From 692d51e286a72aee300e3c4e4bdafab77f2b4f5a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Th=C3=BCm?= <thomas.thuem@uni-ulm.de>
Date: Sun, 13 Dec 2020 00:33:06 +0100
Subject: [PATCH 01/10] feat: Add multiplication and its generalization called
 expression

Resolves #1
---
 .../de/uulm/sp/swt/profcalculator/Add.java    | 10 +++------
 .../sp/swt/profcalculator/Expression.java     | 15 +++++++++++++
 .../sp/swt/profcalculator/Multiplication.java | 18 ++++++++++++++++
 .../sp/swt/profcalculator/ProfCalculator.java | 21 ++++++++++++-------
 4 files changed, 50 insertions(+), 14 deletions(-)
 create mode 100644 ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java
 create mode 100644 ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java

diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Add.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Add.java
index d557740..fca66f5 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Add.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Add.java
@@ -1,9 +1,8 @@
 package de.uulm.sp.swt.profcalculator;
 
-public class Add {
+// TODO rename class Add into Addition
+public class Add extends Expression {
 	
-	public Value l, r;
-
 	public Add(Value l, Value r) {
 		this.l = l;
 		this.r = r;
@@ -16,8 +15,5 @@ public String toString() {
 	public int evaluate() {
 		return l.getValue() + r.getValue();
 	}
-
-	public String computeEquation() {
-		return toString() + " = " + evaluate();
-	}
+	
 }
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java
new file mode 100644
index 0000000..0075ceb
--- /dev/null
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java
@@ -0,0 +1,15 @@
+package de.uulm.sp.swt.profcalculator;
+
+public abstract class Expression {
+
+	// TODO rename l and r to left and right
+	public Value l;
+	public Value r;
+
+	public abstract int evaluate();
+
+	public String computeEquation() {
+		return toString() + " = " + evaluate();
+	}
+
+}
\ No newline at end of file
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java
new file mode 100644
index 0000000..6fa8cc8
--- /dev/null
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java
@@ -0,0 +1,18 @@
+package de.uulm.sp.swt.profcalculator;
+
+public class Multiplication extends Expression {
+
+	public Multiplication(Value l, Value r) {
+		this.l = l;
+		this.r = r;
+	}
+
+	public String toString() {
+		return l.toString() + " * " + r.toString();
+	}
+
+	public int evaluate() {
+		return l.getValue() * r.getValue();
+	}
+	
+}
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
index 0e2930e..e73ad8f 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
@@ -16,13 +16,14 @@ public class ProfCalculator	extends Application implements EventHandler<ActionEv
 
 	private final static Value DEFAULT_VALUE = new Value(0);
 
-	private Add addition = new Add(DEFAULT_VALUE, DEFAULT_VALUE);
+	private Expression expression = new Add(DEFAULT_VALUE, DEFAULT_VALUE);
 
 	private Label errorLabel = new Label();
 
 	private TextField inputField = new TextField();
 
-	private Button addButton = new Button("+");
+	private Button additionButton = new Button("+");
+	private Button multiplicationButton = new Button("*");
 
 	private Label resultLabel = new Label();
 
@@ -31,13 +32,14 @@ public void start(Stage stage) throws Exception {
 		stage.setTitle("Professorial Calculator");
 		errorLabel.setTextFill(Color.web("#AA0000"));
 
-		VBox layout = new VBox(10, errorLabel, inputField, addButton, resultLabel);
+		VBox layout = new VBox(10, errorLabel, inputField, additionButton, multiplicationButton, resultLabel);
 		layout.setPadding(new Insets(20, 80, 20, 80));
 		Scene scene = new Scene(layout);
 
 		stage.setScene(scene);
 		stage.show();
-		addButton.setOnAction(this);
+		additionButton.setOnAction(this);
+		multiplicationButton.setOnAction(this);
 		updateGUI();
 	}
 
