1 files changed, 9 insertions, 1 deletions
diff --git a/core/fxcrt/cfx_widestring.h b/core/fxcrt/cfx_widestring.h
index a6d0eca044..242138853b 100644
--- a/core/fxcrt/cfx_widestring.h
+++ b/core/fxcrt/cfx_widestring.h
@@ -81,6 +81,14 @@ class CFX_WideString {
   }
   bool IsEmpty() const { return !GetLength(); }
 
+  bool IsValidIndex(FX_STRSIZE index) const {
+    return 0 <= index && index < GetLength();
+  }
+
+  bool IsValidLength(FX_STRSIZE length) const {
+    return 0 <= length && length <= GetLength();
+  }
+
   const CFX_WideString& operator=(const wchar_t* str);
   const CFX_WideString& operator=(const CFX_WideString& stringSrc);
   const CFX_WideString& operator=(const CFX_WideStringC& stringSrc);
@@ -103,7 +111,7 @@ class CFX_WideString {
   bool operator<(const CFX_WideString& str) const;
 
   CharType operator[](const FX_STRSIZE index) const {
-    ASSERT(index >= 0 && index < GetLength());
+    ASSERT(IsValidIndex(index));
     return m_pData ? m_pData->m_String[index] : 0;
   }