==================
 FORTH on browser
==================

DEMO
====

.. raw:: html

  <script src="repos/FORTH-on-browser/jquery-1.7.2.min.js"></script>
  <script src="repos/FORTH-on-browser/jquery.terminal-0.4.15.js"></script>
  <script src="repos/FORTH-on-browser/forth.js"></script>
  <script src="repos/FORTH-on-browser/forth-words.js"></script>
  <script src="repos/FORTH-on-browser/forth-interface.js"></script>
  <script src="repos/FORTH-on-browser/forth-test.js"></script>
  <!--<script src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.21/jquery-ui.min.js"></script>-->
  <script src="repos/FORTH-on-browser/jquery-ui.min.js"></script>
  <script src="repos/FORTH-on-browser/load_sample.js"></script>
  <link rel="stylesheet" type="text/css" href="repos/FORTH-on-browser/terminal.css" />
  <link rel="stylesheet" type="text/css" href="repos/FORTH-on-browser/style.css" />
  <link rel="stylesheet" type="text/css"
        href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.21/themes/base/jquery-ui.css">
  <script>
    $(function() {
          $('#tabs').tabs();
          forth.interface($('#term'), $('#stack'));
          forth.sourceLoader($('#source'), $('#load'));
          forth.test();
          $('body').click(function() { forth.terminal.disable(); });
          $('#clear').click(function () { forth.terminal.clear(); });
          forth.dbg.init('#debug-');
    });
  </script>

  <div id="term"></div>
  <div id="stack-container">
    <b>Stack</b><br/>
    <div id="stack"></div>
  </div>
  <div id="tabs">
    <ul>
      <li><a href="#source-tab">Source</a></li>
      <li><a href="#debugger-tab">Debugger</a></li>
    </ul>
    <div id="source-tab">
      <textarea id="source">
      </textarea>
      <div id="source-buttons">
        <input type="button" id="clear" value="Clear terminal" />
        <input type="button" id="load" value="Load source" />
      </div>
    </div> <!-- source-tab -->
    <div id="debugger-tab">
      <input type="checkbox" id="debug-mode" value="debug-mode" />
      <label for="debug-mode">Debug mode</label><br>
      Source:
      <div id="debug-source"></div>
      <input type="button" id="debug-run" value="Run" disabled="disabled" />
      <input type="button" id="debug-step-inside" value="Step Inside" disabled="disabled" />
      <input type="button" id="debug-step-over" value="Step Over" disabled="disabled" />
      <br>
      Call stack:
      <div id="debug-call-stack"></div>
    </div> <!-- debugger-tab -->
  </div> <!-- tabs -->

  <p style="clear: both"></p>




HISTORY
=======

- Milestome1: simple stack-based execution

  - the user will be able to input the words in the interpreter to execute them
  - the webpage will show the current state of the stack (as a list on the right side of the terminal)
  - simple words: numbers, arithmetic (+,-,*,/), stack manipulation (dup, drop, swap etc.), printing the result (.)
  - (no procedures yet)
  - "1 2 +" returns "3"

- Milestone2: procedures
  - (: double 2 * ;)
  - "compilation mode / run mode" distinction
  - virtual machine: the target code will consist not of words, but of operations: call(word), push(number)
  - compile and run mode: the words will get executed in run mode, and transformed to the target code in compile mode
  - immediate words: some words will get executed in compile mode
  - ':' word will enter compile mode, compile words until ';' (a definition), and create a new word
  - comments ('(' word)

    - '(' will read input until ')' and disregard it

  - source textbox, as with other interpreters
  - factorial demonstration

    - boolean type and literals (true, false), logic operations (and, or, not)
    - number comparison (=, < etc.),
    - conditionals (if..then, if..else..then), loops (repeat..until)
    - virtual machine will get branching instructions: goto(number), goto-if-false(number)
    - 'if' will be an immediate word that reads words until 'else' and 'then', and adds appropriate branching instruction
    - the same for 'repeat..until'

::

   : fact
     dup 0 = if
       drop 1
     else
       dup 1 - fact
       *
     then
   ;

- Milestone3: variable and debugger

  - variables (variable x), storing and fetching them (x @, x !)
  - other Forth loop constructs (including do..loop with a loop index)

    - original Forth used raw pointers (running 'x' puts 123823 on the stack), we can do something nicer (running 'x' will put <x> on the stack).

  - debugger:

    - show execution state with call stack and all the words, [step into] and [step over] buttons
    - being able to display and step over execution (this is probably a big one)


License
=======

GPLv3 (c) NISHIO Hirokazu 2012


Thanks
======

Paweł Marczewski contributed much to the project.