vitess.io/vitess@v0.16.2/go/flagutil/sets.go (about)

     1  /*
     2  Copyright 2021 The Vitess 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 flagutil
    18  
    19  import (
    20  	"strings"
    21  
    22  	"github.com/spf13/pflag"
    23  	"k8s.io/apimachinery/pkg/util/sets"
    24  )
    25  
    26  var _ pflag.Value = (*StringSetFlag)(nil)
    27  
    28  // StringSetFlag can be used to collect multiple instances of a flag into a set
    29  // of values.
    30  //
    31  // For example, defining the following:
    32  //
    33  //	var x flagutil.StringSetFlag
    34  //	flag.Var(&x, "foo", "")
    35  //
    36  // And then specifying "-foo x -foo y -foo x", will result in a set of {x, y}.
    37  //
    38  // In addition to implemnting the standard flag.Value interface, it also
    39  // provides an implementation of pflag.Value, so it is usable in libraries like
    40  // cobra.
    41  type StringSetFlag struct {
    42  	set sets.Set[string]
    43  }
    44  
    45  // ToSet returns the underlying string set, or an empty set if the underlying
    46  // set is nil.
    47  func (set *StringSetFlag) ToSet() sets.Set[string] {
    48  	if set.set == nil {
    49  		set.set = sets.New[string]()
    50  	}
    51  
    52  	return set.set
    53  }
    54  
    55  // Set is part of the pflag.Value and flag.Value interfaces.
    56  func (set *StringSetFlag) Set(s string) error {
    57  	if set.set == nil {
    58  		set.set = sets.New[string]()
    59  		return nil
    60  	}
    61  
    62  	set.set.Insert(s)
    63  	return nil
    64  }
    65  
    66  // String is part of the pflag.Value and flag.Value interfaces.
    67  func (set *StringSetFlag) String() string {
    68  	if set.set == nil {
    69  		return ""
    70  	}
    71  
    72  	return strings.Join(sets.List(set.set), ", ")
    73  }
    74  
    75  // Type is part of the pflag.Value interface.
    76  func (set *StringSetFlag) Type() string { return "StringSetFlag" }