A data indexer template

This takes some coding out of creating an enum-indexed data list (existing
examples would include lists of player status data, spell data, etc.)

1 files changed, 50 insertions, 0 deletions

diff --git a/crawl-ref/source/data-index.h b/crawl-ref/source/data-index.h
new file mode 100644
index 0000000000..fc84cb4d9c
--- /dev/null
+++ b/crawl-ref/source/data-index.h
@@ -0,0 +1,50 @@
+/**
+ * @file
+ * @brief Functions for managing indexed tables of data attached to enums
+**/
+
+#ifndef DATAINDEX_H
+#define DATAINDEX_H
+
+template <typename TKey, typename TVal, int NMax>
+class data_index
+{
+public:
+    data_index(const TVal* _pop) : pop(_pop), index_created(false)
+    { }
+
+    const TVal* operator[](int i)
+    {
+        check_index();
+        return (&pop[index[i]]);
+    }
+
+    bool contains(TKey key)
+    {
+        check_index();
+        return (index[key] >= 0);
+    }
+
+protected:
+    const TVal* pop;
+    bool index_created;
+    int index[NMax];
+    virtual TKey map(const TVal* val) = 0;
+
+    void check_index()
+    {
+        if (!index_created)
+        {
+            memset(index, -1, sizeof(index));
+            int i = 0;
+            for (const TVal* p = pop; map(p); p++)
+            {
+                index[map(p)] = i;
+                i++;
+            }
+            index_created = true;
+        }
+    }
+};
+
+#endif