---

yaml
---
r: 148460
b: refs/heads/try2
c: 80a2306
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: 1f542cd2640fd969cba328ca3b4059acd6428a83
+refs/heads/try2: 80a2306aee6bb6ccde8692521c32eb96fe942991
 refs/heads/dist-snap: ba4081a5a8573875fed17545846f6f6902c8ba8d
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596
 refs/tags/release-0.3: b5f0d0f648d9a6153664837026ba1be43d3e2503

branches/try2/doc/guide-ffi.md

@@ -249,6 +249,143 @@ fn main() {
 }
 ~~~~
 
+# Callbacks from C code to Rust functions
+
+Some external libraries require the usage of callbacks to report back their
+current state or intermediate data to the caller.
+It is possible to pass functions defined in Rust to an external library.
+The requirement for this is that the callback function is marked as `extern`
+with the correct calling convention to make it callable from C code.
+
+The callback function that can then be sent to through a registration call
+to the C library and afterwards be invoked from there.
+
+A basic example is:
+
+Rust code:
+~~~~ {.xfail-test}
+extern fn callback(a:i32) {
+    println!("I'm called from C with value {0}", a);
+}
+
+#[link(name = "extlib")]
+extern {
+   fn register_callback(cb: extern "C" fn(i32)) -> i32;
+   fn trigger_callback();
+}
+
+fn main() {
+    unsafe {
+        register_callback(callback);
+        trigger_callback(); // Triggers the callback
+    }
+}
+~~~~
+
+C code:
+~~~~ {.xfail-test}
+typedef void (*rust_callback)(int32_t);
+rust_callback cb;
+
+int32_t register_callback(rust_callback callback) {
+    cb = callback;
+    return 1;
+}
+
+void trigger_callback() {
+  cb(7); // Will call callback(7) in Rust
+}
+~~~~
+
+In this example will Rust's `main()` will call `do_callback()` in C,
+which would call back to `callback()` in Rust.
+
+
+## Targetting callbacks to Rust objects
+
+The former example showed how a global function can be called from C-Code.
+However it is often desired that the callback is targetted to a special
+Rust object. This could be the object that represents the wrapper for the
+respective C object. 
+
+This can be achieved by passing an unsafe pointer to the object down to the
+C library. The C library can then include the pointer to the Rust object in
+the notification. This will provide a unsafe possibility to access the 
+referenced Rust object in callback.
+
+Rust code:
+~~~~ {.xfail-test}
+
+struct RustObject {
+    a: i32,
+    // other members
+}
+
+extern fn callback(target: *RustObject, a:i32) {
+    println!("I'm called from C with value {0}", a);
+    (*target).a = a; // Update the value in RustObject with the value received from the callback
+}
+
+#[link(name = "extlib")]
+extern {
+   fn register_callback(target: *RustObject, cb: extern "C" fn(*RustObject, i32)) -> i32;
+   fn trigger_callback();
+}
+
+fn main() {
+    // Create the object that will be referenced in the callback
+    let rust_object = ~RustObject{a: 5, ...};
+     
+    unsafe {
+        // Gets a raw pointer to the object
+        let target_addr:*RustObject = ptr::to_unsafe_ptr(rust_object);
+        register_callback(target_addr, callback);
+        trigger_callback(); // Triggers the callback
+    }
+}
+~~~~
+
+C code:
+~~~~ {.xfail-test}
+typedef void (*rust_callback)(int32_t);
+void* cb_target;
+rust_callback cb;
+
+int32_t register_callback(void* callback_target, rust_callback callback) {
+    cb_target = callback_target;
+    cb = callback;
+    return 1;
+}
+
+void trigger_callback() {
+  cb(cb_target, 7); // Will call callback(&rustObject, 7) in Rust
+}
+~~~~
+
+## Asynchronous callbacks
+
+In the already given examples the callbacks are invoked as a direct reaction
+to a function call to the external C library.
+The control over the current thread switched from Rust to C to Rust for the
+execution of the callback, but in the end the callback is executed on the
+same thread (and Rust task) that lead called the function which triggered
+the callback.
+
+Things get more complicated when the external library spawns it's own threads
+and invokes callbacks from there.
+In these cases access to Rust data structures inside he callbacks is
+especially unsafe and proper synchronization mechanisms must be used.
+Besides classical synchronization mechanisms like mutexes one possibility in
+Rust is to use channels (in `std::comm`) to forward data from the C thread
+that invoked the callback into a Rust task.
+
+If an asychronous callback targets a special object in the Rust address space
+it is also absolutely necessary that no more callbacks are performed by the 
+C library after the respective Rust object get's destroyed. 
+This can be achieved by unregistering the callback it the object's
+destructor and designing the library in a way that guarantees that no
+callback will be performed after unregistration.
+
 # Linking
 
 The `link` attribute on `extern` blocks provides the basic building block for

branches/try2/doc/guide-tasks.md

@@ -290,7 +290,7 @@ be distributed on the available cores.
 fn partial_sum(start: uint) -> f64 {
     let mut local_sum = 0f64;
     for num in range(start*100000, (start+1)*100000) {
-        local_sum += (num as f64 + 1.0).pow(&-2.0);
+        local_sum += (num as f64 + 1.0).powf(&-2.0);
     }
     local_sum
 }
@@ -326,7 +326,7 @@ a single large vector of floats. Each task needs the full vector to perform its
 use extra::arc::Arc;
 
 fn pnorm(nums: &~[f64], p: uint) -> f64 {
-    nums.iter().fold(0.0, |a,b| a+(*b).pow(&(p as f64)) ).pow(&(1.0 / (p as f64)))
+    nums.iter().fold(0.0, |a,b| a+(*b).powf(&(p as f64)) ).powf(&(1.0 / (p as f64)))
 }
 
 fn main() {

branches/try2/doc/guide-testing.md

@@ -33,7 +33,7 @@ test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured
 # Unit testing in Rust
 
 Rust has built in support for simple unit testing. Functions can be
-marked as unit tests using the 'test' attribute.
+marked as unit tests using the `test` attribute.
 
