github.com/jonasnick/go-ethereum@v0.7.12-0.20150216215225-22176f05d387/ethutil/list.go (about) 1 package ethutil 2 3 import ( 4 "encoding/json" 5 "reflect" 6 "sync" 7 ) 8 9 // The list type is an anonymous slice handler which can be used 10 // for containing any slice type to use in an environment which 11 // does not support slice types (e.g., JavaScript, QML) 12 type List struct { 13 mut sync.Mutex 14 val interface{} 15 list reflect.Value 16 Length int 17 } 18 19 // Initialise a new list. Panics if non-slice type is given. 20 func NewList(t interface{}) *List { 21 list := reflect.ValueOf(t) 22 if list.Kind() != reflect.Slice { 23 panic("list container initialized with a non-slice type") 24 } 25 26 return &List{sync.Mutex{}, t, list, list.Len()} 27 } 28 29 func EmptyList() *List { 30 return NewList([]interface{}{}) 31 } 32 33 // Get N element from the embedded slice. Returns nil if OOB. 34 func (self *List) Get(i int) interface{} { 35 if self.list.Len() > i { 36 self.mut.Lock() 37 defer self.mut.Unlock() 38 39 i := self.list.Index(i).Interface() 40 41 return i 42 } 43 44 return nil 45 } 46 47 func (self *List) GetAsJson(i int) interface{} { 48 e := self.Get(i) 49 50 r, _ := json.Marshal(e) 51 52 return string(r) 53 } 54 55 // Appends value at the end of the slice. Panics when incompatible value 56 // is given. 57 func (self *List) Append(v interface{}) { 58 self.mut.Lock() 59 defer self.mut.Unlock() 60 61 self.list = reflect.Append(self.list, reflect.ValueOf(v)) 62 self.Length = self.list.Len() 63 } 64 65 // Returns the underlying slice as interface. 66 func (self *List) Interface() interface{} { 67 return self.list.Interface() 68 } 69 70 // For JavaScript <3 71 func (self *List) ToJSON() string { 72 // make(T, 0) != nil 73 list := make([]interface{}, 0) 74 for i := 0; i < self.Length; i++ { 75 list = append(list, self.Get(i)) 76 } 77 78 data, _ := json.Marshal(list) 79 80 return string(data) 81 }