From 9d9dd6d6e0893a93c5019afb87ca7bb218c98903 Mon Sep 17 00:00:00 2001
From: Jin Chengcheng <chengcheng.jin@intel.com>
Date: Tue, 4 Apr 2023 14:39:15 +0800
Subject: [PATCH] [GLUTEN-1273] Support casting decimal as int (#177)

---
 velox/expression/tests/CastExprTest.cpp | 34 ++++++++++------
 velox/type/Conversions.h                | 54 +++++++++++++++++++------
 2 files changed, 63 insertions(+), 25 deletions(-)

diff --git a/velox/expression/tests/CastExprTest.cpp b/velox/expression/tests/CastExprTest.cpp
index 2a8fbd4a6aa0..a478aaf444f6 100644
--- a/velox/expression/tests/CastExprTest.cpp
+++ b/velox/expression/tests/CastExprTest.cpp
@@ -805,6 +805,12 @@ TEST_F(CastExprTest, toString) {
   ASSERT_EQ("cast((a) as ARRAY<VARCHAR>)", exprSet.exprs()[1]->toString());
 }
 
+TEST_F(CastExprTest, decimalToInt) {
+  // short to short, scale up.
+  auto longFlat = makeLongDecimalFlatVector({8976067200}, DECIMAL(21, 6));
+  testComplexCast("c0", longFlat, makeFlatVector<int32_t>({8976}));
+}
+
 TEST_F(CastExprTest, decimalToDecimal) {
   // short to short, scale up.
   auto shortFlat =
@@ -932,22 +938,24 @@ TEST_F(CastExprTest, integerToDecimal) {
 
 TEST_F(CastExprTest, varcharToDecimal) {
   // varchar to short decimal
-//   auto input = makeFlatVector<StringView>({"-3", "177"});
-//   testComplexCast(
-//       "c0", input, makeShortDecimalFlatVector({-300, 17700}, DECIMAL(6, 2)));
-
-//   // varchar to long decimal
-//   auto input2 = makeFlatVector<StringView>(
-//       {"-300000001234567891234.5", "1771234.5678912345678"});
-//   testComplexCast(
-//       "c0", input2, makeLongDecimalFlatVector({-300, 17700}, DECIMAL(32, 7)));
+  //   auto input = makeFlatVector<StringView>({"-3", "177"});
+  //   testComplexCast(
+  //       "c0", input, makeShortDecimalFlatVector({-300, 17700}, DECIMAL(6,
+  //       2)));
+
+  //   // varchar to long decimal
+  //   auto input2 = makeFlatVector<StringView>(
+  //       {"-300000001234567891234.5", "1771234.5678912345678"});
+  //   testComplexCast(
+  //       "c0", input2, makeLongDecimalFlatVector({-300, 17700}, DECIMAL(32,
+  //       7)));
 
   auto input3 = makeFlatVector<StringView>({"9999999999.99", "9999999999.99"});
   testComplexCast(
-      "c0", input3, makeLongDecimalFlatVector(
-          {-30'000'000'000,
-           -20'000'000'000},
-          DECIMAL(12, 2)));
+      "c0",
+      input3,
+      makeLongDecimalFlatVector(
+          {-30'000'000'000, -20'000'000'000}, DECIMAL(12, 2)));
 }
 
 TEST_F(CastExprTest, castInTry) {
diff --git a/velox/type/Conversions.h b/velox/type/Conversions.h
index de5530b4e0a9..6aba356766b3 100644
--- a/velox/type/Conversions.h
+++ b/velox/type/Conversions.h
@@ -87,13 +87,11 @@ struct Converter<TypeKind::BOOLEAN> {
   }
 
   static T cast(const UnscaledLongDecimal& d, bool& nullOutput) {
-    VELOX_UNSUPPORTED(
-        "Conversion of UnscaledLongDecimal to Boolean is not supported");
+    return folly::to<T>(d.unscaledValue());
   }
 
   static T cast(const UnscaledShortDecimal& d, bool& nullOutput) {
-    VELOX_UNSUPPORTED(
-        "Conversion of UnscaledShortDecimal to Boolean is not supported");
+    return folly::to<T>(d.unscaledValue());
   }
 };
 
@@ -113,6 +111,40 @@ struct Converter<
     VELOX_NYI();
   }
 
+  static T cast(
+      const UnscaledLongDecimal& d,
+      bool& nullOutput,
+      const TypePtr& fromType) {
+    const auto& decimalType = fromType->asLongDecimal();
+    auto scale0Decimal = DecimalUtil::
+        rescaleWithRoundUp<UnscaledLongDecimal, UnscaledLongDecimal>(
+            d,
+            decimalType.precision(),
+            decimalType.scale(),
+            decimalType.precision(),
+            0,
+            false,
+            false);
+    return cast(scale0Decimal.value().unscaledValue(), nullOutput);
+  }
+
+  static T cast(
+      const UnscaledShortDecimal& d,
+      bool& nullOutput,
+      const TypePtr& fromType) {
+    const auto& decimalType = fromType->asShortDecimal();
+    auto scale0Decimal = DecimalUtil::
+        rescaleWithRoundUp<UnscaledShortDecimal, UnscaledShortDecimal>(
+            d,
+            decimalType.precision(),
+            decimalType.scale(),
+            decimalType.precision(),
+            0,
+            false,
+            false);
+    return cast(scale0Decimal.value().unscaledValue(), nullOutput);
+  }
+
   template <typename From>
   static T cast(const From& v, bool& nullOutput) {
     VELOX_UNSUPPORTED(
@@ -318,14 +350,12 @@ struct Converter<
     }
   }
 
-  static T cast(const UnscaledLongDecimal& d, bool& nullOutput) {
-    VELOX_UNSUPPORTED(
-        "Conversion of UnscaledLongDecimal to Boolean is not supported");
-  }
-
-  static T cast(const UnscaledShortDecimal& d, bool& nullOutput) {
-    VELOX_UNSUPPORTED(
-        "Conversion of UnscaledShortDecimal to Boolean is not supported");
+  static T cast(const int128_t& v, bool& nullOutput) {
+    if constexpr (TRUNCATE) {
+      return T(v);
+    } else {
+      return static_cast<T>(v);
+    }
   }
 };