util::unreachable()
     };
-    a[0] = 0; //~ ERROR: use of moved variable
+    a[0] = 0; //~ ERROR: use of moved value
 }

src/test/compile-fail/cap-clause-use-after-move.rs

@@ -11,5 +11,5 @@
 fn main() {
     let x = 5;
     let _y = fn~(move x) { }; //~ WARNING captured variable `x` not used in closure
-    let _z = x; //~ ERROR use of moved variable: `x`
+    let _z = x; //~ ERROR use of moved value: `x`
 }

src/test/compile-fail/liveness-move-from-mode.rs

@@ -14,7 +14,7 @@ fn main() {
 
     let x: int = 25;
     loop {
-        take(move x); //~ ERROR use of moved variable: `x`
+        take(move x); //~ ERROR use of moved value: `x`
         //~^ NOTE move of variable occurred here
     }
 }

src/test/compile-fail/liveness-move-in-loop.rs

@@ -18,10 +18,10 @@ fn main() {
             loop {
                 loop {
 // tjc: Not sure why it prints the same error twice
-                    x = move y; //~ ERROR use of moved variable
-                    //~^ NOTE move of variable occurred here
-                    //~^^ ERROR use of moved variable
-                    //~^^^ NOTE move of variable occurred here
+                    x = move y; //~ ERROR use of moved value
+                    //~^ NOTE move of value occurred here
+                    //~^^ ERROR use of moved value
+                    //~^^^ NOTE move of value occurred here
 
                     copy x;
                 }

src/test/compile-fail/liveness-move-in-while.rs

@@ -16,9 +16,9 @@ fn main() {
         log(debug, y);
 // tjc: not sure why it prints the same error twice
         while true { while true { while true { x = move y; copy x; } } }
-        //~^ ERROR use of moved variable: `y`
-        //~^^ NOTE move of variable occurred here
-        //~^^^ ERROR use of moved variable: `y`
-        //~^^^^ NOTE move of variable occurred here
+        //~^ ERROR use of moved value: `y`
+        //~^^ NOTE move of value occurred here
+        //~^^^ ERROR use of moved value: `y`
+        //~^^^^ NOTE move of value occurred here
     }
 }

src/test/compile-fail/liveness-use-after-move.rs

@@ -10,7 +10,7 @@
 
 fn main() {
     let x = @5;
-    let y = move x; //~ NOTE move of variable occurred here
-    log(debug, *x); //~ ERROR use of moved variable: `x`
+    let y = move x; //~ NOTE move of value occurred here
+    log(debug, *x); //~ ERROR use of moved value: `x`
     copy y;
 }

src/test/compile-fail/liveness-use-after-send.rs

@@ -19,8 +19,8 @@ enum _chan<T> = int;
 // Tests that "log(debug, message);" is flagged as using
 // message after the send deinitializes it
 fn test00_start(ch: _chan<int>, message: int, _count: int) {
-    send(ch, move message); //~ NOTE move of variable occurred here
-    log(debug, message); //~ ERROR use of moved variable: `message`
+    send(ch, move message); //~ NOTE move of value occurred here
+    log(debug, message); //~ ERROR use of moved value: `message`
 }
 
 fn main() { fail; }

src/test/compile-fail/move-based-on-type-tuple.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-fn dup(x: ~int) -> ~(~int,~int) { ~(x, x) } //~ ERROR use of moved variable
+fn dup(x: ~int) -> ~(~int,~int) { ~(x, x) } //~ ERROR use of moved value
 fn main() {
     dup(~3);
 }

src/test/compile-fail/moves-based-on-type-capture-clause-bad.rs

@@ -3,6 +3,6 @@ fn main() {
     do task::spawn {
         io::println(x);
     }
-    io::println(x); //~ ERROR use of moved variable
+    io::println(x); //~ ERROR use of moved value
 }
 

src/test/compile-fail/no-capture-arc.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// error-pattern: use of moved variable
+// error-pattern: use of moved value
 
 extern mod std;
 use std::arc;

src/test/compile-fail/no-reuse-move-arc.rs

@@ -16,12 +16,12 @@ fn main() {
     let v = ~[1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
     let arc_v = arc::ARC(v);
 
-    do task::spawn() |move arc_v| { //~ NOTE move of variable occurred here
+    do task::spawn() |move arc_v| { //~ NOTE move of value occurred here
         let v = *arc::get(&arc_v);
         assert v[3] == 4;
     };
 
-    assert (*arc::get(&arc_v))[2] == 3; //~ ERROR use of moved variable: `arc_v`
+    assert (*arc::get(&arc_v))[2] == 3; //~ ERROR use of moved value: `arc_v`
 
     log(info, arc_v);
 }

src/test/compile-fail/unary-move.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// error-pattern: use of moved variable
+// error-pattern: use of moved value
 
 fn main() {
     let x = 3;

src/test/compile-fail/use-after-move-based-on-type.rs

@@ -11,6 +11,6 @@
 fn main() {
     let x = ~"Hello!";
     let _y = x;
-    io::println(x); //~ ERROR use of moved variable
+    io::println(x); //~ ERROR use of moved value
 }
 

src/test/compile-fail/use-after-move-self-based-on-type.rs

@@ -6,7 +6,7 @@ struct S {
 impl S {
     fn foo(self) -> int {
         self.bar();
-        return self.x;  //~ ERROR use of moved variable
+        return self.x;  //~ ERROR use of moved value
     }
 
     fn bar(self) {}

src/test/compile-fail/use-after-move-self.rs

@@ -5,7 +5,7 @@ struct S {
 impl S {
     fn foo(self) -> int {
         (move self).bar();
-        return self.x;  //~ ERROR use of moved variable
+        return self.x;  //~ ERROR use of moved value
     }
 
     fn bar(self) {}