@@ -45,8 +47,13 @@ public void start(Stage stage) throws Exception {
 	public void handle(ActionEvent event) {
 		try {
 			int newValue = Integer.parseInt(inputField.getText());
-			int oldResult = addition.evaluate();
-			addition = new Add(new Value(oldResult), new Value(newValue));
+			int oldResult = expression.evaluate();
+			if (event.getSource() == additionButton) {
+				expression = new Add(new Value(oldResult), new Value(newValue));
+			}
+			else if (event.getSource() == multiplicationButton) {
+				expression = new Multiplication(new Value(oldResult), new Value(newValue));
+			}
 			updateGUI();
 			inputField.requestFocus();
 		} catch (NumberFormatException e) {
@@ -55,7 +62,7 @@ public void handle(ActionEvent event) {
 	}
 
 	private void updateGUI() {
-		resultLabel.setText(addition.computeEquation());
+		resultLabel.setText(expression.computeEquation());
 		inputField.setText("");
 		errorLabel.setText("");
 	}

From db6d74acfa00a38172133d21ab0794e446f3b3b6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Th=C3=BCm?= <thomas.thuem@uni-ulm.de>
Date: Sun, 13 Dec 2020 00:37:49 +0100
Subject: [PATCH 02/10] refactor: Rename class Add and its fields

---
 .../de/uulm/sp/swt/profcalculator/Add.java    | 19 -------------------
 .../uulm/sp/swt/profcalculator/Addition.java  | 18 ++++++++++++++++++
 .../sp/swt/profcalculator/Expression.java     |  5 ++---
 .../sp/swt/profcalculator/Multiplication.java | 10 +++++-----
 .../sp/swt/profcalculator/ProfCalculator.java |  4 ++--
 5 files changed, 27 insertions(+), 29 deletions(-)
 delete mode 100644 ProfCalculator/src/de/uulm/sp/swt/profcalculator/Add.java
 create mode 100644 ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java

diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Add.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Add.java
deleted file mode 100644
index fca66f5..0000000
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Add.java
+++ /dev/null
@@ -1,19 +0,0 @@
-package de.uulm.sp.swt.profcalculator;
-
-// TODO rename class Add into Addition
-public class Add extends Expression {
-	
-	public Add(Value l, Value r) {
-		this.l = l;
-		this.r = r;
-	}
-
-	public String toString() {
-		return l.toString() + " + " + r.toString();
-	}
-
-	public int evaluate() {
-		return l.getValue() + r.getValue();
-	}
-	
-}
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java
new file mode 100644
index 0000000..f7c3840
--- /dev/null
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java
@@ -0,0 +1,18 @@
+package de.uulm.sp.swt.profcalculator;
+
+public class Addition extends Expression {
+	
+	public Addition(Value left, Value right) {
+		this.left = left;
+		this.right = right;
+	}
+
+	public String toString() {
+		return left.toString() + " + " + right.toString();
+	}
+
+	public int evaluate() {
+		return left.getValue() + right.getValue();
+	}
+	
+}
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java
index 0075ceb..8dba35d 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java
@@ -2,9 +2,8 @@
 
 public abstract class Expression {
 
-	// TODO rename l and r to left and right
-	public Value l;
-	public Value r;
+	public Value left;
+	public Value right;
 
 	public abstract int evaluate();
 
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java
index 6fa8cc8..e56f4a3 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java
@@ -2,17 +2,17 @@
 
 public class Multiplication extends Expression {
 
-	public Multiplication(Value l, Value r) {
-		this.l = l;
-		this.r = r;
+	public Multiplication(Value left, Value right) {
+		this.left = left;
+		this.right = right;
 	}
 
 	public String toString() {
-		return l.toString() + " * " + r.toString();
+		return left.toString() + " * " + right.toString();
 	}
 
 	public int evaluate() {
-		return l.getValue() * r.getValue();
+		return left.getValue() * right.getValue();
 	}
 	
 }
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
index e73ad8f..d6a3151 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
@@ -16,7 +16,7 @@ public class ProfCalculator	extends Application implements EventHandler<ActionEv
 
 	private final static Value DEFAULT_VALUE = new Value(0);
 
-	private Expression expression = new Add(DEFAULT_VALUE, DEFAULT_VALUE);
+	private Expression expression = new Addition(DEFAULT_VALUE, DEFAULT_VALUE);
 
 	private Label errorLabel = new Label();
 
@@ -49,7 +49,7 @@ public void handle(ActionEvent event) {
 			int newValue = Integer.parseInt(inputField.getText());
 			int oldResult = expression.evaluate();
 			if (event.getSource() == additionButton) {
-				expression = new Add(new Value(oldResult), new Value(newValue));
+				expression = new Addition(new Value(oldResult), new Value(newValue));
 			}
 			else if (event.getSource() == multiplicationButton) {
 				expression = new Multiplication(new Value(oldResult), new Value(newValue));

