Adds helper function to get empty string when String is nullptr.

This is to get over the fact that flat buffer builders will record null when data
is not present.

* Fix for #4787

- Updated the grpc generator for go to use full namespace for service
rpc method names

* Formatting Fix

- Set to Google Style Formatting

* Add --force-defaults option to flatc

To emit default values for fields which are not present or which are set
to the default value.

* flatc option --force-defaults should have a default value (false) and take action on the builder_ within the Parser constructor

* Add help text from flatc --force-defaults to Compiler.md doc

* Clarified docs for flatc --force-defaults, and imply that this behaviour is not normally needed.

* Updated docs and flatc help text for --force-defaults option

Change-Id: I64cf42aca79c32d21cd15c1415125ba97665d134

Change-Id: Ic24018a6cd604c71b4d8d3cd35dc7a583fb18394

This was fixed previously here:
https://github.com/google/flatbuffers/commit/5fd0fefab644caa2bb395cda79fbee6103035818
but somehow got undone in intermediate refactors.

Change-Id: I86e45a3f96f67a2b3d84d44081403baef6798921

Current comment is a bit ambiguous. Default values can be read either if field is not written (like in table), or if they are written explicitly by client but not serialized due to optimization. Impression from current comment is that all the default values which are coming during read are from binaries when we turn-on Force-Defaults. However, that will be a wrong interpretation.

Force_Defaults = true ensures to turn OFF later optimization. In case a field is not written, during read we will get default values but they will still not be serialized.

* CreateUnitializedVectorOfStructs and tests

* Incorporating review comments

* snake_case variable names

Will error-out after e.g. 64 levels of nested JSON tables.

Change-Id: I3ab66cdd509378bfab87b85f85c07ab42aded788
Tested: on Linux.

Change-Id: I53366bd14548aa41c3d25bcd187d7436d47e8665
Tested: on Linux.

* 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

* Enabled vector of unions for java, since it seems to work

* Added jitpack config

* Added obj to vector of unions getter

* Removed unneeded accessor

* Bumped jdk version in pom.xml

* Vector of unions support for c#

* Missing TypeScript doc processing

Dart: Generate the enum from 0 if value is null and fix inconsistent naming when generating object builder (#4782)

* Dart: Generate the enum from 0 if value is null

* Dart: Fix inconsistent naming when generating object builder

Change-Id: I45f6326f1b7da2d83eeee72fe44fd9626a288b5b

Change-Id: I8b517fb8eaf02772052d95ca55bdaa0efbffa65a

Change-Id: I27986e8aaf2f672145af9beae6ab659b272c9721

* Python: Generated enum member names are now escaped if they correspond to a Python keyword.

* Keyword list in Python generator is now a const char* instead of an std::string array.

* Moved static functions and keyword list of Python generator into the PythonGenerator class.

* Python generator escapes keyword identifiers in all definitions.

* Python: fix default bool value.

* Small style tweak.

This function cannot work with any offset types (since offsets
must always point forward) so this avoid possible mistakes.

Change-Id: I1b3dfbefc8d40da630345b9b04f9aff4a990e8e5

reason: TYPE_BOOL is a macro defined in some iOS build configurations.

Change-Id: I956b27f37b11988e67d0403a596c0569eacbfc2a

Change-Id: I79d9b2cddc61df5919bc4a93627fba2aa69e5d49
Tested: on Linux.

Fixed a typo in serialising the inventory for Orc.

* Add suppport for ES6 style exports

Adds support for ECMAScript 6 module exports during Javascript
generation. This is useful as many development projects are
switching to this new standard and away from custom module
solutions. By integrating support into flatbuffers, users
do not need to perform additional post-processing of generated
files in order to use flatbuffers output directly in their
codebases.

Reference to ECMAScript 6 modules:
https://www.ecma-international.org/ecma-262/6.0/#sec-exports

Changes:
* Added `--es6-js-export` option to cli parser tool
* Added conditional code to generate a ES6 style export
  line, replacing the normal NodeJS/RequireJS line.

* Fixed missing export statements

Added exports for definition and struct names that were not inside namespaces

* Updated Compiler.md with new generator option

Added entry to Compiler.md in docs for the `--es6-js-export` flag, including a brief description of the effects and usefulness.

This is to not need static variables, which could trip up users
with destruction order problems.

This potentially makes these operations slightly slower, but I
think they're infrequent enough that this should not be noticable.

Also there is one breaking API change, for a method that is not
used by any code in FlatBuffers and is assumed to affect very
few if any users. A namechange and comment ensures that those
affected, if any, will not run into trouble silently.

Change-Id: I16c1352d1dfc9092c816ddb7e353ed7f5f417444
Tested: on Linux.

* Add [Dart] support

* fix enum vectors

* Allow for opt out of string interning

* fix comment style, make interning opt in

* remove Offset<T>, prefer int

* avoid creating unnecessary vtable objects

* start work on tests - do not generate builder if struct has 0 fields - add int64

* support reading structs properly

* correctly handle reading vectors of structs, dartfmt

* support structs, fix unnecessary prepares

* fix bool customizations

* undo unintentional removal of file

* docs updates, complete tutorial, bug fix for codegen

* more documentation

* Update docs, add to doxygen file

* update package structure, add samples script/code

* rearrange sample

* Tests

* Add readme for pub

* cleanup package for pub

* update docs for renamed file

* remove custom matcher, use `closeTo` instead

* remove unintentional file

* remove unintended file checkin

* use auto, move method, cleanup

* refactor to ObjectBuilders, add Builders

* Update tests, examples

* Add files missing from previous commit

* documentation and example updates

* Update LICENSE, make dartanalyzer happy, fix minor bugs, get rid of duplicate files, publish script

* fix sample for slightly different schema

* Update pubspec.yaml

Fix for the issue #4744: Ambiguous side-effect execution on vector_downward::make_space() method.
C++ does not impose evaluation order on the two expressions on the right side of the assignment, so compiler can freely decide. As ensure_space() method can change the value of "cur_" variable, the result of the subtraction may be different depending on the evaluation order, which is ambiguous in C++.
In order to make this code deterministic and correct, cur_ must be evaluated after ensure_space() is called.

* Python: handle bool table fields properly.

* Small refactor.

* Use snake_case instead of camelCase. Use auto.

* 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

* Enabled vector of unions for java, since it seems to work

* Added jitpack config

* Added obj to vector of unions getter

* Removed unneeded accessor

* Bumped jdk version in pom.xml

* Vector of unions support for c#

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.