marshal.js

"use strict";
/**
 * @author geoff
 */

var Marshal = (function() {
  
	var debug = false;
	var symbols;
	var marshal_major = 4, marshal_minor = 8;
	var charBuffer = new Buffer(1);
	var types = {
		TYPE_NIL:		'0',
		TYPE_TRUE:		'T',
		TYPE_FALSE:		'F',
		TYPE_FIXNUM:	'i',

		TYPE_EXTENDED:	'e',
		TYPE_UCLASS:	'C',
		TYPE_OBJECT:	'o',
		TYPE_DATA:		'd',
		TYPE_USERDEF:	'u',
		TYPE_USRMARSHAL:'U',
		TYPE_FLOAT:		'f',
		TYPE_BIGNUM:	'l',
		TYPE_STRING:	'"',
		TYPE_REGEXP:	'/',
		TYPE_ARRAY:		'[',
		TYPE_HASH:		'{',
		TYPE_HASH_DEF:	'}',
		TYPE_STRUCT:	'S',
		TYPE_MODULE_OLD:'M',
		TYPE_CLASS:		'c',
		TYPE_MODULE:	'm',

		TYPE_SYMBOL:	':',
		TYPE_SYMLINK:	';',

		TYPE_IVAR:		'I',
		TYPE_LINK:		'@' }
	
	var r_char = function(data, type) {
		charBuffer[0] = data.val[data.pos++];
		return charBuffer.toString('ascii');
	};
	
	var r_byte = function(data, type) {
		if (type == 'string') {
		//DO SOMETHING
		}
		else {
			return data.val[data.pos++];
		}
	};
	
	var r_bytes = function(data, type) {
		if (type == 'string') {
			var len = r_long(data);
			return data.val.toString().substring(data.pos, ( data.pos += len ) );
		}
	};
	
	var r_long = function(data) {
		var c = (r_byte(data) ^ 128) - 128; //TODO: Fix
		
		if (c == 0) {
			return 0;
		};
		
		if (c > 0) {
			if (4 < c && c < 128) {
				return c - 5;
			}
			
			var x = 0;
			
			for (var i = 0; i < c; i++) {
				x |= r_byte(data) << (8*i);
			}
		}
		else {
			if (-129 < c && c < -4) {
				return c + 5;
			}
			c = -c;
			x = -1;
			for (var i = 0; i < c; i++) {
				x &= ~(0xff << (8*i));
				x |= r_byte(data) << (8*i);
			}
		}
		
		return x;
	};
	
	var r_symreal = function(data) {
		var str = r_bytes(data, 'string');
		symbols.push(str);
		return str;
	}
	
	var r_ivar = function(data) {
		var len = r_long(data);
		var ivars = {};
		
		for (var i = 0; i < len; i++) {
			var sym = parseToken(data);
			var val = parseToken(data);
			ivars[sym] = val; //TODO: Should we bother with instance variables?
		}
		
		return ivars;
	};
	
	var transforms = {
		'0': function() { return null },
		'T': function() { return true },
		'F': function() { return false },
		'i': function(data) {
			return r_long(data);
		},
		'"': function(data) {
			return r_bytes(data, 'string');
		},
		'{': function(data) {
			var len = r_long(data);
			var res = {};
			var k, v, i = 0;
			//try {
				while (i++ < len && data.pos < data.val.length) {
					k = parseToken(data);
					v = parseToken(data);
					res[k] = v;
				}
			//} catch (e) {
			//	if (e.message != "hash-end") {
			//		throw e;
			//	}
			//}
			return res;
		},
		'}': function(data) {
			throw "hash-end"; 
		},
		':': function(data) {
			return r_symreal(data);
		},
		';': function(data) {
			return symbols[r_long(data)];
		},
		'[': function(data) {
			var len = r_long(data);
			var res = new Array();
			for (var i = 0; i < len; i++) {
				res.push(parseToken(data));
			}
			return res;
		},
		'I': function(data) {
			var v = parseToken(data);
			var ivars = r_ivar(data);
			for (var k in ivars) {
				v[k] = ivars[k];
			}
			return v;
		},
		'C': function(data) {
			var res = {};
			var sym = parseToken(data);
			var inst = parseToken(data);
			return res[sym] = inst;
		},
		'o': function(data) {
			var res = {};
			var sym = parseToken(data);
			var ivars = r_ivar(data);
			return sym;
		}
	};
	
	var parseToken = function(data) {
		var token = r_char(data);
		if (debug) console.log(["Parsing token", data, token, data.pos, data.val[data.pos - 1] ]);
		var res = transforms[token](data);
		if (debug) console.log(res);
		return res;
	};
	
	var _unmarshal = function(val) {
		var res = [];
		var data = { pos: 0, val: val }
		var major = r_byte(data);
		var minor = r_byte(data);
		symbols = [];
		
		if (major != marshal_major || minor > marshal_minor) throw "Invalid version (expected " + marshal_major + "," + marshal_minor + "), (got " + major + "," + minor + ")"; 
		
		while (data.pos < data.val.length) {
			res.push(parseToken(data));
		}
		
		return res;
	}
	
	return {
		load: function(val) {
			return _unmarshal(val);
		}
	}
})();

module.exports = Marshal;