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|
package chi
import (
"context"
"net/http"
"strings"
"time"
)
// URLParam returns the url parameter from a http.Request object.
func URLParam(r *http.Request, key string) string {
if rctx := RouteContext(r.Context()); rctx != nil {
return rctx.URLParam(key)
}
return ""
}
// URLParamFromCtx returns the url parameter from a http.Request Context.
func URLParamFromCtx(ctx context.Context, key string) string {
if rctx := RouteContext(ctx); rctx != nil {
return rctx.URLParam(key)
}
return ""
}
// RouteContext returns chi's routing Context object from a
// http.Request Context.
func RouteContext(ctx context.Context) *Context {
val, _ := ctx.Value(RouteCtxKey).(*Context)
return val
}
// NewRouteContext returns a new routing Context object.
func NewRouteContext() *Context {
return &Context{}
}
var (
// RouteCtxKey is the context.Context key to store the request context.
RouteCtxKey = &contextKey{"RouteContext"}
)
// Context is the default routing context set on the root node of a
// request context to track route patterns, URL parameters and
// an optional routing path.
type Context struct {
Routes Routes
// Routing path/method override used during the route search.
// See Mux#routeHTTP method.
RoutePath string
RouteMethod string
// Routing pattern stack throughout the lifecycle of the request,
// across all connected routers. It is a record of all matching
// patterns across a stack of sub-routers.
RoutePatterns []string
// URLParams are the stack of routeParams captured during the
// routing lifecycle across a stack of sub-routers.
URLParams RouteParams
// The endpoint routing pattern that matched the request URI path
// or `RoutePath` of the current sub-router. This value will update
// during the lifecycle of a request passing through a stack of
// sub-routers.
routePattern string
// Route parameters matched for the current sub-router. It is
// intentionally unexported so it cant be tampered.
routeParams RouteParams
// methodNotAllowed hint
methodNotAllowed bool
// parentCtx is the parent of this one, for using Context as a
// context.Context directly. This is an optimization that saves
// 1 allocation.
parentCtx context.Context
}
// Reset a routing context to its initial state.
func (x *Context) Reset() {
x.Routes = nil
x.RoutePath = ""
x.RouteMethod = ""
x.RoutePatterns = x.RoutePatterns[:0]
x.URLParams.Keys = x.URLParams.Keys[:0]
x.URLParams.Values = x.URLParams.Values[:0]
x.routePattern = ""
x.routeParams.Keys = x.routeParams.Keys[:0]
x.routeParams.Values = x.routeParams.Values[:0]
x.methodNotAllowed = false
x.parentCtx = nil
}
// URLParam returns the corresponding URL parameter value from the request
// routing context.
func (x *Context) URLParam(key string) string {
for k := len(x.URLParams.Keys) - 1; k >= 0; k-- {
if x.URLParams.Keys[k] == key {
return x.URLParams.Values[k]
}
}
return ""
}
// RoutePattern builds the routing pattern string for the particular
// request, at the particular point during routing. This means, the value
// will change throughout the execution of a request in a router. That is
// why its advised to only use this value after calling the next handler.
//
// For example,
//
// func Instrument(next http.Handler) http.Handler {
// return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// next.ServeHTTP(w, r)
// routePattern := chi.RouteContext(r.Context()).RoutePattern()
// measure(w, r, routePattern)
// })
// }
func (x *Context) RoutePattern() string {
routePattern := strings.Join(x.RoutePatterns, "")
return replaceWildcards(routePattern)
}
// replaceWildcards takes a route pattern and recursively replaces all
// occurrences of "/*/" to "/".
func replaceWildcards(p string) string {
if strings.Contains(p, "/*/") {
return replaceWildcards(strings.Replace(p, "/*/", "/", -1))
}
return p
}
// RouteParams is a structure to track URL routing parameters efficiently.
type RouteParams struct {
Keys, Values []string
}
// Add will append a URL parameter to the end of the route param
func (s *RouteParams) Add(key, value string) {
s.Keys = append(s.Keys, key)
s.Values = append(s.Values, value)
}
// directContext provides direct access to the routing *Context object,
// while implementing the context.Context interface, thereby allowing
// us to saving 1 allocation during routing.
type directContext Context
var _ context.Context = (*directContext)(nil)
func (d *directContext) Deadline() (deadline time.Time, ok bool) {
return d.parentCtx.Deadline()
}
func (d *directContext) Done() <-chan struct{} {
return d.parentCtx.Done()
}
func (d *directContext) Err() error {
return d.parentCtx.Err()
}
func (d *directContext) Value(key interface{}) interface{} {
if key == RouteCtxKey {
return (*Context)(d)
}
return d.parentCtx.Value(key)
}
// contextKey is a value for use with context.WithValue. It's used as
// a pointer so it fits in an interface{} without allocation. This technique
// for defining context keys was copied from Go 1.7's new use of context in net/http.
type contextKey struct {
name string
}
func (k *contextKey) String() string {
return "chi context value " + k.name
}
|
