Active Software Documentation using Soul and IntensiVE

Active Software Documentation
using
Soul and IntensiVE
Johan Brichau, Kim Mens,
Coen De Roover, Andy Kellens,
Roel Wuyts

Département d’Ingénierie Informatique - Université catholique de Louvain

Monday 30 March 2009

Documenting Software...
Software Documentation

import java.io.*;
import java.util.zip.*;
/**
* Command line program to copy a file to another directory.
* @author Marco Schmidt
*/
public class CopyFile {

// constant values for the override option

public static final int OVERWRITE_ALWAYS = 1;

public static final int OVERWRITE_NEVER = 2;

public static final int OVERWRITE_ASK = 3;

// program options initialized to default values
private static int bufferSize = 4 * 1024;
private static boolean clock = true;
private static boolean copyOriginalTimestamp = true;
private static boolean verify = true;
private static int override = OVERWRITE_ASK;

public static Long copyFile(File srcFile, File destFile)

throws IOException {

InputStream in = new FileInputStream(srcFile);

OutputStream out = new FileOutputStream(destFile);

long millis = System.currentTimeMillis();

CRC32 checksum = null;

if (verify) {

checksum = new CRC32();

checksum.reset();

}

byte[] buffer = new byte[bufferSize];

int bytesRead;

while ((bytesRead = in.read(buffer)) >= 0) {

if (verify) {

checksum.update(buffer, 0, bytesRead);

}

out.write(buffer, 0, bytesRead);

}

out.close();

in.close();

if (clock) {

millis = System.currentTimeMillis() - millis;

System.out.println("Second(s): " + (millis/1000L));

}

if (verify) {

return new Long(checksum.getValue());

} else {

return null;

}
}

public static Long createChecksum(File file) throws IOException {


InputStream in = new FileInputStream(file);

CRC32 checksum = new CRC32();

checksum.reset();


int bytesRead;



}

in.close();

if (clock) {



}

}

/**
* Determine if data is to be copied to given file.
* Take into consideration override option and
* ask user in case file exists and override option is ask.
* @param file File object for potential destination file
* @return true if data is to be copied to file, false if not
*/
public static boolean doCopy(File file) {

boolean exists = file.exists();

if (override == OVERWRITE_ALWAYS || !exists) {

return true;

} else

if (override == OVERWRITE_NEVER) {

return false;

} else

if (override == OVERWRITE_ASK) {

return readYesNoFromStandardInput("File exists. " +

"Overwrite (y/n)?");

} else {

throw new InternalError("Program error. Invalid " +

"value for override: " + override);

}
}

public static void main(String[] args) throws IOException {

// make sure there are exactly two arguments

if (args.length != 2) {

System.err.println("Usage: CopyFile SRC-FILE-NAME DEST-DIR-NAME");

System.exit(1);

}

// make sure the source file is indeed a readable file

File srcFile = new File(args[0]);

if (!srcFile.isFile() || !srcFile.canRead()) {

System.err.println("Not a readable file: " + srcFile.getName());

System.exit(1);

}

// make sure the second argument is a directory

File destDir = new File(args[1]);

if (!destDir.isDirectory()) {

System.err.println("Not a directory: " + destDir.getName());

System.exit(1);

}

// create File object for destination file

File destFile = new File(destDir, srcFile.getName());

// check if copying is desired given overwrite option
if (!doCopy(destFile)) {

return;
}

// copy file, optionally creating a checksum
Long checksumSrc = copyFile(srcFile, destFile);

// copy timestamp of last modification
if (copyOriginalTimestamp) {

if (!destFile.setLastModified(srcFile.lastModified())) {

System.err.println("Error: Could not set " +

"timestamp of copied file.");

}
}

}

// optionally verify file
if (verify) {

System.out.print("Verifying destination file...");

Long checksumDest = createChecksum(destFile);

if (checksumSrc.equals(checksumDest)) {

System.out.println(" OK, files are equal.");

} else {

System.out.println(" Error: Checksums differ.");

}
}

}

*/
public class FileDownload {
public static void download(String address, String localFileName) {
OutputStream out = null;
URLConnection conn = null;
InputStream in = null;
try {
URL url = new URL(address);
out = new BufferedOutputStream(
new FileOutputStream(localFileName));
conn = url.openConnection();
in = conn.getInputStream();
byte[] buffer = new byte[1024];
int numRead;
long numWritten = 0;
while ((numRead = in.read(buffer)) != -1) {
out.write(buffer, 0, numRead);
numWritten += numRead;
}
System.out.println(localFileName + "t" + numWritten);
} catch (Exception exception) {
exception.printStackTrace();
} finally {
try {
if (in != null) {
in.close();
}
if (out != null) {
out.close();
}
} catch (IOException ioe) {
}
}
}

/**
* Print a message to standard output and read lines from
* standard input until yes or no (y or n) is entered.
* @param message informative text to be answered by user
* @return user answer, true for yes, false for no.
*/
public static boolean readYesNoFromStandardInput(String message) {

System.out.println(message);

String line;

BufferedReader in = new BufferedReader(new InputStreamReader(

System.in));

Boolean answer = null;

try

{

while ((line = in.readLine()) != null) {

line = line.toLowerCase();

if ("y".equals(line) || "yes".equals(line)) {

answer = Boolean.TRUE;

break;

}

else

if ("n".equals(line) || "no".equals(line)) {

answer = Boolean.FALSE;

break;