From b3dd5b033e4405984665b2bc290c37a4d431f47c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Th=C3=BCm?= <thomas.thuem@uni-ulm.de>
Date: Wed, 16 Dec 2020 18:39:50 +0100
Subject: [PATCH 03/10] refactor: Push down fields from class Expression

---
 ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java | 3 +++
 .../src/de/uulm/sp/swt/profcalculator/Expression.java          | 3 ---
 .../src/de/uulm/sp/swt/profcalculator/Multiplication.java      | 3 +++
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java
index f7c3840..298a3b3 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java
@@ -2,6 +2,9 @@
 
 public class Addition extends Expression {
 	
+	public Value left;
+	public Value right;
+
 	public Addition(Value left, Value right) {
 		this.left = left;
 		this.right = right;
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java
index 8dba35d..f0e4d17 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java
@@ -2,9 +2,6 @@
 
 public abstract class Expression {
 
-	public Value left;
-	public Value right;
-
 	public abstract int evaluate();
 
 	public String computeEquation() {
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java
index e56f4a3..b7b896b 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java
@@ -2,6 +2,9 @@
 
 public class Multiplication extends Expression {
 
+	public Value left;
+	public Value right;
+
 	public Multiplication(Value left, Value right) {
 		this.left = left;
 		this.right = right;

From 63d059b7c6d3f8f6dd6a3dfba116a6ce64ee0111 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Th=C3=BCm?= <thomas.thuem@uni-ulm.de>
Date: Wed, 16 Dec 2020 18:45:35 +0100
Subject: [PATCH 04/10] feat: Show complete computation as formula

---
 .../src/de/uulm/sp/swt/profcalculator/Addition.java       | 8 ++++----
 .../src/de/uulm/sp/swt/profcalculator/Multiplication.java | 8 ++++----
 .../src/de/uulm/sp/swt/profcalculator/ProfCalculator.java | 7 +++----
 .../src/de/uulm/sp/swt/profcalculator/Value.java          | 6 ++++--
 4 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java
index 298a3b3..a994ff0 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java
@@ -2,10 +2,10 @@
 
 public class Addition extends Expression {
 	
-	public Value left;
-	public Value right;
+	public Expression left;
+	public Expression right;
 
-	public Addition(Value left, Value right) {
+	public Addition(Expression left, Expression right) {
 		this.left = left;
 		this.right = right;
 	}
@@ -15,7 +15,7 @@ public String toString() {
 	}
 
 	public int evaluate() {
-		return left.getValue() + right.getValue();
+		return left.evaluate() + right.evaluate();
 	}
 	
 }
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java
index b7b896b..758447d 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java
@@ -2,10 +2,10 @@
 
 public class Multiplication extends Expression {
 
-	public Value left;
-	public Value right;
+	public Expression left;
+	public Expression right;
 
-	public Multiplication(Value left, Value right) {
+	public Multiplication(Expression left, Expression right) {
 		this.left = left;
 		this.right = right;
 	}
@@ -15,7 +15,7 @@ public String toString() {
 	}
 
 	public int evaluate() {
-		return left.getValue() * right.getValue();
+		return left.evaluate() * right.evaluate();
 	}
 	
 }
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
index d6a3151..47ee734 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
@@ -16,7 +16,7 @@ public class ProfCalculator	extends Application implements EventHandler<ActionEv
 
 	private final static Value DEFAULT_VALUE = new Value(0);
 
-	private Expression expression = new Addition(DEFAULT_VALUE, DEFAULT_VALUE);
+	private Expression expression = DEFAULT_VALUE;
 
 	private Label errorLabel = new Label();
 
@@ -47,12 +47,11 @@ public void start(Stage stage) throws Exception {
 	public void handle(ActionEvent event) {
 		try {
 			int newValue = Integer.parseInt(inputField.getText());
-			int oldResult = expression.evaluate();
 			if (event.getSource() == additionButton) {
-				expression = new Addition(new Value(oldResult), new Value(newValue));
+				expression = new Addition(expression, new Value(newValue));
 			}
 			else if (event.getSource() == multiplicationButton) {
-				expression = new Multiplication(new Value(oldResult), new Value(newValue));
+				expression = new Multiplication(expression, new Value(newValue));
 			}
 			updateGUI();
 			inputField.requestFocus();
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Value.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Value.java
index 85e75c7..dc30780 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Value.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Value.java
@@ -1,6 +1,6 @@
 package de.uulm.sp.swt.profcalculator;
 
