source: doc/uC++toCFA/uC++toCFA.tex@ 0a10dc8

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -*- Mode: Latex -*- %%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%% Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
%%
%% The contents of this file are covered under the licence agreement in the
%% file "LICENCE" distributed with Cforall.
%%
%% user.tex --
%%
%% Author           : Peter A. Buhr
%% Created On       : Wed Apr  6 14:53:29 2016
%% Last Modified By : Peter A. Buhr
%% Last Modified On : Mon Sep  8 18:10:30 2025
%% Update Count     : 6534
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\input{common}                                                                                  % common CFA document macros
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\newcommand{\uC}{$\mu$\CC}

% Default underscore is too low and wide. Cannot use lstlisting "literate" as replacing underscore
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\CFAStyle                                                                                               % use default CFA format-style
\lstset{language=CFA}                                                                   % CFA default lnaguage
\lstnewenvironment{C++}[1][]                            % use C++ style
{\lstset{language=C++,escapechar=\$,mathescape=false,moredelim=**[is][\protect\color{red}]{@}{@},#1}}{}
\lstnewenvironment{uC++}[1][]
{\lstset{language=uC++,escapechar=\$,mathescape=false,moredelim=**[is][\protect\color{red}]{@}{@},#1}}{}

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\title{\vspace*{-0.5in}
\uC to \CFA Cheat Sheet}
%\author{Peter A. Buhr}
\date{}

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\begin{document}
\pagestyle{headings}
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\renewcommand{\sectionmark}[1]{\markboth{\thesection\quad #1}{\thesection\quad #1}}
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%\linenumbers                                            % comment out to turn off line numbering

\maketitle
\vspace*{-0.65in}

\section{Introduction}

\CFA is an extension of the C programming with a trait-style type-system rather then templates and objects as in \CC.
\CFA allows overloading of variables and routines using the left-hand assignment type to precisely select among overloaded names.
\begin{cfa}
int x;  char x;  double x;    // overload name x
int x();  double x();  char x();
\end{cfa}
\vspace*{-8pt}
\begin{cquote}
\begin{tabular}{@{}l@{\hspace{1in}}|l@{}}
\begin{cfa}
x += 42;        $\C[1in]{// int x}$
x += 42.2;      $\C{// double x}$
x += 'a';       $\C{// char x}\CRT$
\end{cfa}
&
\begin{cfa}
int j = x();    $\C[1in]{// int x()}$
double j = x(); $\C{// double x();}$
char j = x();   $\C{// char x()}\CRT$
\end{cfa}
\end{tabular}
\end{cquote}
\CFA generalizes reference types, allowing multiple and rebindable references (like pointers).
\begin{cquote}
\begin{tabular}{@{}l|l@{}}
\multicolumn{2}{@{}l}{\lstinline{       int x = 1, y = 2, * p1x = &x, * p1y = &y, ** p2i = &p1x,}} \\
\multicolumn{2}{@{}l}{\lstinline{\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ & r1x = x, & r1y = y, && r2i = r1x;}} \\
\begin{uC++}
**p2i = 3;
p2i = &p1y;
**p2i = 3;
p1x = p1y;
**p2i = 4;
p1x = @nullptr@;
\end{uC++}
&
\begin{cfa}
r2i = 3;         $\C[0.875in]{// change x}$
&r2i = &r1y; $\C{// change p2i / r2i}$
r2i = 3;         $\C{// change y}$
&r1x = &r1y; $\C{// change p1x / r1x}$
r2i = 4;         $\C{// change y}$
&r1x = @0p@; $\C{// reset}\CRT$
\end{cfa}
\end{tabular}
\end{cquote}
Non-rebindable reference (\CC reference) is a @const@ reference (@const@ pointer).
\begin{cfa}
int & @const@ cr = x; // must initialize, no null pointer
int & @const@ & @const@ crcr = cr; // generalize
\end{cfa}