}

else

{

System.out.println("Could not understand answer ("" +

line + ""). Please use y for yes or n for no.");

}

}

if (answer == null) {

throw new IOException("Unexpected end of input from stdin.");

}

in.close();

return answer.booleanValue();

}

catch (IOException ioe)

{

throw new InternalError(

"Cannot read from stdin or write to stdout.");

}
}

public static void download(String address) {
int lastSlashIndex = address.lastIndexOf('/');
if (lastSlashIndex >= 0 &&
lastSlashIndex < address.length() - 1) {
download(address, address.substring(lastSlashIndex + 1));
} else {
System.err.println("Could not figure out local file name for " +
address);
}
}
public static void main(String[] args) {
for (int i = 0; i < args.length; i++) {
download(args[i]);
}
}

}

public class HappyNewYear implements Runnable
private
private
private
private
private

*/

{
static NumberFormat formatter = NumberFormat.getInstance();
JFrame frame;
JLabel label;
long newYearMillis;
String message;

public HappyNewYear(JFrame frame, JLabel label)
{
// store argument GUI elements
this.frame = frame;
this.label = label;
// compute beginning of next year
Calendar cal = new GregorianCalendar();
int nextYear = cal.get(Calendar.YEAR) + 1;
cal.set(Calendar.YEAR, nextYear);
cal.set(Calendar.MONTH, Calendar.JANUARY);
cal.set(Calendar.DAY_OF_MONTH, 1);
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
newYearMillis = cal.getTime().getTime();
// prepare a message
message = "Happy " + nextYear + "!";
}
public static int determineFontSize(JFrame frame,
int componentWidth, String fontName, int fontStyle,
String text)
{
int fontSize = componentWidth * 2 / text.length();
Font font = new Font(fontName, fontStyle, fontSize);
FontMetrics fontMetrics = frame.getGraphics().
getFontMetrics(font);
int stringWidth = fontMetrics.stringWidth(text);
return (int)(fontSize * 0.95 *
componentWidth / stringWidth);
}

}
public void run()
{

}

}

public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.addKeyListener(new KeyListener()
{
public void keyPressed(KeyEvent event) {}
public void keyReleased(KeyEvent event) {
if (event.getKeyChar() == KeyEvent.VK_ESCAPE)
{
System.exit(0);
}
}
public void keyTyped(KeyEvent event) {}
}
);
frame.setUndecorated(true);
JLabel label = new JLabel(".");
label.setBackground(Color.BLACK);
label.setForeground(Color.WHITE);
label.setOpaque(true);
label.setHorizontalAlignment(SwingConstants.CENTER);
frame.getContentPane().add(label);
GraphicsEnvironment.getLocalGraphicsEnvironment().
getDefaultScreenDevice().setFullScreenWindow(frame);
final int fontStyle = Font.BOLD;
final String fontName = "SansSerif";
int fontSizeNumber = determineFontSize(frame,
Toolkit.getDefaultToolkit().getScreenSize().width,
fontName, fontStyle, formatter.format(88888888));
int fontSizeText = determineFontSize(frame,
fontName, fontStyle, "Happy 8888!");
label.setFont(new Font(fontName, fontStyle,
Math.min(fontSizeNumber, fontSizeText)));
new HappyNewYear(frame, label).run();

boolean newYear = false;
do
{
long time = System.currentTimeMillis();
long remaining = (newYearMillis - time) / 1000L;
String output;
if (remaining < 1)
{
// new year!
newYear = true;
output = message;
}
else
{
// make a String from the number of seconds
output = formatter.format(remaining);
}
label.setText(output);
try
{
Thread.sleep(1000);

Active Software Documentation using Logic Metaprogramming

2


import java.io.*;
/**
*/












if (verify) {


checksum.reset();

}


int bytesRead;


if (verify) {


}


}

out.close();

in.close();

if (clock) {



}

if (verify) {


} else {

return null;

}
}





checksum.reset();


int bytesRead;



}

in.close();

if (clock) {



}

}

/**
*/



return true;

} else


return false;

} else




} else {



}
}





System.exit(1);

}





System.exit(1);

}





System.exit(1);

}




return;
}






}
}

}

if (verify) {





} else {


}
}

}

*/
try {
int numRead;
}
} finally {
try {
if (in != null) {
in.close();
}
if (out != null) {
out.close();
}
}
}
}

/**
*/


String line;


System.in));


try

{





break;

}

else



break;

}

else

{



}

}



}

in.close();


}


{



}
}

} else {
address);
}
}
download(args[i]);
}
}

}

private
private
private
private
private

*/

- After state change
- Follows DB protocol
(open + (read/write) + close)

{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

{
this.frame = frame;
this.label = label;
}
String text)
{
}

}
public void run()
{

}

}

{
{
{
System.exit(0);
}
}
}
);

do
{
String output;
if (remaining < 1)
{
// new year!
newYear = true;
output = message;
}
else
{
}
try
{
Thread.sleep(1000);


Calls to database

2


import java.io.*;
/**
*/












if (verify) {


checksum.reset();

}


int bytesRead;


if (verify) {


}


}

out.close();

in.close();

if (clock) {



}

if (verify) {


} else {

return null;

}
}





checksum.reset();


int bytesRead;



}

in.close();

if (clock) {



}

}

/**
*/



return true;

} else


return false;

} else




} else {



}
}





System.exit(1);

}





System.exit(1);

}





System.exit(1);

