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>

8 files changed, 28 insertions, 28 deletions

diff --git a/fxbarcode/datamatrix/BC_ASCIIEncoder.cpp b/fxbarcode/datamatrix/BC_ASCIIEncoder.cpp
index de57d81b71..e6b7a2b35b 100644
--- a/fxbarcode/datamatrix/BC_ASCIIEncoder.cpp
+++ b/fxbarcode/datamatrix/BC_ASCIIEncoder.cpp
@@ -37,8 +37,8 @@ void CBC_ASCIIEncoder::Encode(CBC_EncoderContext& context, int32_t& e) {
   int32_t n = CBC_HighLevelEncoder::determineConsecutiveDigitCount(
       context.m_msg, context.m_pos);
   if (n >= 2) {
-    wchar_t code = encodeASCIIDigits(context.m_msg.GetAt(context.m_pos),
-                                     context.m_msg.GetAt(context.m_pos + 1), e);
+    wchar_t code = encodeASCIIDigits(context.m_msg[context.m_pos],
+                                     context.m_msg[context.m_pos + 1], e);
     if (e != BCExceptionNO) {
       return;
     }
diff --git a/fxbarcode/datamatrix/BC_Base256Encoder.cpp b/fxbarcode/datamatrix/BC_Base256Encoder.cpp
index edcd411114..0cbd3fdb10 100644
--- a/fxbarcode/datamatrix/BC_Base256Encoder.cpp
+++ b/fxbarcode/datamatrix/BC_Base256Encoder.cpp
@@ -35,7 +35,7 @@ int32_t CBC_Base256Encoder::getEncodingMode() {
 }
 void CBC_Base256Encoder::Encode(CBC_EncoderContext& context, int32_t& e) {
   CFX_WideString buffer;
-  buffer += (wchar_t)'\0';
+  buffer += L'\0';
   while (context.hasMoreCharacters()) {
     wchar_t c = context.getCurrentChar();
     buffer += c;
@@ -50,7 +50,7 @@ void CBC_Base256Encoder::Encode(CBC_EncoderContext& context, int32_t& e) {
   int32_t dataCount = buffer.GetLength() - 1;
   char buf[128];
   FXSYS_itoa(dataCount, buf, 10);
-  buffer.SetAt(0, wchar_t(*buf) - '0');
+  buffer.SetAt(0, static_cast<wchar_t>(*buf) - '0');
   int32_t lengthFieldSize = 1;
   int32_t currentSize =
       context.getCodewordCount() + dataCount + lengthFieldSize;
@@ -61,10 +61,10 @@ void CBC_Base256Encoder::Encode(CBC_EncoderContext& context, int32_t& e) {
   bool mustPad = (context.m_symbolInfo->dataCapacity() - currentSize) > 0;
   if (context.hasMoreCharacters() || mustPad) {
     if (dataCount <= 249) {
-      buffer.SetAt(0, (wchar_t)dataCount);
+      buffer.SetAt(0, static_cast<wchar_t>(dataCount));
     } else if (dataCount > 249 && dataCount <= 1555) {
-      buffer.SetAt(0, (wchar_t)((dataCount / 250) + 249));
-      buffer.Insert(1, (wchar_t)(dataCount % 250));
+      buffer.SetAt(0, static_cast<wchar_t>((dataCount / 250) + 249));
+      buffer.Insert(1, static_cast<wchar_t>(dataCount % 250));
     } else {
       e = BCExceptionIllegalStateMessageLengthInvalid;
       return;
@@ -79,8 +79,8 @@ wchar_t CBC_Base256Encoder::randomize255State(wchar_t ch,
   int32_t pseudoRandom = ((149 * codewordPosition) % 255) + 1;
   int32_t tempVariable = ch + pseudoRandom;
   if (tempVariable <= 255) {
-    return (wchar_t)tempVariable;
+    return static_cast<wchar_t>(tempVariable);
   } else {
-    return (wchar_t)(tempVariable - 256);
+    return static_cast<wchar_t>(tempVariable - 256);
   }
 }
diff --git a/fxbarcode/datamatrix/BC_C40Encoder.cpp b/fxbarcode/datamatrix/BC_C40Encoder.cpp
index 8edd9eccfe..8a55c922ed 100644
--- a/fxbarcode/datamatrix/BC_C40Encoder.cpp
+++ b/fxbarcode/datamatrix/BC_C40Encoder.cpp
@@ -32,9 +32,9 @@
 namespace {
 
