From 20f017b1ec956af6bfb590c7f3f358e330db8acd Mon Sep 17 00:00:00 2001
From: Peter Vanhoef <petervanhoef@MacBook-Pro-van-Peter.local>
Date: Sun, 11 Jun 2017 20:33:17 +0200
Subject: [PATCH] Implements extra credit 6 (see #18)

---
 .../Calculator/Base.lproj/Main.storyboard     |  6 +--
 Calculator/Calculator/CalculatorBrain.swift   | 34 +++++++++++++++
 .../Calculator/CalculatorViewController.swift | 41 ++++++++++++++++++-
 Calculator/Calculator/Keys.swift              |  1 +
 4 files changed, 78 insertions(+), 4 deletions(-)

diff --git a/Calculator/Calculator/Base.lproj/Main.storyboard b/Calculator/Calculator/Base.lproj/Main.storyboard
index 7ef522f..6516c6d 100755
--- a/Calculator/Calculator/Base.lproj/Main.storyboard
+++ b/Calculator/Calculator/Base.lproj/Main.storyboard
@@ -1,11 +1,11 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="12120" systemVersion="16F73" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" colorMatched="YES" initialViewController="fcY-c8-IEH">
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="12121" systemVersion="16F73" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" colorMatched="YES" initialViewController="fcY-c8-IEH">
     <device id="retina4_7" orientation="portrait">
         <adaptation id="fullscreen"/>
     </device>
     <dependencies>
         <deployment identifier="iOS"/>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="12088"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="12089"/>
         <capability name="Constraints to layout margins" minToolsVersion="6.0"/>
         <capability name="Constraints with non-1.0 multipliers" minToolsVersion="5.1"/>
         <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
@@ -529,6 +529,6 @@
         </scene>
     </scenes>
     <inferredMetricsTieBreakers>
-        <segue reference="Zbq-q6-BA9"/>
+        <segue reference="jyr-Pc-8eS"/>
     </inferredMetricsTieBreakers>
 </document>
diff --git a/Calculator/Calculator/CalculatorBrain.swift b/Calculator/Calculator/CalculatorBrain.swift
index a98083e..f32ed53 100755
--- a/Calculator/Calculator/CalculatorBrain.swift
+++ b/Calculator/Calculator/CalculatorBrain.swift
@@ -181,4 +181,38 @@ struct CalculatorBrain {
         }
         
     }
+    
+    var savedSequence: [AnyObject] {
+        get {
+            var encodedSequence = [AnyObject]()
+            for item in sequence {
+                switch item {
+                case .operand(let operand):
+                    encodedSequence.append(operand as AnyObject)
+                case .operation(let operation):
+                    encodedSequence.append(operation as AnyObject)
+                case .variable(let variable):
+                    encodedSequence.append(variable as AnyObject)
+                }
+            }
+            return encodedSequence
+        }
+        set {
+            var decodedSequence = [ExpressionLiteral]()
+            for item in newValue {
+                if let operand = item as? Double {
+                    decodedSequence.append(.operand(operand))
+                } else {
+                    if let name = item as? String {
+                        if operations[name] != nil {
+                            decodedSequence.append(.operation(name))
+                        } else {
+                            decodedSequence.append(.variable(name))
+                        }
+                    }
+                }
+            }
+            sequence = decodedSequence
+        }
+    }
 }
diff --git a/Calculator/Calculator/CalculatorViewController.swift b/Calculator/Calculator/CalculatorViewController.swift
index 35f6364..4d5d97a 100755
--- a/Calculator/Calculator/CalculatorViewController.swift
+++ b/Calculator/Calculator/CalculatorViewController.swift
@@ -125,7 +125,46 @@ class CalculatorViewController: UIViewController {
         brain.setOperand(variable: symbol)
         displays = brain.evaluateWithErrorReport(using: dictionary)
     }
-    
+  
+    private let defaults = UserDefaults.standard
+
+    private var savedSequence: [AnyObject]? {
+        get {
+            return defaults.value(forKey: Keys.savedSequence) as? [AnyObject]
+        }
+        set {
+            defaults.set(newValue, forKey: Keys.savedSequence)
+        }
+    }
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+
+        // Do any additional setup after loading the view.
+        if savedSequence != nil {
+            brain.savedSequence = savedSequence!
+            displays = brain.evaluateWithErrorReport(using: dictionary)
+
+            var viewController = splitViewController?.viewControllers.last
+            if let navigationController = viewController as? UINavigationController {
+                viewController = navigationController.visibleViewController
+            }
+            if let graphingViewController = viewController as? GraphingViewController {
+                graphingViewController.unaryFunction = { [weak weakSelf = self] operand in
+                    let graphingDictionary: [String: Double] = ["M": operand]
+                    return weakSelf?.brain.evaluate(using: graphingDictionary).result }
+                graphingViewController.navigationItem.title = self.brain.evaluate().description
+            }
+        }
+    }
+
+    override func viewWillDisappear(_ animated: Bool) {
+        super.viewWillDisappear(animated)
+        
+        if !brain.evaluate(using: dictionary).isPending {
+            savedSequence = brain.savedSequence
+        }
+    }
     
     // MARK: - Navigation
     
diff --git a/Calculator/Calculator/Keys.swift b/Calculator/Calculator/Keys.swift
index a40487a..c254faa 100644
--- a/Calculator/Calculator/Keys.swift
+++ b/Calculator/Calculator/Keys.swift
@@ -11,4 +11,5 @@ import Foundation
 struct Keys {
         static let scale = "scale"
         static let origin = "origin"
+        static let savedSequence = "savedSequence"
 }