Extend expression fuzzer test to support decimal

.github/workflows/scheduled.yml

@@ -293,6 +293,7 @@ jobs:
                 --seed ${RANDOM} \
                 --enable_variadic_signatures \
                 --velox_fuzzer_enable_complex_types \
+                --velox_fuzzer_enable_decimal_type \
                 --lazy_vector_generation_ratio 0.2 \
                 --velox_fuzzer_enable_column_reuse \
                 --velox_fuzzer_enable_expression_reuse \
@@ -346,6 +347,7 @@ jobs:
                 --duration_sec 3600 \
                 --enable_variadic_signatures \
                 --velox_fuzzer_enable_complex_types \
+                --velox_fuzzer_enable_decimal_type \
                 --velox_fuzzer_enable_column_reuse \
                 --velox_fuzzer_enable_expression_reuse \
                 --max_expression_trees_per_step 2 \
@@ -465,6 +467,7 @@ jobs:
                 --enable_variadic_signatures \
                 --lazy_vector_generation_ratio 0.2 \
                 --velox_fuzzer_enable_column_reuse \
+                --velox_fuzzer_enable_decimal_type \
                 --velox_fuzzer_enable_expression_reuse \
                 --max_expression_trees_per_step 2 \
                 --retry_with_try \

velox/docs/develop/scalar-functions.rst

@@ -998,6 +998,13 @@ element of the array and returns a new array of the results.
 
 The signature of a function that handles DECIMAL types can additionally take
 variables and constraints to represent the precision and scale values.
+The variables of input decimal types store the input precisions and scales.
+Their names begin with an incrementing prefix starting from 'a', and followed
+by '_precision' or '_scale'. Variables of output decimal types store the output
+precision and scale. Their names begin with 'r', and followed by '_precision'
+or '_scale'. When there is only one input decimal type, and the output type
+holds the same precision and scale with the input type, the variables could be
+named as 'precision' and 'scale'.
 The constraints are evaluated using a type calculator built from Flex and Bison
 tools. The decimal arithmetic addition function has the following signature:
 

velox/docs/develop/testing/fuzzer.rst

@@ -219,6 +219,8 @@ Below are arguments that toggle certain fuzzer features in Expression Fuzzer:
 
 * ``--velox_fuzzer_enable_complex_types``: Enable testing of function signatures with complex argument or return types. Default is false.
 
+* ``--velox_fuzzer_enable_decimal_type``: Enable testing of function signatures with decimal argument or return type. Default is false.
+
 * ``--lazy_vector_generation_ratio``: Specifies the probability with which columns in the input row vector will be selected to be wrapped in lazy encoding (expressed as double from 0 to 1). Default is 0.0.
 
 * ``--velox_fuzzer_enable_column_reuse``: Enable generation of expressions where one input column can be used by multiple subexpressions. Default is false.
@@ -246,6 +248,7 @@ An example set of arguments to run the expression fuzzer with all features enabl
 --enable_variadic_signatures
 --lazy_vector_generation_ratio 0.2
 --velox_fuzzer_enable_complex_types
+--velox_fuzzer_enable_decimal_type
 --velox_fuzzer_enable_expression_reuse
 --velox_fuzzer_enable_column_reuse
 --retry_with_try

velox/expression/ReverseSignatureBinder.cpp

@@ -18,27 +18,7 @@
 
 namespace facebook::velox::exec {
 
-bool ReverseSignatureBinder::hasConstrainedIntegerVariable(
-    const TypeSignature& type) const {
-  if (type.parameters().empty()) {
-    auto it = variables().find(type.baseName());
-    return it != variables().end() && it->second.isIntegerParameter() &&
-        it->second.constraint() != "";
-  }
-
-  const auto& parameters = type.parameters();
-  for (const auto& parameter : parameters) {
-    if (hasConstrainedIntegerVariable(parameter)) {
-      return true;
-    }
-  }
-  return false;
-}
-
 bool ReverseSignatureBinder::tryBind() {
-  if (hasConstrainedIntegerVariable(signature_.returnType())) {
-    return false;
-  }
   return SignatureBinderBase::tryBind(signature_.returnType(), returnType_);
 }
 

velox/expression/ReverseSignatureBinder.h

@@ -44,10 +44,6 @@ class ReverseSignatureBinder : private SignatureBinderBase {
   }
 
  private:
-  /// Return whether there is a constraint on an integer variable in type
-  /// signature.
-  bool hasConstrainedIntegerVariable(const TypeSignature& type) const;
-
   const TypePtr returnType_;
 };
 

velox/expression/tests/ArgumentGenerator.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * 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 "velox/core/ITypedExpr.h"
+#include "velox/expression/tests/utils/FuzzerToolkit.h"
+
+namespace facebook::velox::test {
+
+class ExpressionFuzzer;
+
+class ArgumentGenerator {
+ public:
+  virtual ~ArgumentGenerator() = default;
+
+  // Generates function arguments of the specified signature.
+  virtual std::vector<core::TypedExprPtr> generate(
+      ExpressionFuzzer* expressionFuzzer,
+      const CallableSignature& input,
+      int32_t maxNumVarArgs) = 0;
+};
+
+} // namespace facebook::velox::test