\section{Control Flow}

The @choose@ statement provides an implicit @break@ after the @case@ clause for safety.
It is possible to @break default@ in a @case@ clause to transfer to common code in the @default@ clause.
\begin{cquote}
\begin{tabular}{@{}l|l@{}}
\begin{uC++}
switch ( i ) {
  case 1: ... @break@; // explicit break
  case 2: ... @break@; // explicit break
  default: ... ;
}
\end{uC++}
&
\begin{cfa}
choose ( i ) {
  case 1: ... ; // implicit break
  case 2: ... ; // implicit break
  default: ... ;
}
\end{cfa}
\end{tabular}
\end{cquote}
To simplify creating an infinite loop, the loop condition in optional.
\begin{cquote}
\begin{tabular}{@{}l|l@{}}
\begin{uC++}
while ( true ) ...
for ( ;; ) ...
do ... while ( true )
\end{uC++}
&
\begin{uC++}
while ($\,$) ...
for ($\,$) ...
do ... while ($\,$)
\end{uC++}
\end{tabular}
\end{cquote}
To simplify loop iteration a range is provided, from low to high, and a traversal direction, ascending (@+@) or descending (@-@).
The following is the syntax for the loop range, where @[@\,@]@ means optional.
\begin{cfa}[deletekeywords=default]
[ @index ;@ ] [ [ @min@ (default 0) ] [ direction @+@/@-@ (default +) ] @~@ [ @=@ (include endpoint) ] ] @max@ [ @~ increment@ ]
\end{cfa}
For @=@, the range includes the endpoint (@max@/@min@) depending on the direction (@+@/@-@).
\begin{cquote}
\begin{tabular}{@{}l|l@{}}
\begin{uC++}
for ( int i = 0; i < @10@; i += 1 ) { ... }
for ( int i = @5@; i < @15@; i += @2@ ) { ... }
for ( int i = -2; i <@=@ 10; i += 3 ) { ... }
for ( int i = 10; i > -3; i @-@= 1 ) { ... }
for ( int i = 10; i >@=@ 0; i @-@= 1 ) { ... }
\end{uC++}
&
\begin{cfa}
for ( @10@ ) { ... }  /  for ( i; @10@ ) { ... }  // 0 to 9 by 1
for ( i; @5@ ~ @15@ ~ @2@ ) { ... } // 5 to 14 by 2
for ( i; -2 ~@=@ 10 ~ 3 ) { ... } // -2 to 10 by 3
for ( i; -3 @-@~ 10 ) { ... } // not 10 -~= -3, 10 to -2 by -1
for ( i; 0 @-@~@=@ 10 ) { ... } // not 10 -~= 0, 10 to 0 by -1
\end{cfa}
\end{tabular}
\end{cquote}
A terminating loop @else@ (like Python) is executed if the loop terminates normally, \ie the loop conditional becomes false, which is safer than retesting after the loop.
The loop index is available in the @else@ clause.
\begin{cquote}
\begin{tabular}{@{}l|l@{}}
\begin{uC++}
int i = 0
for ( i = 0; i < 10; i += 1 ) { ... }
@if ( i == 10 )@ { ... }
\end{uC++}
&
\begin{cfa}

for ( i; 10 ) { ... }
@else@ { ... } // i == 10 because of post increment
\end{cfa}
\end{tabular}
\end{cquote}
Single/multiple-level loop exit/continue is provided by the labelled @break@/@continue@. (First example is \CC.)
\begin{cquote}
\begin{tabular}{@{}l|l|l@{}}
\begin{C++}
@L1:@ for ( ;; ) {
        for ( ;; ) {
                ... if ( ... ) @goto L1@; ...
                ... if ( ... ) @goto L2@; ...
        } @L2: ;@
}
\end{C++}
&
\begin{cfa}
@L1:@ for () {
        @L2:@ for () {
                ... if ( ... ) @continue L1@; ...
                ... if ( ... ) @break L2@; ...
        }
}
\end{cfa}
&
\begin{cfa}
@L1:@ for () {
        @L2:@ for () {
                ... if ( ... ) @continue L1@; ...
                ... if ( ... ) @break L2@; ...
        }
}
\end{cfa}
\end{tabular}
\end{cquote}


\section{Exception}

Currently, \CFA uses macros @ExceptionDecl@ and @ExceptionInst@ to declare and instantiate an exception.
\begin{cquote}
\setlength{\tabcolsep}{5pt}
\begin{tabular}{@{}l|ll@{}}
\begin{uC++}

