SkPDF: in-place font subsetting

src/utils/SkBitSet.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkBitSet.h"
 
 SkBitSet::SkBitSet(int numberOfBits)
     : fBitData(nullptr), fDwordCount(0), fBitCount(numberOfBits) {
     SkASSERT(numberOfBits > 0);
     // Round up size to 32-bit boundary.
     fDwordCount = (numberOfBits + 31) / 32;
     fBitData.set(sk_calloc_throw(fDwordCount * sizeof(uint32_t)));
 }
 
-SkBitSet::SkBitSet(const SkBitSet& source)
-    : fBitData(nullptr), fDwordCount(0), fBitCount(0) {
-    *this = source;
-}
-
 SkBitSet::SkBitSet(SkBitSet&& source)
     : fBitData(source.fBitData.release())
     , fDwordCount(source.fDwordCount)
     , fBitCount(source.fBitCount) {
     source.fDwordCount = 0;
     source.fBitCount = 0;
 }
 
-SkBitSet& SkBitSet::operator=(const SkBitSet& rhs) {
-    if (this == &rhs) {
-        return *this;
+SkBitSet& SkBitSet::operator=(SkBitSet&& rhs) {
+    if (this != &rhs) {
+        fBitCount = rhs.fBitCount;
+        fDwordCount = rhs.fDwordCount;
+        fBitData.reset();  // Free old pointer.
+        fBitData.set(rhs.fBitData.release());
+        rhs.fBitCount = 0;
+        rhs.fDwordCount = 0;
     }
-    fBitCount = rhs.fBitCount;
-    fBitData.reset();
-    fDwordCount = rhs.fDwordCount;
-    fBitData.set(sk_malloc_throw(fDwordCount * sizeof(uint32_t)));
-    memcpy(fBitData.get(), rhs.fBitData.get(), fDwordCount * sizeof(uint32_t));
     return *this;
 }
 
 bool SkBitSet::operator==(const SkBitSet& rhs) {
     if (fBitCount == rhs.fBitCount) {
         if (fBitData.get() != nullptr) {
             return (memcmp(fBitData.get(), rhs.fBitData.get(),
                            fDwordCount * sizeof(uint32_t)) == 0);
         }
         return true;
@@ skipping 15 matching lines @@
     if (fBitCount != source.fBitCount) {
         return false;
     }
     uint32_t* targetBitmap = this->internalGet(0);
     uint32_t* sourceBitmap = source.internalGet(0);
     for (size_t i = 0; i < fDwordCount; ++i) {
         targetBitmap[i] |= sourceBitmap[i];
     }
     return true;
 }