convert const TagInfo returns to constexpr

Signed-off-by: Rosen Penev <[email protected]>

Author: neheb

src/tags.cpp

@@ -74,18 +74,16 @@ bool GroupInfo::operator==(const GroupName& groupName) const {
 }
 
 const char* ExifTags::sectionName(const ExifKey& key) {
-  const TagInfo* ti = tagInfo(key.tag(), key.ifdId());
-  if (!ti)
-    return sectionInfo[static_cast<int>(unknownTag.sectionId_)].name_;
-  return sectionInfo[static_cast<int>(ti->sectionId_)].name_;
+  if (auto ti = tagInfo(key.tag(), key.ifdId()))
+    return sectionInfo[static_cast<int>(ti->sectionId_)].name_;
+  return sectionInfo[static_cast<int>(unknownTag.sectionId_)].name_;
 }
 
 /// \todo not used internally. At least we should test it
 uint16_t ExifTags::defaultCount(const ExifKey& key) {
-  const TagInfo* ti = tagInfo(key.tag(), key.ifdId());
-  if (!ti)
-    return unknownTag.count_;
-  return ti->count_;
+  if (auto ti = tagInfo(key.tag(), key.ifdId()))
+    return ti->count_;
+  return unknownTag.count_;
 }
 
 const char* ExifTags::ifdName(const std::string& groupName) {
@@ -236,12 +234,11 @@ ExifKey::ExifKey(uint16_t tag, const std::string& groupName) : p_(std::make_uniq
   if (!Internal::isExifIfd(ifdId) && !Internal::isMakerIfd(ifdId)) {
     throw Error(ErrorCode::kerInvalidIfdId, ifdId);
   }
-  const TagInfo* ti = tagInfo(tag, ifdId);
-  if (!ti) {
-    throw Error(ErrorCode::kerInvalidIfdId, ifdId);
+  if (auto ti = tagInfo(tag, ifdId)) {
+    p_->groupName_ = groupName;
+    p_->makeKey(tag, ifdId, ti);
   }
-  p_->groupName_ = groupName;
-  p_->makeKey(tag, ifdId, ti);
+  throw Error(ErrorCode::kerInvalidIfdId, ifdId);
 }
 
 ExifKey::ExifKey(const TagInfo& ti) : p_(std::make_unique<Impl>()) {

src/tags_int.cpp

@@ -2621,7 +2621,7 @@ URational exposureTime(float shutterSpeedValue) {
 }
 
 uint16_t tagNumber(const std::string& tagName, IfdId ifdId) {
-  const TagInfo* ti = tagInfo(tagName, ifdId);
+  auto ti = tagInfo(tagName, ifdId);
   if (ti && ti->tag_ != 0xffff)
     return ti->tag_;
   if (!isHex(tagName, 4, "0x"))

src/tiffcomposite_int.cpp

@@ -1438,14 +1438,10 @@ static const TagInfo* findTagInfo(uint16_t tag, IfdId group) {
       return Internal::gpsTagList();
     return group == IfdId::exifId ? Internal::exifTagList() : nullptr;
   }();
-  if (!tags)
-    return nullptr;
-
-  for (size_t idx = 0; tags[idx].tag_ != 0xffff; ++idx) {
-    if (tags[idx].tag_ == tag) {
-      return tags + idx;
-    }
-  }
+  if (tags)
+    for (size_t idx = 0; tags[idx].tag_ != 0xffff; ++idx)
+      if (tags[idx].tag_ == tag)
+        return tags + idx;
   return nullptr;
 }
 

src/tiffvisitor_int.cpp

@@ -393,7 +393,7 @@ void TiffDecoder::decodeCanonAFInfo(const TiffEntryBase* object) {
   }
 
   for (const auto& [tag, size, bSigned] : records) {
-    const TagInfo* pTags = ExifTags::tagList("Canon");
+    auto pTags = ExifTags::tagList("Canon");
     if (auto pTag = findTag(pTags, tag)) {
       auto v = Exiv2::Value::create(bSigned ? Exiv2::signedShort : Exiv2::unsignedShort);
       std::string s;