-public class Value {
+public class Value extends Expression {
 
 	Integer value;
 
@@ -12,7 +12,9 @@ public String toString() {
 		return value.toString();
 	}
 
-	public int getValue() {
+	@Override
+	public int evaluate() {
 		return value.intValue();
 	}
+
 }

From 5cf747293a539f944187d00ad150418d18b10a2e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Th=C3=BCm?= <thomas.thuem@uni-ulm.de>
Date: Wed, 16 Dec 2020 18:47:10 +0100
Subject: [PATCH 05/10] refactor: Move classes into a new subpackage for
 expressions

---
 .../src/de/uulm/sp/swt/profcalculator/ProfCalculator.java     | 4 ++++
 .../sp/swt/profcalculator/{ => expressions}/Addition.java     | 2 +-
 .../sp/swt/profcalculator/{ => expressions}/Expression.java   | 2 +-
 .../swt/profcalculator/{ => expressions}/Multiplication.java  | 2 +-
 .../uulm/sp/swt/profcalculator/{ => expressions}/Value.java   | 2 +-
 5 files changed, 8 insertions(+), 4 deletions(-)
 rename ProfCalculator/src/de/uulm/sp/swt/profcalculator/{ => expressions}/Addition.java (87%)
 rename ProfCalculator/src/de/uulm/sp/swt/profcalculator/{ => expressions}/Expression.java (75%)
 rename ProfCalculator/src/de/uulm/sp/swt/profcalculator/{ => expressions}/Multiplication.java (87%)
 rename ProfCalculator/src/de/uulm/sp/swt/profcalculator/{ => expressions}/Value.java (82%)

diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
index 47ee734..0bda3d8 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
@@ -1,5 +1,9 @@
 package de.uulm.sp.swt.profcalculator;
 
+import de.uulm.sp.swt.profcalculator.expressions.Addition;
+import de.uulm.sp.swt.profcalculator.expressions.Expression;
+import de.uulm.sp.swt.profcalculator.expressions.Multiplication;
+import de.uulm.sp.swt.profcalculator.expressions.Value;
 import javafx.application.Application;
 import javafx.event.ActionEvent;
 import javafx.event.EventHandler;
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Addition.java
similarity index 87%
rename from ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java
rename to ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Addition.java
index a994ff0..99a7a8a 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Addition.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Addition.java
@@ -1,4 +1,4 @@
-package de.uulm.sp.swt.profcalculator;
+package de.uulm.sp.swt.profcalculator.expressions;
 
 public class Addition extends Expression {
 	
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Expression.java
similarity index 75%
rename from ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java
rename to ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Expression.java
index f0e4d17..c2624ac 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Expression.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Expression.java
@@ -1,4 +1,4 @@
-package de.uulm.sp.swt.profcalculator;
+package de.uulm.sp.swt.profcalculator.expressions;
 
 public abstract class Expression {
 
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Multiplication.java
similarity index 87%
rename from ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java
rename to ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Multiplication.java
index 758447d..c1f3e2d 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Multiplication.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Multiplication.java
@@ -1,4 +1,4 @@
-package de.uulm.sp.swt.profcalculator;
+package de.uulm.sp.swt.profcalculator.expressions;
 
 public class Multiplication extends Expression {
 
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Value.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Value.java
similarity index 82%
rename from ProfCalculator/src/de/uulm/sp/swt/profcalculator/Value.java
rename to ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Value.java
index dc30780..41c5a07 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Value.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Value.java
@@ -1,4 +1,4 @@
-package de.uulm.sp.swt.profcalculator;
+package de.uulm.sp.swt.profcalculator.expressions;
 
 public class Value extends Expression {
 

From 37d0dac91b2dab40a69d2bc5ce0a8f67d221a070 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Th=C3=BCm?= <thomas.thuem@uni-ulm.de>
Date: Wed, 16 Dec 2020 19:11:44 +0100
Subject: [PATCH 06/10] feat: Add brackets to expressions when needed

