Wrapper to make a string or Buffer look like a Stream object.

MemoryStream.js

function emit_string(obj,data,encoding){
	obj.emit('data',(data instanceof Buffer
			?data.toString(encoding)
			:data[0])
	);
}

function emit_buffer(obj,data){
	obj.emit('data',(data instanceof Buffer
			?data:new Buffer(data[0],data[1]))
	);
}

function setEncoding(enc){
	switch(enc){
			case 'utf8':
			case 'ascii':
			case 'base64':
				return this.encoding = enc;
			default:
				return this.encoding = null;
	}
}

function resume(){
	var i,l,encoder;
	if(this.active) return;
	this.active = true;
	if(l=this.buffer.length-1){
		encoder = this.encoding?emit_string:emit_buffer;
		for(i=0;i<l;i++){encoder(this,this.buffer[i],this.encoding);}
		if(this.buffer[i]===''){this.emit('end');this.destroy();}
		else{encoder(this,this.buffer[i],encoding);}
		this.buffer = [];
	}
}

function write(data,enc){
	if(this.active){
		if(this.encoding){emit_string(this,data,enc||this.encoding);}
		else{emit_buffer(this,data);}
	}else{
		this.buffer.push(data instanceof Buffer
			?data:[data,enc||this.encoding]);
	}
	return true;
}

function end(){
	if(arguments.length){this.write.apply(this,arguments);}
	if(this.active){this.emit('end');this.destroy();}
	else{this.buffer.push('');}
	this.readable = false;
}

function nop(){}

function MemoryStream(i_data,opts){
	var mdata;
	if(this === (function(){return this;}())){
		new MemoryStream(i_data,opts);
	}
	function gen_mdata(){
		this.readable=true;
		this.writable=opts && !opts.readonly;
		this.encoding=null;
		this.active=false;
		this.buffer=i_data
			?[typeof i_data === 'string'?[i_data,(opts && opts.encoding)||'utf8']:i_data]:[]
	}
	gen_mdata.prototype = this;
	mdata = new gen_mdata;
	
	Object.defineProperty(this,"readable",{get:function(){return mdata.readable;},enumerable:true});
	Object.defineProperty(this,"writable",{get:function(){return mdata.writable;},enumerable:true});
	this.setEncoding = setEncoding.bind(mdata);
	this.pause = function(){mdata.active=false;};
	this.resume = resume.bind(mdata);
	this.end = end.bind(mdata);
	this.destroy = function(){
		mdata.active = false;
		this.write = this.destroy = this.resume = nop;
	};
	if(!mdata.writable){
		this.write = nop;
		mdata.buffer.push('');
	}else{
		this.write = write.bind(mdata);
	}
}

MemoryStream.prototype = new process.EventEmitter;
MemoryStream.prototype.pipe = require('stream').Stream.prototype.pipe;

exports.MemoryStream = MemoryStream;