stdlib: Introduce an ivec module into the standard library; add a minimal test case

src/lib/ivec.rs

@@ -0,0 +1,25 @@
+// Interior vector utility functions.
+
+import option::none;
+import option::some;
+
+type operator2[T,U,V] = fn(&T, &U) -> V;
+
+native "rust-intrinsic" mod rusti {
+    fn ivec_len[T](&T[] v) -> uint;
+}
+
+native "rust" mod rustrt {
+    fn ivec_reserve[T](&mutable T[] v, uint n);
+    fn ivec_on_heap[T](&T[] v) -> bool;
+}
+
+/// Reserves space for `n` elements in the given vector.
+fn reserve[T](&mutable T[] v, uint n) {
+    rustrt::ivec_reserve(v, n);
+}
+
+fn on_heap[T](&T[] v) -> bool {
+    ret rustrt::ivec_on_heap(v);
+}
+

src/lib/std.rc

@@ -12,6 +12,7 @@ mod int;
 mod uint;
 mod u8;
 mod vec;
+mod ivec;
 mod str;
 
 // General io and system-services modules.

src/rt/rust_builtin.cpp

@@ -606,6 +606,16 @@ ivec_reserve(rust_task *task, type_desc *ty, rust_ivec *v, size_t n_elems)
     v->alloc = new_alloc;
 }
 
+/**
+ * Returns true if the given vector is on the heap and false if it's on the
+ * stack.
+ */
+extern "C" bool
+ivec_on_heap(rust_task *task, type_desc *ty, rust_ivec *v)
+{
+    return !v->fill && v->payload.ptr;
+}
+
 
 //
 // Local Variables:

src/rt/rustrt.def.in

@@ -9,6 +9,7 @@ debug_trap
 debug_tydesc
 do_gc
 get_time
+ivec_on_heap
 ivec_reserve
 last_os_error
 rand_free

src/test/run-pass/lib-ivec.rs

@@ -0,0 +1,16 @@
+// xfail-stage0
+
+use std;
+import std::ivec;
+
+fn test_reserve_and_on_heap() {
+    let int[] v = ~[ 1, 2 ];
+    assert (!ivec::on_heap(v));
+    ivec::reserve(v, 8u);
+    assert (ivec::on_heap(v));
+}
+
+fn main() {
+    test_reserve_and_on_heap();
+}
+