Move CXFA_ThisProxy helper to CXFA_Object.

Because the other helpers are declared here.
Rename VariablesThis to ThisProxy in a few places; VariablesThis is
a slightly different concept (see GetVariablesThis()).
Then introduce helper for CXFA_List subclass as well.
Remove unused const version of some helpers.

Change-Id: Ia328d8cd170a8b97015e98c1c770fa8a44810455
Reviewed-on: https://pdfium-review.googlesource.com/38670
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>

4 files changed, 31 insertions, 25 deletions

diff --git a/xfa/fxfa/parser/cxfa_object.cpp b/xfa/fxfa/parser/cxfa_object.cpp
index 920e33860e..6daf3aa7b4 100644
--- a/xfa/fxfa/parser/cxfa_object.cpp
+++ b/xfa/fxfa/parser/cxfa_object.cpp
@@ -15,6 +15,7 @@
 #include "xfa/fxfa/cxfa_ffnotify.h"
 #include "xfa/fxfa/parser/cxfa_document.h"
 #include "xfa/fxfa/parser/cxfa_node.h"
+#include "xfa/fxfa/parser/cxfa_thisproxy.h"
 #include "xfa/fxfa/parser/cxfa_treelist.h"
 
 CXFA_Object::CXFA_Object(CXFA_Document* pDocument,
@@ -43,6 +44,10 @@ WideString CXFA_Object::GetSOMExpression() {
   return pScriptContext->GetSomExpression(ToNode(this));
 }
 
+CXFA_List* CXFA_Object::AsList() {
+  return IsList() ? static_cast<CXFA_List*>(this) : nullptr;
+}
+
 CXFA_Node* CXFA_Object::AsNode() {
   return IsNode() ? static_cast<CXFA_Node*>(this) : nullptr;
 }
@@ -51,18 +56,22 @@ CXFA_TreeList* CXFA_Object::AsTreeList() {
   return IsTreeList() ? static_cast<CXFA_TreeList*>(this) : nullptr;
 }
 
-const CXFA_Node* CXFA_Object::AsNode() const {
-  return IsNode() ? static_cast<const CXFA_Node*>(this) : nullptr;
+CXFA_ThisProxy* CXFA_Object::AsThisProxy() {
+  return IsThisProxy() ? static_cast<CXFA_ThisProxy*>(this) : nullptr;
 }
 
-const CXFA_TreeList* CXFA_Object::AsTreeList() const {
-  return IsTreeList() ? static_cast<const CXFA_TreeList*>(this) : nullptr;
+CXFA_List* ToList(CXFA_Object* pObj) {
+  return pObj ? pObj->AsList() : nullptr;
 }
 
 CXFA_Node* ToNode(CXFA_Object* pObj) {
   return pObj ? pObj->AsNode() : nullptr;
 }
 
-const CXFA_Node* ToNode(const CXFA_Object* pObj) {
-  return pObj ? pObj->AsNode() : nullptr;
+CXFA_TreeList* ToTreeList(CXFA_Object* pObj) {
+  return pObj ? pObj->AsTreeList() : nullptr;
+}
+
+CXFA_ThisProxy* ToThisProxy(CXFA_Object* pObj) {
+  return pObj ? pObj->AsThisProxy() : nullptr;
 }
diff --git a/xfa/fxfa/parser/cxfa_object.h b/xfa/fxfa/parser/cxfa_object.h
index 023516a05e..173bf23f25 100644
--- a/xfa/fxfa/parser/cxfa_object.h
+++ b/xfa/fxfa/parser/cxfa_object.h
@@ -24,12 +24,14 @@ enum class XFA_ObjectType {
   TreeList,
   ContainerNode,
   ContentNode,
-  VariablesThis
+  ThisProxy,
 };
 
 class CJX_Object;
 class CXFA_Document;
+class CXFA_List;
 class CXFA_Node;
+class CXFA_ThisProxy;
 class CXFA_TreeList;
 
 class CXFA_Object : public CFXJSE_HostObject {
@@ -42,6 +44,10 @@ class CXFA_Object : public CFXJSE_HostObject {
   CXFA_Document* GetDocument() const { return m_pDocument.Get(); }
   XFA_ObjectType GetObjectType() const { return m_objectType; }
 
