Remove GetAt from string classes

This method duplicates the behaviour of the const [] operator and
doesn't offer any additional safety. Folding them into one
implementation.

SetAt is retained, since implementing the non-const [] operator to
replace SetAt has potential performance concerns. Specifically many
non-obvious cases of reading an element using [] will cause a realloc
& copy.

BUG=pdfium:860

Change-Id: I3ef5e5e5a15376f040256b646eb0d90636e24b67
Reviewed-on: https://pdfium-review.googlesource.com/10870
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

3 files changed, 30 insertions, 32 deletions

diff --git a/core/fpdftext/cpdf_linkextract.cpp b/core/fpdftext/cpdf_linkextract.cpp
index d795e71639..fb228ec832 100644
--- a/core/fpdftext/cpdf_linkextract.cpp
+++ b/core/fpdftext/cpdf_linkextract.cpp
@@ -152,7 +152,7 @@ void CPDF_LinkExtract::ParseLink() {
 
       if (strBeCheck.GetLength() > 5) {
         while (strBeCheck.GetLength() > 0) {
-          wchar_t ch = strBeCheck.GetAt(strBeCheck.GetLength() - 1);
+          wchar_t ch = strBeCheck[strBeCheck.GetLength() - 1];
           if (ch == L')' || ch == L',' || ch == L'>' || ch == L'.') {
             strBeCheck = strBeCheck.Left(strBeCheck.GetLength() - 1);
             nCount--;
@@ -242,7 +242,7 @@ bool CPDF_LinkExtract::CheckMailLink(CFX_WideString* str) {
   // Check the local part.
   int pPos = aPos;  // Used to track the position of '@' or '.'.
   for (int i = aPos - 1; i >= 0; i--) {
-    wchar_t ch = str->GetAt(i);
+    wchar_t ch = (*str)[i];
     if (ch == L'_' || ch == L'-' || FXSYS_iswalnum(ch))
       continue;
 
@@ -278,7 +278,7 @@ bool CPDF_LinkExtract::CheckMailLink(CFX_WideString* str) {
   int nLen = str->GetLength();
   pPos = 0;  // Used to track the position of '.'.
   for (int i = aPos + 1; i < nLen; i++) {
-    wchar_t wch = str->GetAt(i);
+    wchar_t wch = (*str)[i];
     if (wch == L'-' || FXSYS_iswalnum(wch))
       continue;
 
diff --git a/core/fpdftext/cpdf_textpage.cpp b/core/fpdftext/cpdf_textpage.cpp
index 1470ad700d..a4c8b8fba0 100644
--- a/core/fpdftext/cpdf_textpage.cpp
+++ b/core/fpdftext/cpdf_textpage.cpp
@@ -701,7 +701,7 @@ void CPDF_TextPage::CloseTempLine() {
   CFX_WideString str = m_TempTextBuf.MakeString();
   bool bPrevSpace = false;
   for (int i = 0; i < str.GetLength(); i++) {
-    if (str.GetAt(i) != ' ') {
+    if (str[i] != ' ') {
       bPrevSpace = false;
       continue;
     }
@@ -841,8 +841,7 @@ FPDFText_MarkedContent CPDF_TextPage::PreMarkedContent(PDFTEXT_Obj Obj) {
   CPDF_Font* pFont = pTextObj->GetFont();
   bExist = false;
   for (FX_STRSIZE i = 0; i < nItems; i++) {
-    if (pFont->CharCodeFromUnicode(actText.GetAt(i)) !=
-        CPDF_Font::kInvalidCharCode) {
+    if (pFont->CharCodeFromUnicode(actText[i]) != CPDF_Font::kInvalidCharCode) {
       bExist = true;
       break;
     }
@@ -852,7 +851,7 @@ FPDFText_MarkedContent CPDF_TextPage::PreMarkedContent(PDFTEXT_Obj Obj) {
 
   bExist = false;
   for (FX_STRSIZE i = 0; i < nItems; i++) {
-    wchar_t wChar = actText.GetAt(i);
+    wchar_t wChar = actText[i];
     if ((wChar > 0x80 && wChar < 0xFFFD) || (wChar <= 0x80 && isprint(wChar))) {
       bExist = true;
       break;
@@ -889,7 +888,7 @@ void CPDF_TextPage::ProcessMarkedContent(PDFTEXT_Obj Obj) {
   matrix.Concat(Obj.m_formMatrix);
 
