Add Tristate#toBoolean method

base/src/main/java/de/staropensource/sosengine/base/exceptions/TristateConversionException.java

@@ -0,0 +1,36 @@
+/*
+ * STAROPENSOURCE ENGINE SOURCE FILE
+ * Copyright (c) 2024 The StarOpenSource Engine Contributors
+ * Licensed under the GNU Affero General Public License v3
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package de.staropensource.sosengine.base.exceptions;
+
+import de.staropensource.sosengine.base.types.Tristate;
+
+/**
+ * Thrown when converting a {@link Tristate} into a boolean fails.
+ * <p>
+ * This exception inherits {@link RuntimeException} on purpose, as sometimes
+ * you expect or have already validated the {@link Tristate} not being {@link Tristate#UNSET}.
+ *
+ * @since v1-alpha2
+ */
+public class TristateConversionException extends RuntimeException {
+    public TristateConversionException() {
+        super("Can't convert Tristate.UNSET into a boolean");
+    }
+}

base/src/main/java/de/staropensource/sosengine/base/types/Tristate.java

@@ -19,6 +19,9 @@
 
 package de.staropensource.sosengine.base.types;
 
+import de.staropensource.sosengine.base.exceptions.TristateConversionException;
+import org.jetbrains.annotations.NotNull;
+
 /**
  * tl;dr just a boolean but it can be UNSET too.
  *
@@ -45,5 +48,20 @@ public enum Tristate {
      *
      * @since v1-alpha1
      */
-    FALSE
+    FALSE;
+
+    /**
+     * Converts a {@link Tristate} into a boolean.
+     *
+     * @return booleanized {@link Tristate}
+     * @throws TristateConversionException when encountering {@link #UNSET}.
+     * @since v1-alpha2
+     */
+    public static boolean toBoolean(@NotNull Tristate tristate) {
+        return switch (tristate) {
+            case UNSET -> throw new TristateConversionException();
+            case TRUE -> true;
+            case FALSE -> false;
+        };
+    }
 }