---
 .../sp/swt/profcalculator/ProfCalculator.java |  2 ++
 .../profcalculator/expressions/Addition.java  |  4 +--
 .../expressions/Expression.java               |  6 +++++
 .../expressions/Multiplication.java           |  4 +--
 .../expressions/NecessaryBrackets.java        | 25 +++++++++++++++++++
 .../swt/profcalculator/expressions/Value.java |  2 +-
 6 files changed, 38 insertions(+), 5 deletions(-)
 create mode 100644 ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/NecessaryBrackets.java

diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
index 0bda3d8..51994b5 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
@@ -3,6 +3,7 @@
 import de.uulm.sp.swt.profcalculator.expressions.Addition;
 import de.uulm.sp.swt.profcalculator.expressions.Expression;
 import de.uulm.sp.swt.profcalculator.expressions.Multiplication;
+import de.uulm.sp.swt.profcalculator.expressions.NecessaryBrackets;
 import de.uulm.sp.swt.profcalculator.expressions.Value;
 import javafx.application.Application;
 import javafx.event.ActionEvent;
@@ -57,6 +58,7 @@ public void handle(ActionEvent event) {
 			else if (event.getSource() == multiplicationButton) {
 				expression = new Multiplication(expression, new Value(newValue));
 			}
+			expression = new NecessaryBrackets(expression);
 			updateGUI();
 			inputField.requestFocus();
 		} catch (NumberFormatException e) {
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Addition.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Addition.java
index 99a7a8a..290f903 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Addition.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Addition.java
@@ -10,8 +10,8 @@ public Addition(Expression left, Expression right) {
 		this.right = right;
 	}
 
-	public String toString() {
-		return left.toString() + " + " + right.toString();
+	public String toString(Expression parent) {
+		return left.toString(this) + " + " + right.toString(this);
 	}
 
 	public int evaluate() {
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Expression.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Expression.java
index c2624ac..2047d49 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Expression.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Expression.java
@@ -4,6 +4,12 @@ public abstract class Expression {
 
 	public abstract int evaluate();
 
+	public abstract String toString(Expression parent);
+
+	public String toString() {
+		return toString(null);
+	}
+
 	public String computeEquation() {
 		return toString() + " = " + evaluate();
 	}
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Multiplication.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Multiplication.java
index c1f3e2d..7256be3 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Multiplication.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Multiplication.java
@@ -10,8 +10,8 @@ public Multiplication(Expression left, Expression right) {
 		this.right = right;
 	}
 
-	public String toString() {
-		return left.toString() + " * " + right.toString();
+	public String toString(Expression parent) {
+		return left.toString(this) + " * " + right.toString(this);
 	}
 
 	public int evaluate() {
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/NecessaryBrackets.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/NecessaryBrackets.java
new file mode 100644
index 0000000..177b051
--- /dev/null
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/NecessaryBrackets.java
@@ -0,0 +1,25 @@
+package de.uulm.sp.swt.profcalculator.expressions;
+
+public class NecessaryBrackets extends Expression {
+
+	private Expression expression;
+
+	public NecessaryBrackets(Expression expression) {
+		this.expression = expression;
+	}
+	
+	@Override
+	public String toString(Expression parent) {
+		String childString = expression.toString(parent);
+		if (parent instanceof Multiplication && expression instanceof Addition) {
+			childString = "(" + childString + ")";
+		}
+		return childString;
+	}
+
+	@Override
+	public int evaluate() {
+		return expression.evaluate();
+	}
+
+}
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Value.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Value.java
index 41c5a07..c9f9ed6 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Value.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/Value.java
@@ -8,7 +8,7 @@ public Value(int value) {
 		this.value = value;
 	}
 
-	public String toString() {
+	public String toString(Expression parent) {
 		return value.toString();
 	}
 

From 1bf0a967ada84f5bab38ffaa490a3473a7f4e65e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Th=C3=BCm?= <thomas.thuem@uni-ulm.de>
Date: Wed, 16 Dec 2020 19:42:05 +0100
Subject: [PATCH 07/10] feat: Enable logging with the singleton pattern

