BaseImporter::SearchFileHeaderForToken() expected a pointer to a non-const token list. This was probably an oversight, as nobody would realistically expect the function to change the list. Furthermore, it prevented token lists from being compiled to read-only memory, in some cases even causing the compiler to generate thread-safe initialization.
The list is now const and all callers declare their token lists static const, thus compiling them to read-only memory.
The OpenGEX importer defined a few global std::string constants, only to convert them back to C strings on use. This commit defines them as C strings from the beginning.
strncmp() was used to compare these strings to other strings, but the length limit was set to string length, which made it equivalent to strcmp(), just slower. Fixed that as well.
The search for a matching importer had a few issues, see #3791. There were two different mechanisms to determine whether an importer accepts a specific file extension:
1. `aiImporterDesc::mFileExtensions`, which was forwarded to the UI via `BaseImporter::GetExtensionList()`.
2. `BaseImporter::CanRead()` when called with `checkSig == false`, which determines whether to actually use that importer.
Both were redundant and got out of sync repeatedly. I removed 2. completely and replaced it with 1., thereby syncing UI/import and shortening all `BaseImporter::CanRead()` implementations.
Further bugfixes:
- fixed glTF2 importer throwing exceptions when checking whether it can load a file
- removed `BaseImporter::SimpleExtensionCheck()` because it is no longer used and had a bug with case sensitivity
Since the `checkSig` parameter in `BaseImporter::CanRead()` is now useless, it can be removed completely. I’m not sure if this would break ABI compatiblity, so I’ll submit it with a later pull request.
std::string s(""); s = ""; calls the copy constructor, which in turn calls strlen(), … assigning a default-constructed string generates fewer instructions and is therefore preferred.
With C++11 uniform initialization, you’d simply write s = { } instead.