golang-go/doc/progs/eff_sequence.go

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"fmt"
	"sort"
)

func main() {
	seq := Sequence{6, 2, -1, 44, 16}
	sort.Sort(seq)
	fmt.Println(seq)
}

type Sequence []int

// Methods required by sort.Interface.
func (s Sequence) Len() int {
	return len(s)
}
func (s Sequence) Less(i, j int) bool {
	return s[i] < s[j]
}
func (s Sequence) Swap(i, j int) {
	s[i], s[j] = s[j], s[i]
}

// Copy returns a copy of the Sequence.
func (s Sequence) Copy() Sequence {
	copy := make(Sequence, 0, len(s))
	return append(copy, s...)
}

// Method for printing - sorts the elements before printing.
func (s Sequence) String() string {
	s = s.Copy() // Make a copy; don't overwrite argument.
	sort.Sort(s)
	str := "["
	for i, elem := range s { // Loop is O(N²); will fix that in next example.
		if i > 0 {
			str += " "
		}
		str += fmt.Sprint(elem)
	}
	return str + "]"
}