Introduce hazelcast::client::decimal [API-1297] (#967)

sancar · web-flow · commit ac039d1d381b · 2022-04-26T11:19:08.000+03:00
* Introduce hazelcast::client::decimal

This class will be used in SQL and in Compact to match with
Decimal type on SQL and Compact. a.k.a BigDecimal on java.

* add equality operator

* rename decimal to big_decimal
diff --git a/hazelcast/include/hazelcast/client/big_decimal.h b/hazelcast/include/hazelcast/client/big_decimal.h
@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2008-2022, Hazelcast, Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#pragma once
+
+#include <vector>
+#include <boost/multiprecision/cpp_int.hpp>
+#include "hazelcast/util/export.h"
+
+#if defined(WIN32) || defined(_WIN32) || defined(WIN64) || defined(_WIN64)
+#pragma warning(push)
+#pragma warning(disable : 4251) // for dll export
+#endif
+
+namespace hazelcast {
+namespace client {
+/**
+ *  An arbitrary precision and scale floating point number.
+ *  unscaledValue x 10 ^ -scale
+ *
+ *  For arithmetic operations support, it is suggested to use external
+ *  libraries. An usage example with boost::multiprecision::cpp_dec_float
+ *  could be as follows:
+ *  <pre><code>
+ * hazelcast::big_decimal dec{ u, 2 };
+ * boost::multiprecision::cpp_dec_float<10> f(
+ *  (dec.unscaled.str() + "e-" + std::to_string(dec.scale)).c_str());
+ *  std::cout << f.str(100, std::ios_base::dec) << std::endl;
+ *  </code></pre>
+ */
+struct HAZELCAST_API big_decimal
+{
+    boost::multiprecision::cpp_int unscaled;
+    int32_t scale;
+};
+
+bool HAZELCAST_API
+operator==(const big_decimal& lhs, const big_decimal& rhs);
+
+bool HAZELCAST_API
+operator<(const big_decimal& lhs, const big_decimal& rhs);
+} // namespace client
+} // namespace hazelcast
+namespace std {
+template<>
+struct HAZELCAST_API hash<hazelcast::client::big_decimal>
+{
+    std::size_t operator()(const hazelcast::client::big_decimal& f) const;
+};
+} // namespace std
+namespace hazelcast {
+namespace client {
+namespace pimpl {
+
+/**
+ * Takes twos complement of given array where most significant value is first.
+ * This method modifies the vector in place.
+ * @param a the array to take twos complement of
+ */
+
+void HAZELCAST_API
+twos_complement(std::vector<int8_t>& a);
+
+/**
+ * Creates a cpp_int from a vector of int8_t respecting the sign.
+ *
+ * boost::import_bits does not respect the sign, so we have to do it manually.
+ * if v represents a negative number, we take the two's complement of it,
+ * to get positive representation of the same number. Then we add the sign
+ * at the end.
+ * @param v int8_t array to read from
+ * @return cpp_int
+ */
+boost::multiprecision::cpp_int HAZELCAST_API
+from_bytes(std::vector<int8_t> v);
+/**
+ * Creates a twos complement byte array from cpp_int respecting the sign.
+ *
+ * boost::export_bits does not respect the sign, so we have to do it manually.
+ * if i is a negative number, we take the two's complement on resulting vector,
+ * to get negative representation of the number.
+ * We also add one extra byte to the end of the vector to preserve the sign if
+ * sign of the integer is not the same as the most significant byte's sign.
+ * Otherwise we don't add it to have minimum size vector to represent the value.
+ * @param i the number to convert to bytes
+ * @return the vector of int8_t representing the number
+ */
+std::vector<int8_t> HAZELCAST_API
+to_bytes(const boost::multiprecision::cpp_int& i);
+} // namespace pimpl
+} // namespace client
+} // namespace hazelcast
+#if defined(WIN32) || defined(_WIN32) || defined(WIN64) || defined(_WIN64)
+#pragma warning(pop)
+#endif
diff --git a/hazelcast/src/hazelcast/client/client_impl.cpp b/hazelcast/src/hazelcast/client/client_impl.cpp
@@ -45,7 +45,7 @@
 #include "hazelcast/logger.h"
 #include "hazelcast/client/member_selectors.h"
 #include "hazelcast/client/client_properties.h"
-
+#include "hazelcast/client/big_decimal.h"
 #ifndef HAZELCAST_VERSION
 #define HAZELCAST_VERSION "NOT_FOUND"
 #endif
@@ -591,6 +591,79 @@ operator<<(std::ostream& stream, const address& address)
     return stream << address.to_string();
 }
 