@_Exception@ E {        // local or global scope
        ... // exception fields
};
try {
        ... if ( ... ) @_Resume@ E( /* initialization */ ); ...
        ... if ( ... ) @_Throw@ E( /* initialization */ ); ...
} @_CatchResume@( E & /* reference */ ) { ... }
  catch( E & ) { ... }
  catch( ... /* catch any */ ) { ... }
  _Finally { ... }
\end{uC++}
&
\begin{cfa}
#include <Exception.hfa>
@ExceptionDecl@( E,             // must be global scope
        ... // exception fields
);
try {
        ... if ( ... ) @throwResume@ @ExceptionInst@( E, /* intialization */ ); ...
        ... if ( ... ) @throw@ @ExceptionInst@( E, /* intialization */ ); ...
} @catchResume@( E @*@ /* pointer */ ) { ... }
  catch( E * ) { ... }
  catch( exception_t @*@ /* catch any */ ) { ... }
  finally { ... }
\end{cfa}
\end{tabular}
\end{cquote}


\section{Non-local Exception}

\begin{cquote}
\begin{tabular}{@{}l|ll@{}}
\begin{uC++}


void main() {
        try {
                _Enable {
                        ... suspend(); ...
                }
        } @_CatchResume@( E & /* reference */ ) { ... }
          catch( E & ) { ... }
}
\end{uC++}
&
\begin{cfa}
#define resumePoll( coroutine ) resume( coroutine ); poll()
#define suspendPoll suspend; poll()
void main() {
        try {
                enable_ehm();
                ... suspendPoll ...
                disable_ehm();
        } @catchResume@( E * ) { ... }
          catch( E & ) { ... }
}
\end{cfa}
\end{tabular}
\end{cquote}


\section{Stream I/O}

\CFA output streams automatically separate values and insert a newline at the end of the print.
\begin{cquote}
\begin{tabular}{@{}l|l@{}}
\begin{uC++}
#include <@iostream@>
using namespace std;
int i;   double d;   char c;
cin >> i >> d >> c;
cout << i << ' ' << d << ' ' << c << endl;
\end{uC++}
&
\begin{cfa}
#include <@fstream.hfa@>

int i;   double d;   char c;
sin | i | d | c;
sout | i | d | c
\end{cfa}
\end{tabular}
\end{cquote}
To disable/enable automatic newline at the end of printing, use @nlOff@/@nlOn@ and @nl@.
\begin{cquote}
\begin{tabular}{@{}l|l@{}}
\begin{uC++}

for ( int i = 0; i < 5; i += 1 ) cout << i << ' ';
cout << @endl@;
0 1 2 3 4 
\end{uC++}
&
\begin{cfa}
sout | @nlOff@; // disable auto nl
for ( i; 5 ) sout | i;
sout | @nl@; sout | @nlOn@;  // enable auto nl
0 1 2 3 4 
\end{cfa}
\end{tabular}
\end{cquote}
Floating-point numbers without a fraction print with a decimal point, which can be disabled with @nodp@.
\begin{cquote}
\begin{tabular}{@{}l|l@{}}
\begin{uC++}
cout << 3.0 << ' ' << showpoint << setprecision(0) << 3.0 << endl;
3 3.
\end{uC++}
&
\begin{cfa}
sout | @nodp( 3.0 )@ | 3.0;
3 3.
\end{cfa}
\end{tabular}
\end{cquote}


\section{String}

The @string@ type in \CFA is very similar to that in \CC.
\begin{cquote}
\begin{tabular}{@{}l|l@{}}
\multicolumn{2}{@{}l@{}}{\lstinline{string s1, s2;}} \\
\begin{uC++}
s1 = "abcdefg";
s2 = s1;
s1 += s2;
s1 == s2; s1 != s2;
s1 < s2;  s1 <= s2;  s1 > s2;  s1 >= s2;
s1.length();
s1[3];
s1.substr( 2 );  s1.substr( 2, 3 );
s1.replace( 2, 5, s2 );
s1.find( s2 );
s1.find_first_of( "cd" );
s1.find_first_not_of( "cd" );
getline( cin, s1 );
cout << s1 << endl;
\end{uC++}
&
\begin{cfa}
s1 = "abcdefg";
s2 = s1;
s1 += s2;
s1 == s2; s1 != s2;
s1 < s2;  s1 <= s2;  s1 > s2;  s1 >= s2;
len( s1 ); // like C strlen( s1 )
s1[3];
s1( 2 );  s1( 2, 3 );
s1( 2, 5 ) = s2;
find( s1, s2 );
exclude( s1, "cd" );  // longest sequence excluding "c" and "d"
include( s1, "cd" );  // longest sequence including "c" and "d"
sin | getline( s1 );
sout | s1;
\end{cfa}
\end{tabular}
\end{cquote}