}




return;
}






}
}

}

if (verify) {





} else {


}
}

}

*/
try {
int numRead;
}
} finally {
try {
if (in != null) {
in.close();
}
if (out != null) {
out.close();
}
}
}
}

/**
*/


String line;


System.in));


try

{





break;

}

else



break;

}

else

{



}

}



}

in.close();


}


{



}
}

} else {
address);
}
}
download(args[i]);
}
}

}

private
private
private
private
private

*/

String text)
{
}

public void run()
{

}

}

{
{
{
System.exit(0);
}
}
}
);


Factory Methods
- Must be used to create
objects consistently

do
{
String output;
if (remaining < 1)
{
// new year!
newYear = true;
output = message;
}
else
{
}
try
{
Thread.sleep(1000);



{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

{
this.frame = frame;
this.label = label;
}

}

Calls to database

2


import java.io.*;
/**
*/












if (verify) {


checksum.reset();

}


int bytesRead;


if (verify) {


}


}

out.close();

in.close();

if (clock) {



}

if (verify) {


} else {

return null;

}
}





checksum.reset();


int bytesRead;



}

in.close();

if (clock) {



}

}

/**
*/



return true;

} else


return false;

} else




} else {



}
}





System.exit(1);

}





System.exit(1);

}





System.exit(1);

}




return;
}






}
}

}

if (verify) {





} else {


}
}

}

*/
try {
int numRead;
}
} finally {
try {
if (in != null) {
in.close();
}
if (out != null) {
out.close();
}
}
}
}

/**
*/


String line;


System.in));


try

{





break;

}

else



break;

}

else

{



}

}



}

in.close();


}


{



}
}

} else {
address);
}
}
download(args[i]);
}
}

}

private
private
private
private
private

*/

String text)
{
}

public void run()
{

}

}

{
{
{
System.exit(0);
}
}
}
);

do
{
String output;
if (remaining < 1)
{
// new year!
newYear = true;
output = message;
}
else
{
}
try
{
Thread.sleep(1000);



{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

{
this.frame = frame;
this.label = label;
}

}

Calls to database

Factory Methods

Coding Convention
- Classes implementing
events: ‘*Event’
- Must be adhered for
consistency

2


import java.io.*;
/**
*/












if (verify) {


checksum.reset();

}


int bytesRead;


if (verify) {


}


}

out.close();

in.close();

if (clock) {



}

if (verify) {


} else {

return null;

}
}





checksum.reset();


int bytesRead;



}

in.close();

if (clock) {



}

}

/**
*/



return true;

} else


return false;

} else




} else {



}
}





System.exit(1);

}





System.exit(1);

}





System.exit(1);

}




return;
}






}
}

}

if (verify) {





} else {


}
}

}

*/
try {
int numRead;
}
} finally {
try {
if (in != null) {
in.close();
}
if (out != null) {
out.close();
}
}
}
}

/**
*/


String line;


System.in));


try

{





break;

}

else



break;

}

else

{



}

}



}

in.close();


}


{



}
}

Discovering and
Documenting
Regularities
Architecture
Idioms
Patterns
Conventions
} else {
address);
}
}
download(args[i]);
}
}

}

private
private
private
private
private

*/

String text)
{
}

public void run()
{

}

}

{
{
{
System.exit(0);
}
}
}
);

Bugs
Bad smells

do
{
String output;
if (remaining < 1)
{
// new year!
newYear = true;
output = message;
}
else
{
}
try
{
Thread.sleep(1000);



{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

{
this.frame = frame;
this.label = label;
}

}

Calls to database

Factory Methods

Coding Convention
consistency

2

Evolving Software...

import java.io.*;
/**
*/












if (verify) {


checksum.reset();

}


int bytesRead;


if (verify) {


}


}

out.close();

in.close();

if (clock) {



}

if (verify) {


} else {

return null;

}
}





checksum.reset();


int bytesRead;



}

in.close();

if (clock) {



}

}

/**
*/



return true;

} else


return false;

} else




} else {



}
}





System.exit(1);

}





System.exit(1);

}





System.exit(1);

}




return;
}






}
}

}

if (verify) {





} else {


}
}

}

*/
try {
int numRead;
}
} finally {
try {
if (in != null) {
in.close();
}
if (out != null) {
out.close();
}
}
}
}

/**
*/


String line;


System.in));


try

{





break;

}

else



break;

}

else

{



}

}



}

in.close();


}


{



}
}

} else {
address);
}
}
download(args[i]);
}
}

}

private
private
private
private
private

*/

String text)
{
}

public void run()
{

}

}

{
{
{
System.exit(0);
}
}
}
);

do
{
String output;
if (remaining < 1)
{
// new year!
newYear = true;
output = message;
}
else
{
}
try
{
Thread.sleep(1000);



{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

{
this.frame = frame;
this.label = label;
}

}

Calls to database

Factory Methods

Coding Convention
consistency

3


import java.io.*;
/**
*/












if (verify) {


checksum.reset();

}


int bytesRead;


if (verify) {


}


}

out.close();

in.close();

if (clock) {



}

if (verify) {


} else {

return null;

}
}





checksum.reset();


int bytesRead;



}

in.close();

if (clock) {



}

}

/**
*/



return true;

} else


return false;

} else




} else {



}
}





System.exit(1);

}





System.exit(1);

}





System.exit(1);

}




return;
}






}
}

}

if (verify) {





} else {


}
}

}

*/
try {
int numRead;
}
} finally {
try {
if (in != null) {
in.close();
}
if (out != null) {
out.close();
}
}
}
}

