Applications: Move to Userland/Applications/

Userland/Applications/Calculator/Calculator.h

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+/*
+ * Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+// This type implements the regular calculator
+// behavior, such as performing arithmetic
+// operations and providing a memory cell.
+// It does not deal with number input; you
+// have to pass in already parsed double
+// values.
+
+class Calculator final {
+public:
+    Calculator();
+    ~Calculator();
+
+    enum class Operation {
+        None,
+        Add,
+        Subtract,
+        Multiply,
+        Divide,
+
+        Sqrt,
+        Inverse,
+        Percent,
+        ToggleSign,
+
+        MemClear,
+        MemRecall,
+        MemSave,
+        MemAdd
+    };
+
+    double begin_operation(Operation, double);
+    double finish_operation(double);
+
+    bool has_error() const { return m_has_error; }
+
+    void clear_operation();
+    void clear_error() { m_has_error = false; }
+
+private:
+    Operation m_operation_in_progress { Operation::None };
+    double m_saved_argument { 0.0 };
+    double m_mem { 0.0 };
+    bool m_has_error { false };
+};