Added Comments - BrainF*ck interpreter challenge

by nitoyon 03 Jun 2011

• Forked from keim_at_Si's BrainF*ck interpreter challenge
• Diff: 45
• Related works: 7
Embed

/**
 * Copyright nitoyon ( http://wonderfl.net/user/nitoyon )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/uyUc
 */

// forked from keim_at_Si's BrainF*ck interpreter challenge
/**
 * Copyright keim_at_Si ( http://wonderfl.net/user/keim_at_Si )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/49Vu
 */

package {
    import flash.events.*;
    import flash.display.*;
    import com.bit101.components.*;
    
    public class BFInterpreter extends Sprite {
        
        
        
        
// my brainf*ck interpreter (currently in 262 letters) ----------------------------------------------------------------------------------------------------
function $(b,i){
	// b: source chars
	// i: input chars

	// s: memory
	// x: memory position
	// o: output
	// l: loop jump position
	// c: current source char
	// k: skip [] counter
	// p: source position
	for(var s=[0],x=0,o=[],l=[],c,k,p=0;c=b[p];p++)
		//  +    ,    -    .    <    >    [    ](93)
		if((c-43?c-44?c-45?c-46?c-60?c-62?c-91?
			// ] (c == 93)
			(p=l.pop()-1):
			// [ (c == 91)
			(s[x])?l.push(p):b:  // if (s[x]) { l.push(p); } else { /* do for loop */ }
			// >
			(s[++x]||=0):  // x++; if (s[x] == undefined) { s[x] = 0; }
			// <
			--x:
			// .
			o.push(s[x]):
			// -
			--s[x]:
			// ,
			(s[x]=i.shift())?0:(p=-9): // s[x] = i.shift(); if (!s[x]) { break; }
			// +
			s[x]++
		)==b)
			// Skip until ']' appears
			for(k=1;k&&(c=b[++p]);)
				// if (c == '[') k++;
				// if (c == ']') k--;
				k-=c-93?c-91?0:-1:1;
	return o
}
        
        
// User Interface ----------------------------------------------------------------------------------------------------
        function BFInterpreter() { addEventListener(Event.ADDED_TO_STAGE, _setup); }
        
        private function _setup(event:Event) : void {
            event.target.removeEventListener(event.type, arguments.callee);
            _source = _newTextArea("source :", 20,  200);
            _input  = _newTextArea("input :",  240, 18);
            _output = _newTextArea("output :", 280, 160);
            new PushButton(this, 132, 221, "execute", _execute).setSize(200, 18);
            
            // Hello, world! (72, 101, 108, 108, 111, 44, 32, 119, 111, 114, 108, 100, 33)
            _source.text = "+++++++++[>++++++++>+++++++++++>+++++<<<-]>.>++.+++++++..+++.>-.------------.<++++++++.--------.+++.------.--------.>+.";
        }
        
        private function _newTextArea(label:String, ypos:Number, height:Number) : TextArea {
            var textArea:TextArea = new TextArea(this, 32, ypos);
            textArea.setSize(400, height);
            new Label(this, 32, ypos-20, label);
            return textArea;
        }
        
        private function _execute(event:Event) : void {
            var sourceCode:String, sourceChars:Array=[], inputChars:Array=[], outputChars:Array, i:int;
            
            // translate input text to char[]
            sourceCode = _source.text.replace(/[^<>+\-.,[\]]/gm, "");
            for (i=0; i<sourceCode.length;  i++) sourceChars.push(sourceCode.charCodeAt(i));
            for (i=0; i<_input.text.length; i++) inputChars.push(_input.text.charCodeAt(i));
            // null for the end of char[]
            sourceChars.push(0);
            inputChars.push(0);
            
            // execute interpreter
            outputChars = $(sourceChars, inputChars);
            
            // translate output char[] to text
            for (i=0; i<outputChars.length; i++) _output.text += String.fromCharCode(outputChars[i]);
            _output.text += "\n";
        }

        private var _source:TextArea, _input:TextArea, _output:TextArea;
    }
}