structured binding conversions

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

include/exiv2/value.hpp

@@ -1259,9 +1259,7 @@ class ValueType : public Value {
   //! Utility for toInt64, toUint32, etc.
   template <typename I>
   inline I rational_to_integer_helper(size_t n) const {
-    const auto& t = value_.at(n);
-    const auto a = t.first;
-    const auto b = t.second;
+    auto&& [a, b] = value_.at(n);
 
     // Protect against divide-by-zero.
     if (b <= 0) {

src/canonmn_int.cpp

@@ -2763,10 +2763,10 @@ std::ostream& CanonMakerNote::printSi0x0016(std::ostream& os, const Value& value
   if (value.typeId() != unsignedShort || value.count() == 0)
     return os << value;
 
-  URational ur = exposureTime(canonEv(value.toInt64()));
-  os << ur.first;
-  if (ur.second > 1) {
-    os << "/" << ur.second;
+  auto [u, r] = exposureTime(canonEv(value.toInt64()));
+  os << u;
+  if (r > 1) {
+    os << "/" << r;
   }
   os.flags(f);
   return os << " s";

src/convert.cpp

@@ -662,8 +662,8 @@ void Converter::cnvExifDate(const char* from, const char* to) {
     double dhour = pos->toFloat(0);
     double dmin = pos->toFloat(1);
     // Hack: Need Value::toDouble
-    Rational r = pos->toRational(2);
-    double dsec = static_cast<double>(r.first) / r.second;
+    auto [r, s] = pos->toRational(2);
+    double dsec = static_cast<double>(r) / s;
 
     if (!pos->value().ok()) {
 #ifndef SUPPRESS_WARNINGS
@@ -821,8 +821,7 @@ void Converter::cnvExifGPSCoord(const char* from, const char* to) {
   }
   double deg[3];
   for (int i = 0; i < 3; ++i) {
-    const int32_t z = pos->toRational(i).first;
-    const int32_t d = pos->toRational(i).second;
+    const auto [z, d] = pos->toRational(i);
     if (d == 0) {
 #ifndef SUPPRESS_WARNINGS
       EXV_WARNING << "Failed to convert " << from << " to " << to << "\n";

src/epsimage.cpp

@@ -625,13 +625,11 @@ void readWriteEpsMetadata(BasicIo& io, std::string& xmpPacket, NativePreviewList
     }
     removableEmbeddings.emplace_back(posXmpTrailer, posXmpTrailerEnd);
 #ifdef DEBUG
-    EXV_DEBUG << "readWriteEpsMetadata: Recognized unmarked trailer of removable XMP embedding at "
-                 "["
-              << removableEmbeddings.back().first << "," << removableEmbeddings.back().second
-              << ")"
-                 "\n";
+    auto [r, s] = removableEmbeddings.back();
+    EXV_DEBUG << "readWriteEpsMetadata: Recognized unmarked trailer of removable XMP embedding at [" << r << "," << s
+              << ")\n"
 #endif
-    posXmpTrailerEnd = posXmpTrailer;
+        posXmpTrailerEnd = posXmpTrailer;
   }
 
   // interpret comment "%ADO_ContainsXMP:"
@@ -707,8 +705,8 @@ void readWriteEpsMetadata(BasicIo& io, std::string& xmpPacket, NativePreviewList
       if (posOtherXmp >= posEndPageSetup)
         break;
       bool isRemovableEmbedding = false;
-      for (auto&& removableEmbedding : removableEmbeddings) {
-        if (removableEmbedding.first <= posOtherXmp && posOtherXmp < removableEmbedding.second) {
+      for (auto&& [r, s] : removableEmbeddings) {
+        if (r <= posOtherXmp && posOtherXmp < s) {
           isRemovableEmbedding = true;
           break;
         }
@@ -837,8 +835,8 @@ void readWriteEpsMetadata(BasicIo& io, std::string& xmpPacket, NativePreviewList
     if (useFlexibleEmbedding) {
       positions.push_back(xmpPos);
     }
-    for (auto&& removableEmbedding : removableEmbeddings) {
-      positions.push_back(removableEmbedding.first);
+    for (auto&& [r, s] : removableEmbeddings) {
+      positions.push_back(r);
     }
     std::sort(positions.begin(), positions.end());
 