 ~~~
 #[test]
@@ -44,13 +44,13 @@ fn return_none_if_empty() {
 
 A test function's signature must have no arguments and no return
 value. To run the tests in a crate, it must be compiled with the
-'--test' flag: `rustc myprogram.rs --test -o myprogram-tests`. Running
+`--test` flag: `rustc myprogram.rs --test -o myprogram-tests`. Running
 the resulting executable will run all the tests in the crate. A test
 is considered successful if its function returns; if the task running
 the test fails, through a call to `fail!`, a failed `check` or
 `assert`, or some other (`assert_eq`, ...) means, then the test fails.
 
-When compiling a crate with the '--test' flag '--cfg test' is also
+When compiling a crate with the `--test` flag `--cfg test` is also
 implied, so that tests can be conditionally compiled.
 
 ~~~
@@ -63,18 +63,18 @@ mod tests {
 }
 ~~~
 
-Additionally #[test] items behave as if they also have the
-#[cfg(test)] attribute, and will not be compiled when the --test flag
+Additionally `#[test]` items behave as if they also have the
+`#[cfg(test)]` attribute, and will not be compiled when the `--test` flag
 is not used.
 
-Tests that should not be run can be annotated with the 'ignore'
+Tests that should not be run can be annotated with the `ignore`
 attribute. The existence of these tests will be noted in the test
 runner output, but the test will not be run. Tests can also be ignored
 by configuration so, for example, to ignore a test on windows you can
 write `#[ignore(cfg(target_os = "win32"))]`.
 
