+
+/**
+ * Map from a string (name) to an unsigned integer value
+ *
+ * \note
+ * Because of the way this class interacts with the \c hash_table
+ * implementation, values of \c UINT_MAX cannot be stored in the map.
+ */
+struct string_to_uint_map {
+public:
+ string_to_uint_map()
+ {
+ this->ht = hash_table_ctor(0, hash_table_string_hash,
+ hash_table_string_compare);
+ }
+
+ ~string_to_uint_map()
+ {
+ hash_table_call_foreach(this->ht, delete_key, NULL);
+ hash_table_dtor(this->ht);
+ }
+
+ /**
+ * Remove all mappings from this map.
+ */
+ void clear()
+ {
+ hash_table_call_foreach(this->ht, delete_key, NULL);
+ hash_table_clear(this->ht);
+ }
+
+ /**
+ * Get the value associated with a particular key
+ *
+ * \return
+ * If \c key is found in the map, \c true is returned. Otherwise \c false
+ * is returned.
+ *
+ * \note
+ * If \c key is not found in the table, \c value is not modified.
+ */
+ bool get(unsigned &value, const char *key)
+ {
+ const intptr_t v =
+ (intptr_t) hash_table_find(this->ht, (const void *) key);
+
+ if (v == 0)
+ return false;
+
+ value = (unsigned)(v - 1);
+ return true;
+ }
+
+ void put(unsigned value, const char *key)
+ {
+ /* The low-level hash table structure returns NULL if key is not in the
+ * hash table. However, users of this map might want to store zero as a
+ * valid value in the table. Bias the value by +1 so that a
+ * user-specified zero is stored as 1. This enables ::get to tell the
+ * difference between a user-specified zero (returned as 1 by
+ * hash_table_find) and the key not in the table (returned as 0 by
+ * hash_table_find).
+ *
+ * The net effect is that we can't store UINT_MAX in the table. This is
+ * because UINT_MAX+1 = 0.
+ */
+ assert(value != UINT_MAX);
+ char *dup_key = strdup(key);
+ bool result = hash_table_replace(this->ht,
+ (void *) (intptr_t) (value + 1),
+ dup_key);
+ if (result)
+ free(dup_key);
+ }
+
+private:
+ static void delete_key(const void *key, void *data, void *closure)
+ {
+ (void) data;
+ (void) closure;
+
+ free((char *)key);
+ }
+
+ struct hash_table *ht;
+};
+
+#endif /* __cplusplus */