Create some infrastructure for building up @-vectors. Work on #2921.

src/libcore/at_vec.rs

@@ -0,0 +1,192 @@
+//! Shared Vectors
+
+import ptr::addr_of;
+
+export init_op;
+export capacity;
+export build_sized, build;
+export map;
+export from_fn, from_elem;
+export unsafe;
+
+/// Code for dealing with @-vectors. This is pretty incomplete, and
+/// contains a bunch of duplication from the code for ~-vectors.
+
+#[abi = "cdecl"]
+extern mod rustrt {
+    fn vec_reserve_shared_actual(++t: *sys::type_desc,
+                                 ++v: **vec::unsafe::vec_repr,
+                                 ++n: libc::size_t);
+}
+
+#[abi = "rust-intrinsic"]
+extern mod rusti {
+    fn move_val_init<T>(&dst: T, -src: T);
+}
+
+/// A function used to initialize the elements of a vector
+type init_op<T> = fn(uint) -> T;
+
+/// Returns the number of elements the vector can hold without reallocating
+#[inline(always)]
+pure fn capacity<T>(&&v: @[const T]) -> uint {
+    unsafe {
+        let repr: **unsafe::vec_repr =
+            ::unsafe::reinterpret_cast(addr_of(v));
+        (**repr).alloc / sys::size_of::<T>()
+    }
+}
+
+/**
+ * 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 initial size of the vector to reserve
+ * * builder - A function that will construct the vector. It recieves
+ *             as an argument a function that will push an element
+ *             onto the vector being constructed.
+ */
+#[inline(always)]
+pure fn build_sized<A>(size: uint, builder: fn(push: pure fn(+A))) -> @[A] {
+    let mut vec = @[];
+    unsafe {
+        unsafe::reserve(vec, size);
+        // This is an awful hack to be able to make the push function
+        // pure. Is there a better way?
+        ::unsafe::reinterpret_cast::
+            <fn(push: pure fn(+A)), fn(push: fn(+A))>
+            (builder)(|+x| unsafe::push(vec, x));
+    }
+    ret 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 recieves
+ *             as an argument a function that will push an element
+ *             onto the vector being constructed.
+ */
+#[inline(always)]
+pure fn build<A>(builder: fn(push: pure fn(+A))) -> @[A] {
+    build_sized(4, builder)
+}
+
+/// Apply a function to each element of a vector and return the results
+pure fn map<T, U>(v: &[T], f: fn(T) -> U) -> @[U] {
+    do build_sized(v.len()) |push| {
+        for vec::each(v) |elem| {
+            push(f(elem));
+        }
+    }
+}
+
+/**
+ * Creates and initializes an immutable vector.
+ *
+ * Creates an immutable vector of size `n_elts` and initializes the elements
+ * to the value returned by the function `op`.
+ */
+pure fn from_fn<T>(n_elts: uint, op: init_op<T>) -> @[T] {
+    do build_sized(n_elts) |push| {
+        let mut i: uint = 0u;
+        while i < n_elts { push(op(i)); i += 1u; }
+    }
+}
+
+/**
+ * Creates and initializes an immutable vector.
+ *
+ * Creates an immutable vector of size `n_elts` and initializes the elements
+ * to the value `t`.
+ */
+pure fn from_elem<T: copy>(n_elts: uint, t: T) -> @[T] {
+    do build_sized(n_elts) |push| {
+        let mut i: uint = 0u;
+        while i < n_elts { push(t); i += 1u; }
+    }
+}
+
+
+mod unsafe {
+    type vec_repr = vec::unsafe::vec_repr;
+    type slice_repr = vec::unsafe::slice_repr;
+
+    /**
+     * Sets the length of a vector
+     *
+     * This will explicitly set the size of the vector, without actually
+     * modifing its buffers, so it is up to the caller to ensure that
+     * the vector is actually the specified size.
+     */
+    #[inline(always)]
+    unsafe fn set_len<T>(&&v: @[const T], new_len: uint) {
+        let repr: **vec_repr = ::unsafe::reinterpret_cast(addr_of(v));
+        (**repr).fill = new_len * sys::size_of::<T>();
+    }
+
+    /// Append an element to a vector
+    #[inline(always)]
+    unsafe fn push<T>(&v: @[const T], +initval: T) {
+        let repr: **vec_repr = ::unsafe::reinterpret_cast(addr_of(v));
+        let fill = (**repr).fill;
+        if (**repr).alloc > fill {
+            (**repr).fill += sys::size_of::<T>();
+            let p = addr_of((**repr).data);
+            let p = ptr::offset(p, fill) as *mut T;
+            rusti::move_val_init(*p, initval);
+        }
+        else {
+            push_slow(v, initval);
+        }
+    }
+    unsafe fn push_slow<T>(&v: @[const T], +initval: T) {
+        reserve_at_least(v, v.len() + 1u);
+        push(v, initval);
+    }
+    /**
+     * Reserves capacity for exactly `n` elements in the given vector.
+     *
+     * If the capacity for `v` is already equal to or greater than the
+     * requested capacity, then no action is taken.
+     *
+     * # Arguments
+     *
+     * * v - A vector
+     * * n - The number of elements to reserve space for
+     */
+    unsafe fn reserve<T>(&v: @[const T], n: uint) {
+        // Only make the (slow) call into the runtime if we have to
+        if capacity(v) < n {
+            let ptr = addr_of(v) as **vec_repr;
+            rustrt::vec_reserve_shared_actual(sys::get_type_desc::<T>(),
+                                              ptr, n as libc::size_t);
+        }
+    }
+
+    /**
+     * Reserves capacity for at least `n` elements in the given vector.
+     *
+     * This function will over-allocate in order to amortize the
+     * allocation costs in scenarios where the caller may need to
+     * repeatedly reserve additional space.
+     *
+     * If the capacity for `v` is already equal to or greater than the
+     * requested capacity, then no action is taken.
+     *
+     * # Arguments
+     *
+     * * v - A vector
+     * * n - The number of elements to reserve space for
+     */
+    unsafe fn reserve_at_least<T>(&v: @[const T], n: uint) {
+        reserve(v, uint::next_power_of_two(n));
+    }
+
+}

