// Copyright 2013 Bill Campbell, Swami Iyer and Bahar Akbal-Delibas
import jminusminus.CLEmitter;
import static jminusminus.CLConstants.*;
import java.util.ArrayList;
/**
* This class programatically generates the class file for
* the following Java application:
*
* public class IntFactorial
* {
* public int factorial( int n )
* {
* if ( n <= 1 ) {
* return n;
* }
* else {
* return ( n * factorial( n - 1 ) );
* }
* }
*
* public static void main( String[] args )
* {
* IntFactorial f = new IntFactorial();
* int n = Integer.parseInt( args[ 0 ] );
* System.out.println( "Factorial( " + n +
* " ) = " + f.factorial( n ) );
* }
* }
*/
public class GenIntFactorial {
public static void main(String[] args) {
CLEmitter e = new CLEmitter(true);
ArrayList<String> accessFlags = new ArrayList<String>();
// Add IntFactorial class
accessFlags.add("public");
e.addClass(accessFlags, "IntFactorial", "java/lang/Object", null, true);
// Add the implicit no-arg constructor IntFactorial()
accessFlags.clear();
accessFlags.add("public");
e.addMethod(accessFlags, "<init>", "()V", null, true);
e.addNoArgInstruction(ALOAD_0);
e.addMemberAccessInstruction(INVOKESPECIAL, "java/lang/Object",
"<init>", "()V");
e.addNoArgInstruction(RETURN);
// Add factorial() method to IntFactorial
accessFlags.clear();
accessFlags.add("public");
e.addMethod(accessFlags, "factorial", "(I)I", null, true);
e.addNoArgInstruction(ILOAD_1);
e.addNoArgInstruction(ICONST_1);
e.addBranchInstruction(IF_ICMPGT, "Label1");
e.addNoArgInstruction(ILOAD_1);
e.addNoArgInstruction(IRETURN);
e.addLabel("Label1");
e.addNoArgInstruction(ILOAD_1);
e.addNoArgInstruction(ALOAD_0);
e.addNoArgInstruction(ILOAD_1);
e.addNoArgInstruction(ICONST_1);
e.addNoArgInstruction(ISUB);
e.addMemberAccessInstruction(INVOKEVIRTUAL, "IntFactorial",
"factorial", "(I)I");
e.addNoArgInstruction(IMUL);
e.addNoArgInstruction(IRETURN);
// Add main() method to IntFactorial
accessFlags.clear();
accessFlags.add("public");
accessFlags.add("static");
e.addMethod(accessFlags, "main", "([Ljava/lang/String;)V", null, true);
e.addReferenceInstruction(NEW, "IntFactorial");
e.addNoArgInstruction(DUP);
e.addMemberAccessInstruction(INVOKESPECIAL, "IntFactorial", "<init>",
"()V");
e.addNoArgInstruction(ASTORE_1);
e.addNoArgInstruction(ALOAD_0);
e.addNoArgInstruction(ICONST_0);
e.addNoArgInstruction(AALOAD);
e.addMemberAccessInstruction(INVOKESTATIC, "java/lang/Integer",
"parseInt", "(Ljava/lang/String;)I");
e.addNoArgInstruction(ISTORE_2);
e.addMemberAccessInstruction(GETSTATIC, "java/lang/System", "out",
"Ljava/io/PrintStream;");
e.addReferenceInstruction(NEW, "java/lang/StringBuffer");
e.addNoArgInstruction(DUP);
e.addMemberAccessInstruction(INVOKESPECIAL, "java/lang/StringBuffer",
"<init>", "()V");
e.addLDCInstruction("Factorial(");
e.addMemberAccessInstruction(INVOKEVIRTUAL, "java/lang/StringBuffer",
"append", "(Ljava/lang/String;)Ljava/lang/StringBuffer;");
e.addNoArgInstruction(ILOAD_2);
e.addMemberAccessInstruction(INVOKEVIRTUAL, "java/lang/StringBuffer",
"append", "(I)Ljava/lang/StringBuffer;");
e.addLDCInstruction(") = ");
e.addMemberAccessInstruction(INVOKEVIRTUAL, "java/lang/StringBuffer",
"append", "(Ljava/lang/String;)Ljava/lang/StringBuffer;");
e.addNoArgInstruction(ALOAD_1);
e.addNoArgInstruction(ILOAD_2);
e.addMemberAccessInstruction(INVOKEVIRTUAL, "IntFactorial",
"factorial", "(I)I");
e.addMemberAccessInstruction(INVOKEVIRTUAL, "java/lang/StringBuffer",
"append", "(I)Ljava/lang/StringBuffer;");
e.addMemberAccessInstruction(INVOKEVIRTUAL, "java/lang/StringBuffer",
"toString", "()Ljava/lang/String;");
e.addMemberAccessInstruction(INVOKEVIRTUAL, "java/io/PrintStream",
"println", "(Ljava/lang/String;)V");
e.addNoArgInstruction(RETURN);
// Write IntFactorial.class to file system
e.write();
}
}