@@ -955,9 +953,9 @@ void readWriteEpsMetadata(BasicIo& io, std::string& xmpPacket, NativePreviewList
       }
       if (!useFlexibleEmbedding) {
         // remove preceding embedding(s)
-        for (auto&& removableEmbedding : removableEmbeddings) {
-          if (pos == removableEmbedding.first) {
-            skipPos = removableEmbedding.second;
+        for (auto&& [p, s] : removableEmbeddings) {
+          if (pos == p) {
+            skipPos = s;
 #ifdef DEBUG
             EXV_DEBUG << "readWriteEpsMetadata: Skipping to " << skipPos << " at " << __FILE__ << ":" << __LINE__
                       << "\n";

src/nikonmn_int.cpp

@@ -192,13 +192,13 @@ std::ostream& Nikon1MakerNote::print0x0007(std::ostream& os, const Value& value,
 
 std::ostream& Nikon1MakerNote::print0x0085(std::ostream& os, const Value& value, const ExifData*) {
   std::ios::fmtflags f(os.flags());
-  Rational distance = value.toRational();
-  if (distance.first == 0) {
+  auto [r, s] = value.toRational();
+  if (r == 0) {
     os << _("Unknown");
-  } else if (distance.second != 0) {
+  } else if (s != 0) {
     std::ostringstream oss;
     oss.copyfmt(os);
-    os << std::fixed << std::setprecision(2) << static_cast<float>(distance.first) / distance.second << " m";
+    os << std::fixed << std::setprecision(2) << static_cast<float>(r) / s << " m";
     os.copyfmt(oss);
   } else {
     os << "(" << value << ")";
@@ -209,13 +209,13 @@ std::ostream& Nikon1MakerNote::print0x0085(std::ostream& os, const Value& value,
 
 std::ostream& Nikon1MakerNote::print0x0086(std::ostream& os, const Value& value, const ExifData*) {
   std::ios::fmtflags f(os.flags());
-  Rational zoom = value.toRational();
-  if (zoom.first == 0) {
+  auto [r, s] = value.toRational();
+  if (r == 0) {
     os << _("Not used");
-  } else if (zoom.second != 0) {
+  } else if (s != 0) {
     std::ostringstream oss;
     oss.copyfmt(os);
-    os << std::fixed << std::setprecision(1) << static_cast<float>(zoom.first) / zoom.second << "x";
+    os << std::fixed << std::setprecision(1) << static_cast<float>(r) / s << "x";
     os.copyfmt(oss);
   } else {
     os << "(" << value << ")";
@@ -342,13 +342,13 @@ const TagInfo* Nikon2MakerNote::tagList() {
 
 std::ostream& Nikon2MakerNote::print0x000a(std::ostream& os, const Value& value, const ExifData*) {
   std::ios::fmtflags f(os.flags());
-  Rational zoom = value.toRational();
-  if (zoom.first == 0) {
+  auto [r, s] = value.toRational();
+  if (r == 0) {
     os << _("Not used");
-  } else if (zoom.second != 0) {
+  } else if (s != 0) {
     std::ostringstream oss;
     oss.copyfmt(os);
-    os << std::fixed << std::setprecision(1) << static_cast<float>(zoom.first) / zoom.second << "x";
+    os << std::fixed << std::setprecision(1) << static_cast<float>(r) / s << "x";
     os.copyfmt(oss);
   } else {
     os << "(" << value << ")";
@@ -1355,18 +1355,18 @@ std::ostream& Nikon3MakerNote::print0x0084(std::ostream& os, const Value& value,
   const int64_t len1 = value.toInt64(0);
   const int64_t len2 = value.toInt64(1);
 
-  Rational fno1 = value.toRational(2);
-  Rational fno2 = value.toRational(3);
+  auto [r1, s1] = value.toRational(2);
+  auto [r2, s2] = value.toRational(3);
   os << len1;
   if (len2 != len1) {
     os << "-" << len2;
   }
   os << "mm ";
   std::ostringstream oss;
   oss.copyfmt(os);
-  os << "F" << std::setprecision(2) << static_cast<float>(fno1.first) / fno1.second;
-  if (fno2 != fno1) {
-    os << "-" << std::setprecision(2) << static_cast<float>(fno2.first) / fno2.second;
+  os << "F" << std::setprecision(2) << static_cast<float>(r1) / s1;
+  if (r2 != r1) {
+    os << "-" << std::setprecision(2) << static_cast<float>(r2) / s2;
   }
   os.copyfmt(oss);
   os.flags(f);
@@ -1375,13 +1375,13 @@ std::ostream& Nikon3MakerNote::print0x0084(std::ostream& os, const Value& value,
 
