adamdebreceni commented on code in PR #1391: URL: https://github.com/apache/nifi-minifi-cpp/pull/1391#discussion_r979899914
########## libminifi/include/core/flow/Node.h: ########## @@ -0,0 +1,143 @@ +/** + * + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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 <string_view> +#include <tuple> +#include <optional> +#include "nonstd/expected.hpp" + +namespace org::apache::nifi::minifi::core::flow { + +class Node { + public: + struct Cursor { + int line; + int column; + int pos; + }; + + class Impl; + class Iterator { + public: + class Value; + + class Impl { + public: + virtual Impl& operator++() = 0; + virtual bool operator==(const Impl& other) const = 0; + virtual Value operator*() const = 0; + bool operator!=(const Impl& other) const {return !(*this == other);} + + virtual std::unique_ptr<Impl> clone() const = 0; + virtual ~Impl() = default; + }; + + Iterator& operator++() { + impl_->operator++(); + return *this; + } + + explicit Iterator(std::unique_ptr<Impl> impl) : impl_(std::move(impl)) {} + Iterator(const Iterator& other): impl_(other.impl_->clone()) {} + Iterator(Iterator&&) = default; + Iterator& operator=(const Iterator& other) { + if (this == &other) { + return *this; + } + impl_ = other.impl_->clone(); + return *this; + } + Iterator& operator=(Iterator&&) = default; + + bool operator==(const Iterator& other) const {return impl_->operator==(*other.impl_);} + bool operator!=(const Iterator& other) const {return !(*this == other);} + + Value operator*() const; + + private: + std::unique_ptr<Impl> impl_; + }; + + class Impl { + public: + virtual explicit operator bool() const = 0; + virtual bool isSequence() const = 0; + virtual bool isMap() const = 0; + virtual bool isNull() const = 0; + virtual bool isScalar() const = 0; + + virtual nonstd::expected<std::string, std::exception_ptr> getString() const = 0; + virtual nonstd::expected<int, std::exception_ptr> getInt() const = 0; + virtual nonstd::expected<unsigned int, std::exception_ptr> getUInt() const = 0; + virtual nonstd::expected<bool, std::exception_ptr> getBool() const = 0; + virtual nonstd::expected<int64_t, std::exception_ptr> getInt64() const = 0; + virtual nonstd::expected<uint64_t, std::exception_ptr> getUInt64() const = 0; + + virtual std::string getDebugString() const = 0; + + virtual size_t size() const = 0; + virtual Iterator begin() const = 0; + virtual Iterator end() const = 0; + virtual Node operator[](std::string_view key) const = 0; + + virtual std::optional<Cursor> getCursor() const {return std::nullopt;} + + virtual ~Impl() = default; + }; + + Node() = default; + explicit Node(std::shared_ptr<Impl> impl): impl_(std::move(impl)) {} + + explicit operator bool() const {return impl_->operator bool();} + bool isSequence() const {return impl_->isSequence();} + bool isMap() const {return impl_->isMap();} + bool isNull() const {return impl_->isNull();} + bool isScalar() const {return impl_->isScalar();} + + nonstd::expected<std::string, std::exception_ptr> getString() const {return impl_->getString();} + nonstd::expected<bool, std::exception_ptr> getBool() const {return impl_->getBool();} + nonstd::expected<int, std::exception_ptr> getInt() const {return impl_->getInt();} + nonstd::expected<unsigned int, std::exception_ptr> getUInt() const {return impl_->getUInt();} + nonstd::expected<int64_t, std::exception_ptr> getInt64() const {return impl_->getInt64();} + nonstd::expected<uint64_t, std::exception_ptr> getUInt64() const {return impl_->getUInt64();} + + // return a string representation of the node (need not to be deserializable) + std::string getDebugString() const {return impl_->getDebugString();} + + size_t size() const {return impl_->size();} + size_t empty() const { + return size() == 0; + } + Iterator begin() const {return impl_->begin();} + Iterator end() const {return impl_->end();} + Node operator[](std::string_view key) const {return impl_->operator[](key);} + + std::optional<Cursor> getCursor() const {return impl_->getCursor();} + + private: + std::shared_ptr<Impl> impl_; +}; + +class Node::Iterator::Value : public Node, public std::pair<Node, Node> { + public: + Value(Node node, Node key, Node value): Node{std::move(node)}, std::pair<Node, Node>{std::move(key), std::move(value)} {} +}; Review Comment: I wanted to mimic the `yaml-cpp`'s implementation (`node/iterator.h`) allowing uniform iteration on both maps and sequences without having to write forwarding methods if the `Node`-case was a member -- This is an automated message from the Apache Git Service. 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