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scope.go
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scope.go
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package submodule
import (
"context"
"reflect"
"sync"
)
type value struct {
value reflect.Value
e reflect.Value
}
type scope struct {
mu sync.Mutex
values map[Retrievable]*value
parent Scope
inherit bool
middleware []Middleware
}
// A scope is a container for retrievable values.
// To simplify the understanding, a scope is a map, where
// a key is a submodule reference and a value is what will be provided by the factory.
//
// A scope comes with its life-cycle where any submodules can hook to
type Scope interface {
get(g Retrievable) *value
has(g Retrievable) bool
initValue(g Retrievable, v reflect.Value) *value
InitValue(g Retrievable, v any)
initError(g Retrievable, e reflect.Value) *value
InitError(g Retrievable, e error)
Dispose() error
DisposeWithContext(ctx context.Context) error
AppendMiddleware(...Middleware)
Apply(Submodule[Middleware])
}
func (s *scope) has(g Retrievable) bool {
s.mu.Lock()
defer s.mu.Unlock()
if s.inherit && globalScope.has(g) {
return true
}
if s.parent != nil && s.parent.has(g) {
return true
}
_, ok := s.values[g]
return ok
}
func (s *scope) get(g Retrievable) *value {
s.mu.Lock()
defer s.mu.Unlock()
var v *value
var ok bool
if s.parent != nil && s.parent.has(g) {
v = s.parent.get(g)
s.values[g] = v
return v
}
if s.inherit && globalScope.has(g) {
return globalScope.get(g)
}
v, ok = s.values[g]
if !ok {
g.retrieve(s)
v = s.values[g]
}
return v
}
func (s *scope) initValue(g Retrievable, v reflect.Value) *value {
if s.has(g) {
return s.get(g)
}
args := []reflect.Value{v}
for _, m := range s.middleware {
if m.hasOnScopeResolve && v.Type().AssignableTo(m.onScopeResolveType) {
args = m.onScopeResolve.Call(args)
}
}
value := &value{
value: args[0],
}
s.mu.Lock()
defer s.mu.Unlock()
s.values[g] = value
return value
}
// A scope can enforce a submodule to be a specific value no matter what its factory returns.
// This is useful to simulate test scenarios
func (s *scope) InitValue(g Retrievable, v any) {
s.initValue(g, reflect.ValueOf(v))
}
func (s *scope) initError(g Retrievable, e reflect.Value) *value {
if s.has(g) {
return s.get(g)
}
value := &value{
e: e,
}
s.mu.Lock()
defer s.mu.Unlock()
s.values[g] = value
return value
}
// A scope can enforce a submodule to be a specific value no matter what its factory returns.
// This is useful to simulate test scenarios
func (s *scope) InitError(g Retrievable, e error) {
s.initError(g, reflect.ValueOf(e))
}
// Apply middleware to a scope
func (s *scope) Apply(submodule Submodule[Middleware]) {
m := submodule.ResolveWith(s)
s.AppendMiddleware(m)
}
// remove all values in the scope
func (s *scope) release() {
s.mu.Lock()
defer s.mu.Unlock()
for k := range s.values {
delete(s.values, k)
}
}
type middlewareCaller func(Middleware) error
func (s *scope) dispose(cond middlewareCaller) error {
for i := len(s.middleware) - 1; i >= 0; i-- {
if s.middleware[i].hasOnScopeEnd {
if err := cond(s.middleware[i]); err != nil {
return err
}
}
}
return nil
}
var disposeCond = func(m Middleware) error {
if m.onScopeEnd != nil {
return m.onScopeEnd()
}
return nil
}
var disposeWithContextCond = func(ctx context.Context) func(m Middleware) error {
return func(m Middleware) error {
if m.onScopeEndWithContext != nil {
return m.onScopeEndWithContext(ctx)
}
return nil
}
}
// DisposeWithContext dispose scope with context
func (s *scope) DisposeWithContext(ctx context.Context) error {
if err := s.dispose(disposeWithContextCond(ctx)); err != nil {
return err
}
if err := s.dispose(disposeCond); err != nil {
return err
}
s.release()
return nil
}
// Dispose scope to free up all resolved values and trigger scope end middlewares
func (s *scope) Dispose() error {
if err := s.dispose(disposeWithContextCond(context.TODO())); err != nil {
return err
}
if err := s.dispose(disposeCond); err != nil {
return err
}
s.release()
return nil
}
// Append middleware to the scope
func (s *scope) AppendMiddleware(m ...Middleware) {
if len(m) == 0 {
return
}
s.middleware = append(s.middleware, m...)
}
// Append global middleware to the global scope
func AppendGlobalMiddleware(ms ...Middleware) {
if len(ms) == 0 {
return
}
globalScope.AppendMiddleware(ms...)
}
// Dispose global scope to free up all resolved values and trigger scope end middlewares
func DisposeGlobalScope() error {
return globalScope.Dispose()
}
func DisposeGlobalScopeWithContext(ctx context.Context) error {
return globalScope.DisposeWithContext(ctx)
}
// Apply middleware to the global scope
func Apply(s Middleware) {
globalScope.AppendMiddleware(s)
}
// A middleware can add behaviors to a scope via decorator pattern.
// There are two types of middlewares
// - a decorator to specific type that will be resolved in the scope
// - a scope end that will be called when the scope is disposed
type Middleware struct {
hasOnScopeResolve bool
hasOnScopeEnd bool
onScopeResolveType reflect.Type
onScopeResolve reflect.Value
onScopeEnd func() error
onScopeEndWithContext func(context.Context) error
}
type MiddlewareFn func(Middleware) Middleware
func WithScopeResolve[T any](fn func(T) T) Middleware {
return Middleware{
hasOnScopeResolve: true,
onScopeResolveType: reflect.TypeOf(fn).In(0),
onScopeResolve: reflect.ValueOf(fn),
}
}
func WithScopeEnd(fn func() error) Middleware {
return Middleware{
hasOnScopeEnd: true,
onScopeEnd: fn,
}
}
func WithContextScopeEnd(fn func(context.Context) error) Middleware {
return Middleware{
hasOnScopeEnd: true,
onScopeEndWithContext: fn,
}
}
type ScopeOpts struct {
inherit bool
parent Scope
middlewares []Middleware
}
type ScopeOptsFn func(opts ScopeOpts) ScopeOpts
func MakeScopeOpts(fn ScopeOptsFn) ScopeOpts {
return fn(ScopeOpts{})
}
func Inherit(inherit bool) ScopeOptsFn {
return func(opts ScopeOpts) ScopeOpts {
opts.inherit = inherit
return opts
}
}
func WithParent(parent Scope) ScopeOptsFn {
return func(opts ScopeOpts) ScopeOpts {
opts.parent = parent
return opts
}
}
func WithMiddlewares(middlewares ...Middleware) ScopeOptsFn {
return func(opts ScopeOpts) ScopeOpts {
opts.middlewares = middlewares
return opts
}
}
// Create a new scope with modifiers
func CreateScope(fns ...ScopeOptsFn) Scope {
s := &scope{
values: make(map[Retrievable]*value),
}
opt := ScopeOpts{}
for _, fn := range fns {
opt = fn(opt)
}
s.inherit = opt.inherit
s.parent = opt.parent
if len(opt.middlewares) > 0 {
s.middleware = opt.middlewares
}
return s
}
var globalScope = CreateScope(
Inherit(false),
WithParent(nil),
)
// Return the global scope
func GetStore() Scope {
return globalScope
}