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  1. #include <string>
  2. #include <memory>
  3. #include <vector>
  4. #include <iostream>
  5. #include <functional>
  6. class File;
  7. class Directory;
  8. class Visitor {
  9. public:
  10. 	virtual ~Visitor() {}
  11. 	virtual void visit(std::shared_ptr<File>) = 0;
  12. 	virtual void visit(std::shared_ptr<Directory>) = 0;
  13. 	virtual void leave(std::shared_ptr<Directory>) = 0;
  14. };
  15. class Entry {
  16. public:
  17. 	virtual ~Entry() {};
  18. 	virtual std::string getName() const = 0;
  19. 	virtual size_t getSize() = 0;
  20. 	virtual void accept(Visitor &) = 0;
  21. };
  22. class File : public Entry, public std::enable_shared_from_this<File> {
  23. 	struct this_is_private {};
  24. 	std::string name;
  25. 	size_t size;
  26. public:
  27. 	File(this_is_private, std::string name, size_t size) : name(name), size(size) {}
  28. 	std::string getName() const override {return name;}
  29. 	size_t getSize() override {return size;}
  30. 	void accept(Visitor &v) override {v.visit(shared_from_this());}
  31. 	static std::shared_ptr<File> create(std::string name, size_t size) {
  32. 		return std::make_shared<File>(this_is_private(), name, size);
  33. 	}
  34. };
  35. class Directory : public Entry, public std::enable_shared_from_this<Directory> {
  36. 	struct this_is_private {};
  37. 	std::string name;
  38. 	std::vector<std::shared_ptr<Entry>> es;
  39. public:
  40. 	Directory(this_is_private, std::string name) : name(name) {}
  41. 	std::string getName() const override {return name;}
  42. 	size_t getSize() override {
  43. 	size_t sum = 0;
  44. 	for (auto &e : es) sum += e->getSize();
  45. 		return sum;
  46. 	}
  47. 	void accept(Visitor &v) override {
  48. 		v.visit(shared_from_this());
  49. 		for (auto &e : es) e->accept(v);
  50. 		v.leave(shared_from_this());
  51. 	}
  52. 	void add(std::shared_ptr<Entry> entry) {es.push_back(entry);}
  53. 	static std::shared_ptr<Directory> create(std::string name) {
  54. 		return std::make_shared<Directory>(this_is_private(), name);
  55. 	}
  56. };
  57. // こっから↑は安定したクラス階層を想定
  58. //////////////////////////////////////////////////////////////////
  59. // こっから↓はVisitor派生クラスを作ることで「新しいオペレーションを簡単に追加できる」とのこと。
  60. class SizeVisitor : public Visitor {
  61. 	size_t size;
  62. public:
  63. 	SizeVisitor() : size(0) {};
  64. 	void visit(std::shared_ptr<File> file) {size += file->getSize();}
  65. 	void visit(std::shared_ptr<Directory>) {}
  66. 	void leave(std::shared_ptr<Directory>) {}
  67. 	size_t getTotalSize() {return size;}
  68. };
  69. class ListVisitor : public Visitor {
  70. 	std::string cd;
  71. public:
  72. 	ListVisitor() : cd("") {}
  73. 	void visit(std::shared_ptr<File> file) {
  74. 		std::cout << cd << "/" << file->getName() << " (" << file->getSize() << ")" << std::endl;
  75. 	}
  76. 	void visit(std::shared_ptr<Directory> dir) {
  77. 		std::cout << cd << "/" << dir->getName() << " (" << dir->getSize() << ")" << std::endl;
  78. 		cd +=  "/" + dir->getName();
  79. 	}
  80. 	void leave(std::shared_ptr<Directory> dir) {
  81. 		cd.resize(cd.length() - 1 - dir->getName().length());
  82. 	}
  83. };
  84. class FunctionalVisitor : public Visitor {
  85. 	std::function<void(std::shared_ptr<File>)> vf;
  86. 	std::function<void(std::shared_ptr<Directory>)> vd, ld;
  87. public:
  88. 	FunctionalVisitor(
  89. 		std::function<void(std::shared_ptr<File>)> vf, std::function<void(std::shared_ptr<Directory>)> vd, std::function<void(std::shared_ptr<Directory>)> ld
  90. 	) : vf(vf), vd(vd), ld(ld) {}
  91. 	void visit(std::shared_ptr<File> file) {vf(file);}
  92. 	void visit(std::shared_ptr<Directory> dir) {vd(dir);}
  93. 	void leave(std::shared_ptr<Directory> dir) {ld(dir);}
  94. };
  95. int main() {
  96. 	auto a = Directory::create("a");
  97. 	auto b = File::create("b.txt", 100);
  98. 	auto c = File::create("c.txt", 200);
  99. 	auto d = Directory::create("d");
  100. 	auto e = File::create("e.txt", 300);
  101. 	a->add(b);
  102. 	a->add(c);
  103. 	a->add(d);
  104. 	d->add(e);
  105. 	SizeVisitor sv;
  106. 	a->accept(sv);
  107. 	std::cout << "total size: " << sv.getTotalSize() << std::endl;
  108.  
  109. 	ListVisitor lv;
  110. 	std::cout << "\nlist: " << std::endl;
  111. 	a->accept(lv);
  112.  
  113. 	std::vector<std::string> dirs;
  114. 	FunctionalVisitor fv(
  115. 		[&dirs](std::shared_ptr<File> file) {
  116. 			if (file->getName().find(".txt") != std::string::npos) {
  117. 				for (auto &d : dirs) std::cout << "/" << d;
  118. 				std::cout << "/" << file->getName() << std::endl;
  119. 			}
  120. 		}
  121. 		, [&dirs](std::shared_ptr<Directory> dir) {dirs.push_back(dir->getName());}
  122. 		, [&dirs](std::shared_ptr<Directory> dir) {dirs.pop_back();}
  123. 	);
  124. 	std::cout << "\n.txt: " << std::endl;
  125. 	a->accept(fv);
  126. 	return 0;
  127. }
  128. /*
  129. ・https://i...content-available-to-author-only...e.com/p3li2Y を元に若干の整理を行った
  130.  
  131. ・make_shared<File>(this)の多重開放？を修正
  132. 　std::enable_shared_from_thisを使ってJavaの参照型変数っぽい使用感を得た。
  133.  
  134. ・struct this_is_private {};
  135. 　これは単にコンストラクタを実質的にprivateにするためだけに使ってる
  136. 　https://e...content-available-to-author-only...e.com/w/cpp/memory/enable_shared_from_this
  137. 　https://stackoverflow.com/questions/8147027/how-do-i-call-stdmake-shared-on-a-class-with-only-protected-or-private-const
  138. 　このへん参照されたし
  139. */
  140.  
Success #stdin #stdout 0.01s 5284KB
comments (?)
stdin 
Standard input is empty
stdout 
total size: 600

list: 
/a (600)
/a/b.txt (100)
/a/c.txt (200)
/a/d (300)
/a/d/e.txt (300)

.txt: 
/a/b.txt
/a/c.txt
/a/d/e.txt
https://ideone.com/2uUpwH
language:
C++ (gcc 8.3)
created:
112 days ago
visibility:
secret

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