data: added HashMap::fetch() and support in HashTable.

include/elm/data/HashMap.h

@@ -47,6 +47,9 @@ public:
 	inline void clear(void) { _tab.clear(); }
 	inline void add(const K& key, const T& val) { _tab.add(pair(key, val)); }
 
+	inline T& fetch(const K& k)
+		{ auto *n = _tab.get(key(k)); if(n != nullptr) return n->snd; return _tab.add(pair(k, T()))->snd; }
+
 	// Map concept
 	inline Option<T> get(const K& k) const
 		{ auto *r = _tab.get(key(k)); if(r) return some(r->snd); else return none; }

include/elm/data/HashTable.h

@@ -41,6 +41,7 @@ private:
 		T data;
 	};
 
+protected:
 	node_t *find(const T& key) const {
 		int i = H::computeHash(key) % _size;
 		for(node_t *node = _tab[i], *prev = 0; node; prev = node, node = node->next)
@@ -60,6 +61,8 @@ private:
 		return 0;
 	}
 
+private:
+
 	node_t *make(const T& data) {
 		int i = H::computeHash(data) % _size;
 		node_t *node = new(A::allocate(sizeof(node_t))) node_t(data);
@@ -152,7 +155,7 @@ public:
 		}
 	}
 
-	void add(const T& data) { make(data); }
+	T *add(const T& data) { return &make(data)->data; }
 
 	inline self_t& operator+=(const T& x) { add(x); return *this; }
 
@@ -208,6 +211,9 @@ public:
 	}
 	inline self_t& operator=(const HashTable<T, H>& c) { copy(c); return *this; }
 
+	inline T *get(const T& key)
+		{ node_t *node = find(key); return node ? &node->data : 0; }
+
 #	ifdef ELM_STAT
 		int minEntry(void) const { int m = count(0); for(int i = 1; i < _size; i++) m = min(m, count(i)); return m; }
 		int maxEntry(void) const { int m = count(0); for(int i = 1; i < _size; i++) m = max(m, count(i)); return m; }

src/data_HashTable.cpp

@@ -164,6 +164,15 @@ namespace elm {
  * @param size	Table size (default to 211).
  */
 
+/**
+ * @fn T& HashMap::fetch(const K& k);
+ * Get a reference to the data stored with the key k. If no data is already
+ * associated with key k, an entry and corresponding data are created
+ * and returns a reference to it.
+ * @param k		Key of looked data.
+ * @return		Reference to data associated with key.
+ */
+
 /**
  * @fn bool HashMap::isEmpty(void) const;
  * Test if the map is empty.

test/test_hashtable.cpp

@@ -86,6 +86,7 @@ TEST_BEGIN(hashtable)
 			m[1];
 			cm[1];
 			m[1] = 1;
+			m.fetch(1);
 		}
 	}
 
@@ -221,7 +222,7 @@ TEST_BEGIN(hashtable)
 		bool failed = false;
 		for(int i = 0; i < 100; i++) {
 			string k = _ << i << (-i);
-			Option<int> o = map2.get(k);
+			auto o = map2.get(k);
 			if(!o || *o != i) {
 				failed = true;
 				break;