github.com/mymmsc/gox@v1.3.33/util/examples/customcomparator/customcomparator.go (about)

     1  // Copyright (c) 2015, Emir Pasic. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package main
     6  
     7  import (
     8  	"fmt"
     9  	"github.com/mymmsc/gox/util/treeset"
    10  )
    11  
    12  // User model (id and name)
    13  type User struct {
    14  	id   int
    15  	name string
    16  }
    17  
    18  // Comparator function (sort by IDs)
    19  func byID(a, b interface{}) int {
    20  
    21  	// Type assertion, program will panic if this is not respected
    22  	c1 := a.(User)
    23  	c2 := b.(User)
    24  
    25  	switch {
    26  	case c1.id > c2.id:
    27  		return 1
    28  	case c1.id < c2.id:
    29  		return -1
    30  	default:
    31  		return 0
    32  	}
    33  }
    34  
    35  // CustomComparatorExample to demonstrate basic usage of CustomComparator
    36  func main() {
    37  	set := treeset.NewWith(byID)
    38  
    39  	set.Add(User{2, "Second"})
    40  	set.Add(User{3, "Third"})
    41  	set.Add(User{1, "First"})
    42  	set.Add(User{4, "Fourth"})
    43  
    44  	fmt.Println(set) // {1 First}, {2 Second}, {3 Third}, {4 Fourth}
    45  }