arrow/compute/registry.h

0001 // Licensed to the Apache Software Foundation (ASF) under one
0002 // or more contributor license agreements.  See the NOTICE file
0003 // distributed with this work for additional information
0004 // regarding copyright ownership.  The ASF licenses this file
0005 // to you under the Apache License, Version 2.0 (the
0006 // "License"); you may not use this file except in compliance
0007 // with the License.  You may obtain a copy of the License at
0008 //
0009 //   http://www.apache.org/licenses/LICENSE-2.0
0010 //
0011 // Unless required by applicable law or agreed to in writing,
0012 // software distributed under the License is distributed on an
0013 // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
0014 // KIND, either express or implied.  See the License for the
0015 // specific language governing permissions and limitations
0016 // under the License.
0017
0018 // NOTE: API is EXPERIMENTAL and will change without going through a
0019 // deprecation cycle
0020
0021 #pragma once
0022
0023 #include <memory>
0024 #include <string>
0025 #include <vector>
0026
0027 #include "arrow/result.h"
0028 #include "arrow/status.h"
0029 #include "arrow/util/visibility.h"
0030
0031 namespace arrow {
0032 namespace compute {
0033
0034 class Function;
0035 class FunctionOptionsType;
0036
0037 /// \brief A mutable central function registry for built-in functions as well
0038 /// as user-defined functions. Functions are implementations of
0039 /// arrow::compute::Function.
0040 ///
0041 /// Generally, each function contains kernels which are implementations of a
0042 /// function for a specific argument signature. After looking up a function in
0043 /// the registry, one can either execute it eagerly with Function::Execute or
0044 /// use one of the function's dispatch methods to pick a suitable kernel for
0045 /// lower-level function execution.
0046 class ARROW_EXPORT FunctionRegistry {
0047  public:
0048   ~FunctionRegistry();
0049
0050   /// \brief Construct a new registry.
0051   ///
0052   /// Most users only need to use the global registry.
0053   static std::unique_ptr<FunctionRegistry> Make();
0054
0055   /// \brief Construct a new nested registry with the given parent.
0056   ///
0057   /// Most users only need to use the global registry. The returned registry never changes
0058   /// its parent, even when an operation allows overwriting.
0059   static std::unique_ptr<FunctionRegistry> Make(FunctionRegistry* parent);
0060
0061   /// \brief Check whether a new function can be added to the registry.
0062   ///
0063   /// \returns Status::KeyError if a function with the same name is already registered.
0064   Status CanAddFunction(std::shared_ptr<Function> function, bool allow_overwrite = false);
0065
0066   /// \brief Add a new function to the registry.
0067   ///
0068   /// \returns Status::KeyError if a function with the same name is already registered.
0069   Status AddFunction(std::shared_ptr<Function> function, bool allow_overwrite = false);
0070
0071   /// \brief Check whether an alias can be added for the given function name.
0072   ///
0073   /// \returns Status::KeyError if the function with the given name is not registered.
0074   Status CanAddAlias(const std::string& target_name, const std::string& source_name);
0075
0076   /// \brief Add alias for the given function name.
0077   ///
0078   /// \returns Status::KeyError if the function with the given name is not registered.
0079   Status AddAlias(const std::string& target_name, const std::string& source_name);
0080
0081   /// \brief Check whether a new function options type can be added to the registry.
0082   ///
0083   /// \return Status::KeyError if a function options type with the same name is already
0084   /// registered.
0085   Status CanAddFunctionOptionsType(const FunctionOptionsType* options_type,
0086                                    bool allow_overwrite = false);
0087
0088   /// \brief Add a new function options type to the registry.
0089   ///
0090   /// \returns Status::KeyError if a function options type with the same name is already
0091   /// registered.
0092   Status AddFunctionOptionsType(const FunctionOptionsType* options_type,
0093                                 bool allow_overwrite = false);
0094
0095   /// \brief Retrieve a function by name from the registry.
0096   Result<std::shared_ptr<Function>> GetFunction(const std::string& name) const;
0097
0098   /// \brief Return vector of all entry names in the registry.
0099   ///
0100   /// Helpful for displaying a manifest of available functions.
0101   std::vector<std::string> GetFunctionNames() const;
0102
0103   /// \brief Retrieve a function options type by name from the registry.
0104   Result<const FunctionOptionsType*> GetFunctionOptionsType(
0105       const std::string& name) const;
0106
0107   /// \brief The number of currently registered functions.
0108   int num_functions() const;
0109
0110   /// \brief The cast function object registered in AddFunction.
0111   ///
0112   /// Helpful for get cast function as needed.
0113   const Function* cast_function() const;
0114
0115  private:
0116   FunctionRegistry();
0117
0118   // Use PIMPL pattern to not have std::unordered_map here
0119   class FunctionRegistryImpl;
0120   std::unique_ptr<FunctionRegistryImpl> impl_;
0121
0122   explicit FunctionRegistry(FunctionRegistryImpl* impl);
0123 };
0124
0125 }  // namespace compute
0126 }  // namespace arrow