---
 .../de/uulm/sp/swt/profcalculator/Logger.java | 23 +++++++++++++++++++
 .../sp/swt/profcalculator/ProfCalculator.java |  2 ++
 2 files changed, 25 insertions(+)
 create mode 100644 ProfCalculator/src/de/uulm/sp/swt/profcalculator/Logger.java

diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Logger.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Logger.java
new file mode 100644
index 0000000..8786ac8
--- /dev/null
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Logger.java
@@ -0,0 +1,23 @@
+package de.uulm.sp.swt.profcalculator;
+
+public class Logger {
+	
+	public static final boolean LOGGING = true;
+	
+	private static Logger logger = new Logger();
+
+	private Logger() {
+		log("Logging enabled");
+	}
+
+	public void log(String message) {
+		if (LOGGING) {
+			System.out.println(message);
+		}
+	}
+	
+	public static Logger getLogger() {
+		return logger;
+	}
+
+}
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
index 51994b5..e6ceb82 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
@@ -54,9 +54,11 @@ public void handle(ActionEvent event) {
 			int newValue = Integer.parseInt(inputField.getText());
 			if (event.getSource() == additionButton) {
 				expression = new Addition(expression, new Value(newValue));
+				Logger.getLogger().log("+ " + newValue);
 			}
 			else if (event.getSource() == multiplicationButton) {
 				expression = new Multiplication(expression, new Value(newValue));
+				Logger.getLogger().log("* " + newValue);
 			}
 			expression = new NecessaryBrackets(expression);
 			updateGUI();

From 6164eb5a4e6c0b8b8f1b690834c7486b93cce311 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Th=C3=BCm?= <thomas.thuem@uni-ulm.de>
Date: Wed, 16 Dec 2020 20:09:33 +0100
Subject: [PATCH 08/10] feat: Allow to change the visual style of the
 calculator

---
 .../sp/swt/profcalculator/ProfCalculator.java | 12 ++++++---
 .../gui/BlueFontGUIFactory.java               | 26 +++++++++++++++++++
 .../sp/swt/profcalculator/gui/GUIFactory.java | 12 +++++++++
 .../gui/LargeFontGUIFactory.java              | 25 ++++++++++++++++++
 4 files changed, 71 insertions(+), 4 deletions(-)
 create mode 100644 ProfCalculator/src/de/uulm/sp/swt/profcalculator/gui/BlueFontGUIFactory.java
 create mode 100644 ProfCalculator/src/de/uulm/sp/swt/profcalculator/gui/GUIFactory.java
 create mode 100644 ProfCalculator/src/de/uulm/sp/swt/profcalculator/gui/LargeFontGUIFactory.java

diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
index e6ceb82..8f7fb4f 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
@@ -5,6 +5,8 @@
 import de.uulm.sp.swt.profcalculator.expressions.Multiplication;
 import de.uulm.sp.swt.profcalculator.expressions.NecessaryBrackets;
 import de.uulm.sp.swt.profcalculator.expressions.Value;
+import de.uulm.sp.swt.profcalculator.gui.BlueFontGUIFactory;
+import de.uulm.sp.swt.profcalculator.gui.GUIFactory;
 import javafx.application.Application;
 import javafx.event.ActionEvent;
 import javafx.event.EventHandler;
@@ -22,15 +24,17 @@ public class ProfCalculator	extends Application implements EventHandler<ActionEv
 	private final static Value DEFAULT_VALUE = new Value(0);
 
 	private Expression expression = DEFAULT_VALUE;
+	
+	private GUIFactory guiFactory = new BlueFontGUIFactory();
 
-	private Label errorLabel = new Label();
+	private Label errorLabel = guiFactory.createLabel();
 
 	private TextField inputField = new TextField();
 
-	private Button additionButton = new Button("+");
-	private Button multiplicationButton = new Button("*");
+	private Button additionButton = guiFactory.createButton("+");
+	private Button multiplicationButton = guiFactory.createButton("*");
 
-	private Label resultLabel = new Label();
+	private Label resultLabel = guiFactory.createLabel();
 