 std::ostream& Nikon3MakerNote::print0x0085(std::ostream& os, const Value& value, const ExifData*) {
   std::ios::fmtflags f(os.flags());
-  Rational distance = value.toRational();
-  if (distance.first == 0) {
+  auto [r, s] = value.toRational();
+  if (r == 0) {
     os << _("Unknown");
-  } else if (distance.second != 0) {
+  } else if (s != 0) {
     std::ostringstream oss;
     oss.copyfmt(os);
-    os << std::fixed << std::setprecision(2) << static_cast<float>(distance.first) / distance.second << " m";
+    os << std::fixed << std::setprecision(2) << static_cast<float>(r) / s << " m";
     os.copyfmt(oss);
   } else {
     os << "(" << value << ")";
@@ -1392,13 +1392,13 @@ std::ostream& Nikon3MakerNote::print0x0085(std::ostream& os, const Value& value,
 
 std::ostream& Nikon3MakerNote::print0x0086(std::ostream& os, const Value& value, const ExifData*) {
   std::ios::fmtflags f(os.flags());
-  Rational zoom = value.toRational();
-  if (zoom.first == 0) {
+  auto [r, s] = value.toRational();
+  if (r == 0) {
     os << _("Not used");
-  } else if (zoom.second != 0) {
+  } else if (s != 0) {
     std::ostringstream oss;
     oss.copyfmt(os);
-    os << std::fixed << std::setprecision(1) << static_cast<float>(zoom.first) / zoom.second << "x";
+    os << std::fixed << std::setprecision(1) << static_cast<float>(r) / s << "x";
     os.copyfmt(oss);
   } else {
     os << "(" << value << ")";

src/olympusmn_int.cpp

@@ -1483,14 +1483,14 @@ std::ostream& OlympusMakerNote::print0x0305(std::ostream& os, const Value& value
     return os << value;
   }
 
-  Rational distance = value.toRational();
-  if (static_cast<uint32_t>(distance.first) == 0xffffffff) {
+  auto [r, s] = value.toRational();
+  if (static_cast<uint32_t>(r) == 0xffffffff) {
     os << _("Infinity");
   } else {
     std::ostringstream oss;
     oss.copyfmt(os);
     os << std::fixed << std::setprecision(2);
-    os << static_cast<float>(distance.first) / 1000 << " m";
+    os << static_cast<float>(r) / 1000 << " m";
     os.copyfmt(oss);
   }
   os.flags(f);

src/tiffcomposite_int.cpp

@@ -1282,10 +1282,10 @@ uint32_t TiffImageEntry::doWriteImage(IoWrapper& ioWrapper, ByteOrder /*byteOrde
               << std::hex << tag() << std::dec << ": Writing " << strips_.size() << " strips";
 #endif
     len = 0;
-    for (auto&& strip : strips_) {
-      ioWrapper.write(strip.first, strip.second);
-      len += strip.second;
-      uint32_t align = strip.second & 1;  // Align strip data to word boundary
+    for (auto&& [f, s] : strips_) {
+      ioWrapper.write(f, s);
+      len += s;
+      uint32_t align = s & 1;  // Align strip data to word boundary
       if (align)
         ioWrapper.putb(0x0);
       len += align;

src/types.cpp

@@ -561,13 +561,13 @@ int64_t parseInt64(const std::string& s, bool& ok) {
   if (ok)
     return static_cast<int64_t>(f);
 
-  auto r = stringTo<Rational>(s, ok);
+  auto [r, st] = stringTo<Rational>(s, ok);
   if (ok) {
-    if (r.second <= 0) {
+    if (st <= 0) {
       ok = false;
       return 0;
     }
-    return static_cast<int64_t>(static_cast<float>(r.first) / r.second);
+    return static_cast<int64_t>(static_cast<float>(r) / st);
   }
 
   bool b = stringTo<bool>(s, ok);
@@ -591,13 +591,13 @@ float parseFloat(const std::string& s, bool& ok) {
   if (ok)
     return ret;
 