/**
*/


String line;


System.in));


try

{





break;

}

else



break;

}

else

{



}

}



}

in.close();


}


{



}
}

private
private
private
private
private

} else {
address);
}
}
download(args[i]);
}
}

}

private
private
private
private
private

String text)
{
}

*/

}
public void run()
{

{
this.frame = frame;
this.label = label;
}

}

}


{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

{
this.frame = frame;
this.label = label;
}

{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

String text)
{
}
{
{
{
System.exit(0);
}
}
);
JLabel label = new JLabel("."); label.setForeground(Color.WHITE);

*/

Calls to database

{
{
{
System.exit(0);
}
}
}
);

do
{
String output;
if (remaining < 1)
{
// new year!
newYear = true;
output = message;
}
else
{
}
try
{
Thread.sleep(1000);

Factory Methods

Coding Convention
consistency

}


3


import java.io.*;
/**
*/












if (verify) {


checksum.reset();

}


int bytesRead;


if (verify) {


}


}

out.close();

in.close();

if (clock) {



}

if (verify) {


} else {

return null;

}
}





checksum.reset();


int bytesRead;



}

in.close();

if (clock) {



}

}

/**
*/



return true;

} else


return false;

} else




} else {



}
}





System.exit(1);

}





System.exit(1);

}





System.exit(1);

}




return;
}






}
}

}

if (verify) {





} else {


}
}

}

*/
try {
int numRead;
}
} finally {
try {
if (in != null) {
in.close();
}
if (out != null) {
out.close();
}
}
}
}

/**
*/


String line;


System.in));


try

{





break;

}

else



break;

}

else

{



}

}



}

in.close();


}


{



}
}

?

private
private
private
private
private

} else {
address);
}
}
download(args[i]);
}
}

}

private
private
private
private
private

String text)
{
}

*/

}
public void run()
{

{
this.frame = frame;
this.label = label;
}

}

}

}

{
{
{
System.exit(0);
}
}
}
);

do
{
String output;
if (remaining < 1)
{
// new year!
newYear = true;
output = message;
}
else
{
}
try
{
Thread.sleep(1000);



{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

{
this.frame = frame;
this.label = label;
}

{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

String text)
{
}
{
{
{
System.exit(0);
}
}
);

*/

Calls to database

Factory Methods

Coding Convention
consistency

3


import java.io.*;
/**
*/












if (verify) {


checksum.reset();

}


int bytesRead;


if (verify) {


}


}

out.close();

in.close();

if (clock) {



}

if (verify) {


} else {

return null;

}
}





checksum.reset();


int bytesRead;



}

in.close();

if (clock) {



}

}

/**
*/



return true;

} else


return false;

} else




} else {



}
}





System.exit(1);

}





System.exit(1);

}





System.exit(1);

}




return;
}






}
}

}

if (verify) {





} else {


}
}

}

*/
try {
int numRead;
}
} finally {
try {
if (in != null) {
in.close();
}
if (out != null) {
out.close();
}
}
}
}

/**
*/


String line;


System.in));


try

{





break;

}

else



break;

}

else

{



}

}



}

in.close();


}


{



}
}

private
private
private
private
private

} else {
address);
}
}
download(args[i]);
}
}

}

private
private
private
private
private

String text)
{
}

*/

}
public void run()
{

{
this.frame = frame;
this.label = label;
}

}

}


{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

{
this.frame = frame;
this.label = label;
}

{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

String text)
{
}
{
{
{
System.exit(0);
}
}
);

*/

Calls to database

{
{
{
System.exit(0);
}
}
}
);

do
{
String output;
if (remaining < 1)
{
// new year!
newYear = true;
output = message;
}
else
{
}
try
{
Thread.sleep(1000);

Factory Methods

Coding Convention
consistency

}


4


import java.io.*;
/**
*/












if (verify) {


checksum.reset();

}


int bytesRead;


if (verify) {


}


}

out.close();

in.close();

if (clock) {



}

if (verify) {


} else {

return null;

}
}





checksum.reset();


int bytesRead;



}

in.close();

if (clock) {



}

}

/**
*/



return true;

} else


return false;

} else




} else {



}
}





System.exit(1);

}





System.exit(1);

}





System.exit(1);

}



}

}

*/
try {
int numRead;
}
} finally {
try {
if (in != null) {
in.close();
}
if (out != null) {
out.close();
}
}
}
}

/**
*/


String line;


System.in));


try

{





break;

}

else



break;

}

else

{



}

}



}

in.close();


}


{



}
}

?

} else {
address);
}
}
download(args[i]);
}
}

}

private
private
private
private
private






}
}

String text)
{
}

if (verify) {





} else {


}
}

private
private
private
private
private

*/

{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

}
public void run()
{

{
this.frame = frame;
this.label = label;
}
String text)
{
}
{
{
{
System.exit(0);
}
}
);

}

}


{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

{
this.frame = frame;
this.label = label;
}


return;
}


*/

Calls to database

{
{
{
System.exit(0);
}
}
}
);

do
{
String output;
if (remaining < 1)
{
// new year!
newYear = true;
output = message;
}
else
{
}
try
{
Thread.sleep(1000);

Factory Methods

Coding Convention
consistency

}


4

Software Erosion Problem
• Architectural drift and design decay
• Documentation of source code becomes inconsistent
• Original design structure and architecture is eroded
import java.io.*;
/**
*/