 Tests that are intended to fail can be annotated with the
-'should_fail' attribute. The test will be run, and if it causes its
+`should_fail` attribute. The test will be run, and if it causes its
 task to fail then the test will be counted as successful; otherwise it
 will be counted as a failure. For example:
 
@@ -87,11 +87,11 @@ fn test_out_of_bounds_failure() {
 }
 ~~~
 
-A test runner built with the '--test' flag supports a limited set of
+A test runner built with the `--test` flag supports a limited set of
 arguments to control which tests are run: the first free argument
 passed to a test runner specifies a filter used to narrow down the set
-of tests being run; the '--ignored' flag tells the test runner to run
-only tests with the 'ignore' attribute.
+of tests being run; the `--ignored` flag tells the test runner to run
+only tests with the `ignore` attribute.
 
 ## Parallelism
 

branches/try2/doc/rust.md

@@ -2211,12 +2211,9 @@ dereferences (`*expr`), [indexing expressions](#index-expressions)
 (`expr[expr]`), and [field references](#field-expressions) (`expr.f`).
 All other expressions are rvalues.
 
-The left operand of an [assignment](#assignment-expressions),
-[binary move](#binary-move-expressions) or
+The left operand of an [assignment](#assignment-expressions) or
 [compound-assignment](#compound-assignment-expressions) expression is an lvalue context,
-as is the single operand of a unary [borrow](#unary-operator-expressions),
-or [move](#unary-move-expressions) expression,
-and _both_ operands of a [swap](#swap-expressions) expression.
+as is the single operand of a unary [borrow](#unary-operator-expressions).
 All other expression contexts are rvalue contexts.
 
 When an lvalue is evaluated in an _lvalue context_, it denotes a memory location;
@@ -2229,9 +2226,8 @@ A temporary's lifetime equals the largest lifetime of any reference that points
 
 When a [local variable](#memory-slots) is used
 as an [rvalue](#lvalues-rvalues-and-temporaries)
-the variable will either be [moved](#move-expressions) or copied,
-depending on its type.
-For types that contain [owning pointers](#owning-pointers)
+the variable will either be moved or copied, depending on its type.
+For types that contain [owning pointers](#pointer-types)
 or values that implement the special trait `Drop`,
 the variable is moved.
 All other types are copied.
@@ -2890,16 +2886,26 @@ match x {
 
 The first pattern matches lists constructed by applying `Cons` to any head value, and a
 tail value of `~Nil`. The second pattern matches _any_ list constructed with `Cons`,
-ignoring the values of its arguments. The difference between `_` and `*` is that the pattern `C(_)` is only type-correct if
-`C` has exactly one argument, while the pattern `C(..)` is type-correct for any enum variant `C`, regardless of how many arguments `C` has.
-
-To execute an `match` expression, first the head expression is evaluated, then
-its value is sequentially compared to the patterns in the arms until a match
+ignoring the values of its arguments. The difference between `_` and `*` is that the pattern
+`C(_)` is only type-correct if `C` has exactly one argument, while the pattern `C(..)` is
+type-correct for any enum variant `C`, regardless of how many arguments `C` has.
+
+A `match` behaves differently depending on whether or not the head expression
+is an [lvalue or an rvalue](#lvalues-rvalues-and-temporaries).
+If the head expression is an rvalue, it is
+first evaluated into a temporary location, and the resulting value
+is sequentially compared to the patterns in the arms until a match
 is found. The first arm with a matching pattern is chosen as the branch target
 of the `match`, any variables bound by the pattern are assigned to local
 variables in the arm's block, and control enters the block.
 
-An example of an `match` expression:
+When the head expression is an lvalue, the match does not allocate a
+temporary location (however, a by-value binding may copy or move from
+the lvalue). When possible, it is preferable to match on lvalues, as the
+lifetime of these matches inherits the lifetime of the lvalue, rather
+than being restricted to the inside of the match.
+
+An example of a `match` expression:
 
