Revert "Revert "Cleanup some numeric code.""

core/src/fpdftext/fpdf_text.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 "../../../third_party/base/nonstd_unique_ptr.h"
 #include "../../include/fpdfapi/fpdf_page.h"
 #include "../../include/fpdfapi/fpdf_pageobj.h"
 #include "../../include/fpdfapi/fpdf_resource.h"
@@ skipping 418 matching lines @@
         }
       }
     }
   }
   str.Empty();
   str += sBuffer;
 }
 static FX_BOOL IsNumber(CFX_WideString& str) {
   for (int i = 0; i < str.GetLength(); i++) {
     FX_WCHAR ch = str[i];
-    if ((ch < '0' || ch > '9') && ch != '-' && ch != '+' && ch != '.' &&
-        ch != ' ') {
+    if (!std::isdigit(ch) && ch != '-' && ch != '+' && ch != '.' && ch != ' ')
       return FALSE;
-    }
   }
   return TRUE;
 }
 void CTextPage::FindColumns() {
   int i;
   for (i = 0; i < m_BaseLines.GetSize(); i++) {
     CTextBaseLine* pBaseLine = (CTextBaseLine*)m_BaseLines.GetAt(i);
     for (int j = 0; j < pBaseLine->m_TextList.GetSize(); j++) {
       CTextBox* pTextBox = (CTextBox*)pBaseLine->m_TextList.GetAt(j);
       CTextColumn* pColumn = FindColumn(pTextBox->m_Right);
@@ skipping 330 matching lines @@
                                FX_DWORD flags) {
   buffer.EstimateSize(0, 10240);
   CPDF_Page page;
   page.Load(pDoc, pPage);
   CPDF_ParseOptions options;
   options.m_bTextOnly = TRUE;
   options.m_bSeparateForm = FALSE;
   page.ParseContent(&options);
   GetTextStream_Unicode(buffer, &page, TRUE, NULL);
 }