Clean sysouts from java project

Recently I was working in a project that had a lot of sysouts (System.out.println) peppered all over the code. I tried the usual sed approach find . -name '*.java' | xargs sed -i '/System.out.println/d' and that din't work out too well because of multiline sysouts. So, I decided to try the AST approach using the java parser from http://code.google.com/p/javaparser/. So, create a maven project add the javaparser repository and dependency in the pom.xml as given below

	<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>org.fc</groupId>
	<artifactId>sysout-cleanup</artifactId>
	<version>1.0</version>
	<repositories>
	<repository>
	<id>javaparser</id>
	<name>JavaParser Repository</name>
	<url>http://javaparser.googlecode.com/svn/maven2</url>
	<snapshots>
	<enabled>false</enabled>
	</snapshots>
	</repository>
	</repositories>
	<properties>
	<commons-io-version>2.0.1</commons-io-version>
	<java-parser-version>1.0.8</java-parser-version>
	</properties>
	<dependencies>
	<dependency>
	<groupId>commons-io</groupId>
	<artifactId>commons-io</artifactId>
	<version>${commons-io-version}</version>
	</dependency>
	<dependency>
	<groupId>com.google.code.javaparser</groupId>
	<artifactId>javaparser</artifactId>
	<version>${java-parser-version}</version>
	</dependency>
	</dependencies>
	<build>
	<plugins>
	<plugin>
	<artifactId>maven-compiler-plugin</artifactId>
	<configuration>
	<source>1.6</source>
	<target>1.6</target>
	</configuration>
	</plugin>
	</plugins>
	</build>
	</project>

view raw pom.xml hosted with ❤ by GitHub

And the java code that creates the AST and looks for the System.out.println method call

	package org.fc;
	import japa.parser.JavaParser;
	import japa.parser.ast.CompilationUnit;
	import japa.parser.ast.expr.FieldAccessExpr;
	import japa.parser.ast.expr.MethodCallExpr;
	import japa.parser.ast.expr.NameExpr;
	import japa.parser.ast.stmt.BlockStmt;
	import japa.parser.ast.stmt.ExpressionStmt;
	import japa.parser.ast.stmt.Statement;
	import japa.parser.ast.visitor.VoidVisitorAdapter;
	import java.io.File;
	import java.io.FileInputStream;
	import java.io.FileOutputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.PrintStream;
	import java.util.HashMap;
	import java.util.Iterator;
	import java.util.List;
	import java.util.Map;
	import org.apache.commons.io.FileUtils;
	import org.apache.commons.io.IOUtils;
	public class CleanupSysOut {
	File inputFile;
	File outputFile;
	Map<String, String> namespaceMap = new HashMap<String, String>();
	public CleanupSysOut(File file) {
	inputFile = file;
	}
	public CleanupSysOut(File in, File out) {
	inputFile = in;
	outputFile = out;
	}
	protected CompilationUnit getCompilationUnit() {
	CompilationUnit cu = null;
	InputStream in = null;
	try {
	in = new FileInputStream(inputFile);
	cu = JavaParser.parse(in);
	} catch (Exception e) {
	throw new RuntimeException(e);
	} finally {
	IOUtils.closeQuietly(in);
	}
	return cu;
	}
	protected void writeOutput(CompilationUnit cu) throws IOException {
	PrintStream out = new PrintStream(new FileOutputStream(outputFile));
	out.println(cu.toString());
	IOUtils.closeQuietly(out);
	}
	protected String debugPrint(CompilationUnit cu) throws IOException {
	return cu.toString();
	}
	// MethodVisitor
	private class MethodVisitor extends VoidVisitorAdapter&lt;Object&gt; {
	private boolean isSysout(MethodCallExpr methodCall) {
	if ( "println".equals(methodCall.getName()) ) {
	if ( methodCall.getScope() instanceof FieldAccessExpr ) {
	FieldAccessExpr fieldExpr = (FieldAccessExpr) methodCall.getScope();
	if ( "out".equals(fieldExpr.getField()) ) {
	if ( fieldExpr.getScope() instanceof NameExpr ) {
	NameExpr clazz = (NameExpr) fieldExpr.getScope();
	if ( "System".equals(clazz.getName()) ) {
	return true;
	}
	}
	}
	}
	}
	return false;
	}
	@Override
	public void visit(BlockStmt blockStmt, Object arg) {
	List<Statement> stmts = blockStmt.getStmts();
	if ( null != stmts ) {
	Iterator<Statement> itr = stmts.iterator();
	while ( itr.hasNext() ) {
	Statement stmt = itr.next();
	if ( stmt instanceof ExpressionStmt ) {
	if ( ((ExpressionStmt) stmt).getExpression() instanceof MethodCallExpr ) {
	MethodCallExpr methodCall = (MethodCallExpr) ((ExpressionStmt) stmt).getExpression();
	if ( isSysout(methodCall) ) {
	itr.remove();
	}
	}
	} else {
	stmt.accept(this, arg);
	}
	}
	}
	}
	}
	// MethodVisitor ends
	public void doCleanup() {
	try {
	CompilationUnit cu = getCompilationUnit();
	new MethodVisitor().visit(cu, null);
	if ( null != outputFile ) {
	writeOutput(cu);
	}
	} catch (Exception e) {
	throw new RuntimeException(e);
	}
	}
	static void cleanupDir(File inputDir, File outputDir) {
	for ( File java : FileUtils.listFiles(inputDir, new String[] { "java" }, true) ) {
	String relativePath = java.getAbsolutePath().replace(inputDir.getAbsolutePath(), "").substring(1);
	File outputFile = new File(outputDir, relativePath);
	outputFile.getParentFile().mkdirs();
	new CleanupSysOut(java, outputFile).doCleanup();
	}
	}
	public static void main(String[] args) {
	if ( args.length == 2 ) {
	cleanupDir(new File(args[0]), new File(args[1]));
	} else {
	System.err.println("Usage: java " + CleanupSysOut.class.getName() + " <input-dir> <output-dir>");
	}
	}
	}

view raw CleanupSysOut.java hosted with ❤ by GitHub

Luhn algorithm in elisp

I was looking for the checksum validation of credit card numbers and came across the Luhn Algorithm. I had emacs open and on a whim decided I'll try and implement it using elisp. I'm no lisp programmer but, have in the past managed to write some basic elisp in .emacs so, I guessed it would take me about .5hr at most.

I guessed wrong. It took me a lot longer to wrap my head around even some of the simple elisp constructs like let and lambda took quite a while and it took a lot longer than I anticipated. Here, I present to you the fruit of my labors :)

	(defun luhn-sum (list n)
	(if (null list)
	0
	(+ (let ((x (car list)))
	(if (= 1 (mod n 2))
	(let ((y (* 2 x)))
	(if (> y 9)
	(+ 1 (mod y 10))
	y))
	x))
	(luhn-sum (cdr list) (+ 1 n)))
	)
	)
	(defun card-no-str-to-num (card-no)
	(mapcar (lambda (x) (string-to-number x 10)) (cdr (reverse (cdr (split-string card-no "")))))
	)
	(defun luhn-check (card-no)
	(eq 0 (mod (luhn-sum (card-no-str-to-num card-no) 0) 10))
	)
	(luhn-check "49927398716")

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