src/libcore/core.rc

@@ -36,7 +36,7 @@
 export int, i8, i16, i32, i64;
 export uint, u8, u16, u32, u64;
 export float, f32, f64;
-export box, char, str, ptr, vec, bool;
+export box, char, str, ptr, vec, at_vec, bool;
 export either, option, result, iter;
 export libc, os, io, run, rand, sys, unsafe, logging;
 export arc, comm, task, future, pipes;
@@ -150,6 +150,7 @@ mod f64;
 mod str;
 mod ptr;
 mod vec;
+mod at_vec;
 mod bool;
 mod tuple;
 

src/libcore/vec.rs

@@ -17,6 +17,7 @@ export capacity;
 export len;
 export from_fn;
 export from_elem;
+export build, build_sized;
 export to_mut;
 export from_mut;
 export head;
@@ -211,6 +212,47 @@ pure fn from_elem<T: copy>(n_elts: uint, t: T) -> ~[T] {
     ret v;
 }
 
+/**
+ * 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 initial size of the vector to reserve
+ * * builder - A function that will construct the vector. It recieves
+ *             as an argument a function that will push an element
+ *             onto the vector being constructed.
+ */
+#[inline(always)]
+pure fn build_sized<A>(size: uint, builder: fn(push: pure fn(+A))) -> ~[A] {
+    let mut vec = ~[];
+    unsafe {
+        reserve(vec, size);
+        // This is an awful hack to be able to make the push function
+        // pure. Is there a better way?
+        ::unsafe::reinterpret_cast::
+            <fn(push: pure fn(+A)), fn(push: fn(+A))>
+            (builder)(|+x| push(vec, x));
+    }
+    ret 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 recieves
+ *             as an argument a function that will push an element
+ *             onto the vector being constructed.
+ */
+#[inline(always)]
+pure fn build<A>(builder: fn(push: pure fn(+A))) -> ~[A] {
+    build_sized(4, builder)
+}
+
 /// Produces a mut vector from an immutable vector.
 pure fn to_mut<T>(+v: ~[T]) -> ~[mut T] {
     unsafe { ::unsafe::transmute(v) }
@@ -444,8 +486,7 @@ fn push<T>(&v: ~[const T], +initval: T) {
         let repr: **unsafe::vec_repr = ::unsafe::reinterpret_cast(addr_of(v));
         let fill = (**repr).fill;
         if (**repr).alloc > fill {
-            let sz = sys::size_of::<T>();
-            (**repr).fill += sz;
+            (**repr).fill += sys::size_of::<T>();
             let p = ptr::addr_of((**repr).data);
             let p = ptr::offset(p, fill) as *mut T;
             rusti::move_val_init(*p, initval);
@@ -457,17 +498,8 @@ fn push<T>(&v: ~[const T], +initval: T) {
 }
 
 fn push_slow<T>(&v: ~[const T], +initval: T) {
-    unsafe {
-        let ln = v.len();
-        reserve_at_least(v, ln + 1u);
-        let repr: **unsafe::vec_repr = ::unsafe::reinterpret_cast(addr_of(v));
-        let fill = (**repr).fill;
-        let sz = sys::size_of::<T>();
-        (**repr).fill += sz;
-        let p = ptr::addr_of((**repr).data);
-        let p = ptr::offset(p, fill) as *mut T;
-        rusti::move_val_init(*p, initval);
-    }
+    reserve_at_least(v, v.len() + 1u);
+    push(v, initval);
 }
 
