package G4ip;+
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+
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import java.applet.*;+
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import java.awt.*;+
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import G4ip.Sequent.*;+
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import G4ip.Prover.*;+
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import G4ip.Parser.*;+
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+
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/** The applet for the prover.+
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  * @author      Christian Urban+
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  */+
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public class ProverApplet extends Applet {+
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  Prover prover;+
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  Parser parser;+
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+
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  Button start;           +
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  Button clear;           +
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  Button next;            +
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  Button stop;           +
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  TextField lhs_text;     // place for the program formulae+
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  TextField rhs_text;     // place for the goal formula+
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  /** A field for various messages (e.g. error messages).+
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    */+
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  public Label messages;  // to be verbose   +
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+
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  public void init() {+
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    setLayout(new BorderLayout());+
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    // NORTH+
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    Panel textfields = new Panel();+
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    add("North", textfields);+
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       // the parameters LHS_size and RHS_size are given in the html-file+
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    int LHS_size = Integer.parseInt(this.getParameter("LHS_size"));+
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    int RHS_size = Integer.parseInt(this.getParameter("RHS_size"));+
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    lhs_text = new TextField(LHS_size);    // program textfield+
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    rhs_text = new TextField(RHS_size);    // goal textfield+
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    Label separation = new Label("=>");    // for separation+
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+
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    if (LHS_size > 0) {     // if someone prefears only single side sequents +
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    textfields.add(lhs_text);   }         +
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    textfields.add(separation);+
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    textfields.add(rhs_text);+
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+
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    // CENTER+
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    Panel buttonfield = new Panel();+
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    add("Center", buttonfield);+
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    start = new Button("Start");         +
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    clear = new Button("Clear");         +
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    next  = new Button("Next");          +
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    stop  = new Button("Stop");            +
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+
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    switch_into_input_mode();   // start in input mode+
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    buttonfield.add(start);+
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    buttonfield.add(clear);+
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    buttonfield.add(next);+
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    buttonfield.add(stop);+
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+
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    // SOUTH+
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    messages = new Label("");   // for any kind of message+
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    messages.setAlignment(Label.CENTER);+
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    add("South",messages);+
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  }+
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  +
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  /** When start is pressed; +
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    * start and clear button are disabled;+
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    * next and stop button are enabled. +
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    */+
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  public void switch_into_prove_mode() { +
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      start.disable();    next.enable();+
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      clear.disable();    stop.enable();+
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      repaint();+
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    }+
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+
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  /** When start is pressed +
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    * and (hopefully) when prover finishes. +
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    */  +
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  public void switch_into_input_mode() { +
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      start.enable();    next.disable(); +
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      clear.enable();    stop.disable();+
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      repaint();+
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    }+
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+
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  /** Initiates the parse and prove process. +
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    */  +
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  void initiate_proving() {+
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      Sequent sequ;+
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      messages.setText(""); +
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      messages.repaint();+
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      repaint(); +
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      Parser rhs_parser = new Parser(rhs_text.getText());+
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      Parser lhs_parser = new Parser(lhs_text.getText());+
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      try {                          // try to parse the input +
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	sequ = new Sequent(lhs_parser.parseFormulae(),+
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			   rhs_parser.parseFormula());+
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      }+
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      catch (Exception exc) {        // there was a parser exception +
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	messages.setText(exc.getMessage()); +
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	messages.repaint();+
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	repaint(); +
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	return;                     // in case there was an exception+
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      }                             // don't run the following code+
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      System.out.println(sequ.G.internalString()); +
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      switch_into_prove_mode();+
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      prover = new Prover(sequ,this);+
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      prover.start();+
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  }+
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+
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  /** Forces the prover to dispose all open frames.+
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    */+
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  public void destroy() {  +
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    if (prover != null && prover.isAlive()) { +
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      prover.stop(); +
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      prover.finalize();+
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    }+
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  }+
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+
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+
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  /** The actions for the buttons:+
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    * this bit of code would be different in Java 1.1+
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    */+
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  public boolean action(Event e, Object arg) {+
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    // clear button has been pressed+
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    if (e.target == clear) {+
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      messages.setText(""); +
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      lhs_text.setText("");+
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      rhs_text.setText(""); +
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      messages.repaint();+
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      repaint(); +
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    }+
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    // start button has been pressed+
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    if (e.target == start) {+
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      initiate_proving();+
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      return true; +
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    }+
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    // stop button has been pressed+
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    if (e.target == stop) {+
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      switch_into_input_mode();+
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      if (prover != null && prover.isAlive()) { prover.stop();  }+
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      return true; +
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    }+
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    // next button has been pressed+
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    if (e.target == next) {+
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      if (prover != null && prover.isAlive()) { prover.resume();} +
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      return true; +
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    }+
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    return false;+
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  }+
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+
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}+
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+
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