ICU-22390 Transliterator.<clinit> can be optimized - part 2

WIDTH_FIX instance could be lazily initialized, because it's used
only if transliterate() is called on the AnyTransliterator instance,
but apparently not used by other Transliterator instance.

icu4c/source/i18n/transreg.cpp

@@ -11,6 +11,7 @@
 */
 
 #include "unicode/utypes.h"
+#include <unicode/rep.h>
 
 #if !UCONFIG_NO_TRANSLITERATION
 
@@ -531,7 +532,7 @@ TransliteratorRegistry::TransliteratorRegistry(UErrorCode& status) :
     registry(true, status),
     specDAG(true, SPECDAG_INIT_SIZE, status),
     variantList(VARIANT_LIST_INIT_SIZE, status),
-    availableIDs(AVAILABLE_IDS_INIT_SIZE, status)
+    availableIDs(true, AVAILABLE_IDS_INIT_SIZE, status)
 {
     registry.setValueDeleter(deleteEntry);
     variantList.setDeleter(uprv_deleteUObject);
@@ -540,8 +541,6 @@ TransliteratorRegistry::TransliteratorRegistry(UErrorCode& status) :
     if (emptyString != nullptr) {
         variantList.adoptElement(emptyString, status);
     }
-    availableIDs.setDeleter(uprv_deleteUObject);
-    availableIDs.setComparer(uhash_compareCaselessUnicodeString);
     specDAG.setValueDeleter(uhash_deleteHashtable);
 }
 
@@ -714,7 +713,7 @@ void TransliteratorRegistry::remove(const UnicodeString& ID) {
     TransliteratorIDParser::STVtoID(source, target, variant, id);
     registry.remove(id);
     removeSTV(source, target, variant);
-    availableIDs.removeElement((void*) &id);
+    availableIDs.remove(id);
 }
 
 //----------------------------------------------------------------------
@@ -728,7 +727,7 @@ void TransliteratorRegistry::remove(const UnicodeString& ID) {
  * i from 0 to countAvailableIDs() - 1.
  */
 int32_t TransliteratorRegistry::countAvailableIDs() const {
-    return availableIDs.size();
+    return availableIDs.count();
 }
 
 /**
@@ -738,10 +737,27 @@ int32_t TransliteratorRegistry::countAvailableIDs() const {
  * range, the result of getAvailableID(0) is returned.
  */
 const UnicodeString& TransliteratorRegistry::getAvailableID(int32_t index) const {
-    if (index < 0 || index >= availableIDs.size()) {
+    if (index < 0 || index >= availableIDs.count()) {
         index = 0;
     }
-    return *(const UnicodeString*) availableIDs[index];
+
+    int32_t pos = UHASH_FIRST;
+    const UHashElement *e = nullptr;
+    while (index-- >= 0) {
+        e = availableIDs.nextElement(pos);
+        if (e == nullptr) {
+            break;
+        }
+    }
+
+    if (e != nullptr) {
+        return *(UnicodeString*) e->key.pointer;
+    }
+
+    // If the code reaches here, the hash table was likely modified during iteration.
+    // Return an statically initialized empty string due to reference return type.
+    static UnicodeString empty;
+    return empty;
 }
 
 StringEnumeration* TransliteratorRegistry::getAvailableIDs() const {
@@ -852,14 +868,14 @@ UnicodeString& TransliteratorRegistry::getAvailableVariant(int32_t index,
 //----------------------------------------------------------------------
 
 TransliteratorRegistry::Enumeration::Enumeration(const TransliteratorRegistry& _reg) :
-    index(0), reg(_reg) {
+    pos(UHASH_FIRST), size(_reg.availableIDs.count()), reg(_reg) {
 }
 
 TransliteratorRegistry::Enumeration::~Enumeration() {
 }
 
 int32_t TransliteratorRegistry::Enumeration::count(UErrorCode& /*status*/) const {
-    return reg.availableIDs.size();
+    return size;
 }
 
 const UnicodeString* TransliteratorRegistry::Enumeration::snext(UErrorCode& status) {
@@ -875,22 +891,27 @@ const UnicodeString* TransliteratorRegistry::Enumeration::snext(UErrorCode& stat
     if (U_FAILURE(status)) {
         return nullptr;
     }
-    int32_t n = reg.availableIDs.size();
-    if (index > n) {
+    int32_t n = reg.availableIDs.count();
+    if (n != size) {
         status = U_ENUM_OUT_OF_SYNC_ERROR;
-    }
-    // index == n is okay -- this means we've reached the end
-    if (index < n) {
-        // Copy the string! This avoids lifetime problems.
-        unistr = *(const UnicodeString*)reg.availableIDs[index++];
-        return &unistr;
-    } else {
         return nullptr;
     }
+
+    const UHashElement* element = reg.availableIDs.nextElement(pos);
+    if (element == nullptr) {
+        // If the code reaches this point, it means that it's out of sync
+        // or the caller keeps asking for snext().
+        return nullptr;
+    }
+
+    // Copy the string! This avoids lifetime problems.
+    unistr = *(const UnicodeString*) element->key.pointer;
+    return &unistr;
 }
 
 void TransliteratorRegistry::Enumeration::reset(UErrorCode& /*status*/) {
-    index = 0;
+    pos = UHASH_FIRST;
+    size = reg.availableIDs.count();
 }
 
