JavaShrinker.java

package org.psjava.judgesubmit;

import com.abbajoa.codecombine.util.StringUtil;
import japa.parser.JavaParser;
import japa.parser.ParseException;
import japa.parser.ast.CompilationUnit;
import japa.parser.ast.body.*;

import java.io.ByteArrayInputStream;
import java.io.UnsupportedEncodingException;

public class JavaShrinker {

	public static String cunstructShirinked(String original) throws ParseException {
		CompilationUnit cu = null;
		try {
			cu = JavaParser.parse(new ByteArrayInputStream(original.getBytes("UTF-8")), "UTF-8");
		} catch (UnsupportedEncodingException e) {
			throw new RuntimeException(e);
		}
		for (TypeDeclaration td : cu.getTypes())
			processType(td);
		original = cu.toString();
		original = shrink(original);
		return original;
	}

	private static String shrink(String lines) {
		StringBuilder sb = new StringBuilder();
		for (String line : StringUtil.toLineList(lines))
			sb.append(line.trim() + "\n");
		return sb.toString();
	}

	private static void processType(TypeDeclaration td) {
		if (td.getJavaDoc() != null)
			td.setJavaDoc(null);
		if (td.getMembers() != null) {
			int ccount = 0;
			for (BodyDeclaration bd : td.getMembers()) {
				if (bd instanceof TypeDeclaration)
					processType((TypeDeclaration) bd);
				if (bd.getJavaDoc() != null)
					bd.setJavaDoc(null);
				if (bd.getAnnotations() != null)
					for (int i = bd.getAnnotations().size() - 1; i >= 0; i--)
						if (bd.getAnnotations().get(i).getName().getName().equals("SuppressWarnings"))
							bd.getAnnotations().remove(i);
				if (bd instanceof MethodDeclaration) {
					MethodDeclaration md = (MethodDeclaration) bd;
					md.setModifiers(removeUnnecessaryModifiers(md.getModifiers()));
				}
				if (bd instanceof ConstructorDeclaration) {
					ConstructorDeclaration cd = (ConstructorDeclaration) bd;
					cd.setModifiers(removeUnnecessaryModifiers(cd.getModifiers()));
					ccount++;
				}
				if (bd instanceof FieldDeclaration) {
					FieldDeclaration fd = (FieldDeclaration) bd;
					fd.setModifiers(removeUnnecessaryModifiers(fd.getModifiers()));
				}
			}
			if (ccount == 1) {
				ConstructorDeclaration toRemove = null;
				for (BodyDeclaration bd : td.getMembers()) {
					if (bd instanceof ConstructorDeclaration) {
						ConstructorDeclaration cd = (ConstructorDeclaration) bd;
						if (cd.getParameters() == null && cd.getBlock().getStmts() == null)
							toRemove = cd;
					}
				}
				if (toRemove != null)
					td.getMembers().remove(toRemove);
			}
		}
	}

	private static int removeUnnecessaryModifiers(int oldSet) {
		if (ModifierSet.isPrivate(oldSet))
			oldSet = ModifierSet.removeModifier(oldSet, ModifierSet.PRIVATE);
		if (ModifierSet.isFinal((oldSet)))
			oldSet = ModifierSet.removeModifier(oldSet, ModifierSet.FINAL);
		return oldSet;
	}

}