base::OffsetAdjuster: Refactor offset limiting logic into the base::OffsetAdjuster

base/strings/utf_offset_string_conversions.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/strings/utf_offset_string_conversions.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 #include <memory>
 
 #include "base/logging.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/utf_string_conversion_utils.h"
 
 namespace base {
 
+namespace {
+
+// Limiting function callable by std::for_each which will replace any value
+// which is greater than |limit| with npos.
+struct LimitOffset {
+  explicit LimitOffset(size_t limit) : limit_(limit) {}
+
+  void operator()(size_t& offset) {
+    if (offset > limit_)
+      offset = string16::npos;
+  }
+
+  size_t limit_;
+};
+
+}  // namespace
+
 OffsetAdjuster::Adjustment::Adjustment(size_t original_offset,
                                        size_t original_length,
                                        size_t output_length)
     : original_offset(original_offset),
       original_length(original_length),
       output_length(output_length) {
 }
 
 // static
-void OffsetAdjuster::AdjustOffsets(
-    const Adjustments& adjustments,
-    std::vector<size_t>* offsets_for_adjustment) {
-  if (!offsets_for_adjustment || adjustments.empty())
-    return;
+void OffsetAdjuster::AdjustOffsets(const Adjustments& adjustments,
+                                   std::vector<size_t>* offsets_for_adjustment,
+                                   size_t limit) {
+  DCHECK(offsets_for_adjustment);
   for (std::vector<size_t>::iterator i(offsets_for_adjustment->begin());
        i != offsets_for_adjustment->end(); ++i)
-    AdjustOffset(adjustments, &(*i));
+    AdjustOffset(adjustments, &(*i), limit);
 }
 
 // static
 void OffsetAdjuster::AdjustOffset(const Adjustments& adjustments,
-                                  size_t* offset) {
+                                  size_t* offset,
+                                  size_t limit) {
+  DCHECK(offset);
   if (*offset == string16::npos)
     return;
   int adjustment = 0;
   for (Adjustments::const_iterator i = adjustments.begin();
        i != adjustments.end(); ++i) {
     if (*offset <= i->original_offset)
       break;
     if (*offset < (i->original_offset + i->original_length)) {
       *offset = string16::npos;
       return;
     }
     adjustment += static_cast<int>(i->original_length - i->output_length);
   }
   *offset -= adjustment;
+
+  if (*offset > limit)
+    *offset = string16::npos;
 }
 
 // static
 void OffsetAdjuster::UnadjustOffsets(
     const Adjustments& adjustments,
     std::vector<size_t>* offsets_for_unadjustment) {
   if (!offsets_for_unadjustment || adjustments.empty())
     return;
   for (std::vector<size_t>::iterator i(offsets_for_unadjustment->begin());
        i != offsets_for_unadjustment->end(); ++i)
@@ skipping 165 matching lines @@
     const base::StringPiece& utf8,
     base::OffsetAdjuster::Adjustments* adjustments) {
   string16 result;
   UTF8ToUTF16WithAdjustments(utf8.data(), utf8.length(), &result, adjustments);
   return result;
 }
 
 string16 UTF8ToUTF16AndAdjustOffsets(
     const base::StringPiece& utf8,
     std::vector<size_t>* offsets_for_adjustment) {
-  std::for_each(offsets_for_adjustment->begin(),
-                offsets_for_adjustment->end(),
-                LimitOffset<base::StringPiece>(utf8.length()));
+  std::for_each(offsets_for_adjustment->begin(), offsets_for_adjustment->end(),
+                LimitOffset(utf8.length()));
   OffsetAdjuster::Adjustments adjustments;
   string16 result = UTF8ToUTF16WithAdjustments(utf8, &adjustments);
   OffsetAdjuster::AdjustOffsets(adjustments, offsets_for_adjustment);
   return result;
 }
 
 std::string UTF16ToUTF8AndAdjustOffsets(
     const base::StringPiece16& utf16,
     std::vector<size_t>* offsets_for_adjustment) {
-  std::for_each(offsets_for_adjustment->begin(),
-                offsets_for_adjustment->end(),
-                LimitOffset<base::StringPiece16>(utf16.length()));
+  std::for_each(offsets_for_adjustment->begin(), offsets_for_adjustment->end(),
+                LimitOffset(utf16.length()));
   std::string result;
   PrepareForUTF8Output(utf16.data(), utf16.length(), &result);
   OffsetAdjuster::Adjustments adjustments;
   ConvertUnicode(utf16.data(), utf16.length(), &result, &adjustments);
   OffsetAdjuster::AdjustOffsets(adjustments, offsets_for_adjustment);
   return result;
 }
 
 }  // namespace base