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https://github.com/RGBCube/serenity
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53eb35caba
The purpose of this patch is to support addition, subtraction, multiplication and division without using conversion to double. To this end, we use the BigFraction class of LibCrypto. With this solution, we can store values without any losses and forward rounding as the last step before displaying.
138 lines
3.8 KiB
C++
138 lines
3.8 KiB
C++
/*
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* Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
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* Copyright (c) 2021, Max Wipfli <mail@maxwipfli.ch>
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* Copyright (c) 2022, the SerenityOS developers.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include "Keypad.h"
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#include <AK/StringBuilder.h>
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#include <LibCrypto/BigFraction/BigFraction.h>
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#include <LibCrypto/BigInt/UnsignedBigInteger.h>
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#include <LibCrypto/NumberTheory/ModularFunctions.h>
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void Keypad::type_digit(int digit)
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{
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switch (m_state) {
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case State::External:
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m_state = State::TypingInteger;
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m_int_value = digit;
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m_frac_value.set_to_0();
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m_frac_length.set_to_0();
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break;
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case State::TypingInteger:
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VERIFY(m_frac_value == 0);
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VERIFY(m_frac_length == 0);
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m_int_value.set_to(m_int_value.multiplied_by(10));
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m_int_value.set_to(m_int_value.plus(digit));
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break;
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case State::TypingDecimal:
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m_frac_value.set_to(m_frac_value.multiplied_by(10));
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m_frac_value.set_to(m_frac_value.plus(digit));
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m_frac_length.set_to(m_frac_length.plus(1));
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break;
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}
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}
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void Keypad::type_decimal_point()
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{
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switch (m_state) {
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case State::External:
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m_int_value.set_to_0();
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m_frac_value.set_to_0();
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m_frac_length.set_to_0();
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m_state = State::TypingDecimal;
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break;
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case State::TypingInteger:
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VERIFY(m_frac_value == 0);
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VERIFY(m_frac_length == 0);
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m_state = State::TypingDecimal;
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break;
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case State::TypingDecimal:
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// Ignore it.
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break;
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}
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}
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void Keypad::type_backspace()
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{
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switch (m_state) {
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case State::External:
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m_int_value.set_to_0();
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m_frac_value.set_to_0();
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m_frac_length.set_to_0();
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break;
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case State::TypingDecimal:
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if (m_frac_length > 0) {
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m_frac_value.set_to(m_frac_value.divided_by(10).quotient);
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m_frac_length.set_to(m_frac_length.minus(1));
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break;
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}
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VERIFY(m_frac_value == 0);
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m_state = State::TypingInteger;
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[[fallthrough]];
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case State::TypingInteger:
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VERIFY(m_frac_value == 0);
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VERIFY(m_frac_length == 0);
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m_int_value.set_to(m_int_value.divided_by(10).quotient);
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break;
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}
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}
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Crypto::BigFraction Keypad::value() const
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{
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if (m_state != State::External) {
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Crypto::SignedBigInteger sum { m_int_value.multiplied_by(Crypto::NumberTheory::Power("10"_bigint, m_frac_length)).plus(m_frac_value) };
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Crypto::BigFraction res { move(sum), Crypto::NumberTheory::Power("10"_bigint, m_frac_length) };
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m_internal_value = move(res);
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}
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return m_internal_value;
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}
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void Keypad::set_value(Crypto::BigFraction value)
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{
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m_state = State::External;
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m_internal_value = move(value);
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}
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void Keypad::set_to_0()
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{
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m_int_value.set_to_0();
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m_frac_value.set_to_0();
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m_frac_length.set_to_0();
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m_internal_value.set_to_0();
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m_state = State::External;
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}
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String Keypad::to_string() const
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{
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// TODO: Implement custom rounding length in the calculator.
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constexpr auto maximum_precision = 6;
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if (m_state == State::External)
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return m_internal_value.to_string(maximum_precision);
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StringBuilder builder;
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String const integer_value = m_int_value.to_base(10);
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String const frac_value = m_frac_value.to_base(10);
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unsigned const number_pre_zeros = m_frac_length.to_u64() - (frac_value.length() - 1) - (frac_value == "0" ? 0 : 1);
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builder.append(integer_value);
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// NOTE: We test for the state so the decimal point appears on screen as soon as you type it.
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if (m_state == State::TypingDecimal) {
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builder.append('.');
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builder.append_repeated('0', number_pre_zeros);
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if (frac_value != "0")
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builder.append(frac_value);
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}
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return builder.to_string();
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}
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