Use Optional<> return from CXFA_LocaleMgr::GetConfigLocaleName().

Its only caller returns an optional, too.

Change-Id: I700f15b69c7eee75d73a1a7c271e5482951e224e
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/74110
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>

xfa/fxfa/parser/cxfa_localemgr.cpp

diff --git a/xfa/fxfa/parser/cxfa_localemgr.cpp b/xfa/fxfa/parser/cxfa_localemgr.cpp
index e1b7b5c..b5da74e 100644
--- a/xfa/fxfa/parser/cxfa_localemgr.cpp
+++ b/xfa/fxfa/parser/cxfa_localemgr.cpp
@@ -1231,32 +1231,40 @@
   m_pDefLocale = pLocale;
 }
 
-WideString CXFA_LocaleMgr::GetConfigLocaleName(CXFA_Node* pConfig) {
-  if (m_hasSetLocaleName)
+Optional<WideString> CXFA_LocaleMgr::GetConfigLocaleName(
+    CXFA_Node* pConfig) const {
+  if (m_bConfigLocaleCached)
     return m_wsConfigLocale;
 
-  m_hasSetLocaleName = true;
-  m_wsConfigLocale.clear();
+  ASSERT(!m_wsConfigLocale.has_value());
+  m_bConfigLocaleCached = true;
   if (!pConfig)
     return m_wsConfigLocale;
 
-  CXFA_Node* pChildfConfig =
+  CXFA_Node* pChildConfig =
       pConfig->GetFirstChildByClass<CXFA_Acrobat>(XFA_Element::Acrobat);
-  if (!pChildfConfig) {
-    pChildfConfig =
+  if (!pChildConfig) {
+    pChildConfig =
         pConfig->GetFirstChildByClass<CXFA_Present>(XFA_Element::Present);
+    if (!pChildConfig)
+      return m_wsConfigLocale;
   }
-  CXFA_Common* pCommon = pChildfConfig
-                             ? pChildfConfig->GetFirstChildByClass<CXFA_Common>(
-                                   XFA_Element::Common)
-                             : nullptr;
+
+  CXFA_Common* pCommon =
+      pChildConfig->GetFirstChildByClass<CXFA_Common>(XFA_Element::Common);
+  if (!pCommon)
+    return m_wsConfigLocale;
+
   CXFA_Locale* pLocale =
-      pCommon ? pCommon->GetFirstChildByClass<CXFA_Locale>(XFA_Element::Locale)
-              : nullptr;
-  if (pLocale) {
-    m_wsConfigLocale = pLocale->JSObject()
-                           ->TryCData(XFA_Attribute::Value, false)
-                           .value_or(WideString());
-  }
+      pCommon->GetFirstChildByClass<CXFA_Locale>(XFA_Element::Locale);
+  if (!pLocale)
+    return m_wsConfigLocale;
+
+  Optional<WideString> wsMaybeLocale =
+      pLocale->JSObject()->TryCData(XFA_Attribute::Value, false);
+  if (!wsMaybeLocale.has_value() || wsMaybeLocale.value().IsEmpty())
+    return m_wsConfigLocale;
+
+  m_wsConfigLocale = wsMaybeLocale;
   return m_wsConfigLocale;
 }

xfa/fxfa/parser/cxfa_localemgr.h

diff --git a/xfa/fxfa/parser/cxfa_localemgr.h b/xfa/fxfa/parser/cxfa_localemgr.h
index 8cb6f04..e9fdf44 100644
--- a/xfa/fxfa/parser/cxfa_localemgr.h
+++ b/xfa/fxfa/parser/cxfa_localemgr.h
@@ -13,6 +13,7 @@
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxcrt/widestring.h"
 #include "fxjs/gc/heap.h"
+#include "third_party/base/optional.h"
 #include "v8/include/cppgc/garbage-collected.h"
 #include "v8/include/cppgc/member.h"
 #include "xfa/fgas/crt/locale_mgr_iface.h"
@@ -34,7 +35,7 @@
   GCedLocaleIface* GetLocaleByName(const WideString& wsLocaleName) override;
 
   void SetDefLocale(GCedLocaleIface* pLocale);
-  WideString GetConfigLocaleName(CXFA_Node* pConfig);
+  Optional<WideString> GetConfigLocaleName(CXFA_Node* pConfig) const;
 
  private:
   CXFA_LocaleMgr(cppgc::Heap* pHeap,
@@ -49,9 +50,17 @@
   std::vector<cppgc::Member<CXFA_XMLLocale>> m_XMLLocaleArray;
   cppgc::Member<GCedLocaleIface> m_pDefLocale;
 
-  WideString m_wsConfigLocale;
+  // Note: three possiblities
+  // 1. we might never have tried to determine |m_wsConfigLocale|.
+  // 2. we might have tried but gotten nothing and want to continue
+  //    to return nothing without ever trying again.
+  // 3. we might have tried and gotten something.
+  // So |m_bConfigLocaleCached| indicates whether we've already tried,
+  // and |m_wsConfigLocale| is the possibly nothing we got if we tried.
+  mutable Optional<WideString> m_wsConfigLocale;
+  mutable bool m_bConfigLocaleCached = false;
+
   uint16_t m_dwDeflcid;
-  bool m_hasSetLocaleName = false;
 };
 
 #endif  // XFA_FXFA_PARSER_CXFA_LOCALEMGR_H_

xfa/fxfa/parser/cxfa_node.cpp

diff --git a/xfa/fxfa/parser/cxfa_node.cpp b/xfa/fxfa/parser/cxfa_node.cpp
index 55dc84a..9b67810 100644
--- a/xfa/fxfa/parser/cxfa_node.cpp
+++ b/xfa/fxfa/parser/cxfa_node.cpp
@@ -1403,39 +1403,39 @@
 Optional<WideString> CXFA_Node::GetLocaleName() {
   CXFA_Node* pForm = ToNode(GetDocument()->GetXFAObject(XFA_HASHCODE_Form));
   if (!pForm)
-    return {};
+    return pdfium::nullopt;
 
   CXFA_Subform* pTopSubform =
       pForm->GetFirstChildByClass<CXFA_Subform>(XFA_Element::Subform);
   if (!pTopSubform)
-    return {};
+    return pdfium::nullopt;
 
+  Optional<WideString> localeName;
   CXFA_Node* pLocaleNode = this;
   do {
-    Optional<WideString> localeName =
+    localeName =
         pLocaleNode->JSObject()->TryCData(XFA_Attribute::Locale, false);
-    if (localeName)
+    if (localeName.has_value())
       return localeName;
 
     pLocaleNode = pLocaleNode->GetParent();
   } while (pLocaleNode && pLocaleNode != pTopSubform);
 
   CXFA_Node* pConfig = ToNode(GetDocument()->GetXFAObject(XFA_HASHCODE_Config));
-  WideString wsLocaleName =
-      GetDocument()->GetLocaleMgr()->GetConfigLocaleName(pConfig);
-  if (!wsLocaleName.IsEmpty())
-    return wsLocaleName;
+  localeName = GetDocument()->GetLocaleMgr()->GetConfigLocaleName(pConfig);
+  if (localeName.has_value())
+    return localeName;
 
   if (pTopSubform) {
-    Optional<WideString> localeName =
+    localeName =
         pTopSubform->JSObject()->TryCData(XFA_Attribute::Locale, false);
-    if (localeName)
+    if (localeName.has_value())
       return localeName;
   }
 
   LocaleIface* pLocale = GetDocument()->GetLocaleMgr()->GetDefLocale();
   if (!pLocale)
-    return {};
+    return pdfium::nullopt;
 
   return pLocale->GetName();
 }