\section{\texorpdfstring{\lstinline{uArray}}{uArray}}

\begin{cquote}
\setlength{\tabcolsep}{5pt}
\begin{tabular}{@{}l|l@{}}
\begin{uC++}
#include <iostream>
using namespace std;

struct S {
        int i;
        S( int i ) { S::i = i; }
};
void f( @uArrayRef( S, parm )@ );
int main() {
        enum { N = 5 };
        @uArray( S, s, N );@   // stack, no ctor calls
        for ( int i = 0; i < N; i += 1 ) @s[i]( i )@; // ctor calls
        for ( int i = 0; i < N; i += 1 ) cout << s[i]@->@i << endl;
        f( s );
        @uArrayPtr( S, sp, N );@   // heap, no ctor calls
        for ( int i = 0; i < N; i += 1 ) @sp[i]( i )@; // ctor calls
        for ( int i = 0; i < N; i += 1 ) cout << sp[i]@->@i << endl;
        f( sp );
} // delete s, sp
\end{uC++}
&
\begin{cfa}
#include <fstream.hfa>
#include <array.hfa>
#include <memory.hfa>
struct S {
        int i;
};
void ?{}( S & s, int i ) { s.i = i; }
@forall( [N] )@ void f( @array( S, N ) & parm@ ) {}
int main() {
        enum { N = 5 };
        @array( S, N ) s = { delay_init };@ // no ctor calls
        for ( i; N ) @s[i]{ i }@; // ctor calls
        for ( i; N ) sout | s[i]@.@i;
        f( s );
    @unique_ptr( array( S, N ) )@ sp = { delay_init }; // heap
    for ( int i = 0; i < N; i += 1 ) @(*sp)@[i]{ i }; // ctor calls
    for ( int i = 0; i < N; i += 1 ) sout | @(*sp)@[i].i;
        f( @*sp@ );
} // delete s, sp
\end{cfa}
\end{tabular}
\end{cquote}


\section{\texorpdfstring{Structures (object-oriented \protect\vs routine style)}{Structures (object-oriented vs. routine style)}}

\CFA is NOT an object-oriented programming-language, so there is no receiver (\lstinline[language=c++]{this}) or nested structure routines.
The equivalent of a \emph{member} routine has an explicit structure parameter in any parameter position (often the first).
\begin{cquote}
\begin{tabular}{@{}l|l@{}}
\begin{uC++}
struct S {
        int i = 0;  // cheat, implicit default constructor
        int setter( int j ) { int t = i; i = j; return t; }
        int getter() { return i; }
};
S s;
@s.@setter( 3 );  // object calls
int k = @s.@getter();
\end{uC++}
&
\begin{cfa}
struct S {  int i;  };
void ?{}( S & s ) { s.i = 0; } // explicit default constructor
int setter( @S & s,@ int j ) @with( s )@ { int t = i; i = j; return t; }
int getter( @S & s@ ) @with( s )@ { return i; }

S s;
setter( @s,@ 3 );  // normal calls
int k = getter( @s@ );
\end{cfa}
\end{tabular}
\end{cquote}
Aggregate qualification is reduced or eliminated by opening scopes using the @with@ clause.
\begin{cfa}
struct S { int i; int j; double m; };  // field i has same type in structures S and T
struct T { int i; int k; int m; };
void foo( S s, T t ) @with( s, t )@ {   // open structure scope s and t in parallel
        j + k;                          $\C[1.6in]{// unambiguous, s.j + t.k}$
        m = 5.0;                        $\C{// unambiguous, s.m = 5.0}$
        m = 1;                          $\C{// unambiguous, t.m = 1}$
        int a = m;                      $\C{// unambiguous, a = t.m}$
        double b = m;           $\C{// unambiguous, b = s.m}$
        int c = s.i + t.i;      $\C{// unambiguous with qualification}$
        (double)m;                      $\C{// unambiguous with cast s.m}\CRT$
}
\end{cfa}
\noindent
In subsequent code examples, the left example is \CC/\uC and the right example is \CFA.


