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chain.go
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package chi
import "net/http"
// Chain returns a Middlewares type from a slice of middleware handlers.
func Chain(middlewares ...func(http.Handler) http.Handler) Middlewares {
return Middlewares(middlewares)
}
// Handler builds and returns a http.Handler from the chain of middlewares,
// with `h http.Handler` as the final handler.
func (mws Middlewares) Handler(h http.Handler) http.Handler {
return &ChainHandler{h, chain(mws, h), mws}
}
// HandlerFunc builds and returns a http.Handler from the chain of middlewares,
// with `h http.Handler` as the final handler.
func (mws Middlewares) HandlerFunc(h http.HandlerFunc) http.Handler {
return &ChainHandler{h, chain(mws, h), mws}
}
// ChainHandler is a http.Handler with support for handler composition and
// execution.
type ChainHandler struct {
Endpoint http.Handler
chain http.Handler
Middlewares Middlewares
}
func (c *ChainHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
c.chain.ServeHTTP(w, r)
}
// chain builds a http.Handler composed of an inline middleware stack and endpoint
// handler in the order they are passed.
func chain(middlewares []func(http.Handler) http.Handler, endpoint http.Handler) http.Handler {
// Return ahead of time if there aren't any middlewares for the chain
if len(middlewares) == 0 {
return endpoint
}
// Wrap the end handler with the middleware chain
h := middlewares[len(middlewares)-1](endpoint)
for i := len(middlewares) - 2; i >= 0; i-- {
h = middlewares[i](h)
}
return h
}