golang中对map操作类

package beeku  
 
import (  
    "sort"  
)  
 
type MapSorter struct {  
    Keys []string  
    Vals []string  
}  
 
func NewMapSorter(m map[string]string) *MapSorter {  
    ms := &MapSorter{  
        Keys: make([]string, 0, len(m)),  
        Vals: make([]string, 0, len(m)),  
    }  
    for k, v := range m {  
        ms.Keys = append(ms.Keys, k)  
        ms.Vals = append(ms.Vals, v)  
    }  
    return ms  
}  
 
func (ms *MapSorter) Sort() {  
    sort.Sort(ms)  
}  
 
func (ms *MapSorter) Len() int           { return len(ms.Keys) }  
func (ms *MapSorter) Less(i, j int) bool { return ms.Keys[i] < ms.Keys[j] }  
func (ms *MapSorter) Swap(i, j int) {  
    ms.Vals[i], ms.Vals[j] = ms.Vals[j], ms.Vals[i]  
    ms.Keys[i], ms.Keys[j] = ms.Keys[j], ms.Keys[i]  
}