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
|
// Copyright 2018 Google Inc.
//
// 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.
package container
import (
"errors"
"fmt"
)
// traversal.go provides functions that navigate the container tree.
// rootCont returns the root container.
func rootCont(c *Container) *Container {
for p := c.parent; p != nil; p = c.parent {
c = p
}
return c
}
// visitFunc is executed during traversals when node is visited.
// If the visit function returns an error, the traversal terminates and the
// errStr is set to the text of the returned error.
type visitFunc func(*Container) error
// preOrder performs pre-order DFS traversal on the container tree.
func preOrder(c *Container, errStr *string, visit visitFunc) {
if c == nil || *errStr != "" {
return
}
if err := visit(c); err != nil {
*errStr = err.Error()
return
}
preOrder(c.first, errStr, visit)
preOrder(c.second, errStr, visit)
}
// postOrder performs post-order DFS traversal on the container tree.
func postOrder(c *Container, errStr *string, visit visitFunc) {
if c == nil || *errStr != "" {
return
}
postOrder(c.first, errStr, visit)
postOrder(c.second, errStr, visit)
if err := visit(c); err != nil {
*errStr = err.Error()
return
}
}
// findID finds container with the provided ID.
// Returns an error of there is no container with the specified ID.
func findID(root *Container, id string) (*Container, error) {
if id == "" {
return nil, errors.New("the container ID must not be empty")
}
var (
errStr string
cont *Container
)
preOrder(root, &errStr, visitFunc(func(c *Container) error {
if c.opts.id == id {
cont = c
}
return nil
}))
if cont == nil {
return nil, fmt.Errorf("cannot find container with ID %q", id)
}
return cont, nil
}
|