+bool
+operator==(const big_decimal& lhs, const big_decimal& rhs)
+{
+    return lhs.unscaled == rhs.unscaled && lhs.scale == rhs.scale;
+}
+
+bool
+operator<(const big_decimal& lhs, const big_decimal& rhs)
+{
+    if (lhs.scale != rhs.scale) {
+        return lhs.scale < rhs.scale;
+    }
+    return lhs.unscaled < rhs.unscaled;
+}
+
+namespace pimpl {
+
+void
+twos_complement(std::vector<int8_t>& a)
+{
+    // twos complement is calculated via flipping the bits and adding 1
+    // flip the bits
+    for (auto& item : a) {
+        item = ~item;
+    }
+    // add 1
+    int8_t carry = 1;
+    for (int i = a.size() - 1; i >= 0; i--) {
+        a[i] = a[i] + carry;
+        if (a[i] == 0) {
+            carry = 1;
+        } else {
+            break;
+        }
+    }
+}
+
+boost::multiprecision::cpp_int
+from_bytes(std::vector<int8_t> v)
+{
+    boost::multiprecision::cpp_int i;
+    bool is_negative = v[0] < 0;
+    if (is_negative) {
+        twos_complement(v);
+    }
+    import_bits(i, v.begin(), v.end(), 8);
+    if (is_negative) {
+        return -i;
+    }
+    return i;
+}
+
+std::vector<int8_t>
+to_bytes(const boost::multiprecision::cpp_int& i)
+{
+    std::vector<int8_t> v;
+    export_bits(i, std::back_inserter(v), 8);
+    if (i < 0) {
+        twos_complement(v);
+        if (v[0] > 0) {
+            // add -1 as the most significant to have a negative sign bit
+            v.insert(v.begin(), -1);
+        }
+    } else {
+        // add 0 as the most significant byte to have a positive sign bit
+        if (v[0] < 0) {
+            v.insert(v.begin(), 0);
+        }
+    }
+    return v;
+}
+} // namespace pimpl
+
 namespace serialization {
 int32_t
 hz_serializer<address>::get_factory_id()
@@ -1152,4 +1225,14 @@ hash<hazelcast::client::address>::operator()(
     boost::hash_combine(seed, address.type_);
     return seed;
 }
+
+std::size_t
+hash<hazelcast::client::big_decimal>::operator()(
+  const hazelcast::client::big_decimal& dec) const
+{
+    std::size_t seed = 0;
+    boost::hash_combine(seed, dec.unscaled);
+    boost::hash_combine(seed, dec.scale);
+    return seed;
+};
 } // namespace std
diff --git a/hazelcast/test/src/HazelcastTests2.cpp b/hazelcast/test/src/HazelcastTests2.cpp
@@ -55,6 +55,7 @@
 #include <hazelcast/util/concurrent/locks/LockSupport.h>
 #include <hazelcast/util/MurmurHash3.h>
 #include <hazelcast/util/Util.h>
+#include <hazelcast/client/big_decimal.h>
 
 #include "ClientTest.h"
 #include "HazelcastServer.h"
@@ -71,6 +72,80 @@
 namespace hazelcast {
 namespace client {
 namespace test {
+
+/**
+ * All the hardcoded values are generated via java.util.BigInteger.toByteArray()
+ * method
+ */
+class DecimalTest : public ::testing::Test
+{};
+
+void
+assert_equal(const std::string& expected_string,
+             const std::vector<int8_t>& expected_vector)
+{
+    using boost::multiprecision::cpp_int;
+    cpp_int expected_int(expected_string);
+
+    std::vector<int8_t> actual_vector = pimpl::to_bytes(expected_int);
+    ASSERT_EQ(expected_vector, actual_vector);
+    cpp_int actual_int = pimpl::from_bytes(expected_vector);
+    ASSERT_EQ(expected_int, actual_int);
+}
+
+TEST_F(DecimalTest, positive_test)
+{
+    assert_equal(
+      "236095134049630962491764987683473058401811134068823290126231516129",
+      {
+        2,  61, -22, 92, -44, -54, -45, -9,  -17, -4, -66, -5,  -12, 19,
+        64, -5, -98, 12, -70, -24, 105, -66, -57, 61, -14, 109, -77, -31,
+      });
+}
+
+TEST_F(DecimalTest, negative_test)
+{
+    assert_equal("-158058224523514071900098807210097354699988293366",
+                 {
+                   -28, 80,  108, -112, -19, -44, 84,  -98,  96,  106,
+                   53,  -88, 77,  -45,  89,  119, 109, -109, -87, 10,
+                 });
+}
+
+TEST_F(DecimalTest, preserve_positive_sign_test)
+{
+    assert_equal("53220513728803604", { 0, -67, 19, -58, 119, -111, -77, 20 });
+}
+
+TEST_F(DecimalTest, preserve_negative_sign_test)
+{
+    assert_equal(
+      "-78097809300018214368298043748751294327036591272091714272720014418",
+      {
+        -1,  66, 39,  -99,  44,  53, -23, 60,  125, 105, 65,   -21, 104, -36,
+        -49, 79, -13, -115, 122, 57, -63, 106, 64,  -39, -112, 16,  -77, -82,
+      });
+}
+
+TEST_F(DecimalTest, carry_bit_test)
+{
+    assert_equal(
+      "-4172290065390264938962604145655817690459633380799476516330728"
+      "71499276353298132342018230923743606150479511296",
+      {
+        -46, -123, 61,  41,   -1,   115,  -54,  91,   -48, 79, 55, 25,
+        41,  -90,  14,  109,  -115, 68,   -122, 46,   70,  90, 47, -103,
+        -21, -39,  126, -45,  37,   58,   60,   -76,  -44, 91, 97, 52,
+        31,  -38,  23,  -111, 18,   -112, -109, -127, 0,
+      });
+}
+
+TEST_F(DecimalTest, cascading_carry_bit_test)
+{
+    assert_equal("-1234506895138773532672",
+                 { -67, 19, -58, 119, -111, -77, 0, 0, 0 });
+}
+
 class AddressHelperTest : public ClientTest
 {};
 
diff --git a/hazelcast/test/src/compact_test.cpp b/hazelcast/test/src/compact_test.cpp
@@ -25,6 +25,7 @@
 #endif
 
 #include <hazelcast/client/serialization/serialization.h>
+#include <hazelcast/client/big_decimal.h>
 
 #if defined(WIN32) || defined(_WIN32) || defined(WIN64) || defined(_WIN64)
 #pragma warning(push)
