Use an array of indices for prefs in selectKeys()

Author: catamorphism

icu4c/source/i18n/messageformat2.cpp

@@ -420,12 +420,12 @@ void MessageFormatter::matchSelectorKeys(const UVector& keys,
     LocalArray<UnicodeString> adoptedKeys(keysArr);
 
     // Create an array to hold the output
-    UnicodeString* prefsArr = new UnicodeString[keysLen];
+    int32_t* prefsArr = new int32_t[keysLen];
     if (prefsArr == nullptr) {
         status = U_MEMORY_ALLOCATION_ERROR;
         return;
     }
-    LocalArray<UnicodeString> adoptedPrefs(prefsArr);
+    LocalArray<int32_t> adoptedPrefs(prefsArr);
     int32_t prefsLen = 0;
 
     // Call the selector
@@ -450,7 +450,8 @@ void MessageFormatter::matchSelectorKeys(const UVector& keys,
     // Copy the resulting keys (if there was no error)
     keysOut.removeAllElements();
     for (int32_t i = 0; i < prefsLen; i++) {
-        UnicodeString* k = message2::create<UnicodeString>(std::move(prefsArr[i]), status);
+        UnicodeString* k =
+            message2::create<UnicodeString>(std::move(keysArr[prefsArr[i]]), status);
         if (k == nullptr) {
             status = U_MEMORY_ALLOCATION_ERROR;
             return;

icu4c/source/i18n/messageformat2_function_registry.cpp

@@ -608,7 +608,7 @@ StandardFunctions::Number::pluralType(const FunctionOptions& opts) {
 
 void StandardFunctions::NumberValue::selectKeys(const UnicodeString* keys,
                                                 int32_t keysLen,
-                                                UnicodeString* prefs,
+                                                int32_t* prefs,
                                                 int32_t& prefsLen,
                                                 UErrorCode& errorCode) {
     CHECK_ERROR(errorCode);
@@ -658,7 +658,7 @@ void StandardFunctions::NumberValue::selectKeys(const UnicodeString* keys,
             // 5i(a). If key and exact consist of the same sequence of Unicode code points, then
             if (exact == keys[i]) {
                 // 5i(a)(a) Append key as the last element of the list resultExact.
-		prefs[prefsLen] = keys[i];
+		prefs[prefsLen] = i;
                 prefsLen++;
                 break;
             }
@@ -679,7 +679,7 @@ void StandardFunctions::NumberValue::selectKeys(const UnicodeString* keys,
         // 5ii(a). If key and keyword consist of the same sequence of Unicode code points, then
         if (keyword == keys[i]) {
             // 5ii(a)(a) Append key as the last element of the list resultKeyword.
-            prefs[prefsLen] = keys[i];
+            prefs[prefsLen] = i;
             prefsLen++;
         }
     }
@@ -1078,7 +1078,7 @@ StandardFunctions::StringValue::StringValue(const FunctionContext& context,
 
 void StandardFunctions::StringValue::selectKeys(const UnicodeString* keys,
                                                 int32_t keysLen,
-                                                UnicodeString* prefs,
+                                                int32_t* prefs,
                                                 int32_t& prefsLen,
                                                 UErrorCode& errorCode) {
     CHECK_ERROR(errorCode);
@@ -1093,7 +1093,7 @@ void StandardFunctions::StringValue::selectKeys(const UnicodeString* keys,
 
     for (int32_t i = 0; i < keysLen; i++) {
         if (keys[i] == formattedString) {
-	    prefs[0] = keys[i];
+	    prefs[0] = i;
             prefsLen = 1;
             break;
         }

icu4c/source/i18n/messageformat2_function_registry_internal.h

@@ -114,7 +114,7 @@ namespace message2 {
             UnicodeString formatToString(UErrorCode&) const override;
             void selectKeys(const UnicodeString* keys,
                             int32_t keysLen,
-                            UnicodeString* prefs,
+                            int32_t* prefs,
                             int32_t& prefsLen,
                             UErrorCode& status) override;
             UBool isSelectable() const override { return true; }
@@ -165,7 +165,7 @@ namespace message2 {
             UnicodeString formatToString(UErrorCode&) const override;
             void selectKeys(const UnicodeString* keys,
                             int32_t keysLen,
-                            UnicodeString* prefs,
+                            int32_t* prefs,
                             int32_t& prefsLen,
                             UErrorCode& status) override;
             UBool isSelectable() const override { return true; }

icu4c/source/i18n/unicode/messageformat2_function_registry.h

@@ -406,9 +406,11 @@ namespace message2 {
              *
              * @param keys An array of strings to compare to the input.
              * @param keysLen The length of `keys`.
-             * @param prefs An array of strings with length `keysLen`. The contents of
+             * @param prefs An array of indices into `keys`.
+             *        The initial contents of
              *        the array is undefined. `selectKey()` should set the contents
-             *        of `prefs` to a subset of `keys`, with the best match placed at the lowest index.
+             *        of `prefs` to a subset of the indices in `keys`,
+             *        with the best match placed at the lowest index in `prefs`.
              * @param prefsLen A reference that `selectKey()` should set to the length of `prefs`,
              *        which must be less than or equal to `keysLen`.
              * @param status    Input/output error code.
@@ -418,7 +420,7 @@ namespace message2 {
              */
             virtual void selectKeys(const UnicodeString* keys,
                                     int32_t keysLen,
-                                    UnicodeString* prefs,
+                                    int32_t* prefs,
                                     int32_t& prefsLen,
                                     UErrorCode& status) {
                 (void) keys;