\section{Constructor / Destructor}

A constructor/destructor must have its structure type as the first parameter and be a reference.
\begin{cquote}
\begin{tabular}{@{}l|l@{}}
\begin{uC++}

struct S {
        int i, j;
        @S@() { i = j = 3; }
        @S@( int i, int j ) { S::i = i; S::j = j; }
        @S@( const S & s ) { *this = s; }
        @~S@() {}
};
S s0;
S s1 = { 1, 2 };

S * s2 = new S{ 1, 2 };
delete s2;
s2 = new S{ 1, 2 };
delete s2;
S & s3 = *new S{ 1, 2 };
delete &s3;
s3 = *new S{ 1, 2 };
delete &s3;
\end{uC++}
&
\begin{cfa}
#include <stdlib.hfa> // new (malloc)
struct S { int i, j; };

void @?{}@( @S & s@ ) { s.i = s.j = 3; } $\C[3in]{// default}$
void @?{}@( @S & s@, int i, int j ) { s.i = i; s.j = j; } $\C{// initializer}$
void @?{}@( @S & s@, const S rhs ) { ?{}( s, rhs.i, rhs.j ); } $\C{// copy}$
void @^?{}@( @S & s@ ) { s.i = 0; s.j = 0; } $\C{// destructor}\CRT$

S s0;
S s1 = { 1, 2 };
// bug, cannot use 0/1 (zero_t/one_t) with "new"
S * s2 = new( 0@n@, 2 ); // suffix n => (natural int)
delete( s2 );
s2 = new( 1@n@, 2 );
delete( s2 );
S & s3 = *new( 2, 2 );
delete( &s3 );
&s3 = &*new( 3, 2 );
delete( &s3 );
\end{cfa}
\end{tabular}
\end{cquote}


\section{Coroutine}

\begin{cquote}
\begin{tabular}{@{}l|ll@{}}
\begin{uC++}
@_Coroutine@ C {
        // private coroutine fields
        void main() {
                ... @suspend();@ ...
                ... @_Resume E( ... ) _At partner;@
                ... @uThisCoroutine();@ ...

        }
  public:
        void mem( ... ) {
                ... @resume();@ ...
        }
};
\end{uC++}
&
\begin{cfa}
#include <$coroutine$.hfa>
@coroutine@ C {
        // private coroutine fields

};
void main( C & c ) {
        ... @suspend;@ ... // keyword not routine
        ... @resumeAt( partner, ExceptionInst( E, ... ) );@
        ... @active_coroutine();@ ...
}
void mem( C & c, ... ) {
        ... @resume( c );@ ...
}
\end{cfa}
\\
\multicolumn{2}{@{}l@{}}{\lstinline{C c;}}
\end{tabular}
\end{cquote}


\section{\lstinline{COBEGIN}/\lstinline{COFOR}}

\begin{cquote}
\begin{tabular}{@{}l|ll@{}}
\begin{uC++}

#include <uCobegin.h>
int main() {
        @COBEGIN@
                BEGIN osacquire( cout ) << "A" << endl; END
                BEGIN osacquire( cout ) << "B" << endl; END
                BEGIN osacquire( cout ) << "C" << endl; END
                BEGIN osacquire( cout ) << "D" << endl; END
        @COEND@
        @COFOR@( i, 1, 10,
                osacquire( cout ) << i << endl;
        )
}
\end{uC++}
&
\begin{cfa}
#include <mutex_stmt.hfa>
#include <$cofor$.hfa>
int main() {
        {
                @corun@ { mutex( sout ) sout | "A"; }
                corun { mutex( sout ) sout | "B"; }
                corun { mutex( sout ) sout | "C"; }
                corun { mutex( sout ) sout | "D"; }
        }
        @cofor@( i; 10 ) {
                mutex( sout ) sout | i;
    }
}
\end{cfa}
\end{tabular}
\end{cquote}


