C++17 Extension

This extension implements a C++17 generator for Zserio.

Motivation

Zserio already provides a C++ generator which uses the C++11 standard.

The user experience with the current C++ generator has led to new ideas and enhancements that could improve the usability of the generated code. Additionally, as time flies, users have requested support for the more modern C++17 standard. However, such changes to the generated code would break backward compatibility with existing user applications, which is undesirable. Therefore, this brand new C++17 generator with an incompatible API has been developed.

Advantages

The following two main features of a C++17 generator offer significant advantages over the current C++ generator:

• Implementation of the Parameterized Types

  New C++17 generator implements Zserio Structures, Choices, and Unions using a new Data View abstraction. This new abstraction naturally solves tge implementation of Parameterized Types without the need for two-phase initialization or custom copy and move constructors.

• Implementation of the Templates

  New C++17 generator implements Zserio templates using C++ native templates. To distinguish which Zserio native type is used as a template argument (e.g. Zserio bit:5 and bit:7 types are stored in the same C++ uint8_t type), this approach also involves implementing dedicated C++ Zserio types for all Zserio built-in types within the C++ runtime library.

Supported Platforms

Zserio C++17 generator supports the following platforms:

• 64-bit Linux
• 32-bit Linux
• 64-bit Windows

Supported Compilers

Zserio C++17 generator supports the following C++ compilers:

• g++ 11.4.0
• clang 14.0.0
• clang 18.1.3
• MinGW 11.2.0
• MSVC 2022

Although newer C++ compilers are not tested, they should work as well as long as they are backward compatible.

Current State

The Design Document acts as the primary source of information about the C++17 generator design.

The Command Line Parameters section lists command line parameters related to the C++17 generator.

The generator fully supports the Zserio language and Zserio templates are generated as native C++ templates.

How to Get the latest C++17 Generator

Download the latest Zserio bundle jar (together with Zserio runtime library) from the GitHub action artifacts using the following steps:

• Go to the Actions page
• Click on the latest Linux workflow
• Scroll down to the Artifacts
• Download zserio-java8 artifact for Zserio bundle jar
• Alternatively, download zserio-runtime-cpp artifact for Zserio runtime library

How to Run the latest C++17 Generator

Run the Zserio C++17 generator using the following steps:

• Unzip zserio-java8 to get zserio.jar binary
• Run the command java -jar zserio.jar schema_name.zs -cpp17 output_directory_name

Command line parameters for the C++17 Generator

java -jar zserio.jar
    [-cpp17 <output directory>]
    [-setCppAllocator <allocator>]
    [-setTopLevelPackage <package>]
    [-src <source directory>]
    [-withSourcesAmalgamation|-withoutSourcesAmalgamation]
    [-withTypeInfoCode|-withoutTypeInfoCode]
    <input file>

-cpp17

Zserio will generate C++17 API into a given output directory.

-setCppAllocator

Sets the C++ allocator type to be used in generated code. Possible values: std (default), pmr, ppmr.

std stands for std::allocator class implemented in standard C++ library.

pmr stands for std::pmr::polymorphic_allocator class implemented in standard C++ library.

ppmr stands for zserio::pmr::PropagatingPolymorphicAllocator class implemented in Zserio C++ runtime library.

-setTopLevelPackage

Sets the top level package for generated Java sources and top level namespace for generated C++ sources.

Parameter -setTopLevelPackage appl.Zserio forces all generated Java sources to be in the package appl.Zserio and all generated C++ sources to be in the namespace appl::Zserio.

-src

Defines the root directory for the input file and all imported packages. If this option is missing, the default value is the current working directory. Currently, only one source directory can be specified. A list of directories as in the Java CLASSPATH is not supported.

If the source path is C:\zserio and the input file is com\acme\foo.zs, Zserio will try parsing C:\zserio\com\acme\foo.zs. If foo.zs contains the declaration import com.acme.bar.*, Zserio will try parsing C:\zserio\com\acme\bar.zs.

-withSourcesAmalgamation|-withoutSourcesAmalgamation

Enables/disables amalgamation of generated C++ sources. By default the code for each zserio object is placed in one header and one source file. When amalgamation is enabled, C++ sources will be automatically amalgamated to speed up C++ compilation time. C++ sources generated in different subdirectories will be amalgamated separately. Thus, if amalgamation is enabled, each generated subdirectory will contain only one C++ source module.

-withTypeInfoCode|-withoutTypeInfoCode

Enables/disables generation of type information code. By default is disabled.