JavaToGosu.java

/*
 * Copyright 2013 Guidewire Software, Inc.
 */

package gw.plugin.ij.util.transform.java;


import gw.plugin.ij.util.transform.java.Visitor.GosuVisitor;
import com.sun.source.tree.*;
import com.sun.tools.javac.api.JavacTaskImpl;
import com.sun.tools.javac.api.JavacTool;

import javax.tools.JavaCompiler;
import javax.tools.StandardJavaFileManager;
import java.io.IOException;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.List;

public class JavaToGosu {

  public static String ConvertString(String JavaSource) {
    Wrap[] wraps = new Wrap[]{
            new Wrap("", "", "", ""),
            new Wrap("class _JAVA_TO_GOSU_INTERNAL_ {",
                    "\n}",
                    "class _JAVA_TO_GOSU_INTERNAL_  {\n\n",
                    "\n}\n"),
            new Wrap("class _JAVA_TO_GOSU_INTERNAL_ { void _JAVA_TO_GOSU_INTERNAL_METHOD_() {",
                    "\n}}",
                    "class _JAVA_TO_GOSU_INTERNAL_  {\n\n  function _JAVA_TO_GOSU_INTERNAL_METHOD_() : void {\n",
                    "\n  }\n\n}\n"),
            new Wrap("class _JAVA_TO_GOSU_INTERNAL_ { void _JAVA_TO_GOSU_INTERNAL_METHOD_() {",
                    ";\n}}",
                    "class _JAVA_TO_GOSU_INTERNAL_  {\n\n  function _JAVA_TO_GOSU_INTERNAL_METHOD_() : void {\n",
                    "\n  }\n\n}\n"),
            new Wrap("class _JAVA_TO_GOSU_INTERNAL_ { void _JAVA_TO_GOSU_INTERNAL_METHOD_() { if(",
                    ");\n}}",
                    "class _JAVA_TO_GOSU_INTERNAL_  {\n\n  function _JAVA_TO_GOSU_INTERNAL_METHOD_() : void {\n    if (",
                    ") {\n      \n    }\n  }\n\n}\n")
    };
    String JAVA_WRAP_START = "";
    String JAVA_WRAP_END = "";
    String GOSU_WRAP_START = "";
    String GOSU_WRAP_END = "";
    List<CompilationUnitTree> trees = null;
    boolean parsed = false;
    String output = null;
    int i = wraps.length - 1;

    while (i >= 0 && !parsed) {
      JAVA_WRAP_START = wraps[i].JAVA_WRAP_START;
      JAVA_WRAP_END = wraps[i].JAVA_WRAP_END;
      GOSU_WRAP_START = wraps[i].GOSU_WRAP_START;
      GOSU_WRAP_END = wraps[i].GOSU_WRAP_END;
      trees = new ArrayList<CompilationUnitTree>();
      String src = JAVA_WRAP_START + JavaSource + JAVA_WRAP_END;
      parsed = parseJava(trees, src);
      i--;
    }
    if (!parsed) {
      return "";
    }
    GosuVisitor visitor = new GosuVisitor(2);
    for (CompilationUnitTree tree : trees) {
      tree.accept(visitor, null);
    }
    output = visitor.getOutput().toString();

    if (!JAVA_WRAP_START.isEmpty()) {
      int b = output.indexOf(GOSU_WRAP_START) + GOSU_WRAP_START.length();
      int e = output.lastIndexOf(GOSU_WRAP_END);
      output = unIndent(output.substring(b, e));
    }
    return output;
  }

  private static String unIndent(String output) {
    StringBuilder src = new StringBuilder();
    String[] lines = output.split("\n");
    int tab = 0;
    char[] chars = lines[0].toCharArray();
    while(tab < chars.length && chars[tab] == ' ') {
      tab++;
    }
    for (String line : lines) {
      if(!line.trim().isEmpty()) {
        if(line.length() > tab && line.substring(0, tab).trim().isEmpty()) {
         src.append(line.substring(tab));
        } else {
         src.append(line);
        }
        src.append("\n");
      }
    }
    return src.toString();
  }

  private static boolean parseJava(List<CompilationUnitTree> trees, String src) {
    JavaCompiler compiler = JavacTool.create();
    StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null);
    boolean success = true;

    ArrayList<JavaStringObject> javaStringObjects = new ArrayList<JavaStringObject>();
    javaStringObjects.add(new JavaStringObject(src));
    StringWriter errors = new StringWriter();
    JavaCompiler.CompilationTask task = compiler.getTask(errors, fileManager, null, null, null, javaStringObjects );
    JavacTaskImpl javacTask = (JavacTaskImpl) task;
    try {
      Iterable<? extends CompilationUnitTree> iterable = javacTask.parse();
      for (CompilationUnitTree x : iterable) {
        trees.add(x);
      }
      fileManager.close();
    } catch (IOException e) {
      success = false;
    }
    if (!errors.toString().isEmpty()) {
      success = false;
    }
    return success;
  }
}