Reduce repeating item_glyph regexp matches by caching results per name.

This still requires costly production of the item's name, once per every
item visible on screen every single round.

1 files changed, 13 insertions, 0 deletions

diff --git a/crawl-ref/source/showsymb.cc b/crawl-ref/source/showsymb.cc
index 004035ea09..80544488ec 100644
--- a/crawl-ref/source/showsymb.cc
+++ b/crawl-ref/source/showsymb.cc
@@ -212,6 +212,13 @@ static cglyph_t _get_item_override(const item_def &item)
     string name = stash_annotate_item(STASH_LUA_SEARCH_ANNOTATE, &item)
                 + item.name(DESC_PLAIN);
 
+    {
+        // Check the cache...
+        map<string, cglyph_t>::const_iterator ir = Options.item_glyph_cache.find(name);
+        if (ir != Options.item_glyph_cache.end())
+            return ir->second;
+    }
+
     for (map<string, cglyph_t>::const_iterator ir = Options.item_glyph_overrides.begin();
          ir != Options.item_glyph_overrides.end(); ++ir)
     {
@@ -228,6 +235,12 @@ static cglyph_t _get_item_override(const item_def &item)
         }
     }
 
+    // Matching against a list of regexps can be costly, save up to 1000
+    // last matches.
+    if (Options.item_glyph_cache.size() >= 1000)
+        Options.item_glyph_cache.clear();
+    Options.item_glyph_cache[name] = g;
+
     return g;
 }