ICU-20392 Simplify code by removing Locale::initBaseName().

Whatever the purpose of this helper function originally was,
subsequent refactorings have now made it obsolete.

It requires both less code and less processing to assign baseName
together with the other data fields, instead of starting over and
searching for the '@' character once again and possibly having to
move payload from Nest to Heap.

Author: roubert

icu4c/source/common/locid.cpp

@@ -1957,6 +1957,7 @@ Locale& Locale::init(StringPiece localeID, UBool canonicalize)
         } else {
             fieldLen[fieldIdx - 1] = length - static_cast<int32_t>(field[fieldIdx - 1] - fullName);
         }
+        bool hasKeywords = at != nullptr && uprv_strchr(at + 1, '=') != nullptr;
 
         if (fieldLen[0] >= ULOC_LANG_CAPACITY)
         {
@@ -1987,9 +1988,14 @@ Locale& Locale::init(StringPiece localeID, UBool canonicalize)
         if (fieldLen[variantField] > 0) {
             /* We have a variant */
             variantBegin = static_cast<int32_t>(field[variantField] - fullName);
+        } else if (hasKeywords) {
+            // The original computation of variantBegin leaves it equal to the length
+            // of fullName if there is no variant.  It should instead be
+            // the length of the baseName.
+            variantBegin = static_cast<int32_t>(at - fullName);
         }
 
-        if (Nest::fits(length, language, script, region)) {
+        if (!hasKeywords && Nest::fits(length, language, script, region)) {
             U_ASSERT(fullName == nest.baseName);
             U_ASSERT(fullNameBuffer.isEmpty());
             nest.init(language, script, region, variantBegin);
@@ -2008,11 +2014,14 @@ Locale& Locale::init(StringPiece localeID, UBool canonicalize)
             }
             U_ASSERT(!fullNameBuffer.isEmpty());
             heap->fullName = std::move(fullNameBuffer);
-        }
-
-        initBaseName(err);
-        if (U_FAILURE(err)) {
-            break;
+            if (hasKeywords) {
+                if (std::string_view::size_type baseNameLength = at - fullName; baseNameLength > 0) {
+                    heap->baseName = {heap->fullName.data(), baseNameLength};
+                    if (heap->baseName.isEmpty()) {
+                        break; // error: out of memory
+                    }
+                }
+            }
         }
 
         if (canonicalize) {
@@ -2040,77 +2049,6 @@ Locale& Locale::init(StringPiece localeID, UBool canonicalize)
     return *this;
 }
 
-/*
- * Set up the base name.
- * If there are no key words, it's exactly the full name.
- * If key words exist, it's the full name truncated at the '@' character.
- * Need to set up both at init() and after setting a keyword.
- */
-void
-Locale::initBaseName(UErrorCode &status) {
-    if (U_FAILURE(status)) {
-        return;
-    }
-    U_ASSERT(!isBogus());
-
-    std::unique_ptr<Heap>* heap = std::get_if<std::unique_ptr<Heap>>(&payload);
-    if (heap != nullptr && *heap && !(*heap)->baseName.isEmpty()) {
-        return;
-    }
-
-    const char *fullName = getName();
-    const char *atPtr = uprv_strchr(fullName, '@');
-    const char *eqPtr = uprv_strchr(fullName, '=');
-    if (atPtr && eqPtr && atPtr < eqPtr) {
-        // Key words exist.
-        int32_t baseNameLength = static_cast<int32_t>(atPtr - fullName);
-        if (baseNameLength == 0) { return; }
-
-        if (heap == nullptr) {
-            // There are keywords, so the payload needs to be moved from Nest
-            // to Heap so that it can get a baseName.
-            const Nest* nest = std::get_if<Nest>(&payload);
-            U_ASSERT(nest != nullptr);
-            std::unique_ptr<Heap> copy = std::make_unique<Heap>(nest->language,
-                                                                nest->script,
-                                                                nest->region,
-                                                                nest->variantBegin);
-            if (!copy) {
-                status = U_MEMORY_ALLOCATION_ERROR;
-                setToBogus();
-                return;
-            }
-            copy->fullName = fullName;
-            if (copy->fullName.isEmpty()) {
-                status = U_MEMORY_ALLOCATION_ERROR;
-                setToBogus();
-                return;
-            }
-            heap = &payload.emplace<std::unique_ptr<Heap>>(std::move(copy));
-            if (!*heap) {
-                status = U_MEMORY_ALLOCATION_ERROR;
-                setToBogus();
-                return;
-            }
-        }
-
-        // The original computation of variantBegin leaves it equal to the length
-        // of fullName if there is no variant.  It should instead be
-        // the length of the baseName.
-        if ((*heap)->variantBegin > baseNameLength) {
-            (*heap)->variantBegin = baseNameLength;
-        }
-
-        (*heap)->baseName = {fullName, static_cast<std::string_view::size_type>(baseNameLength)};
-        if ((*heap)->baseName.isEmpty()) {
-            status = U_MEMORY_ALLOCATION_ERROR;
-            setToBogus();
-            return;
-        }
-    }
-}
-
-
 int32_t
 Locale::hashCode() const
 {
@@ -2753,8 +2691,11 @@ Locale::setKeywordValue(StringPiece keywordName,
         return;
     }
 
+    const char* at = locale_getKeywordsStart(localeID.toStringPiece());
+    bool hasKeywords = at != nullptr && uprv_strchr(at + 1, '=') != nullptr;
+
     Nest* nest = std::get_if<Nest>(&payload);
-    if (locale_getKeywordsStart(localeID.toStringPiece()) == nullptr) {
+    if (!hasKeywords) {
         if (nest == nullptr) {
             // There are no longer any keywords left, so it might now be
             // possible to move the payload from Heap to Nest.
@@ -2814,7 +2755,14 @@ Locale::setKeywordValue(StringPiece keywordName,
 
         if ((*heap)->baseName.isEmpty()) {
             // Has added the first keyword, meaning that the fullName is no longer also the baseName.
-            initBaseName(status);
+            if (std::string_view::size_type baseNameLength = at - localeID.data(); baseNameLength > 0) {
+                (*heap)->baseName = {(*heap)->fullName.data(), baseNameLength};
+                if ((*heap)->baseName.isEmpty()) {
+                    status = U_MEMORY_ALLOCATION_ERROR;
+                    setToBogus();
+                    return;
+                }
+            }
         }
     }
 }

icu4c/source/common/unicode/locid.h

@@ -1237,8 +1237,6 @@ class U_COMMON_API_CLASS Locale : public UObject {
               const char* (Heap::*const HEAP)() const>
     const char* getField() const;
 
-    void initBaseName(UErrorCode& status);
-
     static const Locale &getLocale(int locid);
 
     /**