refa Split BluCat into several namespacesHEADmaster

1 files changed, 92 insertions, 0 deletions

diff --git a/src/blu_cat/com/command.hpp b/src/blu_cat/com/command.hpp
new file mode 100644
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+++ b/src/blu_cat/com/command.hpp
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+/*
+ * Copyright 2022 Frederico de Oliveira Linhares
+ *
+ * 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.
+ */
+
+#ifndef BLU_CAT_COM_COMMAND_CHAIN_H
+#define BLU_CAT_COM_COMMAND_CHAIN_H 1
+
+#include <cstdint>
+#include <initializer_list>
+#include <stdexcept>
+#include <string>
+#include <vector>
+
+class CommandChain;
+
+struct CommandError: public std::exception
+{
+  CommandError(const std::string &m);
+  CommandError(const char &m);
+
+  const char* what() const noexcept;
+
+private:
+  std::string error;
+};
+
+/**
+ * Stores a reversible action.
+ */
+struct Command
+{
+  void (*do_command)(void *obj);
+  void (*undo_command)(void *obj);
+};
+
+/**
+ * Stores a sequence of functions that must be executed and rolled back in
+ * order.
+ *
+ * For example, if the variable _commands contain A→B→C→D→E, it will load A,
+ * then B, then C, etc. If D fails, it unloads C, then B, then A.
+ */
+class CommandChain
+{
+  std::vector<Command> _commands;
+
+  void
+  partial_revert(void *obj, int32_t step) const;
+
+public:
+  CommandChain(std::initializer_list<Command> commands);
+
+/**
+ * Adds a reversible action to the command. The first action added is the first
+ * to de executed the last rolled back, and so on. Those functions are stored
+ * inside _commands.
+ *
+ * @param[unload] the undo/rollback action, if the action do not need a
+ *   rollback, this pointer can be set to null.
+ */
+  void
+  add(const Command &c);
+
+/**
+ * Execute all of the load functions in the _commands. If one of them fails,
+ * roll back everything inside _commands.
+ * @return true on success and false on fail.
+ */
+  void
+  execute(void *obj) const;
+
+/**
+ * Roll back all loaded function inside commands, if there are any.
+ */
+  void
+  revert(void *obj) const;
+
+};
+
+#endif /* BLU_CAT_COM_COMMAND_CHAIN_H */