OperatorOverloading

//: Playground - noun: a place where people can play
// From: http://www.raywenderlich.com/80818/operator-overloading-in-swift-tutorial

import UIKit

var str = "Hello, playground"
/**********************************************************************
* These are some of the basic ways to overload an operator. 
* The first example is for overloading an existing operator
* The second is creating your own operator
***********************************************************************/
var array = [1, 2, 3]
var array2 = [1, 2, 3]


/**********************************************************************
* Here we are overloading the '+' operator
* the "left:" and "right:" are the parameters used to specify how you
* will treat the expression to the left of the operator and the expression
* to the right of the operator
***********************************************************************/

func +(left: [Int], right: [Int]) -> [Int] { // 1  -overloading the '+' operator with two int arrays given and one int array returned
    var sum = [Int]() // 2   -creating the return array
    assert(left.count == right.count, "vector of same length only")  // 3   -make sure that there's equal amount of values in both arrays
    for (key, _) in left.enumerate() {
        sum.append(left[key] + right[key]) // 4
      
    }
    return sum
}



var array3 = array + array2


/**********************************************************************
* Creating your own operator
* infix specifies that the operator will be used between the expressions
* the "precedence" is the priority it has over other operators
* There is probably another location where it lists it, but here are
* the numerical values:
* http://stackoverflow.com/questions/28328697/what-are-the-precedence-levels-of-the-swift-operators
* You can also type "import Swift" into XCode, command click "Swift", and 
* it'll show the list of operators with their associated presedence
* values.
* The associativity means they associate with the expression to
* the left or right
***********************************************************************/

infix operator ⊕ { associativity left precedence 140 } // 1  -
func ⊕(left: [Int], right: [Int]) -> [Int] { // 2
    var sum = [Int](count: left.count, repeatedValue: 0)
    assert(left.count == right.count, "vector of same length only")
    for (key, _) in left.enumerate() {
        sum[key] = left[key] + right[key]
    }
    return sum
}
var sumArray = [1, 2, 3] ⊕ [1, 2, 3]