   for (FX_STRSIZE k = 0; k < nItems; k++) {
-    wchar_t wChar = actText.GetAt(k);
+    wchar_t wChar = actText[k];
     if (wChar <= 0x80 && !isprint(wChar))
       wChar = 0x20;
     if (wChar >= 0xFFFD)
@@ -1005,12 +1004,12 @@ void CPDF_TextPage::ProcessTextObject(PDFTEXT_Obj Obj) {
               pTextObj->GetFont()->UnicodeFromCharCode(item.m_CharCode);
           if (wstrItem.IsEmpty())
             wstrItem += (wchar_t)item.m_CharCode;
-          wchar_t curChar = wstrItem.GetAt(0);
+          wchar_t curChar = wstrItem[0];
           if (curChar == 0x2D || curChar == 0xAD)
             return;
         }
         while (m_TempTextBuf.GetSize() > 0 &&
-               m_TempTextBuf.AsStringC().GetAt(m_TempTextBuf.GetLength() - 1) ==
+               m_TempTextBuf.AsStringC()[m_TempTextBuf.GetLength() - 1] ==
                    0x20) {
           m_TempTextBuf.Delete(m_TempTextBuf.GetLength() - 1, 1);
           m_TempCharList.pop_back();
@@ -1053,7 +1052,7 @@ void CPDF_TextPage::ProcessTextObject(PDFTEXT_Obj Obj) {
       CFX_WideString str = m_TempTextBuf.MakeString();
       if (str.IsEmpty())
         str = m_TextBuf.AsStringC();
-      if (str.IsEmpty() || str.GetAt(str.GetLength() - 1) == TEXT_SPACE_CHAR)
+      if (str.IsEmpty() || str[str.GetLength() - 1] == TEXT_SPACE_CHAR)
         continue;
 
       float fontsize_h = pTextObj->m_TextState.GetFontSizeH();
@@ -1164,7 +1163,7 @@ void CPDF_TextPage::ProcessTextObject(PDFTEXT_Obj Obj) {
       }
       if (!bDel) {
         for (int nIndex = 0; nIndex < nTotal; nIndex++) {
-          charinfo.m_Unicode = wstrItem.GetAt(nIndex);
+          charinfo.m_Unicode = wstrItem[nIndex];
           if (charinfo.m_Unicode) {
             charinfo.m_Index = m_TextBuf.GetLength();
             m_TempTextBuf.AppendChar(charinfo.m_Unicode);
@@ -1175,8 +1174,7 @@ void CPDF_TextPage::ProcessTextObject(PDFTEXT_Obj Obj) {
         }
       } else if (i == 0) {
         CFX_WideString str = m_TempTextBuf.MakeString();
-        if (!str.IsEmpty() &&
-            str.GetAt(str.GetLength() - 1) == TEXT_SPACE_CHAR) {
+        if (!str.IsEmpty() && str[str.GetLength() - 1] == TEXT_SPACE_CHAR) {
           m_TempTextBuf.Delete(m_TempTextBuf.GetLength() - 1, 1);
           m_TempCharList.pop_back();
         }
@@ -1225,12 +1223,12 @@ bool CPDF_TextPage::IsHyphen(wchar_t curChar) {
   if (nCount < 1)
     return false;
   int nIndex = nCount - 1;
-  wchar_t wcTmp = strCurText.GetAt(nIndex);
+  wchar_t wcTmp = strCurText[nIndex];
   while (wcTmp == 0x20 && nIndex > 0 && nIndex <= nCount - 1)
-    wcTmp = strCurText.GetAt(--nIndex);
+    wcTmp = strCurText[--nIndex];
   if (0x2D == wcTmp || 0xAD == wcTmp) {
     if (--nIndex > 0) {
-      wchar_t preChar = strCurText.GetAt((nIndex));
+      wchar_t preChar = strCurText[nIndex];
       if (FXSYS_iswalpha(preChar) && FXSYS_iswalpha(curChar))
         return true;
     }
@@ -1268,7 +1266,7 @@ CPDF_TextPage::GenerateCharacter CPDF_TextPage::ProcessInsertObject(
       pObj->GetFont()->UnicodeFromCharCode(item.m_CharCode);
   if (wstrItem.IsEmpty())
     wstrItem += static_cast<wchar_t>(item.m_CharCode);
-  wchar_t curChar = wstrItem.GetAt(0);
+  wchar_t curChar = wstrItem[0];
   if (WritingMode == TextOrientation::Horizontal) {
     if (this_rect.Height() > 4.5 && prev_rect.Height() > 4.5) {
       float top = this_rect.top < prev_rect.top ? this_rect.top : prev_rect.top;
@@ -1357,7 +1355,7 @@ CPDF_TextPage::GenerateCharacter CPDF_TextPage::ProcessInsertObject(
       m_pPreTextObj->GetFont()->UnicodeFromCharCode(PrevItem.m_CharCode);
   if (PrevStr.IsEmpty())
     return GenerateCharacter::None;
-  wchar_t preChar = PrevStr.GetAt(PrevStr.GetLength() - 1);
+  wchar_t preChar = PrevStr[PrevStr.GetLength() - 1];
   CFX_Matrix matrix = pObj->GetTextMatrix();
   matrix.Concat(formMatrix);
 
