path.go

Documentation: k8s.io/apimachinery/pkg/util/validation/field

     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  type pathOptions struct {
    26  	path *Path
    27  }
    28  
    29  // PathOption modifies a pathOptions
    30  type PathOption func(o *pathOptions)
    31  
    32  // WithPath generates a PathOption
    33  func WithPath(p *Path) PathOption {
    34  	return func(o *pathOptions) {
    35  		o.path = p
    36  	}
    37  }
    38  
    39  // ToPath produces *Path from a set of PathOption
    40  func ToPath(opts ...PathOption) *Path {
    41  	c := &pathOptions{}
    42  	for _, opt := range opts {
    43  		opt(c)
    44  	}
    45  	return c.path
    46  }
    47  
    48  // Path represents the path from some root to a particular field.
    49  type Path struct {
    50  	name   string // the name of this field or "" if this is an index
    51  	index  string // if name == "", this is a subscript (index or map key) of the previous element
    52  	parent *Path  // nil if this is the root element
    53  }
    54  
    55  // NewPath creates a root Path object.
    56  func NewPath(name string, moreNames ...string) *Path {
    57  	r := &Path{name: name, parent: nil}
    58  	for _, anotherName := range moreNames {
    59  		r = &Path{name: anotherName, parent: r}
    60  	}
    61  	return r
    62  }
    63  
    64  // Root returns the root element of this Path.
    65  func (p *Path) Root() *Path {
    66  	for ; p.parent != nil; p = p.parent {
    67  		// Do nothing.
    68  	}
    69  	return p
    70  }
    71  
    72  // Child creates a new Path that is a child of the method receiver.
    73  func (p *Path) Child(name string, moreNames ...string) *Path {
    74  	r := NewPath(name, moreNames...)
    75  	r.Root().parent = p
    76  	return r
    77  }
    78  
    79  // Index indicates that the previous Path is to be subscripted by an int.
    80  // This sets the same underlying value as Key.
    81  func (p *Path) Index(index int) *Path {
    82  	return &Path{index: strconv.Itoa(index), parent: p}
    83  }
    84  
    85  // Key indicates that the previous Path is to be subscripted by a string.
    86  // This sets the same underlying value as Index.
    87  func (p *Path) Key(key string) *Path {
    88  	return &Path{index: key, parent: p}
    89  }
    90  
    91  // String produces a string representation of the Path.
    92  func (p *Path) String() string {
    93  	if p == nil {
    94  		return "<nil>"
    95  	}
    96  	// make a slice to iterate
    97  	elems := []*Path{}
    98  	for ; p != nil; p = p.parent {
    99  		elems = append(elems, p)
   100  	}
   101  
   102  	// iterate, but it has to be backwards
   103  	buf := bytes.NewBuffer(nil)
   104  	for i := range elems {
   105  		p := elems[len(elems)-1-i]
   106  		if p.parent != nil && len(p.name) > 0 {
   107  			// This is either the root or it is a subscript.
   108  			buf.WriteString(".")
   109  		}
   110  		if len(p.name) > 0 {
   111  			buf.WriteString(p.name)
   112  		} else {
   113  			fmt.Fprintf(buf, "[%s]", p.index)
   114  		}
   115  	}
   116  	return buf.String()
   117  }
   118
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