//
// Cforall Version 1.0.0 Copyright (C) 2017 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// cntparens.cfa -- match left/right parenthesis
//
// Author           : Peter A. Buhr
// Created On       : Sat Apr 20 11:04:45 2019
// Last Modified By : Peter A. Buhr
// Last Modified On : Sat Apr 20 11:06:21 2019
// Update Count     : 1
//

#include <fstream.hfa>
#include <coroutine.hfa>

enum Status { Cont, Match, Error };
coroutine CntParens {
	char ch;											// used for communication
	Status status;
	unsigned int cnt;
}; // CntParens

void main( CntParens & cpns ) with( cpns ) {
	for ( ; ch == '('; cnt += 1 ) {						// left parenthesis
		suspend;
	}
	for ( ; ch == ')' && cnt > 1; cnt -= 1 ) {			// right parenthesis
		suspend;
	}
	status = ch == ')' ? Match : Error;
} // main

void ?{}( CntParens & cpns ) with( cpns ) { status = Cont; cnt = 0; }

Status next( CntParens & cpns, char c ) with( cpns ) {
	ch = c;
	resume( cpns );
	return status;
}

int main() {
	CntParens cpns;
	char ch;

	for () {											// read until end of file
		sin | ch;										// read one character
	  if ( eof( sin ) ) { sout | "Error"; break; }		// eof ?
		Status ret = next( cpns, ch );					// push character for formatting
	  if ( ret == Match ) { sout | "Match"; break; }
	  if ( ret == Error ) { sout | "Error"; break; }
	} // for
} // main

// Local Variables: //
// tab-width: 4 //
// compile-command: "cfa -g -Wall -Wextra cntparens.cfa" //
// End: //