!636
!quickmain
!auto-import
!standard functions

interface Learner {
  public void processInOut(String in, String out);
  public String processIn(String in);
  public void toJava(Code code);
}

class Code {
  StringBuilder buf = new StringBuilder();
  
  void line(String line) {
    buf.append(line).append('\n');
  }
}

main {
  static List<String[]> fullExamples = new ArrayList<String[]>();
  static List<String> halfExamples = new ArrayList<String>();
  static List<String[]> examples1, examples2;
  
  psvm {
    parse(args.length != 0 ? args[0] : null);
    calculate();
  }
  
  static void parse(String arg) tex {
    String text;
    if (arg != null)
      text = loadSnippet(arg);
    else {
      text = loadTextFile("input/input.txt", null);
      if (text == null) text = loadSnippet("#2000455"); // example input
    }
      
    System.out.println(text);
    String in = null, out = null;
    
    for (String line : toLines(text)) {
      if (line.startsWith("I")) { // "In: " or "I: "
        if (in != null)
          halfExamples.add(in);
        in = unquote(line.substring(line.indexOf(':')+1).trim());
        out = null;
      } else if (line.startsWith("O")) { // "Out: " or "O: "
        out = unquote(line.substring(line.indexOf(':')+1).trim());
        System.out.println(quote(in) + " => " + quote(out));
        fullExamples.add(new String[] {in, out});
        in = out = null;
      }
    }
    
    if (in != null)
      halfExamples.add(in);
  }
  
  static void calculate() tex {
    if (fullExamples.size() < 2)
      throw new RuntimeException("Too few examples (" + fullExamples.size() + ")");
    int splitPoint = fullExamples.size()-1;
    System.out.println("Full examples: " + fullExamples.size() + ", splitPoint: " + splitPoint);
    examples1 = fullExamples.subList(0, splitPoint);
    examples2 = fullExamples.subList(splitPoint, fullExamples.size());
    
    Learner learner = findOKLearner();
    if (learner == null)
      print "\nProblem not solved"
    else {
      print "\nSolved!\n"
      Code code = new Code();
      learner.toJava(code);
      System.out.println(code.buf);
      for (String in : halfExamples) {
        String out = learner.processIn(in);
        System.out.println(quote(in) + " =>! " + quote(out));
      }
    }
  }
  
  static Learner findOKLearner() {
    for (Learner learner : makeLearners()) try {
      if (learnerOK(learner))
        return learner;
    } catch (Throwable e) {
      e.printStackTrace();
    }
    return null;
  }
  
  static boolean learnerOK(Learner learner) {
    for (String[] e : examples1) {
      learner.processInOut(e[0], e[1]);
    }
    for (String[] e : fullExamples) {
      String out = learner.processIn(e[0]);
      if (!e[1].equals(out)) {
        System.out.println("[fail] " + learner + " on " + quote(e[0]) + " - " + quote(out) + " vs " + quote(e[1]));
        return false;
      }
    }
    return true; // all test examples passed
  }
  
  static Iterable<Learner> makeLearners() {
    List<Learner> list = new ArrayList<Learner>();
    //list.add(new LId()); // subsumed by trivial case of PrefixSuffix
    list.add(new LPrefixSuffix());
    list.add(new LSplitInput(new LOutPattern()));
    list.add(new LInputPattern());
    return list;
  }
  
  public static String unquote(String s) {
    if (s.startsWith("\"") && s.endsWith("\"") && s.length() > 1)
      return s.substring(1, s.length()-1).replace("\\\"", "\"").replace("\\\\", "\\"); // SHOULD work...
    else
      return s; // Return SOMETHING
  }
  
  public static String quote(String s) {
    if (s == null) return "null";
    return "\"" + s.replace("\\", "\\\\").replace("\"", "\\\"") + "\"";
  }
  
  // splits the input at some point, takes only one part
  static class LSplitInput implements Learner {
    int splitIdx = 1; // split after first character
    Learner baseLearner;
    
    LSplitInput(Learner baseLearner) {
      this.baseLearner = baseLearner;
    }
    
    public void processInOut(String in, String out) {
      in = in.substring(splitIdx);
      baseLearner.processInOut(in, out);
    }
    
    public String processIn(String in) {
      in = in.substring(splitIdx);
      return baseLearner.processIn(in);
    }
    
    public void toJava(Code code) {
      code.line("in = in.substring(" + splitIdx + ");");
      baseLearner.toJava(code);
    }
  }
  
  // if input appears in output in fixed pattern
  static class LOutPattern implements Learner {
    String pattern = "%!%";

    public void processInOut(String in, String out) {
      pattern = out.replace(in, "%!%");
    }
    
    public String processIn(String in) {
      return pattern.replace("%!%", in);
    }
    
    public void toJava(Code code) {
      code.line("in = " + quote(pattern) + ".replace(" + quote("%!%") + ", in);");
    }
  }
  
  // learns to exchange common prefixes and suffixes
  static class LPrefixSuffix implements Learner {
    String prefixIn, suffixIn, prefixOut, suffixOut;
    
    public void processInOut(String in, String out) {
      updateIn(in);
      prefixOut = prefixOut == null ? out : commonPrefix(prefixOut, out);
      suffixOut = suffixOut == null ? out : commonSuffix(suffixOut, out);
    }
    
    void updateIn(String in) {
      prefixIn = prefixIn == null ? in : commonPrefix(prefixIn, in);
      suffixIn = suffixIn == null ? in : commonSuffix(suffixIn, in);
    }

    public String processIn(String in) {
      //System.out.println("[before last info] " + quote(prefixIn) + " " + quote(suffixIn) + " " + quote(prefixOut) + " " + quote(suffixOut));
      //System.out.println("[last info] " + quote(in));
      
      // use latest information
      String p = prefixIn, s = suffixIn;
      updateIn(in);
      prefixOut = prefixOut.substring(0, prefixOut.length()-(p.length()-prefixIn.length()));
      suffixOut = suffixOut.substring(s.length()-suffixIn.length());
      
      //System.out.println("[after last info] " + quote(prefixIn) + " " + quote(suffixIn) + " " + quote(prefixOut) + " " + quote(suffixOut));
      String core = in.substring(prefixIn.length(), in.length()-suffixIn.length());
      return prefixOut + core + suffixOut;
    }
    
    public void toJava(Code code) {
      throw new RuntimeException("TODO");
    }
  }
  
  // for "find" tasks (e.g. "abcde" to "[[abc]]de")
  static class LInputPattern implements Learner {
    String regexp = "";
    
    public void processInOut(String in, String out) {
      int i = out.indexOf("[["), j = out.indexOf("]]", i+1);
      if (j < 0) return;
      String s = out.substring(i+2, j);
      regexp = s.replaceAll("\\d+", Matcher.quoteReplacement("\\d+"));
      System.out.println("regexp: " + regexp);
    }
    
    public String processIn(String in) {
      if (regexp.length() == 0)
        return in;
      else
        return in.replaceAll("(" + regexp + ")", "[[$1]]");
    }
    
    public void toJava(Code code) {
      code.line("in = in.replaceAll(" + quote("(" + regexp + ")") + ", \"[[$1]]\");");
    }
  }
  
}

Began life as a copy of #677