Test the hashmap more, exercising hash collision, element removal, and a forced rehashing that actually causes elements to change buckets. In the process, find a bug in hashmap's remove() and fix it.

src/lib/map.rs

@@ -13,6 +13,7 @@ type hashfn[K] = fn(&K) -> uint;
 type eqfn[K] = fn(&K, &K) -> bool;
 
 type hashmap[K, V] = obj {
+  fn size() -> uint;
   fn insert(&K key, &V val) -> bool;
   fn contains_key(&K key) -> bool;
   fn get(&K key) -> V;
@@ -141,6 +142,8 @@ fn mk_hashmap[K, V](&hashfn[K] hasher, &eqfn[K] eqer) -> hashmap[K, V] {
                     mutable uint nelts,
                     util.rational lf)
   {
+    fn size() -> uint { ret nelts; }
+
     fn insert(&K key, &V val) -> bool {
       let util.rational load = rec(num=(nelts + 1u) as int, den=nbkts as int);
       if (!util.rational_leq(load, lf)) {
@@ -181,17 +184,19 @@ fn mk_hashmap[K, V](&hashfn[K] hasher, &eqfn[K] eqer) -> hashmap[K, V] {
       while (i < nbkts) {
         let uint j = (hash[K](hasher, nbkts, key, i));
         alt (bkts.(j)) {
-          case (some[K, V](_, val)) {
-            bkts.(j) = deleted[K, V]();
-            ret util.some[V](val);
-          }
-          case (deleted[K, V]()) {
-            nelts += 1u;
+          case (some[K, V](k, v)) {
+            if (eqer(key, k)) {
+              bkts.(j) = deleted[K, V]();
+              nelts -= 1u;
+              ret util.some[V](v);
+            }
           }
+          case (deleted[K, V]()) { }
           case (nil[K, V]()) {
             ret util.none[V]();
           }
         }
+        i += 1u;
       }
       ret util.none[V]();
     }

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

@@ -2,6 +2,7 @@
 
 use std;
 import std.map;
+import std.util;
 
 fn test_simple() {
   log "*** starting test_simple";
@@ -17,18 +18,18 @@ fn test_simple() {
   let map.eqfn[uint] eqer = eq;
   let map.hashmap[uint, uint] hm = map.mk_hashmap[uint, uint](hasher, eqer);
 
-  hm.insert(10u, 12u);
-  hm.insert(11u, 13u);
-  hm.insert(12u, 14u);
+  check (hm.insert(10u, 12u));
+  check (hm.insert(11u, 13u));
+  check (hm.insert(12u, 14u));
 
   check (hm.get(11u) == 13u);
   check (hm.get(12u) == 14u);
   check (hm.get(10u) == 12u);
 
-  hm.insert(12u, 14u);
+  check (!hm.insert(12u, 14u));
   check (hm.get(12u) == 14u);
 
-  hm.insert(12u, 12u);
+  check (!hm.insert(12u, 12u));
   check (hm.get(12u) == 12u);
 
   log "*** finished test_simple";
@@ -55,7 +56,7 @@ fn test_growth() {
 
   let uint i = 0u;
   while (i < num_to_insert) {
-    hm.insert(i, i * i);
+    check (hm.insert(i, i * i));
     log "inserting " + std._uint.to_str(i, 10u)
       + " -> " + std._uint.to_str(i * i, 10u);
     i += 1u;
@@ -71,7 +72,7 @@ fn test_growth() {
     i += 1u;
   }
 
-  hm.insert(num_to_insert, 17u);
+  check (hm.insert(num_to_insert, 17u));
   check (hm.get(num_to_insert) == 17u);
 
   log "-----";
@@ -89,7 +90,128 @@ fn test_growth() {
   log "*** finished test_growth";
 }
 
+fn test_removal() {
+  log "*** starting test_removal";
+
+  let uint num_to_insert = 64u;
+
+  fn eq(&uint x, &uint y) -> bool { ret x == y; }
+  fn hash(&uint u) -> uint {
+    // This hash function intentionally causes collisions between
+    // consecutive integer pairs.
+    ret (u / 2u) * 2u;
+  }
+
+  let map.hashfn[uint] hasher = hash;
+  let map.eqfn[uint] eqer = eq;
+  let map.hashmap[uint, uint] hm = map.mk_hashmap[uint, uint](hasher, eqer);
+
+  let uint i = 0u;
+  while (i < num_to_insert) {
+    check (hm.insert(i, i * i));
+    log "inserting " + std._uint.to_str(i, 10u)
+      + " -> " + std._uint.to_str(i * i, 10u);
+    i += 1u;
+  }
+
+  check (hm.size() == num_to_insert);
+
+  log "-----";
+  log "removing evens";
+
+  i = 0u;
+  while (i < num_to_insert) {
+    /**
+     * FIXME (issue #150): we want to check the removed value as in the
+     * following:
+
+    let util.option[uint] v = hm.remove(i);
+    alt (v) {
+      case (util.some[uint](u)) {
+        check (u == (i * i));
+      }
+      case (util.none[uint]()) { fail; }
+    }
+
+     * but we util.option is a tag type so util.some and util.none are
+     * off limits until we parse the dwarf for tag types.
+     */
+
+    hm.remove(i);
+    i += 2u;
+  }
+
+  check (hm.size() == (num_to_insert / 2u));
+
+  log "-----";
+
+  i = 1u;
+  while (i < num_to_insert) {
+    log "get(" + std._uint.to_str(i, 10u) + ") = "
+      + std._uint.to_str(hm.get(i), 10u);
+    check (hm.get(i) == i * i);
+    i += 2u;
+  }
+
+  log "-----";
+  log "rehashing";
+
+  hm.rehash();
+
+  log "-----";
+
+  i = 1u;
+  while (i < num_to_insert) {
+    log "get(" + std._uint.to_str(i, 10u) + ") = "
+      + std._uint.to_str(hm.get(i), 10u);
+    check (hm.get(i) == i * i);
+    i += 2u;
+  }
+
+  log "-----";
+
+  i = 0u;
+  while (i < num_to_insert) {
+    check (hm.insert(i, i * i));
+    log "inserting " + std._uint.to_str(i, 10u)
+      + " -> " + std._uint.to_str(i * i, 10u);
+    i += 2u;
+  }
+
+  check (hm.size() == num_to_insert);
+
+  log "-----";
+
+  i = 0u;
+  while (i < num_to_insert) {
+    log "get(" + std._uint.to_str(i, 10u) + ") = "
+      + std._uint.to_str(hm.get(i), 10u);
+    check (hm.get(i) == i * i);
+    i += 1u;
+  }
+
+  log "-----";
+  log "rehashing";
+
+  hm.rehash();
+
+  log "-----";
+
+  check (hm.size() == num_to_insert);
+
+  i = 0u;
+  while (i < num_to_insert) {
+    log "get(" + std._uint.to_str(i, 10u) + ") = "
+      + std._uint.to_str(hm.get(i), 10u);
+    check (hm.get(i) == i * i);
+    i += 1u;
+  }
+
+  log "*** finished test_removal";
+}
+
 fn main() {
   test_simple();
   test_growth();
+  test_removal();
 }