Avoid needless construction of CFX_ByteStrings during string building

core/fpdfdoc/doc_utils.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include <algorithm>
 #include <vector>
 
 #include "core/fpdfapi/fpdf_font/include/cpdf_font.h"
@@ skipping 73 matching lines @@
   CPDF_SimpleParser syntax(m_csDA.AsStringC());
   return syntax.FindTagParamFromStart("Tf", 2);
 }
 CFX_ByteString CPDF_DefaultAppearance::GetFontString() {
   CFX_ByteString csFont;
   if (m_csDA.IsEmpty()) {
     return csFont;
   }
   CPDF_SimpleParser syntax(m_csDA.AsStringC());
   if (syntax.FindTagParamFromStart("Tf", 2)) {
-    csFont += (CFX_ByteString)syntax.GetWord();
+    csFont += syntax.GetWord();
     csFont += " ";
-    csFont += (CFX_ByteString)syntax.GetWord();
+    csFont += syntax.GetWord();
     csFont += " ";
-    csFont += (CFX_ByteString)syntax.GetWord();
+    csFont += syntax.GetWord();
   }
   return csFont;
 }
 void CPDF_DefaultAppearance::GetFont(CFX_ByteString& csFontNameTag,
                                      FX_FLOAT& fFontSize) {
   csFontNameTag = "";
   fFontSize = 0;
   if (m_csDA.IsEmpty()) {
     return;
   }
@@ skipping 19 matching lines @@
   return syntax.FindTagParamFromStart(bStrokingOperation ? "K" : "k", 4);
 }
 CFX_ByteString CPDF_DefaultAppearance::GetColorString(
     FX_BOOL bStrokingOperation) {
   CFX_ByteString csColor;
   if (m_csDA.IsEmpty()) {
     return csColor;
   }
   CPDF_SimpleParser syntax(m_csDA.AsStringC());
   if (syntax.FindTagParamFromStart(bStrokingOperation ? "G" : "g", 1)) {
-    csColor += (CFX_ByteString)syntax.GetWord();
+    csColor += syntax.GetWord();
     csColor += " ";
-    csColor += (CFX_ByteString)syntax.GetWord();
+    csColor += syntax.GetWord();
     return csColor;
   }
   if (syntax.FindTagParamFromStart(bStrokingOperation ? "RG" : "rg", 3)) {
-    csColor += (CFX_ByteString)syntax.GetWord();
+    csColor += syntax.GetWord();
     csColor += " ";
-    csColor += (CFX_ByteString)syntax.GetWord();
+    csColor += syntax.GetWord();
     csColor += " ";
-    csColor += (CFX_ByteString)syntax.GetWord();
+    csColor += syntax.GetWord();
     csColor += " ";
-    csColor += (CFX_ByteString)syntax.GetWord();
+    csColor += syntax.GetWord();
     return csColor;
   }
   if (syntax.FindTagParamFromStart(bStrokingOperation ? "K" : "k", 4)) {
-    csColor += (CFX_ByteString)syntax.GetWord();
+    csColor += syntax.GetWord();
     csColor += " ";
-    csColor += (CFX_ByteString)syntax.GetWord();
+    csColor += syntax.GetWord();
     csColor += " ";
-    csColor += (CFX_ByteString)syntax.GetWord();
+    csColor += syntax.GetWord();
     csColor += " ";
-    csColor += (CFX_ByteString)syntax.GetWord();
+    csColor += syntax.GetWord();
     csColor += " ";
-    csColor += (CFX_ByteString)syntax.GetWord();
+    csColor += syntax.GetWord();
   }
   return csColor;
 }
 void CPDF_DefaultAppearance::GetColor(int& iColorType,
                                       FX_FLOAT fc[4],
                                       FX_BOOL bStrokingOperation) {
   iColorType = COLORTYPE_TRANSPARENT;
   for (int c = 0; c < 4; c++) {
     fc[c] = 0;
   }
@@ skipping 65 matching lines @@
   return syntax.FindTagParamFromStart("Tm", 6);
 }
 CFX_ByteString CPDF_DefaultAppearance::GetTextMatrixString() {
   CFX_ByteString csTM;
   if (m_csDA.IsEmpty()) {
     return csTM;
   }
   CPDF_SimpleParser syntax(m_csDA.AsStringC());
   if (syntax.FindTagParamFromStart("Tm", 6)) {
     for (int i = 0; i < 6; i++) {
-      csTM += (CFX_ByteString)syntax.GetWord();
+      csTM += syntax.GetWord();
       csTM += " ";
     }
-    csTM += (CFX_ByteString)syntax.GetWord();
+    csTM += syntax.GetWord();
   }
   return csTM;
 }
 CFX_Matrix CPDF_DefaultAppearance::GetTextMatrix() {
   CFX_Matrix tm;
   if (m_csDA.IsEmpty()) {
     return tm;
   }
   CPDF_SimpleParser syntax(m_csDA.AsStringC());
   if (syntax.FindTagParamFromStart("Tm", 6)) {
@@ skipping 483 matching lines @@
   CPDF_Object* pAttr = pFieldDict->GetDirectObjectBy(name);
   if (pAttr) {
     return pAttr;
   }
   CPDF_Dictionary* pParent = pFieldDict->GetDictBy("Parent");
   if (!pParent) {
     return NULL;
   }
   return FPDF_GetFieldAttr(pParent, name, nLevel + 1);
 }