Unpacking structures without eval

[wirelyre]

My environment disallows eval and variants. It fails to construct a function at runtime (line 444):

msgpackr/unpack.js

Lines 441 to 455 in 3a6c46e

 function readObject() { 
 	// This initial function is quick to instantiate, but runs slower. After several iterations pay the cost to build the faster function 
 	if (readObject.count++ > 2) { 
 		let readObject = structure.read = (new Function('r', 'return function(){return {' + structure.map(key => validName.test(key) ? key + ':r()' : ('[' + JSON.stringify(key) + ']:r()')).join(',') + '}}'))(read) 
 		if (structure.highByte === 0) 
 			structure.read = createSecondByteReader(firstId, structure.read) 
 		return readObject() // second byte is already read, if there is one so immediately read object 
 	} 
 	let object = {} 
 	for (let i = 0, l = structure.length; i < l; i++) { 
 		let key = structure[i] 
 		object[key] = read() 
 	} 
 	return object 
 } 

Is there a configuration option to just use the slow path? I'd like to keep using the record extension to save space — I'm assuming it's probably still faster than decoding a regular map anyway.

[Kris Zyp]

Yeah, that seems reasonable to support. Would this need a configuration option, or can these be detected automatically? That is, does a test call like new Function('') throw an error in your environment, that can be caught to detect that eval-variants are disallowed and automatically opt of using it?

[wirelyre]

I didn't think of that!

Yes, it throws an EvalError, and yes, it can be caught.

[wirelyre]

Brilliant: fixed in 2c84ce6, works perfectly.

Thank you so much!

[Kris Zyp]

Thanks for verifying. Published in v1.5.5.