Add define/ifdef blocks, alternate sprintf implementation via FLATBUFFERS_PREFER_PRINTF [C++] (#4700)

* Add define/ifdef blocks for FLATBUFFERS_PREFER_PRINTF to avoid using std::*streams for idl_parser

* Use string::size() as limit in snprintf

* Refactored FLATBUFFERS_PREFER_PRINTF guarded feature into NumToStringImplWrapper around sprintf

* Remove '.0' where not needed from IntToDigitCount

* Remove leading dot from name in GetFullyQualifiedName when FLATBUFFERS_PREFER_PRINTF is enabled

* Return string directly from conversion functions where possible when FLATBUFFERS_PREFER_PRINTF is enabled

* Use string instead of stringstream for GetFullyQualifiedName

* Revert removing leading dot from GetFullyQualifiedName, it does need to be there for parity with the stringstream implementation

* Dot is single char in Namespace::GetFullyQualifiedName

* Remove trailing (duplicate) null-byte from NumToStringImplWrapper when using FLATBUFFERS_PREFER_PRINTF.

* Update preprocessor indenting (and use clang-format off/on) for FLATBUFFERS_PREFER_PRINTF

* Reduce whitespace, unneeded braces in FLATBUFFERS_PREFER_PRINTF string width functions

* Remove unneeded use of iostream from idl_parser.cpp, std::string is used instead

* Tell snprintf to use the trailing null byte expected at the end of std::string buffer

* Add view() method on flatbuffers::String, to return a string_view type
if support for std::string_view (or alternately
std::experimental::string_view) is found

* Move detection/definition of FLATBUFFERS_STRING_VIEW to base.h, use the
macro (if it is defined) as the argument type for an overload of CreateString

* Rename String::view() to String::string_view() and use the existing c_str() method for the data pointer

* Add and explain minimum C++ standard version checks for FLATBUFFERS_STRING_VIEW implementations

* Updated preprocessor indenting for FLATBUFFERS_STRING_VIEW

* Convert FLATBUFFERS_STRING_VIEW macro to typedef in flatbuffers:: namespace, and boolean feature toggle macro FLATBUFFERS_HAS_STRING_VIEW

* Prepend flatbuffers:: namespace to disambiguate flatbuffers::string_view typedef from String::string_view()

* clang-format as-she-is-spoke for FLATBUFFERS_HAS_STRING_VIEW

[BREAKING CHANGE] Python: return None for missing strings.

@Nullable is only a compiler informational attribute.
Removing for required fields improves compiler warnings
but doesn't impact any running code.

* Add --root-type option to flatc

To select or override a root_type

* Add help text from flatc --root-type to Compiler.md doc

Change-Id: I7c9bb5406ae8df951afe12a008f0d071e0195bfa

* Added support for the non-escaped print of utf-8 string.

* EscapeString: the first invalid symbol resets print_natural_utf8 flag to false.

* Move the test to ParseAndGenerateTextTest. Fixes.

* Removed dependence between `natural_utf8` and `allow_non_utf8` flags.

* Fix union escaping order.

Fixes #4712

* style

* Addition of Go FinishWithFileIdentifier, allows for Go flatbuffer data to contain a file identifier

* adding panic as per review if fileIdentifier does not match length, letting prep pad the file identifier

* updated error message to not use fmt.Sprintf

* using minalign for alignment for file identifier

* include service in reflection data (fixes #4639)

* changes from review

* regenerated test data

* Adding JS  function to get the File Identifier

* Update flatbuffers.js

* The asserts replaced by FLATBUFFERS_ASSERT. Several asserts have converted to static_asserts.

* Regenerate header monster generate_code.sh

In file included from include/flatbuffers/flexbuffers.h:24,
                 from src/idl_gen_text.cpp:20:
include/flatbuffers/util.h: In function 'int flatbuffers::FromUTF8(const char**)':
include/flatbuffers/util.h:324:45: error: type qualifiers ignored on cast result type [-Werror=ignored-qualifiers]
   if ((static_cast<const unsigned char>(**in) << len) & 0x80) return -1;  // Bit after leading 1's must be 0.
                                             ^
cc1plus: all warnings being treated as errors
make[2]: *** [CMakeFiles/flatbuffers_shared.dir/build.make:92: CMakeFiles/flatbuffers_shared.dir/src/idl_gen_text.cpp.o] Error 1

* User-declared attribute should be either identifier or string with the identifier.

* Attribute can be identifier or string in metadata.

