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USCXML C-Style Wrapper (for C++ Builder, Delphi, Qt)

State Machines in C++ Builder, Delphi

The main objective of the project is to execute dynamic SCXML state charts in C++ Builder by using such a great library as USCXML. But the problem is that USCXML source code can not be compiled by Borland C++ Compiler (not full C11 support, compiler bugs etc). We have an option to use uscxml-transformer application for transpiling SCXML source code to ANSI-C. But in this case you have to compile application every time once you've made corrections to state chart. The solution seems to have a common library wrapper with only C-functions, which could be executed on all versions of C++ Builder.

UscxmlCLib consists of only 1 lib and 1 header which should be added to C++ Builder to start executing state charts.

However it is possible and easy to use UscxmlCLib in other systems such as Qt.

Supported Operating System

Windows 7, Windows 8, Windows 10

Supported Compilers for building UscxmlCLib from source code

MSVC 2015 SP3

Supported Compilers for using UscxmlCLib.dll

UscxmlCLib\Lib\UscxmlCLib_borland.lib - for Borland C++ Compiler (tests were performed on C++ Builder 2010, C++ Builder XE7)

UscxmlCLib\Lib\UscxmlCLib.lib - for MSVC 2015 SP3

Installation

1. Install Visual C++ Redistributable for Visual Studio 2015 SP3

2. Put UscxmlCLib\Bin binaries to Windows search path or add dir with binaries to PATH environment settings

Build from source code

There will be special article

Getting Started

Let's start 'Hello, world' example in C++ Builder

1. Add library to project

#include "UscxmlCLib.h"

#pragma comment(lib,"UscxmlCLib_borland.lib")

2. Set callbacks from interpreter and notifiers for main thread

class TLogNotify : public TIdNotify {
	const UnicodeString FMessage;

protected:
	virtual void __fastcall DoNotify(void) {
		FormHelloWorld->Memo1->Lines->Add(FMessage);
	}

public:
	__fastcall TLogNotify(const UnicodeString &sMsg) : FMessage(sMsg) {
	}
};

void __stdcall OnInterpreterLogCallback(const UsclibInterpreter *AInterpreter, const int nSeverity, const char *chMessage, void *AUser) {
	(new TLogNotify(chMessage))->Notify();
}

3. Work with interprter

if (USCLIB_SUCCESS != usclib_OpenInterpreter(&g_Interpreter, 0, 0, 0))
	throw Exception(usclib_GetLastError());

usclib_RegisterLogCallback(g_Interpreter, OnInterpreterLogCallback, NULL);

if (USCLIB_SUCCESS != usclib_StartInterpreter(g_Interpreter, g_chScxml, USCLIB_SCXML_AS_TEXT))
	throw Exception(usclib_GetLastError());

if (USCLIB_SUCCESS != usclib_CloseInterpreter(g_Interpreter))
	throw Exception(usclib_GetLastError());

Output

Library Usage Chart

Licensing

UscxmlCLib itself is distributed under under the terms of the BSD 3-Clause License but it include external components with their own licensies

Project	License	Comment
uSCXML	Simplified BSD license	This wrapper mostly based on uSCXML original SDK
libcurl	MIT/X derivate	Used in uSCXML to fetch remote content
Xerces-C++	Apache v2	XML parser and DOM implementation
libevent	3-clause BSD	Delayed event queues
uriparser	New BSD	Referring and resolving URIs
Lua	Under the terms of the MIT license	Lua Data Model
JavaScriptCore	Under the LGPL and BSD licenses	EcmaScript Data Model

SCXML Standard Compliance

Almost the same as uSCXML original with some restrictions. Run W3C testing application to get more info

DataModels supported

1. NULL
2. Lua
3. Luavia (Lua datamodel with some non-standard extensions to increase state chart performance)
4. EcmaScript Based on JavaScriptCore binaries

Examples

After installation you are able to start ready-to-use examples.

C++ Builder Examples

• Hello World
• Traffic Light
• Calculator
• Multiple Interpreters
• KT76C Transponder Simulator
• Salus RT500 (Digital Room Thermostat) Simulator
• W3C SCXML Testing Application
• UscxmlCLib Testing Application

Qt Examples

• KT76C Transponder Simulator
• W3C SCXML Testing Application

Take special look at KT76C Transponder Example!

It has ZERO lines of device logic in C++! Just connected GUI controls!

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