Speed up finding message catalog by name in wxTranslations.

Use a helper hash map to allow efficiently finding message catalogs by name
instead of using linear search in a linked list which can be noticeably slow
when many catalogs are used.

This speeds up wxGetTranslation() when the domain is specified.

Closes #16975.

include/wx/translation.h

@@ -183,6 +183,12 @@ private:
     wxTranslationsLoader *m_loader;
 
     wxMsgCatalog *m_pMsgCat; // pointer to linked list of catalogs
+
+    // In addition to keeping all the catalogs in the linked list, we also
+    // store them in a hash map indexed by the domain name to allow finding
+    // them by name efficiently.
+    WX_DECLARE_HASH_MAP(wxString, wxMsgCatalog *, wxStringHash, wxStringEqual, wxMsgCatalogMap);
+    wxMsgCatalogMap m_catalogMap;
 };
 
 

src/common/translation.cpp

@@ -1573,8 +1573,10 @@ bool wxTranslations::LoadCatalog(const wxString& domain, const wxString& lang, c
     {
         // add it to the head of the list so that in GetString it will
         // be searched before the catalogs added earlier
+
         cat->m_pNext = m_pMsgCat;
         m_pMsgCat = cat;
+        m_catalogMap[domain] = cat;
 
         return true;
     }
@@ -1735,18 +1737,12 @@ wxString wxTranslations::GetHeaderValue(const wxString& header,
 }
 
 
-// find catalog by name in a linked list, return NULL if !found
+// find catalog by name
 wxMsgCatalog *wxTranslations::FindCatalog(const wxString& domain) const
 {
-    // linear search in the linked list
+    const wxMsgCatalogMap::const_iterator found = m_catalogMap.find(domain);
-    wxMsgCatalog *pMsgCat;
-    for ( pMsgCat = m_pMsgCat; pMsgCat != NULL; pMsgCat = pMsgCat->m_pNext )
-    {
-        if ( pMsgCat->GetDomain() == domain )
-            return pMsgCat;
-    }
 
-    return NULL;
+    return found == m_catalogMap.end() ? NULL : found->second;
 }
 
 // ----------------------------------------------------------------------------