added example for sorting keys

Use the allocator of the Schema for its Pointer.

CMake: remove hardcoded CMAKECONFIG_INSTALL_DIR path

Correct complexity claim

Currently this path is hardcoded to lib/cmake.
Some distributions have different library path (like lib64).
So reuse LIB_INSTALL_DIR for that to make CMAKECONFIG_INSTALL_DIR
configurable and usable in such distros.
Signed-off-by: Ruslan Bilovol <rbilovol@cisco.com>

The Pointer passed to construct the Schema can be from the stack or any
transient storage, so the copy stored in the Schema must have the same
lifetime/allocator as the Schema itself.

Add "less than" operator to Pointer.

Allow to (std::)Swap two pointers.

Speed is more important than alphabetical order (which makes few sense in
JSON in general, and with pointers especially). The use case is indexing
in std containers, i.e. O(log n) with rbtree, so the faster comparison
the better.

I must be too dumb to understand the mess MSVC (32bit only) did with the
previous loop, and to figure out how it might have make it never end.
Anyway, hopefully any compiler can grok this new loop...

Allows to sort pointers in (std-)containers and/or index by them.

Fix off by one in FileReadStream::Peek4()

Optimize FileReadStream and BasicIStreamWrapper.

GenericRegex: don't throw/abort on syntax error (unclosed parenthesis).

Until Read() reaches EOF, Peek4() must not take off by one in
bufferLast_ into account; otherwise a buffer of size exactly 4 always
returns NULL.

On (my) linux, perftest reports:
- ~40% gain for FileReadStream (Take() loop),
- ~10% gain for ReaderParse_DummyHandler_FileReadStream.

With the same logic applied to BasicIStreamWrapper, which thus can now
also be created with a user buffer, performances align with those of
FileReadStream (same buffer size).

The "unbuffered" versions (added for FileReadStream) work solely with
the internal peekBuffer (Ch[4]) and are measured in perftest.  When
performances don't matter much, they can avoid the use of large
stack/heap buffers.

Fix a memory leak for invalid std::regex in Schema.

Use passed in allocator for internal regex parser.

silence clang-7 self-assign-overloaded warning

Fix warning when NDEBUG is defined [-Wunused-variable]

Because `isPeek()` is side effect free this should not change anything.

The reason this warning is not shown in the unit tests is because the asserts
are always evaluated in the unit test:

#define RAPIDJSON_ASSERT(x) (!(x) ? throw AssertException(RAPIDJSON_STRINGIFY(x)) : (void)0u)

Co-Authored-By: yhager <yhager@users.noreply.github.com>