*/
public static void download(String
address, String localFileName) {
OutputStream out =
null;
URLConnection conn =
null;
try {
URL url
= new URL(address);

source code
v1.0

public static Long copyFile(File srcFile, File


InputStream in = new
FileInputStream(srcFile);

OutputStream out = new
FileOutputStream(destFile);

long millis =
System.currentTimeMillis();


if (verify) {

new CRC32();

checksum.reset();

}

byte[] buffer = new
byte[bufferSize];

int bytesRead;

while ((bytesRead =
in.read(buffer)) >= 0) {

{



}

destFile)

checksum =

if (verify)

}

*/
{
private static
NumberFormat formatter =
NumberFormat.getInstance();
private JFrame
frame;
private JLabel
label;
private long
newYearMillis;
private String
message;
public
HappyNewYear(JFrame frame, JLabel label)
{
this.frame = frame;
this.label = label;

documentation
v1.0

time


5

Software Erosion Problem
• Architectural drift and design decay
• Documentation of source code becomes inconsistent
• Original design structure and architecture is eroded
import java.io.*;
/**
*/






import java.io.*;

*/
OutputStream out =
null;
null;
try {
URL url
= new URL(address);

/**
*/





source code
v1.0





long millis =


if (verify) {

new CRC32();

checksum.reset();

}

byte[] buffer = new
byte[bufferSize];

int bytesRead;

while ((bytesRead =

{



}

if (verify)

}

source code
v2.0





long millis =


if (verify) {

new CRC32();

checksum.reset();

}

byte[] buffer = new
byte[bufferSize];

int bytesRead;

while ((bytesRead =

{



}

destFile)

checksum =


*/
{
private static
private JFrame
frame;
private JLabel
label;
private long
newYearMillis;
private String
message;
public
{

destFile)

checksum =

if (verify)

}

this.label = label;

*/
{
private static
private JFrame
frame;
private JLabel
label;
private long
newYearMillis;
private String
message;
public
{

this.frame = frame;

*/
OutputStream out =
null;
null;
try {
URL url
= new URL(address);

*/
{
private static NumberFormat formatter =
private JFrame frame;
private JLabel label;
private long newYearMillis;
private String message;
JLabel label)
elements

next year
GregorianCalendar();
cal.get(Calendar.YEAR) + 1;

this.frame = frame;
this.label = label;

public HappyNewYear(JFrame frame,
{

// store argument GUI

this.frame = frame;
this.label = label;
// compute beginning of
Calendar cal = new
int nextYear =

}

documentation
v1.0

documentation
v1.0

time


5


import java.io.*;
/**
*/












if (verify) {


checksum.reset();

}


int bytesRead;


if (verify) {


}


}

out.close();

in.close();

if (clock) {



}

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} else {

return null;

}
}





checksum.reset();


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}

in.close();

if (clock) {



}

}

/**
*/



return true;

} else


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}
}





System.exit(1);

}





System.exit(1);

}





System.exit(1);

}




return;
}






}
}

}

if (verify) {





} else {


}
}

}

*/
try {
int numRead;
}
} finally {
try {
if (in != null) {
in.close();
}
if (out != null) {
out.close();
}
}
}
}

/**
*/


String line;


System.in));


try

{





break;

}

else



break;

}

else

{



}

}



}

in.close();


}


{



}
}

Discovering,
documenting and
enforcing
Regularities
Architecture
Idioms
Patterns
Conventions
} else {
address);
}
}
download(args[i]);
}
}

}

private
private
private
private
private

*/

String text)
{
}

public void run()
{

}

}

{
{
{
System.exit(0);
}
}
}
);

do
{
String output;
if (remaining < 1)
{
// new year!
newYear = true;
output = message;
}
else
{
}
try
{
Thread.sleep(1000);

Bugs
Bad smells



{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

{
this.frame = frame;
this.label = label;
}

}

Calls to database

Factory Methods

Coding Convention
consistency

6

Code Software Documentation
CCallssadatabase
au to l
Queries
Lin state change
- Afterk
Discovering,
import java.io.*;

/**
*/












if (verify) {


checksum.reset();

}


int bytesRead;


if (verify) {


}


}

out.close();

in.close();

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}

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} else {

return null;

}
}





checksum.reset();


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}

in.close();

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}

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/**
*/



return true;

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}
}





System.exit(1);

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System.exit(1);

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System.exit(1);

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return;
}






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}

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if (verify) {





} else {


}
}

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*/
try {
int numRead;
}
} finally {
try {
if (in != null) {
in.close();
}
if (out != null) {
out.close();
}
}
}
}

/**
*/


String line;


System.in));


try

{





break;

}

else



break;

}

else

{



}

}



}

in.close();


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{



}
}

} else {
address);
}
}

documenting and
enforcing
Regularities
Architecture
Idioms
Patterns
Conventions
download(args[i]);
}
}

}

private
private
private
private
private

*/

String text)
{
}

public void run()
{

}

}

{
{
{
System.exit(0);
}
}
}
);

do
{
String output;
if (remaining < 1)
{
// new year!
newYear = true;
output = message;
}
else
{
}
try
{
Thread.sleep(1000);

Bugs
Bad smells



{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

{
this.frame = frame;
this.label = label;
}

}


Factory Methods

Coding Convention
consistency

6

Small programs vs. Large projects
import java.io.*;
/**
*/












if (verify) {


checksum.reset();

}


int bytesRead;


if (verify) {


}


}

out.close();

in.close();