-  auto r = stringTo<Rational>(s, ok);
+  auto [r, st] = stringTo<Rational>(s, ok);
   if (ok) {
-    if (r.second == 0) {
+    if (st == 0) {
       ok = false;
       return 0.0;
     }
-    return static_cast<float>(r.first) / r.second;
+    return static_cast<float>(r) / st;
   }
 
   bool b = stringTo<bool>(s, ok);

src/value.cpp

@@ -733,11 +733,11 @@ std::ostream& LangAltValue::write(std::ostream& os) const {
   }
 
   // Write the others
-  for (auto&& v : value_) {
-    if (v.first != x_default) {
+  for (auto&& [lang, s] : value_) {
+    if (lang != x_default) {
       if (!first)
         os << ", ";
-      os << "lang=\"" << v.first << "\" " << v.second;
+      os << "lang=\"" << lang << "\" " << s;
       first = false;
     }
   }

src/version.cpp

@@ -503,9 +503,7 @@ void Exiv2::dumpLibraryInfo(std::ostream& os, const std::vector<std::regex>& key
 
   Exiv2::Dictionary ns;
   Exiv2::XmpProperties::registeredNamespaces(ns);
-  for (auto&& n : ns) {
-    std::string xmlns = n.first;
-    std::string uri = n.second;
+  for (auto&& [xmlns, uri] : ns) {
     output(os, keys, name, xmlns + ":" + uri);
   }
 #endif

src/xmp.cpp

@@ -822,11 +822,11 @@ int XmpParser::encode(std::string& xmpPacket, const XmpData& xmpData, uint16_t f
       return 2;
     }
     // Register custom namespaces with XMP-SDK
-    for (auto&& i : XmpProperties::nsRegistry_) {
+    for (auto&& [xmp, uri] : XmpProperties::nsRegistry_) {
 #ifdef EXIV2_DEBUG_MESSAGES
-      std::cerr << "Registering " << i.second.prefix_ << " : " << i.first << "\n";
+      std::cerr << "Registering " << uri.prefix_ << " : " << xmp << "\n";
 #endif
-      registerNs(i.first, i.second.prefix_);
+      registerNs(xmp, uri.prefix_);
     }
     SXMPMeta meta;
     for (auto&& i : xmpData) {
@@ -840,12 +840,12 @@ int XmpParser::encode(std::string& xmpPacket, const XmpData& xmpData, uint16_t f
           throw Error(ErrorCode::kerEncodeLangAltPropertyFailed, i.key());
 
         int idx = 1;
-        for (auto&& k : la->value_) {
-          if (!k.second.empty()) {  // remove lang specs with no value
-            printNode(ns, i.tagName(), k.second, 0);
-            meta.AppendArrayItem(ns.c_str(), i.tagName().c_str(), kXMP_PropArrayIsAlternate, k.second.c_str());
+        for (auto&& [lang, specs] : la->value_) {
+          if (!specs.empty()) {  // remove lang specs with no value
+            printNode(ns, i.tagName(), specs, 0);
+            meta.AppendArrayItem(ns.c_str(), i.tagName().c_str(), kXMP_PropArrayIsAlternate, specs.c_str());
             const std::string item = i.tagName() + "[" + toString(idx++) + "]";
-            meta.SetQualifier(ns.c_str(), item.c_str(), kXMP_NS_XML, "lang", k.first.c_str());
+            meta.SetQualifier(ns.c_str(), item.c_str(), kXMP_NS_XML, "lang", lang.c_str());
           }
         }
         continue;

src/xmpsidecar.cpp

@@ -114,11 +114,9 @@ void XmpSidecar::writeMetadata() {
     copyIptcToXmp(iptcData_, xmpData_);
 
     // #1112 - restore dates if they lost their TZ info
-    for (auto&& date : dates_) {
-      std::string sKey = date.first;
+    for (auto&& [sKey, value_orig] : dates_) {
       Exiv2::XmpKey key(sKey);
       if (xmpData_.findKey(key) != xmpData_.end()) {
-        std::string value_orig(date.second);
         std::string value_now(xmpData_[sKey].value().toString());
         // std::cout << key << " -> " << value_now << " => " << value_orig << std::endl;
         if (value_orig.find(value_now.substr(0, 10)) != std::string::npos) {