github.com/whtcorpsinc/milevadb-prod@v0.0.0-20211104133533-f57f4be3b597/soliton/set/string_set.go (about)

     1  // Copyright 2020 WHTCORPS INC, Inc.
     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  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package set
    15  
    16  // StringSet is a string set.
    17  type StringSet map[string]struct{}
    18  
    19  // NewStringSet builds a string set.
    20  func NewStringSet(ss ...string) StringSet {
    21  	set := make(StringSet, len(ss))
    22  	for _, s := range ss {
    23  		set.Insert(s)
    24  	}
    25  	return set
    26  }
    27  
    28  // Exist checks whether `val` exists in `s`.
    29  func (s StringSet) Exist(val string) bool {
    30  	_, ok := s[val]
    31  	return ok
    32  }
    33  
    34  // Insert inserts `val` into `s`.
    35  func (s StringSet) Insert(val string) {
    36  	s[val] = struct{}{}
    37  }
    38  
    39  // Intersection returns the intersection of two sets
    40  func (s StringSet) Intersection(rhs StringSet) StringSet {
    41  	newSet := NewStringSet()
    42  	for elt := range s {
    43  		if rhs.Exist(elt) {
    44  			newSet.Insert(elt)
    45  		}
    46  	}
    47  	return newSet
    48  }
    49  
    50  // Count returns the number in Set s.
    51  func (s StringSet) Count() int {
    52  	return len(s)
    53  }