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}

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} else {

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}
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checksum.reset();


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}

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}

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/**
*/



return true;

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}
}





System.exit(1);

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System.exit(1);

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System.exit(1);

}




return;
}






}
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if (verify) {





} else {


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}

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try {
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}
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in.close();
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}

/**
*/


String line;


System.in));


try

{





break;

}

else



break;

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}

}



}

in.close();


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{



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}

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address);
}
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download(args[i]);
}
}

}

private
private
private
private
private

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{
JFrame frame;
JLabel label;
long newYearMillis;
String message;

{
this.frame = frame;
this.label = label;
}
String text)
{
}

}
public void run()
{

}

}

{
{
{
System.exit(0);
}
}
}
);

do
{
String output;
if (remaining < 1)
{
// new year!
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output = message;
}
else
{
}
try
{
Thread.sleep(1000);


7

Small programs vs. Large projects
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import java.io.*;

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Manual exploration
& documentation
do not scale

Tool Support Needed

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finale ear = fontStyle, "Happy; 8888!");
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Thread.sleep(1000);
}
}

}
}


7

Querying Code
- (Simple) name-based searches
- Mostly textual matching


8

Querying Code

- Name-based searches
- Limited use of
structural reflection


8

Querying Code

- Name-based searches
- Limited use of
structural reflection

PQL
ASTLOG

.....

.....

JTL

.....

- Full query language
- Based on reflection,
metaprogramming,
analysis, etc..
8

SOUL
• Smalltalk Open Unification Language
• Prolog-based query language

• Hybrid (Prolog + Smalltalk)
• Inter-language Reflection
• Metalanguage over Smalltalk base language

• Execute queries over programs
• using full structural and computational reflection
• using combination of logic and imperative paradigms
• Declarative Reasoning about the Structure of Object-Oriented Systems, Roel Wuyts. Proc. TOOLS USA 1998, pp.

112-124. IEEE Computer Society Press, 1998.
• Co-evolution of Object-Oriented Software Design and Implementation. Theo D'Hondt, Kris De Volder, Kim Mens & Roel
Wuyts, Proc. SACT 2000. Kluwer Academic Publishers, 2000.
• A Logic Meta-Programming Approach to Support the Co-Evolution of Object-Oriented Design and Implementation. Roel
Wuyts. PhD thesis, Dept. of Computer Science, VUB, 2001.
• Supporting software development through declaratively codified programming patterns. Kim Mens, Isabel Michiels &
Roel Wuyts. Journal on Expert Systems with Applications, Volume 23, Issue 4, November 2002, Page 405, Elsevier.

9

Meta Programming
“Standard” Program

SQL query

Queries
Expenses Database


10

Meta Programming

Meta Program

SQL query

Soul query

Queries

Queries

Expenses Database

Software Database
Compiler compiles programs
JavaDoc generates documentation for programs
...


10

Meta Programming

Meta Program

SQL query

Soul query

Queries

Queries

Expenses Database

Software Database
Compiler compiles programs
JavaDoc generates documentation for programs
...

Meta Program

Programs

Works with
Program

Data
10

SOUL: Prolog-based query language
Joe
parent of

Christine

Mark

parent of parent of

Kevin

parent of

Sarah
parent of

Family Structure

parent of

Sophie


Frank

11

Joe
parent of

Christine

Mark

parent of parent of

Kevin

parent of

Sarah
parent of

Frank
parent of

Sophie

parentOf(Joe,Mark).
parentOf(Joe,Sarah).
parentOf(Mark,Kevin).
parentOf(Christine,Kevin).
parentOf(Sarah,Sophie).
parentOf(Frank,Sophie).

Family Structure

SOUL representation
of the
family Structure

11

Joe
parent of

Christine

Mark

parent of parent of

Kevin

parent of

Sarah
parent of

Frank
parent of

Sophie

parentOf(Joe,Mark).

Family Structure

SOUL representation
of the
family Structure
Logic fact
11

Joe
parent of

Christine

Mark

parent of parent of

Kevin

parent of

Sarah
parent of

Frank
parent of

Sophie

parentOf(Joe,Mark).

Family Structure

Predicate
SOUL representation
of the
family Structure
Logic fact
11

Joe
parent of

Christine

Mark

parent of parent of

Kevin

parent of

Sarah
parent of

Frank

Family Structure

parent of

Sophie

SOUL Constant
parentOf(Joe,Mark).

Predicate
SOUL representation
of the
family Structure
Logic fact
11

Joe
parent of

Christine

parent of

if
Mark parentOf(?parent,?child) Family Structure
Sarah
Frank

parent of parent of

Kevin

parent of

parent of

Sophie
?child -> Mark
?parent -> Joe SOUL Constant

parentOf(Joe,Mark).
?child -> Sarah Predicate
?parent -> Joe
SOUL representation
of the
...
family Structure

Logic fact


11

grandparent of

Joe

parent of

couple

Christine

Mark

grandparent of

parent of

couple

Sarah

parent of parent of

parent of

Kevin

Frank
parent of

Deduced
Family Structure

Sophie
cousin


12

grandparent of

Joe

parent of

couple

Christine

Mark

grandparent of

parent of

couple

Sarah

parent of parent of

parent of

Kevin

Frank
parent of

Deduced
Family Structure

Sophie
cousin

grandparentOf(?grandparent,?grandchild) if
parentOf(?grandparent,?parent),
parentOf(?parent,?grandchild).
couple(?personA,?personB) if
parentOf(?personA,?child),
parentOf(?personB,?child)