 	@Override
 	public void start(Stage stage) throws Exception {
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/gui/BlueFontGUIFactory.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/gui/BlueFontGUIFactory.java
new file mode 100644
index 0000000..2895784
--- /dev/null
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/gui/BlueFontGUIFactory.java
@@ -0,0 +1,26 @@
+package de.uulm.sp.swt.profcalculator.gui;
+
+import javafx.scene.control.Button;
+import javafx.scene.control.Label;
+import javafx.scene.paint.Color;
+import javafx.scene.text.Font;
+
+public class BlueFontGUIFactory implements GUIFactory {
+	
+	final static Color BLUE = Color.web("#0000AA");
+	
+	@Override
+	public Label createLabel() {
+		Label label = new Label();
+		label.setTextFill(BLUE);
+		return label;
+	}
+
+	@Override
+	public Button createButton(String title) {
+		Button button = new Button(title);
+		button.setTextFill(BLUE);
+		return button;
+	}
+
+}
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/gui/GUIFactory.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/gui/GUIFactory.java
new file mode 100644
index 0000000..146d358
--- /dev/null
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/gui/GUIFactory.java
@@ -0,0 +1,12 @@
+package de.uulm.sp.swt.profcalculator.gui;
+
+import javafx.scene.control.Button;
+import javafx.scene.control.Label;
+
+public interface GUIFactory {
+
+	Label createLabel();
+
+	Button createButton(String title);
+
+}
\ No newline at end of file
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/gui/LargeFontGUIFactory.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/gui/LargeFontGUIFactory.java
new file mode 100644
index 0000000..f482bb3
--- /dev/null
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/gui/LargeFontGUIFactory.java
@@ -0,0 +1,25 @@
+package de.uulm.sp.swt.profcalculator.gui;
+
+import javafx.scene.control.Button;
+import javafx.scene.control.Label;
+import javafx.scene.text.Font;
+
+public class LargeFontGUIFactory implements GUIFactory {
+	
+	final static Font FONT = new Font("Arial", 24);
+	
+	@Override
+	public Label createLabel() {
+		Label label = new Label();
+		label.setFont(FONT);
+		return label;
+	}
+
+	@Override
+	public Button createButton(String title) {
+		Button button = new Button(title);
+		button.setFont(FONT);
+		return button;
+	}
+
+}

From 8c0298a9713b5c91b1ee6a73092360216850e988 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Th=C3=BCm?= <thomas.thuem@uni-ulm.de>
Date: Wed, 16 Dec 2020 20:43:08 +0100
Subject: [PATCH 09/10] feat: Increase the default value by one every second

---
 .../sp/swt/profcalculator/ProfCalculator.java |  8 ++---
 .../expressions/CounterValue.java             | 33 +++++++++++++++++++
 2 files changed, 37 insertions(+), 4 deletions(-)
 create mode 100644 ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/CounterValue.java

diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
index 8f7fb4f..3018f37 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
@@ -1,6 +1,8 @@
 package de.uulm.sp.swt.profcalculator;
 
 import de.uulm.sp.swt.profcalculator.expressions.Addition;
+import de.uulm.sp.swt.profcalculator.expressions.CounterValue;
+import de.uulm.sp.swt.profcalculator.expressions.CounterValue;
 import de.uulm.sp.swt.profcalculator.expressions.Expression;
 import de.uulm.sp.swt.profcalculator.expressions.Multiplication;
 import de.uulm.sp.swt.profcalculator.expressions.NecessaryBrackets;
@@ -21,9 +23,7 @@
 
 public class ProfCalculator	extends Application implements EventHandler<ActionEvent> {
 
-	private final static Value DEFAULT_VALUE = new Value(0);
-
-	private Expression expression = DEFAULT_VALUE;
+	private Expression expression = new CounterValue(this);
 	
 	private GUIFactory guiFactory = new BlueFontGUIFactory();
 
@@ -72,7 +72,7 @@ else if (event.getSource() == multiplicationButton) {
 		}
 	}
 
-	private void updateGUI() {
+	public void updateGUI() {
 		resultLabel.setText(expression.computeEquation());
 		inputField.setText("");
 		errorLabel.setText("");
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/CounterValue.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/CounterValue.java
new file mode 100644
index 0000000..8ba1c98
--- /dev/null
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/CounterValue.java
@@ -0,0 +1,33 @@
+package de.uulm.sp.swt.profcalculator.expressions;
+
+import de.uulm.sp.swt.profcalculator.ProfCalculator;
+import javafx.application.Platform;
+
+public class CounterValue extends Value implements Runnable {
+	
+	private ProfCalculator calc;
+
+	public CounterValue(ProfCalculator calc) {
+		super(0);
+		this.calc = calc;
+		new Thread(this).start();
+	}
+
+	@Override
+	public void run() {
+		while (value < 10) {
+			try {
+				Thread.sleep(1000);
+			} catch (InterruptedException e) {
+			}
+			value++;
+			Platform.runLater(new Runnable() {
+				@Override
+				public void run() {
+					calc.updateGUI();
+				}
+			});
+		}
+	}
+
+}

