Use godep

Godeps/_workspace/src/github.com/codegangsta/inject/inject.go

@@ -0,0 +1,122 @@
+package inject
+
+import (
+	"fmt"
+	"reflect"
+)
+
+type Injector interface {
+	Applicator
+	Invoker
+	TypeMapper
+	SetParent(Injector)
+}
+
+type Applicator interface {
+	Apply(interface{}) error
+}
+
+type Invoker interface {
+	Invoke(interface{}) ([]reflect.Value, error)
+}
+
+type TypeMapper interface {
+	Map(interface{}) TypeMapper
+	MapTo(interface{}, interface{}) TypeMapper
+	Get(reflect.Type) reflect.Value
+}
+
+type injector struct {
+	values map[reflect.Type]reflect.Value
+	parent Injector
+}
+
+func InterfaceOf(value interface{}) reflect.Type {
+	t := reflect.TypeOf(value)
+
+	for t.Kind() == reflect.Ptr {
+		t = t.Elem()
+	}
+
+	if t.Kind() != reflect.Interface {
+		panic("Called inject.InterfaceOf with a value that is not a pointer to an interface. (*MyInterface)(nil)")
+	}
+
+	return t
+}
+
+func New() Injector {
+	return &injector{
+		values: make(map[reflect.Type]reflect.Value),
+	}
+}
+
+func (inj *injector) Invoke(f interface{}) ([]reflect.Value, error) {
+	t := reflect.TypeOf(f)
+
+	var in = make([]reflect.Value, t.NumIn())
+	for i := 0; i < t.NumIn(); i++ {
+		argType := t.In(i)
+		val := inj.Get(argType)
+		if !val.IsValid() {
+			return nil, fmt.Errorf("Value not found for type %v", argType)
+		}
+
+		in[i] = val
+	}
+
+	return reflect.ValueOf(f).Call(in), nil
+}
+
+func (inj *injector) Apply(val interface{}) error {
+	v := reflect.ValueOf(val)
+
+	for v.Kind() == reflect.Ptr {
+		v = v.Elem()
+	}
+
+	if v.Kind() != reflect.Struct {
+		return nil
+	}
+
+	t := v.Type()
+
+	for i := 0; i < v.NumField(); i++ {
+		f := v.Field(i)
+		structField := t.Field(i)
+		if f.CanSet() && structField.Tag == "inject" {
+			ft := f.Type()
+			v := inj.Get(ft)
+			if !v.IsValid() {
+				return fmt.Errorf("Value not found for type %v", ft)
+			}
+
+			f.Set(v)
+		}
+
+	}
+
+	return nil
+}
+
+func (i *injector) Map(val interface{}) TypeMapper {
+	i.values[reflect.TypeOf(val)] = reflect.ValueOf(val)
+	return i
+}
+
+func (i *injector) MapTo(val interface{}, ifacePtr interface{}) TypeMapper {
+	i.values[InterfaceOf(ifacePtr)] = reflect.ValueOf(val)
+	return i
+}
+
+func (i *injector) Get(t reflect.Type) reflect.Value {
+	val := i.values[t]
+	if !val.IsValid() && i.parent != nil {
+		val = i.parent.Get(t)
+	}
+	return val
+}
+
+func (i *injector) SetParent(parent Injector) {
+	i.parent = parent
+}