SOUL deduction
rules

12

grandparent of

Joe

parent of

couple

Christine

Mark

grandparent of

parent of

couple

Sarah

parent of parent of

parent of

Kevin

Deduced
Family Structure

Frank
parent of

Sophie
cousin

logic rule


SOUL deduction
rules

12

grandparent of

Joe

parent of

couple

Christine

Mark

grandparent of

parent of

couple

Sarah

parent of parent of

parent of

Kevin

Deduced
Family Structure

Frank
parent of

Sophie
cousin

logic rule SOUL variable


SOUL deduction
rules

12

grandparent of

Joe

parent of

couple

Christine

grandparent of

parent of

couple

if grandparentOf(?grandparent,?child)
Deduced
Mark
Sarah
Frank

parent of parent of

parent of

Kevin

parent of

Family Structure

Sophie

logic rule SOUL variable
?grandparent -> Joe
?child -> Kevin
parentOf(?grandparent,?parent),-> Joe
?grandparent
?child -> Sophie
SOUL deduction
rules
cousin


12

Node
name
printOn:

Expression
...
...

Statement
...
...

Composite
Node
children
getChildren
printOn:

VariableRef
var

Message
Send
message

printOn:
printOn:

MethodNode
source
header
printOn:

StatementList
printOn:


Software
structure

13

Node
name
printOn:

Expression
...
...

Statement
...
...

Composite
Node
children
getChildren
printOn:

VariableRef
var

Message
Send
message

printOn:
printOn:

MethodNode
source
header
printOn:

StatementList
printOn:

class(Node).
class(StatementList).
subclassOf(StatementList,CompositeNode).
variableInClass(name,Node).
methodInClass(getChildren,CompositeNode).
....

Software
structure
Reification

Representational
mapping

13

Node
name
printOn:

Expression
...
...

if class(?x)
Statement

...
...

Composite
Node
children
getChildren
printOn:

VariableRef
var

Message
Send
message

printOn:
printOn:

MethodNode
source
header
printOn:

StatementList
printOn:

class(Node).
class(StatementList). Smalltalk classes --- all
subclassOf(StatementList,CompositeNode).
variableInClass(name,Node).
methodInClass(getChildren,CompositeNode).
....

Software
structure
Reification

Representational
mapping

13

SOUL: Reification
The SOUL results contain the *real* classes.
i.e.: the Smalltalk class values

idem for methods, packages, namespaces, etc...

Representational mapping is computed using a
logic rule that uses Smalltalk reflection


14

Node
name
printOn:

Expression
...
...

Statement
...
...

Composite
Node
children
getChildren
printOn:

VariableRef
var

Message
Send
message

printOn:
printOn:

MethodNode
source
header
printOn:

StatementList
printOn:

classInHierarchyOf(?class,?superclass) if
subclassOf(?class,?superclass).
subclassOf(?interclass,?superclass),
classInHierarchyOf(?class,?interclass).


Deduced
Software structure

SOUL logic
reasoning

15

Node
name
printOn:

Expression
...
...

Statement
...
...

Deduced
Software structure

Composite
Node
children
getChildren
printOn:

VariableRef
var

Message
Send
message

printOn:
printOn:

MethodNode
source
header
printOn:

StatementList
printOn:

logic alternatives

subclassOf(?class,?superclass).


SOUL logic
reasoning

15

Node
name
printOn:

if classInHierarchyOf(?class,[ApplicationModel])
Expression
...
...

Statement
...
...

Composite
Node
children
getChildren
printOn:

VariableRef
var

Message
Send
message

printOn:
printOn:

MethodNode
source
header
printOn:

Deduced
Software structure

StatementList
printOn:

logic alternatives

-- all subclasses of ApplicationModel -subclassOf(?class,?superclass).
SOUL logic
reasoning


15

• Unification:
• powerful pattern matching
• multi-way predicates
• Recursion: detection of...
• ...recursive patterns in code
• ...composite structures in code
• Declarative:
• focuses on ‘what’ instead of ‘how’
• multiple alternative descriptions of same pattern


16

Smalltalk vs Soul
result := Collection new.
Smalltalk allClasses do:[:class |
class selectors do:[:selector | | method |

method := class compiledMethodAt: selector.

class instVarNames do:[:name |

(method writesField:(class instVarIndexFor: name))
ifTrue:[result add: method]]]].
^result

if methodInClass(?method,?class),
methodWithAssignment(?method, assign(?ﬁeld,?value)),
instanceVariableInClass(?ﬁeld,?class)


17

SOUL: Reasoning over OO programs
Finding a hard coupling between a class and its subclass:
SuperClass
someMethod

<<references>>

SubClass


18

Finding a hard coupling between a class and its subclass:
SuperClass
someMethod

<<references>>

SubClass

if class(?c),
methodInClass(?method,?c),
methodReferencesClass(?method,?s),
classBelow(?s,?c)


18

Finding subclass dependencies
SuperClass
someMethod

<<references>>

SubClass


19

SuperClass
someMethod

<<references>>

SubClass

if class(?c),
methodInClass(?method,?c),
methodReferencesClass(?method,?s),
classBelow(?s,?c)


19


Queries through 7734 classes and 72962 methods
in 44 seconds to find 360 solutions

20

Finding the “Composite” design pattern

compositePattern(?comp,?composite,?msg) if
compositeStructure(?comp,?composite),
compositeAggregation(?comp,?composite,?msg)


