github.com/fafucoder/cilium@v1.6.11/pkg/set/set.go (about)

     1  // Copyright 2019 Authors of Cilium
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package set
    16  
    17  // SliceSubsetOf checks whether the first slice is a subset of the second slice. If
    18  // not, it also returns slice of elements which are the difference of both
    19  // input slices.
    20  func SliceSubsetOf(sub, main []string) (bool, []string) {
    21  	var diff []string
    22  	occurrences := make(map[string]int, len(main))
    23  	result := true
    24  	for _, element := range main {
    25  		occurrences[element]++
    26  	}
    27  	for _, element := range sub {
    28  		if count, ok := occurrences[element]; !ok {
    29  			// Element was not found in the main slice.
    30  			result = false
    31  			diff = append(diff, element)
    32  		} else if count < 1 {
    33  			// The element is in both slices, but the sub slice
    34  			// has more duplicates.
    35  			result = false
    36  		} else {
    37  			occurrences[element]--
    38  		}
    39  	}
    40  	return result, diff
    41  }