Continued sketching out code for checking states against preconditions.

It's still sketchy. I added a typestate annotation field to statements
tagged stmt_decl or stmt_expr, because a stmt_decl statement has a typestate
that's different from that of its child node. This necessitated trivial
changes to a bunch of other files all over to the compiler. I also added a
few small standard library functions, some of which I didn't actually end
up using but which I thought might be useful anyway.

src/lib/_vec.rs

@@ -1,5 +1,6 @@
 import option.none;
 import option.some;
+import util.orb;
 
 type vbuf = rustrt.vbuf;
 
@@ -230,6 +231,26 @@ fn foldl[T, U](fn (&U, &T) -> U p, &U z, &vec[T] v) -> U {
     }
 }
 
+fn unzip[T, U](&vec[tup(T, U)] v) -> tup(vec[T], vec[U]) {
+    auto sz = len[tup(T, U)](v);
+
+    if (sz == 0u) {
+        ret tup(alloc[T](0u), alloc[U](0u));
+    }
+    else {
+        auto rest = slice[tup(T, U)](v, 1u, sz);
+        auto tl   = unzip[T, U](rest);
+        auto a    = vec(v.(0)._0);
+        auto b    = vec(v.(0)._1);
+        ret tup(a + tl._0, b + tl._1);
+    }
+}
+
+fn or(&vec[bool] v) -> bool {
+    auto f = orb;
+    be _vec.foldl[bool, bool](f, false, v);
+}
+
 // Local Variables:
 // mode: rust;
 // fill-column: 78;

src/lib/bitv.rs

@@ -135,6 +135,28 @@ impure fn set(&t v, uint i, bool x) {
     }
 }
 
+/* true if all bits are 1 */
+fn is_true(&t v) -> bool {
+    for(uint i in v.storage) {
+        if (i != 1u) {
+            ret false;
+        }
+    }
+
+    ret true;
+}
+
+/* true if all bits are non-1 */
+fn is_false(&t v) -> bool {
+    for(uint i in v.storage) {
+        if (i == 1u) {
+            ret false;
+        }
+    }
+
+    ret true;
+}
+
 fn init_to_vec(t v, uint i) -> uint {
     if (get(v, i)) {
         ret 1u;

src/lib/option.rs

@@ -38,6 +38,13 @@ fn is_none[T](&t[T] opt) -> bool {
     }
 }
 
+fn from_maybe[T](&T def, &t[T] opt) -> T {
+    alt(opt) {
+        case (none[T])     { ret def; }
+        case (some[T](?t)) { ret t; }
+    }
+}
+
 // Local Variables:
 // mode: rust;
 // fill-column: 78;

src/lib/util.rs

@@ -11,6 +11,18 @@ fn rational_leq(&rational x, &rational y) -> bool {
     ret x.num * y.den <= y.num * x.den;
 }
 
+fn fst[T, U](&tup(T, U) x) -> T {
+    ret x._0;
+}
+
+fn snd[T, U](&tup(T, U) x) -> U {
+    ret x._1;
+}
+
+fn orb(&bool a, &bool b) -> bool {
+    ret a || b;
+}
+
 // Local Variables:
 // mode: rust;
 // fill-column: 78;