From 547cf043b8610127142ad01a387ee98e508ce8a3 Mon Sep 17 00:00:00 2001
From: Simon Schall <simon-1.schall@uni-ulm.de>
Date: Sat, 17 Jul 2021 22:39:06 +0200
Subject: [PATCH 10/10] add observer pattern to avoid explicit reference to
 calculator in CounterValue

---
 .../uulm/sp/swt/profcalculator/Observer.java  |  5 ++++
 .../sp/swt/profcalculator/ProfCalculator.java |  7 ++++-
 .../uulm/sp/swt/profcalculator/Subject.java   |  7 +++++
 .../expressions/CounterValue.java             | 29 ++++++++++++++++---
 4 files changed, 43 insertions(+), 5 deletions(-)
 create mode 100644 ProfCalculator/src/de/uulm/sp/swt/profcalculator/Observer.java
 create mode 100644 ProfCalculator/src/de/uulm/sp/swt/profcalculator/Subject.java

diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Observer.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Observer.java
new file mode 100644
index 0000000..9d01f2d
--- /dev/null
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Observer.java
@@ -0,0 +1,5 @@
+package de.uulm.sp.swt.profcalculator;
+
+public interface Observer {
+	void update();
+}
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
index 3018f37..9ccbfa7 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/ProfCalculator.java
@@ -21,7 +21,7 @@
 import javafx.scene.paint.Color;
 import javafx.stage.Stage;
 
-public class ProfCalculator	extends Application implements EventHandler<ActionEvent> {
+public class ProfCalculator	extends Application implements EventHandler<ActionEvent>, Observer {
 
 	private Expression expression = new CounterValue(this);
 	
@@ -82,4 +82,9 @@ public static void main(String[] args) {
 		launch(args);
 	}
 
+	@Override
+	public void update() {
+		updateGUI();
+	}
+
 }
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Subject.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Subject.java
new file mode 100644
index 0000000..dabadaf
--- /dev/null
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/Subject.java
@@ -0,0 +1,7 @@
+package de.uulm.sp.swt.profcalculator;
+
+public interface Subject {
+	void register(Observer observer);
+	void unregister(Observer observer);
+	void notifyObservers();
+}
diff --git a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/CounterValue.java b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/CounterValue.java
index 8ba1c98..3b402ae 100644
--- a/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/CounterValue.java
+++ b/ProfCalculator/src/de/uulm/sp/swt/profcalculator/expressions/CounterValue.java
@@ -1,15 +1,19 @@
 package de.uulm.sp.swt.profcalculator.expressions;
 
+import java.util.LinkedList;
+
+import de.uulm.sp.swt.profcalculator.Observer;
 import de.uulm.sp.swt.profcalculator.ProfCalculator;
+import de.uulm.sp.swt.profcalculator.Subject;
 import javafx.application.Platform;
 
-public class CounterValue extends Value implements Runnable {
+public class CounterValue extends Value implements Runnable, Subject {
 	
-	private ProfCalculator calc;
+	private LinkedList<Observer> observerList = new LinkedList<Observer>();
 
 	public CounterValue(ProfCalculator calc) {
 		super(0);
-		this.calc = calc;
+		observerList.add(calc);
 		new Thread(this).start();
 	}
 
@@ -24,10 +28,27 @@ public void run() {
 			Platform.runLater(new Runnable() {
 				@Override
 				public void run() {
-					calc.updateGUI();
+					notifyObservers();
 				}
 			});
 		}
 	}
 
+	@Override
+	public void register(Observer observer) {
+		observerList.add(observer);
+	}
+
+	@Override
+	public void unregister(Observer observer) {
+		observerList.remove(observer);
+	}
+
+	@Override
+	public void notifyObservers() {
+		for(int i=0;i<observerList.size();i++) {
+			observerList.get(i).update();
+		}
+	}
+
 }