diff --git a/core/fpdftext/cpdf_textpagefind.cpp b/core/fpdftext/cpdf_textpagefind.cpp
index 3c8e532a7f..55f940cad7 100644
--- a/core/fpdftext/cpdf_textpagefind.cpp
+++ b/core/fpdftext/cpdf_textpagefind.cpp
@@ -110,7 +110,7 @@ bool CPDF_TextPageFind::FindFirst(const CFX_WideString& findwhat,
   m_csFindWhatArray.clear();
   int i = 0;
   while (i < len) {
-    if (findwhatStr.GetAt(i) != ' ')
+    if (findwhatStr[i] != ' ')
       break;
     i++;
   }
@@ -150,7 +150,7 @@ bool CPDF_TextPageFind::FindNext() {
     CFX_WideString csWord = m_csFindWhatArray[iWord];
     if (csWord.IsEmpty()) {
       if (iWord == nCount - 1) {
-        wchar_t strInsert = m_strText.GetAt(nStartPos);
+        wchar_t strInsert = m_strText[nStartPos];
         if (strInsert == TEXT_LINEFEED_CHAR || strInsert == TEXT_SPACE_CHAR ||
             strInsert == TEXT_RETURN_CHAR || strInsert == 160) {
           nResultPos = nStartPos + 1;
@@ -174,16 +174,16 @@ bool CPDF_TextPageFind::FindNext() {
     bool bMatch = true;
     if (iWord != 0 && !bSpaceStart) {
       int PreResEndPos = nStartPos;
-      int curChar = csWord.GetAt(0);
+      int curChar = csWord[0];
       CFX_WideString lastWord = m_csFindWhatArray[iWord - 1];
-      int lastChar = lastWord.GetAt(lastWord.GetLength() - 1);
+      int lastChar = lastWord[lastWord.GetLength() - 1];
       if (nStartPos == nResultPos &&
           !(IsIgnoreSpaceCharacter(lastChar) ||
             IsIgnoreSpaceCharacter(curChar))) {
         bMatch = false;
       }
       for (int d = PreResEndPos; d < nResultPos; d++) {
-        wchar_t strInsert = m_strText.GetAt(d);
+        wchar_t strInsert = m_strText[d];
         if (strInsert != TEXT_LINEFEED_CHAR && strInsert != TEXT_SPACE_CHAR &&
             strInsert != TEXT_RETURN_CHAR && strInsert != 160) {
           bMatch = false;
@@ -192,7 +192,7 @@ bool CPDF_TextPageFind::FindNext() {
       }
     } else if (bSpaceStart) {
       if (nResultPos > 0) {
-        wchar_t strInsert = m_strText.GetAt(nResultPos - 1);
+        wchar_t strInsert = m_strText[nResultPos - 1];
         if (strInsert != TEXT_LINEFEED_CHAR && strInsert != TEXT_SPACE_CHAR &&
             strInsert != TEXT_RETURN_CHAR && strInsert != 160) {
           bMatch = false;
@@ -293,7 +293,7 @@ void CPDF_TextPageFind::ExtractFindWhat(const CFX_WideString& findwhat) {
     int pos = 0;
     while (pos < csWord.GetLength()) {
       CFX_WideString curStr = csWord.Mid(pos, 1);
-      wchar_t curChar = csWord.GetAt(pos);
+      wchar_t curChar = csWord[pos];
       if (IsIgnoreSpaceCharacter(curChar)) {
         if (pos > 0 && curChar == 0x2019) {
           pos++;
@@ -326,12 +326,12 @@ bool CPDF_TextPageFind::IsMatchWholeWord(const CFX_WideString& csPageText,
   int char_count = endPos - startPos + 1;
   if (char_count < 1)
     return false;
-  if (char_count == 1 && csPageText.GetAt(startPos) > 255)
+  if (char_count == 1 && csPageText[startPos] > 255)
     return true;
   if (startPos - 1 >= 0)
-    char_left = csPageText.GetAt(startPos - 1);
+    char_left = csPageText[startPos - 1];
   if (startPos + char_count < csPageText.GetLength())
-    char_right = csPageText.GetAt(startPos + char_count);
+    char_right = csPageText[startPos + char_count];
   if ((char_left > 'A' && char_left < 'a') ||
       (char_left > 'a' && char_left < 'z') ||
       (char_left > 0xfb00 && char_left < 0xfb06) || std::iswdigit(char_left) ||
@@ -348,9 +348,9 @@ bool CPDF_TextPageFind::IsMatchWholeWord(const CFX_WideString& csPageText,
     return false;
   }
   if (char_count > 0) {
-    if (std::iswdigit(char_left) && std::iswdigit(csPageText.GetAt(startPos)))
+    if (std::iswdigit(char_left) && std::iswdigit(csPageText[startPos]))
       return false;
-    if (std::iswdigit(char_right) && std::iswdigit(csPageText.GetAt(endPos)))
+    if (std::iswdigit(char_right) && std::iswdigit(csPageText[endPos]))
       return false;
   }
   return true;
@@ -386,7 +386,7 @@ CFX_WideString CPDF_TextPageFind::MakeReverse(const CFX_WideString& str) {
   str2.clear();
   int nlen = str.GetLength();
   for (int i = nlen - 1; i >= 0; i--)
-    str2 += str.GetAt(i);
+    str2 += str[i];
   return str2;
 }