f4a9c5325b
Fix "One Definition Rule" violation when using flatbuffers::Verifier with FLATBUFFERS_TRACK_VERIFIER_BUFFER_SIZE defined in some compilation units and not defined in other compilation units. The fix is to make Verifier a template class, with a boolean template parameter replacing the "#ifdef" conditionals; to rename it as VerifierTemplate; and then to use "#ifdef" only for a "using" declaration that defines the original name Verifier an an alias for the instantiated template. In this way, even if FLATBUFFERS_TRACK_VERIFIER_BUFFER_SIZE is defined in some compilation units and not in others, as long as clients only reference flatbuffers::Verifier in .cc files, not header files, there will be no ODR violation, since the only part whose definition varies is the "using" declaration, which does not have external linkage. There is still some possibility of clients creating ODR violations if the client header files (rather than .cc files) reference flatbuffers::Verifier. To avoid that, this change also deprecates FLATBUFFERS_TRACK_VERIFIER_BUFFER_SIZE, and instead introduces flatbuffers::SizeVerifier as a public name for the template instance with the boolean parameter set to true, so that clients don't need to define the macro at all.
FlatBuffers
FlatBuffers is a cross platform serialization library architected for maximum memory efficiency. It allows you to directly access serialized data without parsing/unpacking it first, while still having great forwards/backwards compatibility.
Quick Start
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Build the compiler for flatbuffers (
flatc)Use
cmaketo create the build files for your platform and then perform the compliation (Linux example).cmake -G "Unix Makefiles" make -j -
Define your flatbuffer schema (
.fbs)Write the schema to define the data you want to serialize. See monster.fbs for an example.
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Generate code for your language(s)
Use the
flatccompiler to take your schema and generate language-specific code:./flatc --cpp --rust monster.fbsWhich generates
monster_generated.handmonster_generated.rsfiles. -
Serialize data
Use the generated code, as well as the
FlatBufferBuilderto construct your serialized buffer. (C++example) -
Transmit/store/save Buffer
Use your serialized buffer however you want. Send it to someone, save it for later, etc...
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Read the data
Use the generated accessors to read the data from the serialized buffer.
It doesn't need to be the same language/schema version, FlatBuffers ensures the data is readable across languages and schema versions. See the
Rustexample reading the data written byC++.
Documentation
Go to our landing page to browse our documentation.
Supported operating systems
- Windows
- macOS
- Linux
- Android
- And any others with a recent C++ compiler (C++ 11 and newer)
Supported programming languages
Code generation and runtime libraries for many popular languages.
- C
- C++ - snapcraft.io
- C# - nuget.org
- Dart - pub.dev
- Go - go.dev
- Java - Maven
- JavaScript - NPM
- Kotlin
- Lobster
- Lua
- PHP
- Python - PyPI
- Rust - crates.io
- Swift - swiftpackageindex
- TypeScript - NPM
- Nim
Versioning
FlatBuffers does not follow traditional SemVer versioning (see rationale) but rather uses a format of the date of the release.
Contribution
- FlatBuffers Issues Tracker to submit an issue.
- stackoverflow.com with
flatbufferstag for any questions regarding FlatBuffers.
To contribute to this project, see CONTRIBUTING.
Community
Security
Please see our Security Policy for reporting vulnerabilities.
Licensing
Flatbuffers is licensed under the Apache License, Version 2.0. See LICENSE for the full license text.