 CFX_WideString EncodeToCodewords(const CFX_WideString& sb, int32_t startPos) {
-  wchar_t c1 = sb.GetAt(startPos);
-  wchar_t c2 = sb.GetAt(startPos + 1);
-  wchar_t c3 = sb.GetAt(startPos + 2);
+  wchar_t c1 = sb[startPos];
+  wchar_t c2 = sb[startPos + 1];
+  wchar_t c3 = sb[startPos + 2];
   int32_t v = (1600 * c1) + (40 * c2) + c3 + 1;
   wchar_t cw[2];
   cw[0] = static_cast<wchar_t>(v / 256);
diff --git a/fxbarcode/datamatrix/BC_DefaultPlacement.cpp b/fxbarcode/datamatrix/BC_DefaultPlacement.cpp
index 405b4f72a1..934d79503c 100644
--- a/fxbarcode/datamatrix/BC_DefaultPlacement.cpp
+++ b/fxbarcode/datamatrix/BC_DefaultPlacement.cpp
@@ -107,7 +107,7 @@ void CBC_DefaultPlacement::module(int32_t row,
     col += m_numcols;
     row += 4 - ((m_numcols + 4) % 8);
   }
-  int32_t v = m_codewords.GetAt(pos);
+  int32_t v = m_codewords[pos];
   v &= 1 << (8 - bit);
   setBit(col, row, v != 0);
 }
diff --git a/fxbarcode/datamatrix/BC_EdifactEncoder.cpp b/fxbarcode/datamatrix/BC_EdifactEncoder.cpp
index c7d6b317c1..7407efb47e 100644
--- a/fxbarcode/datamatrix/BC_EdifactEncoder.cpp
+++ b/fxbarcode/datamatrix/BC_EdifactEncoder.cpp
@@ -38,10 +38,10 @@ CFX_WideString EncodeToCodewords(const CFX_WideString& sb, int32_t startPos) {
   if (len == 0)
     return CFX_WideString();
 
-  wchar_t c1 = sb.GetAt(startPos);
-  wchar_t c2 = len >= 2 ? sb.GetAt(startPos + 1) : 0;
-  wchar_t c3 = len >= 3 ? sb.GetAt(startPos + 2) : 0;
-  wchar_t c4 = len >= 4 ? sb.GetAt(startPos + 3) : 0;
+  wchar_t c1 = sb[startPos];
+  wchar_t c2 = len >= 2 ? sb[startPos + 1] : 0;
+  wchar_t c3 = len >= 3 ? sb[startPos + 2] : 0;
+  wchar_t c4 = len >= 4 ? sb[startPos + 3] : 0;
   int32_t v = (c1 << 18) + (c2 << 12) + (c3 << 6) + c4;
   constexpr int32_t kBuflen = 3;
   wchar_t cw[kBuflen];
diff --git a/fxbarcode/datamatrix/BC_EncoderContext.cpp b/fxbarcode/datamatrix/BC_EncoderContext.cpp
index 404c07d980..eaf3768f49 100644
--- a/fxbarcode/datamatrix/BC_EncoderContext.cpp
+++ b/fxbarcode/datamatrix/BC_EncoderContext.cpp
@@ -36,8 +36,8 @@ CBC_EncoderContext::CBC_EncoderContext(const CFX_WideString& msg,
   CFX_WideString sb;
   FX_STRSIZE c = dststr.GetLength();
   for (FX_STRSIZE i = 0; i < c; i++) {
-    wchar_t ch = static_cast<wchar_t>(dststr.GetAt(i) & 0xff);
-    if (ch == '?' && dststr.GetAt(i) != '?') {
+    wchar_t ch = static_cast<wchar_t>(dststr[i] & 0xff);
+    if (ch == '?' && dststr[i] != '?') {
       e = BCExceptionCharactersOutsideISO88591Encoding;
     }
     sb += ch;
@@ -60,10 +60,10 @@ void CBC_EncoderContext::setSkipAtEnd(int32_t count) {
   m_skipAtEnd = count;
 }
 wchar_t CBC_EncoderContext::getCurrentChar() {
-  return m_msg.GetAt(m_pos);
+  return m_msg[m_pos];
 }
 wchar_t CBC_EncoderContext::getCurrent() {
-  return m_msg.GetAt(m_pos);
+  return m_msg[m_pos];
 }
 
