jmp test...

#include "ofApp.h"
#include <csetjmp>

class Continuation{
public:
	Continuation() : done(false), jumped(false){}
	
	
	bool work(){
		if( done ) return true;
		
		// remember this place, we will jump back here!
		int val=setjmp(of_env);
		if( val == 0 ){
			// we got here through the call from ofApp#update
			if( jumped ){
			  // todo: restore 2 stack levels somehow??
				longjmp(work_env, 1);
			}
			else{
				run();
				// eventually, at one point, we'll end up here.
				done = true;
				return true;
			}
		}
		else if( val == 1 ){
			// we got here because continueLater() was called from work
			return false;
		}
		else if( val == 2 ){
			// we got here because work is done. hurray!
			done = true;
			return true;
		}
	}
	
protected:
	// override this.
	// call continueLater() to pause execution
	virtual void run() = 0;
	
	void continueLater(){
		// remember this point for later ...
		jumped = true;
		int val = setjmp(work_env);
		if( val == 0 ){
			// we got here because of a call from run()
			// todo: save 2 stack levels, somehow??
			
			// jump back to openframeworks method
			longjmp(of_env, 1); // pass 1, means we got work to do
		}
		else if( val == 1 ){
			// we got here because of a call from work()
			// weirdly this also means that run() is below us in the stack.
			// so we can just return, and continue were we left off.
		}
	}
private:
	jmp_buf work_env;
	jmp_buf of_env;
	bool done;
	bool jumped;
};


class ContinuationTest : public Continuation{
	
	void run(){
		int x = 3;
		cout << "x = " << 3 << endl;
		
		// back to OF for a little while...
		continueLater();
		
		int y = 2;
		cout << "x = " << x << ", y = " << y << endl;
		
		// back to OF for a little while...
		continueLater();
		
		int z = 7;
		cout << "x = " << x << ", y = " << y << ", z = " << z << endl;
	}
};

ContinuationTest test;


//--------------------------------------------------------------
void ofApp::setup(){

}

//--------------------------------------------------------------
void ofApp::update(){
	test.work(); 
}

//--------------------------------------------------------------
void ofApp::draw(){

}

//--------------------------------------------------------------
void ofApp::keyPressed(int key){

}

//--------------------------------------------------------------
void ofApp::keyReleased(int key){

}

//--------------------------------------------------------------
void ofApp::mouseMoved(int x, int y){

}

//--------------------------------------------------------------
void ofApp::mouseDragged(int x, int y, int button){

}

//--------------------------------------------------------------
void ofApp::mousePressed(int x, int y, int button){

}

//--------------------------------------------------------------
void ofApp::mouseReleased(int x, int y, int button){

}

//--------------------------------------------------------------
void ofApp::windowResized(int w, int h){

}

//--------------------------------------------------------------
void ofApp::gotMessage(ofMessage msg){

}

//--------------------------------------------------------------
void ofApp::dragEvent(ofDragInfo dragInfo){ 

}

void ofApp::doWork(){
	while( true ){
		
	}
}