 UOBJECT_DEFINE_RTTI_IMPLEMENTATION(TransliteratorRegistry::Enumeration)
@@ -945,18 +966,12 @@ void TransliteratorRegistry::registerEntry(const UnicodeString& ID,
     registry.put(ID, adopted, status);
     if (visible) {
         registerSTV(source, target, variant);
-        if (!availableIDs.contains((void*) &ID)) {
-            UnicodeString *newID = ID.clone();
-            // Check to make sure newID was created.
-            if (newID != nullptr) {
-                // NUL-terminate the ID string
-                newID->getTerminatedBuffer();
-                availableIDs.adoptElement(newID, status);
-            }
+        if (!availableIDs.containsKey(ID)) {
+            availableIDs.puti(ID, /* unused value */ 1, status);
         }
     } else {
         removeSTV(source, target, variant);
-        availableIDs.removeElement((void*) &ID);
+        availableIDs.remove(ID);
     }
 }
 

icu4c/source/i18n/transreg.h

@@ -423,7 +423,8 @@ class TransliteratorRegistry : public UMemory {
         static UClassID U_EXPORT2 getStaticClassID();
         virtual UClassID getDynamicClassID() const override;
     private:
-        int32_t index;
+        int32_t pos;
+        int32_t size;
         const TransliteratorRegistry& reg;
     };
     friend class Enumeration;
@@ -452,7 +453,7 @@ class TransliteratorRegistry : public UMemory {
     /**
      * Vector of public full IDs.
      */
-    UVector availableIDs;
+    Hashtable availableIDs;
 
     TransliteratorRegistry(const TransliteratorRegistry &other); // forbid copying of this class
     TransliteratorRegistry &operator=(const TransliteratorRegistry &other); // forbid copying of this class

icu4j/main/classes/translit/src/com/ibm/icu/text/AnyTransliterator.java

@@ -52,12 +52,6 @@ class AnyTransliterator extends Transliterator {
     static final String NULL_ID = "Null";
     static final String LATIN_PIVOT = "-Latin;Latin-";
 
-    /**
-     * Special code for handling width characters
-     */
-    private static final Transliterator WIDTH_FIX =
-            Transliterator.getInstance("[[:dt=Nar:][:dt=Wide:]] nfkd");
-
     /**
      * Cache mapping UScriptCode values to Transliterator*.
      */
@@ -73,6 +67,15 @@ class AnyTransliterator extends Transliterator {
      */
     private int targetScript;
 
+    /**
+     * Lazily initialize a special Transliterator for handling width characters.
+     */
+    private static class WidthFix {
+        private static final String ID = "[[:dt=Nar:][:dt=Wide:]] nfkd";
+
+        static final Transliterator INSTANCE = Transliterator.getInstance(ID);
+    }
+
     /**
      * Implements {@link Transliterator#handleTransliterate}.
      */
@@ -153,7 +156,7 @@ class AnyTransliterator extends Transliterator {
      * @param filter The Unicode filter.
      * @param target2 the target name.
      * @param targetScript2 the script code corresponding to theTarget.
-     * @param widthFix2 The Transliterator width fix.
+     * @param widthFix2 Not used. This parameter is deprecated.
      * @param cache2 The Map object for cache.
      */
     public AnyTransliterator(String id, UnicodeFilter filter, String target2,
@@ -177,7 +180,7 @@ class AnyTransliterator extends Transliterator {
             if (isWide(targetScript)) {
                 return null;
             } else {
-                return WIDTH_FIX;
+                return WidthFix.INSTANCE;
             }
         }
 
@@ -202,7 +205,7 @@ class AnyTransliterator extends Transliterator {
             if (t != null) {
                 if (!isWide(targetScript)) {
                     List<Transliterator> v = new ArrayList<Transliterator>();
-                    v.add(WIDTH_FIX);
+                    v.add(WidthFix.INSTANCE);
                     v.add(t);
                     t = new CompoundTransliterator(v);
                 }
@@ -211,7 +214,7 @@ class AnyTransliterator extends Transliterator {
                     t = prevCachedT;
                 }
             } else if (!isWide(targetScript)) {
-                return WIDTH_FIX;
+                return WidthFix.INSTANCE;
             }
         }
 
@@ -409,7 +412,7 @@ class AnyTransliterator extends Transliterator {
         if (filter != null && filter instanceof UnicodeSet) {
             filter = new UnicodeSet((UnicodeSet)filter);
         }
-        return new AnyTransliterator(getID(), filter, target, targetScript, WIDTH_FIX, cache);
+        return new AnyTransliterator(getID(), filter, target, targetScript, null, cache);
     }
 
     /* (non-Javadoc)