mirror of https://github.com/poanetwork/quorum.git
122 lines
3.9 KiB
Go
122 lines
3.9 KiB
Go
package xhandler
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import (
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"net/http"
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"golang.org/x/net/context"
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)
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// Chain is a helper for chaining middleware handlers together for easier
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// management.
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type Chain []func(next HandlerC) HandlerC
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// Add appends a variable number of additional middleware handlers
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// to the middleware chain. Middleware handlers can either be
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// context-aware or non-context aware handlers with the appropriate
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// function signatures.
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func (c *Chain) Add(f ...interface{}) {
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for _, h := range f {
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switch v := h.(type) {
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case func(http.Handler) http.Handler:
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c.Use(v)
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case func(HandlerC) HandlerC:
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c.UseC(v)
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default:
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panic("Adding invalid handler to the middleware chain")
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}
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}
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}
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// With creates a new middleware chain from an existing chain,
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// extending it with additional middleware. Middleware handlers
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// can either be context-aware or non-context aware handlers
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// with the appropriate function signatures.
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func (c *Chain) With(f ...interface{}) *Chain {
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n := make(Chain, len(*c))
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copy(n, *c)
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n.Add(f...)
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return &n
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}
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// UseC appends a context-aware handler to the middleware chain.
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func (c *Chain) UseC(f func(next HandlerC) HandlerC) {
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*c = append(*c, f)
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}
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// Use appends a standard http.Handler to the middleware chain without
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// losing track of the context when inserted between two context aware handlers.
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//
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// Caveat: the f function will be called on each request so you are better off putting
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// any initialization sequence outside of this function.
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func (c *Chain) Use(f func(next http.Handler) http.Handler) {
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xf := func(next HandlerC) HandlerC {
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return HandlerFuncC(func(ctx context.Context, w http.ResponseWriter, r *http.Request) {
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n := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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next.ServeHTTPC(ctx, w, r)
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})
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f(n).ServeHTTP(w, r)
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})
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}
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*c = append(*c, xf)
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}
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// Handler wraps the provided final handler with all the middleware appended to
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// the chain and returns a new standard http.Handler instance.
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// The context.Background() context is injected automatically.
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func (c Chain) Handler(xh HandlerC) http.Handler {
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ctx := context.Background()
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return c.HandlerCtx(ctx, xh)
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}
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// HandlerFC is a helper to provide a function (HandlerFuncC) to Handler().
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//
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// HandlerFC is equivalent to:
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// c.Handler(xhandler.HandlerFuncC(xhc))
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func (c Chain) HandlerFC(xhf HandlerFuncC) http.Handler {
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ctx := context.Background()
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return c.HandlerCtx(ctx, HandlerFuncC(xhf))
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}
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// HandlerH is a helper to provide a standard http handler (http.HandlerFunc)
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// to Handler(). Your final handler won't have access to the context though.
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func (c Chain) HandlerH(h http.Handler) http.Handler {
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ctx := context.Background()
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return c.HandlerCtx(ctx, HandlerFuncC(func(ctx context.Context, w http.ResponseWriter, r *http.Request) {
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h.ServeHTTP(w, r)
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}))
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}
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// HandlerF is a helper to provide a standard http handler function
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// (http.HandlerFunc) to Handler(). Your final handler won't have access
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// to the context though.
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func (c Chain) HandlerF(hf http.HandlerFunc) http.Handler {
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ctx := context.Background()
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return c.HandlerCtx(ctx, HandlerFuncC(func(ctx context.Context, w http.ResponseWriter, r *http.Request) {
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hf(w, r)
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}))
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}
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// HandlerCtx wraps the provided final handler with all the middleware appended to
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// the chain and returns a new standard http.Handler instance.
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func (c Chain) HandlerCtx(ctx context.Context, xh HandlerC) http.Handler {
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return New(ctx, c.HandlerC(xh))
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}
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// HandlerC wraps the provided final handler with all the middleware appended to
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// the chain and returns a HandlerC instance.
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func (c Chain) HandlerC(xh HandlerC) HandlerC {
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for i := len(c) - 1; i >= 0; i-- {
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xh = c[i](xh)
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}
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return xh
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}
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// HandlerCF wraps the provided final handler func with all the middleware appended to
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// the chain and returns a HandlerC instance.
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//
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// HandlerCF is equivalent to:
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// c.HandlerC(xhandler.HandlerFuncC(xhc))
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func (c Chain) HandlerCF(xhc HandlerFuncC) HandlerC {
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return c.HandlerC(HandlerFuncC(xhc))
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}
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