 ~~~~
 # fn process_pair(a: int, b: int) { }
@@ -2929,19 +2935,31 @@ Patterns that bind variables
 default to binding to a copy or move of the matched value
 (depending on the matched value's type).
 This can be changed to bind to a reference by
-using the ```ref``` keyword,
-or to a mutable reference using ```ref mut```.
-
-A pattern that's just an identifier,
-like `Nil` in the previous answer,
-could either refer to an enum variant that's in scope,
-or bind a new variable.
-The compiler resolves this ambiguity by forbidding variable bindings that occur in ```match``` patterns from shadowing names of variants that are in scope.
-For example, wherever ```List``` is in scope,
-a ```match``` pattern would not be able to bind ```Nil``` as a new name.
-The compiler interprets a variable pattern `x` as a binding _only_ if there is no variant named `x` in scope.
-A convention you can use to avoid conflicts is simply to name variants with upper-case letters,
-and local variables with lower-case letters.
+using the `ref` keyword,
+or to a mutable reference using `ref mut`.
+
+Patterns can also dereference pointers by using the `&`,
+`~` or `@` symbols, as appropriate. For example, these two matches
+on `x: &int` are equivalent:
+
+~~~~
+# let x = &3;
+let y = match *x { 0 => "zero", _ => "some" };
+let z = match x { &0 => "zero", _ => "some" };
+
+assert_eq!(y, z);
+~~~~
+
+A pattern that's just an identifier, like `Nil` in the previous answer,
+could either refer to an enum variant that's in scope, or bind a new variable.
+The compiler resolves this ambiguity by forbidding variable bindings that occur
+in `match` patterns from shadowing names of variants that are in scope.
+For example, wherever `List` is in scope,
+a `match` pattern would not be able to bind `Nil` as a new name.
+The compiler interprets a variable pattern `x` as a binding _only_ if there is
+no variant named `x` in scope.
+A convention you can use to avoid conflicts is simply to name variants with
+upper-case letters, and local variables with lower-case letters.
 
 Multiple match patterns may be joined with the `|` operator.
 A range of values may be specified with `..`.
@@ -3122,19 +3140,20 @@ A `struct` *type* is a heterogeneous product of other types, called the *fields*
 the *record* types of the ML family,
 or the *structure* types of the Lisp family.]
 
-New instances of a `struct` can be constructed with a [struct expression](#struct-expressions).
+New instances of a `struct` can be constructed with a [struct expression](#structure-expressions).
 
 The memory order of fields in a `struct` is given by the item defining it.
 Fields may be given in any order in a corresponding struct *expression*;
 the resulting `struct` value will always be laid out in memory in the order specified by the corresponding *item*.
 
-The fields of a `struct` may be qualified by [visibility modifiers](#visibility-modifiers),
+The fields of a `struct` may be qualified by [visibility modifiers](#re-exporting-and-visibility),
 to restrict access to implementation-private data in a structure.
 
 A _tuple struct_ type is just like a structure type, except that the fields are anonymous.
 
 A _unit-like struct_ type is like a structure type, except that it has no fields.
-The one value constructed by the associated [structure expression](#structure-expression) is the only value that inhabits such a type.
+The one value constructed by the associated [structure expression](#structure-expressions)
+is the only value that inhabits such a type.
 
 ### Enumerated types
 
@@ -3805,7 +3824,7 @@ over the output format of a Rust crate.
 ### Logging system
 
 The runtime contains a system for directing [logging
-expressions](#log-expressions) to a logging console and/or internal logging
+expressions](#logging-expressions) to a logging console and/or internal logging
 buffers. Logging can be enabled per module.
 
 Logging output is enabled by setting the `RUST_LOG` environment

branches/try2/doc/tutorial.md

@@ -1020,10 +1020,15 @@ being destroyed along with the owner. Since the `list` variable above is
 immutable, the whole list is immutable. The memory allocation itself is the
 box, while the owner holds onto a pointer to it:
 
-      Cons cell        Cons cell        Cons cell
-    +-----------+    +-----+-----+    +-----+-----+
-    |  1  |  ~  | -> |  2  |  ~  | -> |  3  |  ~  | -> Nil
-    +-----------+    +-----+-----+    +-----+-----+
+              List box             List box           List box            List box
+            +--------------+    +--------------+    +--------------+    +--------------+
+    list -> | Cons | 1 | ~ | -> | Cons | 2 | ~ | -> | Cons | 3 | ~ | -> | Nil          |
+            +--------------+    +--------------+    +--------------+    +--------------+
+
+> Note: the above diagram shows the logical contents of the enum. The actual
+> memory layout of the enum may vary. For example, for the `List` enum shown
+> above, Rust guarantees that there will be no enum tag field in the actual
+> structure. See the language reference for more details.
 
 An owned box is a common example of a type with a destructor. The allocated
 memory is cleaned up when the box is destroyed.