mirror of https://gitee.com/bigwinds/arangodb
127 lines
4.0 KiB
C++
127 lines
4.0 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// DISCLAIMER
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///
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/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
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/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
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///
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/// Licensed under the Apache License, Version 2.0 (the "License");
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/// you may not use this file except in compliance with the License.
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/// You may obtain a copy of the License at
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///
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/// http://www.apache.org/licenses/LICENSE-2.0
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///
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/// Unless required by applicable law or agreed to in writing, software
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/// distributed under the License is distributed on an "AS IS" BASIS,
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/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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/// See the License for the specific language governing permissions and
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/// limitations under the License.
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///
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/// Copyright holder is ArangoDB GmbH, Cologne, Germany
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///
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/// @author Jan Steemann
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGOD_AQL_FUNCTION_H
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#define ARANGOD_AQL_FUNCTION_H 1
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#include "Aql/Functions.h"
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#include "Basics/Common.h"
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#include <type_traits>
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namespace arangodb {
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namespace aql {
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struct Function {
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enum class Conversion : uint8_t { None = 0, Optional = 1, Required = 2 };
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/// @brief arbitrary function flags. note that these must be mutually
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/// exclusive when bit-ORed
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enum class Flags : uint8_t {
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None = 0,
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/// @brief whether or not the function is deterministic (i.e. its results
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/// are identical when called repeatedly with the same input values)
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Deterministic = 1,
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/// @brief whether or not the function result is cacheable in the query
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/// cache
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Cacheable = 2,
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/// @brief whether or not the function may be executed on DB servers
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CanRunOnDBServer = 4,
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/// @brief exclude the function from being evaluated during AST optimizations
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/// evaluation of function will only happen at query runtime
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NoEval = 8
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};
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/// @brief helper for building flags
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template <typename... Args>
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static inline std::underlying_type<Flags>::type makeFlags(Flags flag, Args... args) {
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return static_cast<std::underlying_type<Flags>::type>(flag) + makeFlags(args...);
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}
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static inline std::underlying_type<Flags>::type makeFlags() {
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return static_cast<std::underlying_type<Flags>::type>(Flags::None);
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}
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Function() = delete;
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/// @brief create the function
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Function(std::string const& name, char const* arguments,
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std::underlying_type<Flags>::type flags,
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FunctionImplementation implementation = nullptr);
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/// @brief return whether a specific flag is set for the function
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inline bool hasFlag(Flags flag) const {
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return (flags & static_cast<std::underlying_type<Flags>::type>(flag)) != 0;
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}
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/// @brief return the number of required arguments
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inline std::pair<size_t, size_t> numArguments() const {
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return std::make_pair(minRequiredArguments, maxRequiredArguments);
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}
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/// @brief whether or not a positional argument needs to be converted from a
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/// collection parameter to a collection name parameter
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inline Conversion getArgumentConversion(size_t position) const {
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if (position >= conversions.size()) {
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return Conversion::None;
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}
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return conversions[position];
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}
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/// @brief parse the argument list and set the minimum and maximum number of
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/// arguments
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void initializeArguments();
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/// @brief function name (name visible to the end user, may be an alias)
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std::string name;
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/// @brief function arguments
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char const* arguments;
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/// @brief function flags
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std::underlying_type<Flags>::type const flags;
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/// @brief minimum number of required arguments
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size_t minRequiredArguments;
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/// @brief maximum number of required arguments
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size_t maxRequiredArguments;
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/// @brief C++ implementation of the function
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FunctionImplementation const implementation;
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/// @brief function argument conversion information
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std::vector<Conversion> conversions;
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/// @brief maximum number of function arguments that can be used
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static constexpr size_t maxArguments = 65536;
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};
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} // namespace aql
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} // namespace arangodb
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#endif
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