Several optimizations that came from KCacheGrind / calltree fun.

Basically they fall into the categories:
- Don't convert things before you need to
- When you do, use more effecient copy constructors / assignment operators
  (i.e. when copying prefer memcpy to a for loop and when that's not possible
  use an iterator instead of operator[])


git-svn-id: svn://anonsvn.kde.org/home/kde/trunk/kdesupport/taglib@301896 283d02a7-25f6-0310-bc7c-ecb5cbfe19da

mpeg/id3v2/id3v2framefactory.cpp

@@ -252,7 +252,7 @@ bool FrameFactory::updateFrame(Frame::Header *header) const
 // private members
 ////////////////////////////////////////////////////////////////////////////////
 
-void FrameFactory::convertFrame(const ByteVector &from, const ByteVector &to,
+void FrameFactory::convertFrame(const char *from, const char *to,
                                 Frame::Header *header) const
 {
   if(header->frameID() != from)

mpeg/id3v2/id3v2framefactory.h

@@ -124,7 +124,7 @@ namespace TagLib {
        * \a to.  If the frame matches the \a from pattern and converts the frame
        * ID in the \a header or simply does nothing if the frame ID does not match.
        */
-      void convertFrame(const ByteVector &from, const ByteVector &to,
+      void convertFrame(const char *from, const char *to,
                         Frame::Header *header) const;
 
       static FrameFactory *factory;

toolkit/tbytevector.cpp

@@ -26,6 +26,10 @@
 
 #include "tbytevector.h"
 
+// This is a bit ugly to keep writing over and over again.
+
+#define DATA(x) (&(x->data[0]))
+
 namespace TagLib {
   static const uint crcTable[256] = {
     0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b,
@@ -285,7 +289,7 @@ void ByteVector::setData(const char *data, uint length)
   detach();
 
   resize(length);
-  ::memcpy(&(d->data[0]), data, length);
+  ::memcpy(DATA(d), data, length);
 }
 
 void ByteVector::setData(const char *data)
@@ -301,12 +305,12 @@ char *ByteVector::data()
   // http://www.informit.com/isapi/product_id~{9C84DAB4-FE6E-49C5-BB0A-FB50331233EA}/content/index.asp
 
   detach();
-  return &(d->data[0]);
+  return DATA(d);
 }
 
 const char *ByteVector::data() const
 {
-  return &(d->data[0]);
+  return DATA(d);
 }
 
 ByteVector ByteVector::mid(uint index, uint length) const
@@ -402,7 +406,7 @@ void ByteVector::append(const ByteVector &v)
 
   uint originalSize = d->size;
   resize(d->size + v.d->size);
-  ::memcpy(&(d->data[0]) + originalSize, v.data(), v.size());
+  ::memcpy(DATA(d) + originalSize, DATA(v.d), v.size());
 }
 
 void ByteVector::clear()
@@ -418,15 +422,15 @@ TagLib::uint ByteVector::size() const
 
 ByteVector &ByteVector::resize(uint size, char padding)
 {
-  d->size = size;
-
-  if(d->data.size() < size) {
+  if(d->size < size) {
     d->data.reserve(size);
-    d->data.insert(d->data.end(), size - d->data.size(), padding);
+    ::memset(DATA(d), padding, size - d->size);
   }
   else
     d->data.erase(d->data.begin() + size, d->data.end());
 
+  d->size = size;
+
   return *this;
 }
 
@@ -507,15 +511,10 @@ char &ByteVector::operator[](int index)
 
 bool ByteVector::operator==(const ByteVector &v) const
 {
-  if(size() != v.size())
+  if(d->size != v.d->size)
     return false;
 
-  for(uint i = 0; i < size(); i++) {
-    if(at(i) != v.at(i))
-      return false;
-  }
-
-  return true;
+  return ::memcmp(data(), v.data(), size()) == 0;
 }
 
 bool ByteVector::operator!=(const ByteVector &v) const
@@ -525,7 +524,10 @@ bool ByteVector::operator!=(const ByteVector &v) const
 
 bool ByteVector::operator==(const char *s) const
 {
-  return operator==(fromCString(s));
+  if(d->size != ::strlen(s))
+    return false;
+
+  return ::memcmp(data(), s, d->size) == 0;
 }
 
 bool ByteVector::operator!=(const char *s) const

toolkit/tstring.cpp

@@ -88,8 +88,14 @@ String::String(const std::string &s, Type t)
     return;
   }
 
-  for(std::string::const_iterator it = s.begin(); it != s.end(); it++)
-    d->data += uchar(*it);
+  int length = s.length();
+  d->data.resize(length);
+  wstring::iterator targetIt = d->data.begin();
+
+  for(std::string::const_iterator it = s.begin(); it != s.end(); it++) {
+    *targetIt = uchar(*it);
+    ++targetIt;
+  }
 
   prepare(t);
 }
@@ -115,8 +121,15 @@ String::String(const char *s, Type t)
     return;
   }
 
-  for(int i = 0; s[i] != 0; i++)
-    d->data += uchar(s[i]);
+  int length = ::strlen(s);
+  d->data.resize(length);
+
+  wstring::iterator targetIt = d->data.begin();
+
+  for(int i = 0; i < length; i++) {
+    *targetIt = uchar(s[i]);
+    ++targetIt;
+  }
 
   prepare(t);
 }
@@ -146,12 +159,25 @@ String::String(const ByteVector &v, Type t)
   d = new StringPrivate;
 
   if(t == Latin1 || t == UTF8) {
-    for(uint i = 0; i < v.size() && v[i]; i++)
-      d->data += uchar(v[i]);
+
+    d->data.resize(v.size());
+    wstring::iterator targetIt = d->data.begin();
+    for(ByteVector::ConstIterator it = v.begin(); it != v.end() && (*it); ++it) {
+      *targetIt = uchar(*it);
+      ++targetIt;
+    }
   }
   else  {
-    for(uint i = 0; i + 1 < v.size() && combine(v[i], v[i + 1]); i += 2)
-      d->data += combine(v[i], v[i + 1]);
+    d->data.resize(v.size() / 2);
+    wstring::iterator targetIt = d->data.begin();
+
+    for(ByteVector::ConstIterator it = v.begin();
+        it + 1 != v.end() && combine(*it, *(it + 1));
+        it += 2)
+    {
+      *targetIt = combine(*it, *(it + 1));
+      ++targetIt;
+    }
   }
   prepare(t);
 }
@@ -516,8 +542,14 @@ String &String::operator=(const char *s)
 
   d = new StringPrivate;
 
-  for(int i = 0; s[i] != 0; i++)
-    d->data += uchar(s[i]);
+  int length = ::strlen(s);
+  d->data.resize(length);
+
+  wstring::iterator targetIt = d->data.begin();
+  for(int i = 0; i < length; i++) {
+    *targetIt = uchar(s[i]);
+    ++targetIt;
+  }
 
   return *this;
 }
@@ -532,9 +564,11 @@ String &String::operator=(const ByteVector &v)
   wstring::iterator targetIt = d->data.begin();
 
   uint i = 0;
-  for(; i < v.size() && v[i]; i++) {
-    *targetIt = uchar(v[i]);
+
+  for(ByteVector::ConstIterator it = v.begin(); it != v.end() && (*it); ++it) {
+    *targetIt = uchar(*it);
     ++targetIt;
+    ++i;
   }
 
   // If we hit a null in the ByteVector, shrink the string again.