\section{Actor}

\begin{cquote}
\begin{tabular}{@{}l|ll@{}}
\begin{uC++}
#include <iostream>
using namespace std;
#include <uActor.h>

struct StrMsg : @public uActor::Message@ {

        const char * val; // string message

        StrMsg( const char * val ) :
                @Message( uActor::Delete )@, // delete after use
                val( val ) {}
};
\end{uC++}
&
\begin{cfa}
#include <fstream.hfa>
#include <mutex_stmt.hfa>
#include <actor.hfa>

struct StrMsg {
        @inline message;@ // derived message
        const char * val; // string message
};
void ?{}( StrMsg & msg, const char * str ) {
        @set_allocation( msg, Delete );@ // delete after use
        msg.val = str;
}
\end{cfa}
\end{tabular}
\begin{tabular}{@{}l|ll@{}}
\begin{uC++}
_Actor Hello { ${\color{red}\LstCommentStyle{// : public uActor}}$
        Allocation receive( Message & msg ) {
                Case( @StartMsg@, msg ) { // discriminate

                } else Case( StrMsg, msg ) {
                        osacquire( cout ) << msg_d->val << endl;

                } else Case( @StopMsg@, msg )
                        return Delete;  // delete actor
                return Nodelete;  // reuse actor
        }
};
int main() {
        @uActor::start();@ // start actor system
        *new Hello() | uActor::startMsg
                | *new StrMsg( "hello" ) | uActor::stopMsg;
        *new Hello() | uActor::startMsg
                | *new StrMsg( "bonjour" ) | uActor::stopMsg;
        @uActor::stop();@  // wait for actors to terminate
}
\end{uC++}
&
\begin{cfa}
struct Hello { @inline actor;@ }; // derived actor
allocation receive( Hello & receiver, @start_msg_t@ & ) {
        return Nodelete;
}
allocation receive( Hello & receiver, StrMsg & msg ) {
        mutex( sout ) sout | msg.val;
        return Nodelete;  // reuse actor
}
allocation receive( Hello & receiver, @stop_msg_t@ & ) {
        return Delete;  // delete actor
}

int main() {
        @actor_start();@  // start actor system
        *(Hello *)new() | start_msg
                | *(StrMsg *)new( "hello" ) | stop_msg;
        *(Hello *)new() | start_msg
                | *(StrMsg *)new( "bonjour" ) | stop_msg;
        @actor_stop();@  // wait for actors to terminate
}
\end{cfa}
\end{tabular}
\end{cquote}


\section{Thread}

\begin{cquote}
\begin{tabular}{@{}l|ll@{}}
\begin{uC++}

@_Task@ T {
        // private task fields
        void main() {
                ... @_Resume E( ... ) _At partner@;
                ... @uThisTask();@ ...
        }
  public:
};
\end{uC++}
&
\begin{cfa}
#include <$thread$.hfa>
@thread@ T {
        // private task fields

};
void main( @T & t@ ) {
        ... @resumeAt( partner, ExceptionInst( E, ... )@ );
        ... @active_thread();@ ...
}
\end{cfa}
\\
\multicolumn{2}{@{}l@{}}{\lstinline{T t; // start thread in main routine}}
\end{tabular}
\end{cquote}


\section{Locks}

\begin{cquote}
\begin{tabular}{@{}l|ll@{}}
\begin{uC++}

uOwnerLock m;
uCondLock s;
m.acquire();
if ( ! s.empty() ) s.wait( m );
else {
        m.release();
}
@osacquire( cout )@ << i << endl;
\end{uC++}
&
\begin{cfa}
#include <locks.hfa>
owner_lock m;
cond_lock( owner_lock ) s;  // generic type on mutex lock
lock( m );
if ( ! empty( s ) ) wait( s, m );
else {
        unlock( m );
}
@mutex( sout )@ sout | i;  // thread safe I/O
\end{cfa}
\end{tabular}
\end{cquote}


\section{Barrier}

\begin{cquote}
\begin{tabular}{@{}l|ll@{}}
\begin{uC++}
#include <iostream>
using namespace std;
#include <uBarrier.h>

@_Cormonitor@ Barrier
                : @public uBarrier@ { // inheritance
        int total;
        void @last@() { cout << total << endl; }
  public:
        Barrier( unsigned int group ) :
                        @uBarrier( group )@ {
                total = 0;
        }
        void @block@( int subtotal ) {


                total += subtotal;
                @uBarrier::block();@
        }
};
enum { N = 3 };
Barrier b{ N };
\end{uC++}
&
\begin{cfa}
#include <fstream.hfa>
#include <$thread$.hfa>
#include <barrier.hfa>
#include <mutex_stmt.hfa>
struct Barrier {
        @barrier b;@                    // containment
        int total;

