写一个简单的key-value数据库，实现下面几个接口。
db:new() => Db.
db:destroy(Db) => ok.
db:write(Key, Element, Db) => NewDb.
db:delete(Key, Db) => NewDb.
db:read(Key, Db) =>{ok, Element} | {error, instance}.
db:match(Element, Db) => [Key1, ..., KeyN].
例子:
1> c(db).
{ok,db}
2> Db = db:new().
[]
3> Db1 = db:write(111,222, Db).
[{111,222}]
4> Db2 = db:write(333, 444, Db1).
[{333,444},{111,222}]
5> db:read(111, Db2).
{ok,222}
6> Db3 = db:write(555, 444, Db2).
[{555,444},{333,444},{111,222}]
7> db:read(ola, Db3).
{error,instance}
8> db:match(444, Db3).
[555,333]
9> Db4 = db:delete(333, Db3).
[{555,444},{111,222}]
10> db:match(444, Db4).
[555]
1 package main 2 3 import ( 4 "fmt" 5 ) 6 7 type M_Rcd map[string]string 8 9 type T_Tbl struct { 10 tblname string 11 record M_Rcd 12 } 13 14 type T_Kvdb struct { 15 dbname string 16 tbl []T_Tbl 17 } 18 19 func (this *T_Kvdb) c(db T_Kvdb) { 20 this.dbname = db.dbname 21 this.tbl = make([]T_Tbl, 5) 22 fmt.Printf("\ncreate db \"%s\" ok\n", this.dbname) 23 } 24 25 func (this *T_Kvdb) new(tblname string) T_Tbl { 26 var tbl T_Tbl 27 var length int 28 tbl.tblname = tblname 29 tbl.record = make(M_Rcd) 30 31 this.tbl = append(this.tbl, tbl) 32 length = len(this.tbl) 33 fmt.Printf("add new table \"%s\" to db \"%s\" ok\n", tblname, this.dbname) 34 return this.tbl[length-1] 35 } 36 37 func (this *T_Kvdb) destroy(tbl T_Tbl) { 38 for i, _ := range this.tbl { 39 if tbl.tblname == this.tbl[i].tblname { 40 this.tbl = append(this.tbl[:i], this.tbl[i+1:]...) 41 fmt.Println("destroy table ", tbl.tblname, " ok.\n") 42 return 43 } 44 } 45 fmt.Printf("no table \"%s\".\n", tbl.tblname) 46 } 47 48 func (this *T_Kvdb) read(key string, tbl T_Tbl) { 49 for i, _ := range this.tbl { 50 if tbl.tblname == this.tbl[i].tblname { 51 for k, v := range this.tbl[i].record { 52 if k == key { 53 fmt.Println("{", v, "}") 54 return 55 } 56 } 57 } 58 } 59 fmt.Println("error, instance") 60 } 61 62 func (this *T_Kvdb) write(key string, value string, tbl T_Tbl) { 63 fmt.Printf("add {%s,%s} to table \"%s\"", key, value, tbl.tblname) 64 for i, _ := range this.tbl { 65 if tbl.tblname == this.tbl[i].tblname { 66 this.tbl[i].record[key] = value 67 for k, v1 := range this.tbl[i].record { 68 fmt.Print("{", k, ",", v1, "}") 69 } 70 fmt.Printf("\n") 71 return 72 } 73 } 74 fmt.Print("no table \n", tbl.tblname) 75 } 76 77 func (this *T_Kvdb) delete(key string, tbl T_Tbl) { 78 fmt.Printf("delete %s from table %s\n", key, tbl.tblname) 79 fmt.Printf("[") 80 for i, _ := range this.tbl { 81 if tbl.tblname == this.tbl[i].tblname { 82 delete(this.tbl[i].record, key) 83 for k, v1 := range this.tbl[i].record { 84 fmt.Print("{", k, ",", v1, "}") 85 } 86 fmt.Printf("]\n") 87 return 88 } 89 } 90 } 91 92 func (this *T_Kvdb) match(value string, tbl T_Tbl) { 93 var value_in []string 94 95 for i, _ := range this.tbl { 96 if tbl.tblname == this.tbl[i].tblname { 97 for k, v1 := range this.tbl[i].record { 98 if v1 == value { 99 value_in = append(value_in, k) 100 } 101 } 102 fmt.Printf("%v\n", value_in) 103 return 104 } 105 } 106 value_in = append(value_in, "]") 107 fmt.Printf("%v\n", value_in) 108 } 109 110 func (this *T_Kvdb) show() { 111 fmt.Print("show [") 112 for i, _ := range this.tbl { 113 for k, v1 := range this.tbl[i].record { 114 fmt.Print("{", k, ",", v1, "}") 115 } 116 } 117 fmt.Print("]\n\n") 118 }
1 package main 2 3 import () 4 5 func main() { 6 var db1 T_Kvdb 7 var tbl1 T_Tbl 8 db1.dbname = "db1" 9 db1.c(db1) 10 tbl1 = db1.new("tbl1") 11 12 db1.write("111", "222", tbl1) 13 db1.show() 14 db1.read("111", tbl1) 15 16 db1.write("333", "444", tbl1) 17 db1.show() 18 db1.read("333", tbl1) 19 20 db1.read("555", tbl1) 21 22 db1.write("555", "444", tbl1) 23 db1.show() 24 25 db1.match("444", tbl1) 26 27 db1.delete("333", tbl1) 28 db1.show() 29 30 db1.destroy(tbl1) 31 db1.show() 32 tbl1.tblname = "a" 33 db1.destroy(tbl1) 34 db1.show() 35 db1.read("555", tbl1) 36 37 db1.show() 38 }
