status-go/vendor/go.uber.org/fx/supply.go

163 lines
4.6 KiB
Go

// Copyright (c) 2020 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package fx
import (
"fmt"
"reflect"
"strings"
"go.uber.org/fx/internal/fxreflect"
)
// Supply provides instantiated values for dependency injection as if
// they had been provided using a constructor that simply returns them.
// The most specific type of each value (as determined by reflection) is used.
//
// This serves a purpose similar to what fx.Replace does for fx.Decorate.
//
// For example, given:
//
// type (
// TypeA struct{}
// TypeB struct{}
// TypeC struct{}
// )
//
// var a, b, c = &TypeA{}, TypeB{}, &TypeC{}
//
// The following two forms are equivalent:
//
// fx.Supply(a, b, fx.Annotated{Target: c})
//
// fx.Provide(
// func() *TypeA { return a },
// func() TypeB { return b },
// fx.Annotated{Target: func() *TypeC { return c }},
// )
//
// Supply panics if a value (or annotation target) is an untyped nil or an error.
//
// [Private] can be used to restrict access to supplied values.
//
// # Supply Caveats
//
// As mentioned above, Supply uses the most specific type of the provided
// value. For interface values, this refers to the type of the implementation,
// not the interface. So if you supply an http.Handler, fx.Supply will use the
// type of the implementation.
//
// var handler http.Handler = http.HandlerFunc(f)
// fx.Supply(handler)
//
// Is equivalent to,
//
// fx.Provide(func() http.HandlerFunc { return f })
//
// This is typically NOT what you intended. To supply the handler above as an
// http.Handler, we need to use the fx.Annotate function with the fx.As
// annotation.
//
// fx.Supply(
// fx.Annotate(handler, fx.As(new(http.Handler))),
// )
func Supply(values ...interface{}) Option {
constructors := make([]interface{}, 0, len(values))
types := make([]reflect.Type, 0, len(values))
var private bool
for _, value := range values {
var (
typ reflect.Type
ctor any
)
switch value := value.(type) {
case privateOption:
private = true
continue
case annotated:
value.Target, typ = newSupplyConstructor(value.Target)
ctor = value
case Annotated:
value.Target, typ = newSupplyConstructor(value.Target)
ctor = value
default:
ctor, typ = newSupplyConstructor(value)
}
constructors = append(constructors, ctor)
types = append(types, typ)
}
return supplyOption{
Targets: constructors,
Types: types,
Stack: fxreflect.CallerStack(1, 0),
Private: private,
}
}
type supplyOption struct {
Targets []interface{}
Types []reflect.Type // type of value produced by constructor[i]
Stack fxreflect.Stack
Private bool
}
func (o supplyOption) apply(m *module) {
for i, target := range o.Targets {
m.provides = append(m.provides, provide{
Target: target,
Stack: o.Stack,
IsSupply: true,
SupplyType: o.Types[i],
Private: o.Private,
})
}
}
func (o supplyOption) String() string {
items := make([]string, 0, len(o.Targets))
for _, typ := range o.Types {
items = append(items, typ.String())
}
return fmt.Sprintf("fx.Supply(%s)", strings.Join(items, ", "))
}
// Returns a function that takes no parameters, and returns the given value.
func newSupplyConstructor(value interface{}) (interface{}, reflect.Type) {
switch value.(type) {
case nil:
panic("untyped nil passed to fx.Supply")
case error:
panic("error value passed to fx.Supply")
}
typ := reflect.TypeOf(value)
returnTypes := []reflect.Type{typ}
returnValues := []reflect.Value{reflect.ValueOf(value)}
ft := reflect.FuncOf([]reflect.Type{}, returnTypes, false)
fv := reflect.MakeFunc(ft, func([]reflect.Value) []reflect.Value {
return returnValues
})
return fv.Interface(), typ
}