+  bool IsList() const {
+    return m_objectType == XFA_ObjectType::List ||
+           m_objectType == XFA_ObjectType::TreeList;
+  }
   bool IsNode() const {
     return m_objectType == XFA_ObjectType::Node ||
            m_objectType == XFA_ObjectType::NodeC ||
@@ -50,7 +56,7 @@ class CXFA_Object : public CFXJSE_HostObject {
            m_objectType == XFA_ObjectType::TextNode ||
            m_objectType == XFA_ObjectType::ContainerNode ||
            m_objectType == XFA_ObjectType::ContentNode ||
-           m_objectType == XFA_ObjectType::VariablesThis;
+           m_objectType == XFA_ObjectType::ThisProxy;
   }
   bool IsTreeList() const { return m_objectType == XFA_ObjectType::TreeList; }
   bool IsContentNode() const {
@@ -61,15 +67,12 @@ class CXFA_Object : public CFXJSE_HostObject {
   }
   bool IsModelNode() const { return m_objectType == XFA_ObjectType::ModelNode; }
   bool IsNodeV() const { return m_objectType == XFA_ObjectType::NodeV; }
-  bool IsVariablesThis() const {
-    return m_objectType == XFA_ObjectType::VariablesThis;
-  }
+  bool IsThisProxy() const { return m_objectType == XFA_ObjectType::ThisProxy; }
 
+  CXFA_List* AsList();
   CXFA_Node* AsNode();
   CXFA_TreeList* AsTreeList();
-
-  const CXFA_Node* AsNode() const;
-  const CXFA_TreeList* AsTreeList() const;
+  CXFA_ThisProxy* AsThisProxy();
 
   CJX_Object* JSObject() { return m_pJSObject.get(); }
   const CJX_Object* JSObject() const { return m_pJSObject.get(); }
@@ -99,11 +102,13 @@ class CXFA_Object : public CFXJSE_HostObject {
   const XFA_Element m_elementType;
   const uint32_t m_elementNameHash;
   const WideStringView m_elementName;
-
   std::unique_ptr<CJX_Object> m_pJSObject;
 };
 
+// Helper functions that permit nullptr arguments.
+CXFA_List* ToList(CXFA_Object* pObj);
 CXFA_Node* ToNode(CXFA_Object* pObj);
-const CXFA_Node* ToNode(const CXFA_Object* pObj);
+CXFA_TreeList* ToTreeList(CXFA_Object* pObj);
+CXFA_ThisProxy* ToThisProxy(CXFA_Object* pObj);
 
 #endif  // XFA_FXFA_PARSER_CXFA_OBJECT_H_
diff --git a/xfa/fxfa/parser/cxfa_thisproxy.cpp b/xfa/fxfa/parser/cxfa_thisproxy.cpp
index a3593e99b5..60a90b0931 100644
--- a/xfa/fxfa/parser/cxfa_thisproxy.cpp
+++ b/xfa/fxfa/parser/cxfa_thisproxy.cpp
@@ -10,15 +10,9 @@
 #include "third_party/base/ptr_util.h"
 #include "xfa/fxfa/parser/cxfa_node.h"
 
-// static
-CXFA_ThisProxy* CXFA_ThisProxy::FromCXFAObject(CXFA_Object* that) {
-  return that && that->IsVariablesThis() ? static_cast<CXFA_ThisProxy*>(that)
-                                         : nullptr;
-}
-
 CXFA_ThisProxy::CXFA_ThisProxy(CXFA_Node* pThisNode, CXFA_Node* pScriptNode)
     : CXFA_Object(pThisNode->GetDocument(),
-                  XFA_ObjectType::VariablesThis,
+                  XFA_ObjectType::ThisProxy,
                   XFA_Element::Unknown,
                   WideStringView(),
                   pdfium::MakeUnique<CJX_Object>(this)),
diff --git a/xfa/fxfa/parser/cxfa_thisproxy.h b/xfa/fxfa/parser/cxfa_thisproxy.h
index e86a6b5534..197a97da67 100644
--- a/xfa/fxfa/parser/cxfa_thisproxy.h
+++ b/xfa/fxfa/parser/cxfa_thisproxy.h
@@ -13,8 +13,6 @@
 
 class CXFA_ThisProxy : public CXFA_Object {
  public:
-  static CXFA_ThisProxy* FromCXFAObject(CXFA_Object* that);
-
   CXFA_ThisProxy(CXFA_Node* pThisNode, CXFA_Node* pScriptNode);
   ~CXFA_ThisProxy() override;