Varstruct Overview
Varstruct creates struct-like types with runtime-computed array sizes.
Varstruct is a header-only library -- if you can't use the included Bazel-based build config, just add varstruct.h and varstruct_internal.h to your includes.
C-style struct definitions may have internal array fields; however, these field declarations must specify the size of each array at compile time so that the compiler may reserve enough space when computing the offset of each member and the size of the struct.
Unfortunately, many I/O protocols use headers with internal arrays whose size is specified or computed based on other header fields. Therefore, code that parses these headers often has to perform error-prone manual pointer manipulation.
Varstruct is a C++11 library that creates types that may contains internal arrays, and the sizes of these arrays may be passed in at runtime. Varstruct then computes offsets to each member, and can also read and modify fields when given an input pointer.
(Modification is performed via std::memcpy() to avoid memory alignment problems that would otherwise occur accessing misaligned fields -- Varstruct doesn't add any padding of its own).
You can run the tests by running the following in the repo root directory (you will need Google Bazel installed):
bazel test :varstruct_test
See the comments in varstruct.h for more information.
Author: Caleb Raitto
Disclaimer
This is not an official Google product.