parseSignature breaks on zero input params

[kumavis]

src: https://github.com/ethereumjs/ethereumjs-abi/blob/master/lib/index.js#L81-L83

works

/^(\w+)\((.+)\)$/.exec('hi(bytes)')
["hi(bytes)", "hi", "bytes"]

breaks

/^(\w+)\((.+)\)$/.exec('hi()')
null

[kumavis]

this seems to work, will PR

// someMethod()
// someMethod(bytes,uint)
// someMethod(bytes,uint):(boolean)
function parseSignature (sigString) {
  var methodEndIndex = sigString.indexOf('(')
  if (methodEndIndex === -1) {
    throw new Error('Invalid method signature')
  }
  var methodName = sigString.slice(0,methodEndIndex)
  var allArgs = sigString.slice(methodEndIndex+1,-1)
  var [ inputArgs, outputArgs ] = allArgs.split(':')

  return {
    method: methodName,
    args: (inputArgs ? inputArgs.split(',') : []),
    retargs: (outputArgs ? outputArgs.split(',') : null),
  }
}

[mcgwiz]

In order to handle "someMethod():(boolean)" you might consider changing

var [ inputArgs, outputArgs ] = allArgs.split(':')

to

var [ inputArgs, outputArgs ] = allArgs.split('):(')