manual range loop conversions (#1126)

* manual range loop conversions

Signed-off-by: Rosen Penev <rosenp@gmail.com>

* Restore const containers where non const temporaries are iterated

* Use std::as_const() instead of const container copies where possible

---------

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Co-authored-by: Urs Fleisch <ufleisch@users.sourceforge.net>

taglib/ogg/oggpage.cpp

@@ -27,6 +27,7 @@
 
 #include <algorithm>
 #include <array>
+#include <utility>
 
 #include "tstring.h"
 #include "tdebug.h"
@@ -92,8 +93,8 @@ unsigned int pageChecksum(const ByteVector &data)
   };
 
   unsigned int sum = 0;
-  for(auto it = data.begin(); it != data.end(); ++it)
-    sum = (sum << 8) ^ crcTable[((sum >> 24) & 0xff) ^ static_cast<unsigned char>(*it)];
+  for(const auto &byte : data)
+    sum = (sum << 8) ^ crcTable[((sum >> 24) & 0xff) ^ static_cast<unsigned char>(byte)];
   return sum;
 }
 
@@ -212,9 +213,8 @@ ByteVectorList Ogg::Page::packets() const
     d->file->seek(d->fileOffset + d->header.size());
 
     const List<int> packetSizes = d->header.packetSizes();
-
-    for(auto it = packetSizes.begin(); it != packetSizes.end(); ++it)
-      l.append(d->file->readBlock(*it));
+    for(const auto &size : packetSizes)
+      l.append(d->file->readBlock(size));
   }
   else
     debug("Ogg::Page::packets() -- attempting to read packets from an invalid page.");
@@ -242,8 +242,8 @@ ByteVector Ogg::Page::render() const
       debug("Ogg::Page::render() -- this page is empty!");
   }
   else {
-    for(auto it = d->packets.cbegin(); it != d->packets.cend(); ++it)
-      data.append(*it);
+    for(const auto &packet : std::as_const(d->packets))
+      data.append(packet);
   }
 
   // Compute and set the checksum for the Ogg page.  The checksum is taken over
@@ -274,8 +274,8 @@ List<Ogg::Page *> Ogg::Page::paginate(const ByteVectorList &packets,
   if(strategy != Repaginate) {
 
     size_t tableSize = 0;
-    for(auto it = packets.begin(); it != packets.end(); ++it)
-      tableSize += it->size() / 255 + 1;
+    for(const auto &packet : packets)
+      tableSize += packet.size() / 255 + 1;
 
     if(tableSize > 255)
       strategy = Repaginate;
@@ -354,9 +354,9 @@ Ogg::Page::Page(const ByteVectorList &packets,
   ByteVector data;
   List<int> packetSizes;
 
-  for(auto it = packets.begin(); it != packets.end(); ++it) {
-    packetSizes.append((*it).size());
-    data.append(*it);
+  for(const auto &packet : packets) {
+    packetSizes.append(packet.size());
+    data.append(packet);
   }
   d->packets = packets;
   d->header.setPacketSizes(packetSizes);

taglib/ogg/oggpageheader.cpp

@@ -290,7 +290,7 @@ ByteVector Ogg::PageHeader::lacingValues() const
 
     data.resize(data.size() + (*it / 255), '\xff');
 
-    if(it != --d->packetSizes.cend() || d->lastPacketCompleted)
+    if(it != std::prev(d->packetSizes.cend()) || d->lastPacketCompleted)
       data.append(static_cast<unsigned char>(*it % 255));
   }
 

taglib/ogg/xiphcomment.cpp

@@ -31,6 +31,8 @@
 #include "flacpicture.h"
 #include "tpropertymap.h"
 
+#include <utility>
+
 using namespace TagLib;
 
 namespace
@@ -196,8 +198,8 @@ unsigned int Ogg::XiphComment::fieldCount() const
 {
   unsigned int count = 0;
 
-  for(auto it = d->fieldListMap.cbegin(); it != d->fieldListMap.cend(); ++it)
-    count += (*it).second.size();
+  for(const auto &[_, list] : std::as_const(d->fieldListMap))
+    count += list.size();
 
   count += d->pictureList.size();
 
@@ -218,31 +220,27 @@ PropertyMap Ogg::XiphComment::setProperties(const PropertyMap &properties)
 {
   // check which keys are to be deleted
   StringList toRemove;
-  for(auto it = d->fieldListMap.cbegin(); it != d->fieldListMap.cend(); ++it)
-    if (!properties.contains(it->first))
-      toRemove.append(it->first);
+  for(const auto &[field, _] : std::as_const(d->fieldListMap))
+    if(!properties.contains(field))
+      toRemove.append(field);
 
-  for(auto it = toRemove.cbegin(); it != toRemove.cend(); ++it)
-      removeFields(*it);
+  for(const auto &field : std::as_const(toRemove))
+    removeFields(field);
 
   // now go through keys in \a properties and check that the values match those in the xiph comment
   PropertyMap invalid;
-  for(auto it = properties.begin(); it != properties.end(); ++it)
-  {
-    if(!checkKey(it->first))
-      invalid.insert(it->first, it->second);
-    else if(!d->fieldListMap.contains(it->first) || !(it->second == d->fieldListMap[it->first])) {
-      const StringList &sl = it->second;
+  for(const auto &[key, sl] : properties) {
+    if(!checkKey(key))
+      invalid.insert(key, sl);
+    else if(!d->fieldListMap.contains(key) || !(sl == d->fieldListMap[key])) {
       if(sl.isEmpty())
         // zero size string list -> remove the tag with all values
-        removeFields(it->first);
+        removeFields(key);
       else {
         // replace all strings in the list for the tag
-        auto valueIterator = sl.begin();
-        addField(it->first, *valueIterator, true);
-        ++valueIterator;
-        for(; valueIterator != sl.end(); ++valueIterator)
-          addField(it->first, *valueIterator, false);
+        addField(key, *sl.begin(), true);
+        for(auto it = std::next(sl.begin()); it != sl.end(); ++it)
+          addField(key, *it, false);
       }
     }
   }
@@ -353,25 +351,20 @@ ByteVector Ogg::XiphComment::render(bool addFramingBit) const
   // std::pair<String, StringList> where the first String is the field name and
   // the StringList is the values associated with that field.
 
-  for(auto it = d->fieldListMap.cbegin(); it != d->fieldListMap.cend(); ++it) {
-
+  for(const auto &[fieldName, values] : std::as_const(d->fieldListMap)) {
     // And now iterate over the values of the current list.
-
-    String fieldName = (*it).first;
-    const StringList values = (*it).second;
-
-    for(auto valuesIt = values.begin(); valuesIt != values.end(); ++valuesIt) {
+    for(const auto &value : values) {
       ByteVector fieldData = fieldName.data(String::UTF8);
       fieldData.append('=');
-      fieldData.append((*valuesIt).data(String::UTF8));
+      fieldData.append(value.data(String::UTF8));
 
       data.append(ByteVector::fromUInt(fieldData.size(), false));
       data.append(fieldData);
     }
   }
 
-  for(auto it = d->pictureList.cbegin(); it != d->pictureList.cend(); ++it) {
-    ByteVector picture = (*it)->render().toBase64();
+  for(const auto &p : std::as_const(d->pictureList)) {
+    ByteVector picture = p->render().toBase64();
     data.append(ByteVector::fromUInt(picture.size() + 23, false));
     data.append("METADATA_BLOCK_PICTURE=");
     data.append(picture);