 void CBC_EncoderContext::writeCodewords(const CFX_WideString& codewords) {
diff --git a/fxbarcode/datamatrix/BC_ErrorCorrection.cpp b/fxbarcode/datamatrix/BC_ErrorCorrection.cpp
index 4071602303..2e84df5c59 100644
--- a/fxbarcode/datamatrix/BC_ErrorCorrection.cpp
+++ b/fxbarcode/datamatrix/BC_ErrorCorrection.cpp
@@ -150,7 +150,7 @@ CFX_WideString CBC_ErrorCorrection::encodeECC200(CFX_WideString codewords,
     for (int32_t block = 0; block < blockCount; block++) {
       CFX_WideString temp;
       for (int32_t d = block; d < symbolInfo->dataCapacity(); d += blockCount) {
-        temp += (wchar_t)codewords.GetAt(d);
+        temp += (wchar_t)codewords[d];
       }
       CFX_WideString ecc = createECCBlock(temp, errorSizes[block], e);
       if (e != BCExceptionNO)
@@ -158,7 +158,7 @@ CFX_WideString CBC_ErrorCorrection::encodeECC200(CFX_WideString codewords,
       int32_t pos = 0;
       for (int32_t l = block; l < errorSizes[block] * blockCount;
            l += blockCount) {
-        sb.SetAt(symbolInfo->dataCapacity() + l, ecc.GetAt(pos++));
+        sb.SetAt(symbolInfo->dataCapacity() + l, ecc[pos++]);
       }
     }
   }
@@ -186,7 +186,7 @@ CFX_WideString CBC_ErrorCorrection::createECCBlock(CFX_WideString codewords,
   uint16_t* ecc = FX_Alloc(uint16_t, numECWords);
   memset(ecc, 0, numECWords * sizeof(uint16_t));
   for (int32_t l = start; l < start + len; l++) {
-    uint16_t m = ecc[numECWords - 1] ^ codewords.GetAt(l);
+    uint16_t m = ecc[numECWords - 1] ^ codewords[l];
     for (int32_t k = numECWords - 1; k > 0; k--) {
       if (m != 0 && FACTORS[table][k] != 0) {
         ecc[k] = (uint16_t)(ecc[k - 1] ^
diff --git a/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp b/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp
index 6034173ee4..8b8b413c9b 100644
--- a/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp
+++ b/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp
@@ -174,7 +174,7 @@ int32_t CBC_HighLevelEncoder::lookAheadTest(CFX_WideString msg,
       }
       return C40_ENCODATION;
     }
-    wchar_t c = msg.GetAt(startpos + charsProcessed);
+    wchar_t c = msg[startpos + charsProcessed];
     charsProcessed++;
     if (isDigit(c)) {
       charCounts[ASCII_ENCODATION] += 0.5;
@@ -253,7 +253,7 @@ int32_t CBC_HighLevelEncoder::lookAheadTest(CFX_WideString msg,
         if (intCharCounts[C40_ENCODATION] == intCharCounts[X12_ENCODATION]) {
           int32_t p = startpos + charsProcessed + 1;
           while (p < msg.GetLength()) {
-            wchar_t tc = msg.GetAt(p);
+            wchar_t tc = msg[p];
             if (isX12TermSep(tc)) {
               return X12_ENCODATION;
             }
@@ -280,12 +280,12 @@ int32_t CBC_HighLevelEncoder::determineConsecutiveDigitCount(CFX_WideString msg,
   int32_t len = msg.GetLength();
   int32_t idx = startpos;
   if (idx < len) {
-    wchar_t ch = msg.GetAt(idx);
+    wchar_t ch = msg[idx];
     while (isDigit(ch) && idx < len) {
       count++;
       idx++;
       if (idx < len) {
-        ch = msg.GetAt(idx);
+        ch = msg[idx];
       }
     }
   }