A from-scratch C++17 implementation of FlatCityBuf: a reader and a writer, parsing and producing .fcb bytes directly. It replaces the previous CXX-bridge bindings over the Rust core — there is no Rust toolchain, no generated bridge source to compile, and no TLS dependency. All IO goes through one synchronous fcb::RangeReader, so local files, HTTP range requests and your own transport share a single traversal path.

Quick start

cd src/cpp
cmake -B build -S .
cmake --build build
./build/fcb_read_local ../../examples/data/delft.fcb > delft.jsonl

That reads a .fcb out as CityJSONSeq. Writing goes the other way, through fcb::FcbWriter — ./build/fcb_write_cityjson <input.jsonl> <output.fcb>, from examples/write_cityjson.cpp.

The library API (open, select_bbox / select_attr, CityJSON conversion) is shown in docs/cpp.md and INSTALL.md.

Layout

Path	Contents
`include/fcb/`	public headers (`writer/` for the writer API)
`include/fcb/generated/`	committed flatc output (consumers never need flatc)
`src/`	implementation; `src/detail/` is internal
`tests/`	doctest suite and the range-capable HTTP test server
`examples/`	one runnable program per capability — see examples/README.md

Documentation

docs/cpp.md — the C++ guide: status, build options, reading and writing, testing, and where this implementation deliberately differs from the Rust reference
INSTALL.md — dependencies, install, CMake integration, HTTP, custom transports, writing a file
examples/README.md — every example program, with its real output
../../docs/specification.md — the format itself