1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
|
/*
* 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 CANDY_GEAR_COMMAND_CHAIN_H
#define CANDY_GEAR_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 /* CANDY_GEAR_COMMAND_CHAIN_H */
|
