十、composite 组合模式

https://refactoringguru.cn/design-patterns/composite

树状结构, 适合用组合模式, 不断递归, 对各子节点求和, 直到叶子节点为止.

例如, 一个大盒子, 内可以放置物体, 或若干小盒子. 而每个小盒子又同理.

10.1 search_in_file_folder

https://refactoringguru.cn/design-patterns/composite/go/example

希望在一个目录中搜索文件名

目录中有子目录和文件, 这是一个树状结构, 需要递归计算

10composite/101search_in_file_folder
├── file.go
├── folder.go
├── inode.go
├── inode_test.go
└── readme.md

10.1.1 inode_test.go

package _01search_in_file_folderimport ("github.com/stretchr/testify/require""testing"
)func TestExistInTree(t *testing.T) {f1 := &file{name: "f1"}f2 := &file{name: "f2"}f3 := &file{name: "f3"}d1 := &folder{name: "d1", children: []iNode{f1, f2}}d2 := &folder{name: "d2", children: []iNode{f3}}d := &folder{name: "d3", children: []iNode{d1, d2}}require.True(t, d.ExistInTree("f1"))require.True(t, d.ExistInTree("f2"))require.True(t, d.ExistInTree("f3"))require.True(t, d.ExistInTree("d1"))require.True(t, d.ExistInTree("d2"))require.True(t, d.ExistInTree("d3"))require.False(t, d.ExistInTree("a"))require.False(t, d.ExistInTree(""))
}

10.1.2 inode.go

package _01search_in_file_foldertype iNode interface {Name() stringExistInTree(query string) bool
}

10.1.3 file.go

package _01search_in_file_foldertype file struct {name string
}func (f *file) Name() string {return f.name
}func (f *file) ExistInTree(query string) bool {return f.Name() == query
}

10.1.4 folder.go

package _01search_in_file_foldertype folder struct {name     stringchildren []iNode
}func (f *folder) Name() string {return f.name
}func (f *folder) ExistInTree(query string) bool {if f.Name() == query {return true}for _, child := range f.children {exist := child.ExistInTree(query)if exist {return true}}return false
}