 // Unchecked vector indexing

src/rt/boxed_region.cpp

@@ -26,6 +26,26 @@ rust_opaque_box *boxed_region::malloc(type_desc *td, size_t body_size) {
     return box;
 }
 
+rust_opaque_box *boxed_region::realloc(rust_opaque_box *box,
+                                       size_t new_size) {
+    assert(box->ref_count == 1);
+
+    size_t total_size = new_size + sizeof(rust_opaque_box);
+    rust_opaque_box *new_box =
+        (rust_opaque_box*)backing_region->realloc(box, total_size);
+    if (new_box->prev) new_box->prev->next = new_box;
+    if (new_box->next) new_box->next->prev = new_box;
+    if (live_allocs == box) live_allocs = new_box;
+
+
+    LOG(rust_get_current_task(), box,
+        "@realloc()=%p with orig=%p, size %lu==%lu+%lu",
+        new_box, box, total_size, sizeof(rust_opaque_box), new_size);
+
+    return new_box;
+}
+
+
 rust_opaque_box *boxed_region::calloc(type_desc *td, size_t body_size) {
     rust_opaque_box *box = malloc(td, body_size);
     memset(box_body(box), 0, td->size);

src/rt/boxed_region.h

@@ -36,6 +36,7 @@ public:
 
     rust_opaque_box *malloc(type_desc *td, size_t body_size);
     rust_opaque_box *calloc(type_desc *td, size_t body_size);
+    rust_opaque_box *realloc(rust_opaque_box *box, size_t new_size);
     void free(rust_opaque_box *box);
 };
 

src/rt/rust_builtin.cpp

@@ -133,6 +133,14 @@ unsupervise() {
     task->unsupervise();
 }
 
+extern "C" CDECL void
+vec_reserve_shared_actual(type_desc* ty, rust_vec_box** vp,
+                          size_t n_elts) {
+    rust_task *task = rust_get_current_task();
+    reserve_vec_exact_shared(task, vp, n_elts * ty->size);
+}
+
+// This is completely misnamed.
 extern "C" CDECL void
 vec_reserve_shared(type_desc* ty, rust_vec_box** vp,
                    size_t n_elts) {

src/rt/rust_util.h

@@ -62,6 +62,16 @@ vec_data(rust_vec *v) {
     return reinterpret_cast<T*>(v->data);
 }
 
+inline void reserve_vec_exact_shared(rust_task* task, rust_vec_box** vpp,
+                                     size_t size) {
+    rust_opaque_box** ovpp = (rust_opaque_box**)vpp;
+    if (size > (*vpp)->body.alloc) {
+        *vpp = (rust_vec_box*)task->boxed.realloc(
+            *ovpp, size + sizeof(rust_vec));
+        (*vpp)->body.alloc = size;
+    }
+}
+
 inline void reserve_vec_exact(rust_task* task, rust_vec_box** vpp,
                               size_t size) {
     if (size > (*vpp)->body.alloc) {

src/rt/rustrt.def.in

@@ -61,6 +61,7 @@ rust_task_unweaken
 sched_threads
 shape_log_str
 start_task
+vec_reserve_shared_actual
 vec_reserve_shared
 str_reserve_shared
 vec_from_buf_shared

src/test/run-pass/at_vec_building.rs

@@ -0,0 +1,16 @@
+import at_vec::{build, from_fn, from_elem};
+
+// Some code that could use that, then:
+fn seq_range(lo: uint, hi: uint) -> @[uint] {
+    do build |push| {
+        for uint::range(lo, hi) |i| {
+            push(i);
+        }
+    }
+}
+
+fn main() {
+    assert seq_range(10, 15) == @[10, 11, 12, 13, 14];
+    assert from_fn(5, |x| x+1) == @[1, 2, 3, 4, 5];
+    assert from_elem(5, 3.14) == @[3.14, 3.14, 3.14, 3.14, 3.14];
+}