latihan membuat router http server

screenshot.md

contoh :

webrouter.go

package main

import (
	"fmt"
	"net/http"
	"net/url"
)

type (
	Params struct {
		url  *url.URL
		keys []string
		vals [32][2]int
	}
	Brnch struct {
		hndlr   func(http.ResponseWriter, *http.Request, Params)
		prmsKey []string
		nxt     Route
	}
	Route    map[string]Brnch
	RouteCfg []struct {
		path  string
		hndlr func(http.ResponseWriter, *http.Request, Params)
	}
)

func (prms *Params) ByName(name string) (val string) {
	url := prms.url
	for i, key := range prms.keys {
		if key == name {
			bgnEnd := prms.vals[i]
			val = url.Path[bgnEnd[0]:bgnEnd[1]]
		}
	}
	return
}
func RouteTrie(routeCfg RouteCfg) (route Route) {
	route = Route{}
	for _, rCfg := range routeCfg {
		r := route
		path := rCfg.path
		var prmsKey []string
		bgn := 0
		for end, chr := range path {
			if chr == '/' {
				sgmnt := path[bgn:end]
				if sgmnt[0] == ':' {
					prmsKey = append(prmsKey, sgmnt[1:])
					sgmnt = ":"
				}
				_, ok := r[sgmnt]
				if !ok {
					r[sgmnt] = Brnch{nil, nil, Route{}}
				}
				bgn = end + 1
				r = r[sgmnt].nxt
			}
		}
		sgmnt := path[bgn:]
		if sgmnt[0] == ':' {
			prmsKey = append(prmsKey, sgmnt[1:])
			sgmnt = ":"
		}
		_, ok := r[sgmnt]
		if !ok {
			r[sgmnt] = Brnch{rCfg.hndlr, prmsKey, nil}
		}
	}
	return
}
func NewRoute(routeCfg RouteCfg, notFound, methodNotAllowed func(http.ResponseWriter, *http.Request)) (ServeHTTP http.HandlerFunc) {
	route := RouteTrie(routeCfg)
	ServeHTTP = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		brnch, ok := route[r.Method]
		if !ok {
			methodNotAllowed(w, r)
			return
		}
		var brnch_ Brnch
		prms := Params{}
		url := r.URL
		bgn, i := 1, 0
		for end, chr := range url.Path {
			if end != 0 && chr == '/' {
				brnch_, ok = brnch.nxt[url.Path[bgn:end]]
				if ok {
					brnch = brnch_
				} else {
					brnch, ok = brnch.nxt[":"]
					if ok {
						prms.vals[i] = [2]int{bgn, end}
						i++
					} else {
						notFound(w, r)
						return
					}
				}
				bgn = end + 1
			}
		}
		prms.url = url
		brnch_, ok = brnch.nxt[url.Path[bgn:]]
		if ok && brnch_.hndlr != nil {
			prms.keys = brnch_.prmsKey
			brnch_.hndlr(w, r, prms)
		} else {
			brnch, ok = brnch.nxt[":"]
			if ok && brnch.hndlr != nil {
				prms.vals[i] = [2]int{bgn, len(url.Path)}
				prms.keys = brnch.prmsKey
				brnch.hndlr(w, r, prms)
			} else {
				notFound(w, r)
				return
			}
		}
	})
	return
}
func main() {
	newHndlr := func(path string) (hndlr func(http.ResponseWriter, *http.Request, Params)) {
		hndlr = func(w http.ResponseWriter, r *http.Request, params Params) {
			w.WriteHeader(http.StatusOK)
			url := r.URL
			fmt.Fprintf(w, "path %s\n", path)
			for i, key := range params.keys {
				bgnEnd := params.vals[i]
				fmt.Fprintf(w, "param %d key: %s, val: %s, params.ByName(\"%s\") == \"%s\"\n", i, key, url.Path[bgnEnd[0]:bgnEnd[1]], key, params.ByName(key))
			}
			if len(params.keys) == 0 {
				w.Write([]byte("no params"))
			}
		}
		return
	}
	routeCfg := RouteCfg{
		{"GET/def/ghi/jkl", newHndlr("/def/ghi/jkl")},
		/*
			url /def/ghi/jkl
			no params
		*/

		{"GET/def/:ghi/jkl", newHndlr("/def/:ghi/jkl")},
		/*
			url /def/GHI/jkl
			param 0 key: ghi, val: GHI
		*/

		{"GET/def/:ghi/mno/:pqr/stu", newHndlr("/def/:ghi/mno/:pqr/stu")},
		/*
			url /def/GHI/mno/PQR/stu
			param 0 key: ghi, val: GHI
			param 1 key: pqr, val: PQR
		*/

		{"GET/def/:ghi/mno/:pqr/:stu", newHndlr("/def/:ghi/mno/:pqr/:stu")},
		/*
			url /def/GHI/mno/PQR/STU
			param 0 key: ghi, val: GHI
			param 1 key: pqr, val: PQR
			param 2 key: stu, val: STU
		*/

		{"GET/:def/:ghi/pqr", newHndlr("/:def/:ghi/pqr")},
		/*
			url /DEF/GHI/pqr
			param 0 key: def, val: DEF
			param 1 key: ghi, val: GHI
		*/
	}
	ServeHTTP := NewRoute(
		routeCfg,
		func(w http.ResponseWriter, r *http.Request) {
			w.WriteHeader(http.StatusNotFound)
			w.Write([]byte("not found"))
		},
		func(w http.ResponseWriter, r *http.Request) {
			w.WriteHeader(http.StatusMethodNotAllowed)
			w.Write([]byte("method not allowed"))
		},
	)
	http.ListenAndServe(":8080", ServeHTTP)
}