util.cache: Add head() and tail() methods (and tests)

diff --git a/tests/test_util_cache.lua b/tests/test_util_cache.lua
index 72cb5a856ed486cf437e05c588edad228fd2bdfb..ecdc2dc02ef2edbdc99e59e71c8328caf445b018 100644 (file)
--- a/tests/test_util_cache.lua
+++ b/tests/test_util_cache.lua
@@ -1,21 +1,44 @@
-
 function new(new)
        local c = new(5);
 
+       local function expect_kv(key, value, actual_key, actual_value)
+               assert_equal(key, actual_key, "key incorrect");
+               assert_equal(value, actual_value, "value incorrect");
+       end
+
+       expect_kv(nil, nil, c:head());
+       expect_kv(nil, nil, c:tail());
+
        assert_equal(c:count(), 0);
        
        c:set("one", 1)
        assert_equal(c:count(), 1);
+       expect_kv("one", 1, c:head());
+       expect_kv("one", 1, c:tail());
+
        c:set("two", 2)
+       expect_kv("two", 2, c:head());
+       expect_kv("one", 1, c:tail());
+
        c:set("three", 3)
+       expect_kv("three", 3, c:head());
+       expect_kv("one", 1, c:tail());
+
        c:set("four", 4)
        c:set("five", 5);
        assert_equal(c:count(), 5);
+       expect_kv("five", 5, c:head());
+       expect_kv("one", 1, c:tail());
        
        c:set("foo", nil);
        assert_equal(c:count(), 5);
+       expect_kv("five", 5, c:head());
+       expect_kv("one", 1, c:tail());
        
        assert_equal(c:get("one"), 1);
+       expect_kv("five", 5, c:head());
+       expect_kv("one", 1, c:tail());
+
        assert_equal(c:get("two"), 2);
        assert_equal(c:get("three"), 3);
        assert_equal(c:get("four"), 4);
@@ -26,6 +49,8 @@ function new(new)
        
        c:set("six", 6);
        assert_equal(c:count(), 5);
+       expect_kv("six", 6, c:head());
+       expect_kv("two", 2, c:tail());
        
        assert_equal(c:get("one"), nil);
        assert_equal(c:get("two"), 2);

diff --git a/util/cache.lua b/util/cache.lua
index d3639b3f7aebc791bfdf8b57d395af810b03e25e..e53bf4bf8ac7b948676a0b15d81813587a3a5083 100644 (file)
--- a/util/cache.lua
+++ b/util/cache.lua
@@ -92,6 +92,18 @@ function cache_methods:count()
        return self._count;
 end
 
+function cache_methods:head()
+       local head = self._head;
+       if not head then return nil, nil; end
+       return head.key, head.value;
+end
+
+function cache_methods:tail()
+       local tail = self._tail;
+       if not tail then return nil, nil; end
+       return tail.key, tail.value;
+end
+
 local function new(size, on_evict)
        size = assert(tonumber(size), "cache size must be a number");
        size = math.floor(size);