67 lines
2.0 KiB
Go
67 lines
2.0 KiB
Go
package gus
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import "context"
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// Handler is a type which can turn a request into a response.
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//
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// Handle may return a nil response, in which case the Server is expected
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// to build the protocol-appropriate "Not Found" response.
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type Handler interface {
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Handle(context.Context, *Request) *Response
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}
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type handlerFunc func(context.Context, *Request) *Response
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// HandlerFunc is a wrapper to allow using a function as a Handler.
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func HandlerFunc(f func(context.Context, *Request) *Response) Handler {
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return handlerFunc(f)
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}
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// Handle implements Handler.
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func (f handlerFunc) Handle(ctx context.Context, request *Request) *Response {
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return f(ctx, request)
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}
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// Middleware is a handler decorator.
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//
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// It returns a handler which may call the passed-in handler or not, or may
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// transform the request or response in some way.
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type Middleware func(Handler) Handler
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// FallthroughHandler builds a handler which tries multiple child handlers.
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//
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// The returned handler will invoke each of the passed-in handlers in order,
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// stopping when it receives a non-nil response.
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func FallthroughHandler(handlers ...Handler) Handler {
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return HandlerFunc(func(ctx context.Context, request *Request) *Response {
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for _, handler := range handlers {
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if response := handler.Handle(ctx, request); response != nil {
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return response
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}
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}
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return nil
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})
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}
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// Filter builds a middleware which only calls the wrapped Handler under a condition.
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//
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// When the condition function returns false it instead invokes the test-failure
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// handler. The failure handler may also be nil, in which case the final handler will
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// return a nil response whenever the condition fails.
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func Filter(
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condition func(context.Context, *Request) bool,
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failure Handler,
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) Middleware {
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return func(success Handler) Handler {
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return HandlerFunc(func(ctx context.Context, request *Request) *Response {
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if condition(ctx, request) {
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return success.Handle(ctx, request)
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}
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if failure == nil {
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return nil
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}
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return failure.Handle(ctx, request)
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})
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}
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}
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