Rename MANUALLY_ALIGNED_STRUCT to add FLATBUFFERS_ prefix in generated code within tests/. Via running `cd tests && sh generate_code.sh` (#4696)

* Rename STRUCT_END to add FLATBUFFERS_ prefix, now FLATBUFFERS_STRUCT_END. Via running `ag -l STRUCT_END | xargs rpl STRUCT_END FLATBUFFERS_STRUCT_END`

* Rename MANUALLY_ALIGNED_STRUCT to add FLATBUFFERS_ prefix, now FLATBUFFERS_MANUALLY_ALIGNED_STRUCT. Via running `ag -l MANUALLY_ALIGNED_STRUCT | xargs rpl MANUALLY_ALIGNED_STRUCT FLATBUFFERS_MANUALLY_ALIGNED_STRUCT && cd tests && sh generate_code.sh`

* Rename DEFINE_BITMASK_OPERATORS to add FLATBUFFERS_ prefix, now FLATBUFFERS_DEFINE_BITMASK_OPERATORS. Via running `ag -l DEFINE_BITMASK_OPERATORS | xargs rpl DEFINE_BITMASK_OPERATORS FLATBUFFERS_DEFINE_BITMASK_OPERATORS`

Change-Id: I0b0ed43129c4d8fc88a177792df50adfeb52a1e3

Change-Id: I59af6ca1825870461c0badc7e7a045b97befdc1a

* Eclipse ignore

* TypeScript support

* Prefixing enums

* Test results

* Merged JS and TS generators

* Fixed AppVeyor build problems

* Fixed more AppVeyor build problems

* Fixed more AppVeyor build problems

* Changed TS flag to options struct

* Storing options by value

* Removed unneeded const

* Re-export support for unions

* Uint support

* Casting bools to numbers for mutation

* TS shell tests

* Reverted generates js test file to original version

* Backing up js tests and properly generating test data

* Not importing flatbuffers for TS test generation

* Not overwriting generated js for tests

* AppVeyor test fixes

* Generating the most strict TS code possible

* Not returning null when creating vectors

* Not returning null from struct contructors

* Vector of unions for ts/js

* Sanity check for languages

* Indentation fix + output test files

* Vectors of unions for php

* Fixes to union vector handling + tests

* Fix for strictPropertyInitialization

* Fix for new aligned operator new for gcc >= 7.1

* Not generating imports/ns prefixes with --gen-all

* TypeScript docs

* Missing imports of enums

* Missing TS links

Fix #4650

CreateMonster and MonsterBuilder examples fixed for C++

* Eclipse ignore

* TypeScript support

* Prefixing enums

* Test results

* Merged JS and TS generators

* Fixed AppVeyor build problems

* Fixed more AppVeyor build problems

* Fixed more AppVeyor build problems

* Changed TS flag to options struct

* Storing options by value

* Removed unneeded const

* Re-export support for unions

* Uint support

* Casting bools to numbers for mutation

* TS shell tests

* Reverted generates js test file to original version

* Backing up js tests and properly generating test data

* Not importing flatbuffers for TS test generation

* Not overwriting generated js for tests

* AppVeyor test fixes

* Generating the most strict TS code possible

* Not returning null when creating vectors

* Not returning null from struct contructors

* Vector of unions for ts/js

* Sanity check for languages

* Indentation fix + output test files

* Vectors of unions for php

* Fixes to union vector handling + tests

* Fix for strictPropertyInitialization

* Fix for new aligned operator new for gcc >= 7.1

* Not generating imports/ns prefixes with --gen-all

* TypeScript docs

* Missing imports of enums

* Eclipse ignore

* TypeScript support

* Prefixing enums

* Test results

* Merged JS and TS generators

* Fixed AppVeyor build problems

* Fixed more AppVeyor build problems

* Fixed more AppVeyor build problems

* Changed TS flag to options struct

* Storing options by value

* Removed unneeded const

* Re-export support for unions

* Uint support

* Casting bools to numbers for mutation

* TS shell tests

* Reverted generates js test file to original version

* Backing up js tests and properly generating test data

* Not importing flatbuffers for TS test generation

* Not overwriting generated js for tests

* AppVeyor test fixes

* Generating the most strict TS code possible

* Not returning null when creating vectors

* Not returning null from struct contructors

* Vector of unions for ts/js

* Sanity check for languages

* Indentation fix + output test files

* Vectors of unions for php

* Fixes to union vector handling + tests

* Fix for strictPropertyInitialization

* Fix for new aligned operator new for gcc >= 7.1

* Not generating imports/ns prefixes with --gen-all

* TypeScript docs

Const correctness in generated code and in code generators. Added missing \reflection\generate_code.bat file. (#4679)

* Add Bazel support for Go library

* Make flatc compile again.

Was missing java_generator, which is now referenced from source.

