go-avltree sample code

gistfile1.go

package main

import (
        "os"
        "fmt"
        "rand"
        "github.com/ancientlore/go-avltree"
)

func compareString(a interface{}, b interface{}) int {
        if a.(string) < b.(string) {
                return -1
        } else if a.(string) > b.(string) {
                return 1
        }
        return 0
}

func compareInt(a interface{}, b interface{}) int {
        if a.(int) < b.(int) {
                return -1
        } else if a.(int) > b.(int) {
                return 1
        }
        return 0
}

func testCompareInt(a interface{}, b interface{}) int {
        if a.(int) < b.(int) {
                return -1
        } else if a.(int) > b.(int) {
                return 1
        }
        return 0
}

func printString(s interface{}) { fmt.Printf("%-8.8s", s.(string)) }

func main() {

        t := avltree.New(compareString, avltree.AllowDuplicates)
        s := []string{
                "Dharmesh", "Andy", "Sriram", "John", "Daniel",
                "Michael", "Yadira", "Awez", "Robert", "Greg",
                "Steve", "Glen", "Rahul", "Piotr", "Gigi",
        }

        for i := range (s) {
                // fmt.Printf("Adding string at position %d: %s\n", i, s[i]);
                t.Add(s[i])
        }

        t.Print(os.Stdout, printString, 8)

        t.RemoveAt(5)

        t.Print(os.Stdout, printString, 8)

        var x []interface{}

        x = t.Data()
        for i := range (x) {
                fmt.Printf("%s\n", x[i])
        }

        t.Remove("Rahul")

        t.Print(os.Stdout, printString, 8)

        t.Clear()

        for j := 0; j < 100; j++ {
                for i := range (s) {
                        t.Add(s[i])
                }
        }

        fmt.Printf("Added %d items\n", 100*len(s))
        fmt.Printf("Tree contains %d items, could hold %d with the same height of %d\n", t.Len(), t.Cap(), t.Height())

        t.Clear()
        fmt.Printf("Tree contains %d items, could hold %d with the same height of %d\n", t.Len(), t.Cap(), t.Height())

        t.Add("foo")
        fmt.Printf("Tree contains %d items, could hold %d with the same height of %d\n", t.Len(), t.Cap(), t.Height())

        t.Add("bar")
        fmt.Printf("Tree contains %d items, could hold %d with the same height of %d\n", t.Len(), t.Cap(), t.Height())

        t.Init(testCompareInt, avltree.AllowDuplicates)

        for j := 0; j < 100000; j++ {
                t.Add(rand.Int())
        }

        fmt.Printf("Tree contains %d items, could hold %d with the same height of %d\n", t.Len(), t.Cap(), t.Height())

        t.Clear()

        for j := 0; j < 100000; j++ {
                t.Add(j)
        }

        fmt.Printf("Tree contains %d items, could hold %d with the same height of %d\n", t.Len(), t.Cap(), t.Height())

        sm := 0
        t.Do(func(z interface{}) { sm += z.(int) })
        fmt.Printf("Sum is %d\n", sm);

        t.Do(func(z interface{}) { if z.(int) % 3333 == 0 { fmt.Printf("%d ", z); } })
        fmt.Printf("\n");

        for v := range t.Iter() {
                if v.(int) % 3333 == 0 {
                        fmt.Printf("%d ", v);
                }
        }
        fmt.Printf("\n");
        
}

Line 48 contains "for i := range (s) {." I am curious as to why the variable s is contained in parenthesis?