sslobodr | d046be8 | 2019-01-16 10:02:22 -0500 | [diff] [blame] | 1 | /* |
| 2 | Copyright 2015 The Kubernetes Authors. |
| 3 | |
| 4 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | you may not use this file except in compliance with the License. |
| 6 | You may obtain a copy of the License at |
| 7 | |
| 8 | http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | |
| 10 | Unless required by applicable law or agreed to in writing, software |
| 11 | distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | See the License for the specific language governing permissions and |
| 14 | limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package field |
| 18 | |
| 19 | import ( |
| 20 | "bytes" |
| 21 | "fmt" |
| 22 | "strconv" |
| 23 | ) |
| 24 | |
| 25 | // Path represents the path from some root to a particular field. |
| 26 | type Path struct { |
| 27 | name string // the name of this field or "" if this is an index |
| 28 | index string // if name == "", this is a subscript (index or map key) of the previous element |
| 29 | parent *Path // nil if this is the root element |
| 30 | } |
| 31 | |
| 32 | // NewPath creates a root Path object. |
| 33 | func NewPath(name string, moreNames ...string) *Path { |
| 34 | r := &Path{name: name, parent: nil} |
| 35 | for _, anotherName := range moreNames { |
| 36 | r = &Path{name: anotherName, parent: r} |
| 37 | } |
| 38 | return r |
| 39 | } |
| 40 | |
| 41 | // Root returns the root element of this Path. |
| 42 | func (p *Path) Root() *Path { |
| 43 | for ; p.parent != nil; p = p.parent { |
| 44 | // Do nothing. |
| 45 | } |
| 46 | return p |
| 47 | } |
| 48 | |
| 49 | // Child creates a new Path that is a child of the method receiver. |
| 50 | func (p *Path) Child(name string, moreNames ...string) *Path { |
| 51 | r := NewPath(name, moreNames...) |
| 52 | r.Root().parent = p |
| 53 | return r |
| 54 | } |
| 55 | |
| 56 | // Index indicates that the previous Path is to be subscripted by an int. |
| 57 | // This sets the same underlying value as Key. |
| 58 | func (p *Path) Index(index int) *Path { |
| 59 | return &Path{index: strconv.Itoa(index), parent: p} |
| 60 | } |
| 61 | |
| 62 | // Key indicates that the previous Path is to be subscripted by a string. |
| 63 | // This sets the same underlying value as Index. |
| 64 | func (p *Path) Key(key string) *Path { |
| 65 | return &Path{index: key, parent: p} |
| 66 | } |
| 67 | |
| 68 | // String produces a string representation of the Path. |
| 69 | func (p *Path) String() string { |
| 70 | // make a slice to iterate |
| 71 | elems := []*Path{} |
| 72 | for ; p != nil; p = p.parent { |
| 73 | elems = append(elems, p) |
| 74 | } |
| 75 | |
| 76 | // iterate, but it has to be backwards |
| 77 | buf := bytes.NewBuffer(nil) |
| 78 | for i := range elems { |
| 79 | p := elems[len(elems)-1-i] |
| 80 | if p.parent != nil && len(p.name) > 0 { |
| 81 | // This is either the root or it is a subscript. |
| 82 | buf.WriteString(".") |
| 83 | } |
| 84 | if len(p.name) > 0 { |
| 85 | buf.WriteString(p.name) |
| 86 | } else { |
| 87 | fmt.Fprintf(buf, "[%s]", p.index) |
| 88 | } |
| 89 | } |
| 90 | return buf.String() |
| 91 | } |