* initial changes to support size prefixed buffers in Java

* add slice equivalent to CSharp ByteBuffer

* resolve TODO for slicing in CSharp code generation

* add newly generated Java and CSharp test sources

* fix typo in comment

* add FinishSizePrefixed methods to CSharp FlatBufferBuilder as well

* add option to allow writing the prefix as well

* generate size-prefixed monster binary as well

* extend JavaTest to test the size prefixed binary as well

* use constants for size prefix length

* fuse common code for getRootAs and getSizePrefixedRootAs

* pulled file identifier out of if

* add FinishSizePrefixed, GetSizePrefixedRootAs support for Python

* Revert "extend JavaTest to test the size prefixed binary as well"

This reverts commit 68be4420dda47e8d0600bb19691f03be71503a68.

* Revert "generate size-prefixed monster binary as well"

This reverts commit 2939516fdf78df4f061c627221e232b312301417.

* fix ByteBuffer.cs Slice() method; add proper CSharp and Java tests

* fix unused parameter

* increment version number

* pulled out generated methods into separate utility class

* pulled out generated methods into separate utility class for Python

* fix indentation

* remove unnecessary comment

* fix newline and copyright

* add ByteBufferUtil to csproj compilation

* hide ByteBuffer's internal data; track offset into parent's array

* test unsafe versions as well; compile and run in debug mode

* clarify help text for size prefix

* move ByteBuffer slicing behavior to subclass

* fix protection levels

* add size prefix support for text generation

* add ByteBufferSlice to csproj compilation

* revert size prefix handling for nested buffers

* use duplicate instead of slice for removing size prefix

* remove slice subclass and use duplicate for removing size prefix

* remove slice specific tests

* remove superfluous command line option

Const does not make sense here, and compiler actually throws warning
(error with -Werror) when you would try to compile it.

    In file included from include/flatbuffers/flexbuffers.h:24,
                     from include/flatbuffers/idl.h:26,
                     from include/flatbuffers/code_generators.h:22,
                     from src/code_generators.cpp:17:
    include/flatbuffers/util.h: In function ‘int flatbuffers::FromUTF8(const char**)’:
    include/flatbuffers/util.h:325:44: error: type qualifiers ignored on cast result type [-Werror=ignored-qualifiers]
       if ((static_cast<const unsigned char>(tmp) << len) & 0x80) return -1;  // Bit after leading 1's must be 0.
                                            ^
    cc1plus: all warnings being treated as errors

This warning caught by gcc8:

    $ g++ --version
    g++ (GCC) 8.0.1 20180222 (Red Hat 8.0.1-0.16)

* Convert to unsigned char before applying bit shift operator

* convert to const unsigned char inline

* convert to unsigned char inline

to be able to convert to json size prefixed buffers.

An assert in flexbuffers was bit-shifting a 64-bit number by
64 bits, which throws up warnings in some automated tools.

The same assert also checks to see if the number of bytes
being shifted is 8.  Swapped the order, so that the bitshift
only occurs if the number of bits being shifted is not 64.

Should be the same behavior, but plays nicer with diagnostic
tools.

Change-Id: Ie1cab284cb6e0fe5bd2b2c293c3136c148927ac3

* Added '--oneof-union' option.

Used with the .proto -> .fbs converter, will translate protobuff oneofs to flatbuffer unions.
Updated proto test to check both methods of converting oneofs.

* Added '--oneof-union' option.

Used with the .proto -> .fbs converter, will translate protobuff oneofs to flatbuffer unions.
Updated proto test to check both methods of converting oneofs.

* FlatBuffers: Moved MakeCamel() into idl_parser.cpp

Removes library dependency on Java/C# generator code.

Lookup type of nested flatbuffer field with either raw name or fully qualified name as already done in the parser.
LookupCreateStruct tries both the raw name and the fully qualified one.
Without this, we cannot reference types outside of the current namespace, e.g. in a different module.

* added intended use-cases to monster_test.fbs

* added check for `cpp_ptr_type` on hashed fields
added default value 'naked' to `cpp_ptr_type` on hashed fields

* added C++ generation of cpp_type vectors
removed ctor call for vector fields
added condition !vector for cpp_type check
added Pack() and UnPack() code generation for vector of hashes
added generation of correct resolve/rehash for cpp_type elements

* added attribute 'cpp_ptr_type_get' to hold accessor for pointer types possible where '.get()' does not work
use case: cpp_ptr_type:"std::weak_ptr", cpp_ptr_type_get:".lock().get()"

* run flatc to re-generate headers

* added bool param is_ctor to GetDefaultScalarValue() to differentiate between usage places

* modified monster_test.fbs to remove usage of shared_ptr/weak_ptr
reason: STLport does not support std::shared_ptr and std::weak_ptr

* run flatc again to re-generate headers

* fixed symbol unique_ptr not in namespace std when building with STLport

* Java + C#, reuse object in lookup_by_key

* Java + C#, reuse object in lookup_by_key

* added FLATBUFFERS_CONSTEXPR_CPP14 define for C++14 and above constexpr

* made HashFnv functions constexpr (depending on FLATBUFFERS_CONSTEXPR)