Teach WebString about 8 bit strings

public/platform/WebString.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 58 matching lines @@
         return *this;
     }
 
     WEBKIT_EXPORT void reset();
     WEBKIT_EXPORT void assign(const WebString&);
     WEBKIT_EXPORT void assign(const WebUChar* data, size_t len);
 
     WEBKIT_EXPORT bool equals(const WebString& s) const;
 
     WEBKIT_EXPORT size_t length() const;
+    // Deprecated: This function will be removed once all its callers are gone.
     WEBKIT_EXPORT const WebUChar* data() const;
 
     bool isEmpty() const { return !length(); }
     bool isNull() const { return !m_private; }
 
     WEBKIT_EXPORT WebCString utf8() const;
 
     WEBKIT_EXPORT static WebString fromUTF8(const char* data, size_t length);
     WEBKIT_EXPORT static WebString fromUTF8(const char* data);
 
@@ skipping 25 matching lines @@
     }
 
     WebString& operator=(const string16& s)
     {
         assign(s.data(), s.length());
         return *this;
     }
 
     operator string16() const
     {
         size_t len = length();

[darin (slow to review), 2013/05/24 06:12:53]

nit: this seems like a lot of code to inline into all of the callsites where
casting to string16 is required.  perhaps a higher level non-inline method would
be helpful.  hmm, but you are calling two different string16 constructors below.
 hmm...

-        return len ? string16(data(), len) : string16();
+        if (!len)
+            return string16();
+        if (is8Bit()) {
+            const WebLChar* data = this->data8();
+            return string16(data, data + len);
+        }
+        const WebUChar* data = this->data16();
+        return string16(data, data + len);
     }
 
     WebString(const NullableString16& s) : m_private(0)
     {
         if (s.is_null())
             reset();
         else
             assign(s.string().data(), s.string().length());
     }
 
     WebString& operator=(const NullableString16& s)
     {
         if (s.is_null())
             reset();
         else
             assign(s.string().data(), s.string().length());
         return *this;
     }
 
     operator NullableString16() const
     {
         if (!m_private)
             return NullableString16(string16(), true);
-        size_t len = length();
-        return NullableString16(len ? string16(data(), len) : string16(), false);
+        return NullableString16(operator string16(), false);

[darin (slow to review), 2013/05/24 06:12:53]

nit: You could reduce this code down to just:

  return NullableString16(operator string16(), isNull());

[abarth-chromium, 2013/05/24 06:17:44]

Good idea.

     }
 
     template <class UTF8String>
     static WebString fromUTF8(const UTF8String& s)
     {
         return fromUTF8(s.data(), s.length());
     }
 #endif
 
 private:
+    WEBKIT_EXPORT bool is8Bit() const;
+    WEBKIT_EXPORT const WebLChar* data8() const;
+    WEBKIT_EXPORT const WebUChar* data16() const;
+
     void assign(WebStringPrivate*);
     WebStringPrivate* m_private;
 };
 
 inline bool operator==(const WebString& a, const WebString& b)
 {
     return a.equals(b);
 }
 
 inline bool operator!=(const WebString& a, const WebString& b)
 {
     return !(a == b);
 }
 
 } // namespace WebKit
 
 #endif