chain.go

Documentation: github.com/go-chi/chi

     1  package chi
     2  
     3  import "net/http"
     4  
     5  // Chain returns a Middlewares type from a slice of middleware handlers.
     6  func Chain(middlewares ...func(http.Handler) http.Handler) Middlewares {
     7  	return Middlewares(middlewares)
     8  }
     9  
    10  // Handler builds and returns a http.Handler from the chain of middlewares,
    11  // with `h http.Handler` as the final handler.
    12  func (mws Middlewares) Handler(h http.Handler) http.Handler {
    13  	return &ChainHandler{mws, h, chain(mws, h)}
    14  }
    15  
    16  // HandlerFunc builds and returns a http.Handler from the chain of middlewares,
    17  // with `h http.Handler` as the final handler.
    18  func (mws Middlewares) HandlerFunc(h http.HandlerFunc) http.Handler {
    19  	return &ChainHandler{mws, h, chain(mws, h)}
    20  }
    21  
    22  // ChainHandler is a http.Handler with support for handler composition and
    23  // execution.
    24  type ChainHandler struct {
    25  	Middlewares Middlewares
    26  	Endpoint    http.Handler
    27  	chain       http.Handler
    28  }
    29  
    30  func (c *ChainHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    31  	c.chain.ServeHTTP(w, r)
    32  }
    33  
    34  // chain builds a http.Handler composed of an inline middleware stack and endpoint
    35  // handler in the order they are passed.
    36  func chain(middlewares []func(http.Handler) http.Handler, endpoint http.Handler) http.Handler {
    37  	// Return ahead of time if there aren't any middlewares for the chain
    38  	if len(middlewares) == 0 {
    39  		return endpoint
    40  	}
    41  
    42  	// Wrap the end handler with the middleware chain
    43  	h := middlewares[len(middlewares)-1](endpoint)
    44  	for i := len(middlewares) - 2; i >= 0; i-- {
    45  		h = middlewares[i](h)
    46  	}
    47  
    48  	return h
    49  }
    50
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