};
void ?{}( Barrier & B, unsigned int group ) with(B) {
        @?{}( b, group );@              // initialize barrier
        total = 0;
}
unsigned int block( Barrier & B, int subtotal ) with(B) {
        void @last@() { sout | total; } // called by Gth arriving thread
        @mutex( b )@ {  // use barrier's mutual exclusion
                total += subtotal;
                return @block@( b, last ); // wait for barrier trigger
        }
}
enum { N = 3 };
Barrier b{ N };
\end{cfa}
\end{tabular}
\end{cquote}


\enlargethispage{1000pt}

\section{Monitor}

Internal Scheduling
\begin{cquote}
\begin{tabular}{@{}l|ll@{}}
\begin{uC++}

@_Monitor@ BoundedBufferI {
        @uCondition@ full, empty;
        int front = 0, back = 0, count = 0;
        int elements[20];
  public:



        @_Nomutex@ int query() const { return count; }

        void insert( int elem ) {
                if ( count == 20 ) @empty.wait();@
                elements[back] = elem;
                back = ( back + 1 ) % 20;
                count += 1;
                @full.signal();@
        }
        int remove() {
                if ( count == 0 ) @full.wait();@
                int elem = elements[front];
                front = ( front + 1 ) % 20;
                count -= 1;
                @empty.signal();@
                return elem;
        }
};
\end{uC++}
&
\begin{cfa}
#include <$monitor$.hfa>
@monitor@ BoundedBufferI {
        @condition@ full, empty;
        int front, back, count;
        int elements[20];
};
void ?{}( BoundedBufferI & buf ) with( buf ) {
        front = back = count = 0;
}
int query( BoundedBufferI & buf ) { return buf.count; }
int remove( BoundedBufferI & @mutex@ buf ); // forward
void insert( BoundedBufferI & @mutex@ buf, int elem ) with( buf ) {
        if ( count == 20 ) @wait( empty );@
        elements[back] = elem;
        back = ( back + 1 ) % 20;
        count += 1
        @signal( full );@
}
int remove( BoundedBufferI & @mutex@ buf ) with( buf ) {
        if ( count == 0 ) @wait( full );@
        int elem = elements[front];
        front = ( front + 1 ) % 20;
        count -= 1;
        @signal( empty );@
        return elem;
}

\end{cfa}
\end{tabular}
\end{cquote}

\newpage
\noindent
External Scheduling
\begin{cquote}
\begin{tabular}{@{}l|ll@{}}
\begin{uC++}

_Monitor BoundedBuffer {
        int front = 0, back = 0, count = 0;
        int elements[20];
  public:
        _Nomutex int query() const { return count; }
        void insert( int elem );
        int remove();
};

void BoundedBuffer::insert( int elem ) {
        if ( count == 20 ) @_Accept( remove );@
        elements[back] = elem;
        back = ( back + 1 ) % 20;
        count += 1;
}
int BoundedBuffer::remove() {
        if ( count == 0 ) @_Accept( insert );@
        int elem = elements[front];
        front = ( front + 1 ) % 20;
        count -= 1;
        return elem;
}
\end{uC++}
&
\begin{cfa}
#include <$monitor$.hfa>
monitor BoundedBuffer {
        int front, back, count;
        int elements[20];
};
void ?{}( BoundedBuffer & buf ) with( buf ) {
        front = back = count = 0;
}
int query( BoundedBuffer & buf ) { return buf.count; }
int remove( BoundedBuffer & @mutex@ buf ); // forward
void insert( BoundedBuffer & @mutex@ buf, int elem ) with( buf ) {
        if ( count == 20 ) @waitfor( remove : buf );@
        elements[back] = elem;
        back = ( back + 1 ) % 20;
        count += 1;
}
int remove( BoundedBuffer & @mutex@ buf ) with( buf ) {
        if ( count == 0 ) @waitfor( insert : buf );@
        int elem = elements[front];
        front = ( front + 1 ) % 20;
        count -= 1;
        return elem;
}
\end{cfa}
\end{tabular}
\end{cquote}


\input{uC++toCFA.ind}

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