21

Finding the Composite Pattern
Finding the “Composite” structure


22

Finding the “Composite” structure

compositeStructure(?comp,?composite) if
class(?comp),
classInHierarchyOf(?composite,?comp)

22

Finding the “Aggregation” structure

compositeAggregation(?comp,?composite,?msg) if
classesImplementCommonSelector(?comp,?composite,?msg),
methodWithNameInClass(?method,?msg,?composite),
statementOfMethod(?statement,?method),
iterationStatementWithBlock(?statement,?iterationBlock),
blockIteratesMessage(?iterationBlock,?msg)

23

Some of the results in the Smalltalk image:

Queries through 7734 classes and 72962 methods
in 13 minutes to find 81 solutions
(Soul is about 10x slower than commercial Prologs)

24

Teaser: Visual Query Language


25

SOUL: Hybrid Language



26

Smalltalk expression evaluating
to the class ApplicationModel



26



className(?class,?name) if
class(?class),
equals(?name,[?class name]).
smallerThan(?x,?y) if
[?x < ?y]

26



class(?class),
[?x < ?y]

Smalltalk expression
- resulting object is
unified with ?name

26



class(?class),
[?x < ?y]

- resulting object is
unified with ?name
- evaluates to true or
false

26

SOUL: Reification revisited
Node
name
printOn:

Expression
...
...

Statement
...
...

Composite
Node
children
getChildren
printOn:

VariableRef
var

Message
Send
message

printOn:
printOn:

MethodNode
source
header
printOn:

StatementList

Software
structure
Reification

printOn:

class(?class) if
member(?class,[Smalltalk allClasses]).
methodInClass(?method,?class) if
member(?method,[?class selectors
collect:[:sel | ?class compiledMethodAt: sel]])


27

Node
name
printOn:

Expression
...
...

Statement
...
...

Composite
Node
children
getChildren
printOn:

VariableRef
var

Message
Send
message

printOn:
printOn:

MethodNode
source
header
printOn:

StatementList

Software
structure
Reification

printOn:

class(?class) if

a collection of all
classes



27

Node
name
printOn:

Expression
...
...

Statement
...
...

Composite
Node
children
getChildren
printOn:

VariableRef
var

Message
Send
message

printOn:
printOn:

MethodNode
source
header
printOn:

StatementList

Software
structure
Reification

printOn:

class(?class) if

a collection of all
classes


a collection of all
methods on a class

27

SOUL: hybrid language
• Reification of *real* Smalltalk meta-objects:
• Meta-objects are normal objects
• can reason about ‘structure’ and ‘runtime values’
Advantages:
• Open Unification
• Causal link
• Passing of results to other (Smalltalk) tools
• Full reflection inherited from Smalltalk
• Uniform approach for reasoning about any
object, including runtime values


28

SOUL
• Queries on-line over a codebase

• Structural as well as computational reflection
• Supports reasoning over code in a declarative style

SOUL
Inference Engine

Smalltalk
Reflection

Smalltalk
image

Logic Programs


29

SOUL


SOUL
Inference Engine
Logic Programs

Smalltalk
Reflection

Smalltalk
image

JavaConnect
+ JDT

Eclipse
workspace


29

SOUL


SOUL

Logic Programs

Smalltalk
image

JavaConnect
+ JDT

Eclipse
workspace

JavaConnect
+ Soot

Inference Engine

Smalltalk
Reflection

Soot
Analysis


29

SOUL: Open Unification
cfr. ‘Open Implementations’
• Define precise unification semantics for entities
• Hiding ‘imperative matching’ process
• For example:
• Unification of objects based on object identity
• Unification of parsetrees via pattern matching
• Unification of variables based on points-to analysis
• etc....


30

Unification protocol implemented by parsetree items:


31


Objects match based on object identity


31


Method (objects) match if source code is identical


31


Method (objects) match if source code is identical
Enhanced parsetree matching:
Expression match based on points-to-analysis
Method bodies match based on control-flow analysis

31

Demonstration


32


Calls to database

• Enforce:
• Adhering to DB protocol
• Using Factory methods
• Coding conventions

Factory Methods

Coding Convention
consistency


33

Intensional Views
Excerpt from a discussion with a software developer:
I want to be able to express additional semantic constraints on
my programs. An example would be « the GUI module should
never call the database directly ». What I lack is a tool that allows
me to specify such constraints (like « the GUI shouldn't call the DB ») as
queries so that I am able to check to see where in the code base this ad-hoc
rule has been broken. Furthermore, the ability of doing so would allow me to
mould fuzzy or implicit structures in my code base into more concrete
structures. What I mean is that when I'm coding, I often have a
mental concept of my "working set" which might be something
like "The GUI classes and the parts of the back-end which are called directly
from the GUI". I need a tool that allows me to create views
which match my mental model of the program slice which I'm
working on. And these views should preferably be dynamic, so that if my
code changes the views still correspond to the intended slice.


34

Conclusions
Declarative Source Code Queries
Specify what to find in source code rather than focusing on how
Extract patterns, metrics, etc...

Hybrid SOUL Language
Mix of imperative and declarative paradigms
Direct manipulation of objects (easy of integration with external tools)
Domain-specific (i.e. language specific) unification of programs


35

Links...

SOUL: http://prog.vub.ac.be/SOUL/
Declarative Metaprogramming: http://prog.vub.ac.be/DMP/
Intensional Software Views: http://www.intensional.be


36

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