microJ/microJ3.html

﻿<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width">
    <link rel="stylesheet" media="all"
           href="https://maeyler.github.io/JS/sss/inspector.css">
    <script src="https://maeyler.github.io/JS/sss/inspector.js"></script>
    <script src="Lexical.js"></script>
    <script src="Expression.js"></script>
    <script src="microJ1.js"></script>
    <script src="microJ3.js"></script>
    <title>microJ3 Parser </title>
  <style>
    body  { background: #fca; }
    #outx {
      resize: both;
      background: #eee; 
    }
    #inpx, #outx {
      box-sizing: border-box;
      border: 1px solid gray;
      width: 400px;
      height: 14em;
      overflow-y: auto;
      font: 12px monospace; 
    }
    #file  { width: 150px; }
  </style>
</head>

<body>
<h2 id=title>microJ3 Parser &emsp;
<button onClick='doParse()'>Parse</button> 
<input type=file id=file onChange='fileSelect(this)' />
</h2>
<p>
<textarea id=inpx rows=14>
M(k)  { print k; } //Mark
R(n)  { //Rule
  if (n == 0) { return; }
  R(n-1); M(n); R(n-1);
}
ruler(n)  { //main
  n = 5; //read n; 
  R(n); println;
}
</textarea>
</p>
<pre id=outx>
</pre>

<hr />

<script>
"use strict";
function doParse() {
    let str = inpx.value
    if (!str) return
    tokens = Token.list(str)
    let y = [...tokens]  //clone
    display(y); //console.log(y); 
    try {
        tokens.reverse()
        tok = tokens.pop()
        let p = program();
        match(EOF);  //success();
        console.log(p); display(p);
        outx.innerText = p.toTree()
        title.scrollIntoView()
        return p
    } catch(x) {
        showError(inpx)
        outx.innerText = x
        reportError(x)
    }
}

const reader = new FileReader();
function fileSelect(t) { //target is the button
    let f = t.files[0];
    if (f.name.toLowerCase().endsWith(".mj")) {
        reader.onload = function(evt) { //text
            inpx.value = evt.target.result;
            console.log(f.name, f.size); doParse()
        }
        reader.readAsText(f);
    }
}

//the simplest interpreter
var current  //Statement
var SF //current StackFrame

class StackFrame {
      //Method met;       running method
      //float[] values;   current values
      constructor(m, v) {
         this.met = m; this.values = v;
      }
      toString() {
         let s = this.values.join(' ');
         return this.met+"["+ s +" ]";
      }
}

class VM { //virtual machine for interpretation
   static start(p) {
      VM.stopped = false;
      VM.returnValue = NaN;
      try {
         SF = null; printer = '';
         VM.invokeMethod(p.main, []);
         if (printer) console.log(printer)
         if (SF != null) throw ("illegal Frame "+SF);
         return "OK"
      } catch(x) {
         VM.error(x); 
      }
   }
   static error(msg) {
      console.log(msg);
      console.log("at "+SF.met+": "+current);
   }
   static invokeMethod(m, v) { 
      let old = SF; 
      SF = new StackFrame(m, v);
      try {
         VM.runBlock(m);
         VM.returnValue = 0;
      } catch(x) {
         if (typeof x == "number")
            VM.returnValue = x;
            //console.log("return ", x);
         else throw x;
      }
      SF = old;
   }
   static runBlock(b) {
      let old = current;
      for (let s of b.list) {
         if (VM.stopped) 
            throw "Program stopped";
         current = s; s.run();
      }
      current = old; 
   }
   static assertEQ(x, y) {
      if (x != y) throw ("Unexpected "+y);
   }
   static getValue(v) {
      VM.assertEQ(v.met, SF.met); 
      return SF.values[v.ind]; 
   }
   static setValue(v, val) { 
      VM.assertEQ(v.met, SF.met); 
      SF.values[v.ind] = val; 
   }
}

function init() {
    MENU = new Menu() //extends Menu
    MENU.global = window
    display(MENU)
}

    try {
        inspect(document.body, init)
        //inp.value = "_.run()"
    } catch(x) {
        reportError(x)
    }
    inpx.focus(); doParse()
</script>

</body>
</html>