initial implementation with README

Author: SjonHortensius

README.md

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+Introduction
+============
+
+This is an extremely minimal router, for usage in your own application. Supports only 2 things:
+* routing based on request-method and path
+* parameters in URLs
+
+I build it for a json-only REST api with a few routes.
+
+Usage
+=====
+
+This intentionally does NOT implement `ServeHTTP`, as you should implement this
+yourself, to do any wrapping and processing of request or response.
+
+Example
+=======
+
+```go
+package main
+
+import (
+	"encoding/json"
+	"github.com/parse-nl/MinimalRouter"
+	"net/http"
+)
+
+type appController struct{}
+type appRequest    struct{ Params map[string]string }
+type appResponse   struct{ Result string }
+
+var router *minimalrouter.Router
+
+func init() {
+	router = minimalrouter.New()
+
+	router.Add("GET",  "/ping",             handleGetPing)
+	router.Add("POST", "/hello-from/:name", handlePostHello)
+}
+
+func main() {
+	http.ListenAndServe(":8088", &appController{})
+}
+
+// implement the standard ServeHTTP as required by golang
+// handles json encoding and decoding, could implement authentication as well
+func (c *appController) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	var result *appResponse
+
+	fn, params := router.Match(r.Method, r.URL.Path)
+	request := &appRequest{params}
+
+	if fn == nil {
+		w.WriteHeader(http.StatusNotFound)
+		result = &appResponse{"error"}
+	} else {
+		w.WriteHeader(http.StatusOK)
+
+		// convert the generic interface{} to the function-signature we expect
+		result = fn.(func(*appRequest) *appResponse)(request)
+	}
+
+	w.Header().Add("Content-Type", "application/json")
+	enc := json.NewEncoder(w)
+	enc.Encode(result)
+}
+
+func handleGetPing(r *appRequest) *appResponse {
+	return &appResponse{"pong"}
+}
+
+func handlePostHello(r *appRequest) *appResponse {
+	return &appResponse{"hey " + r.Params["name"]}
+}
+
+```

router.go

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+package minimalrouter
+
+import "strings"
+
+func New() *Router {
+	return &Router{children: make(map[string]*Router)}
+}
+
+// Represents both the Router and each node
+type Router struct {
+	children map[string]*Router
+	varName  string
+	handler  interface{}
+}
+
+func (this *Router) Add(method, path string, h interface{}) {
+	if path[0] != '/' {
+		panic("path must begin with '/' in: " + path)
+	} else if path[len(path)-1] == '/' {
+		panic("path must not end with '/' in: " + path)
+	}
+
+	parts := append([]string{method}, strings.Split(path[1:], "/")...)
+	node := this
+
+	for _, p := range parts {
+		if p[0] == ':' && len(p) > 2 {
+			varName := p[1:]
+			p = ":"
+
+			if node.varName == "" {
+				node.varName = varName
+			} else if node.varName != varName {
+				panic("conflict while adding " + path + "; parameter conflicts with :" + node.varName)
+			}
+		}
+
+		n, ok := node.children[p]
+		if !ok {
+			node.children[p] = New()
+			n = node.children[p]
+		}
+
+		node = n
+	}
+
+	node.handler = h
+}
+
+func (this *Router) Match(method, path string) (interface{}, map[string]string) {
+	parts := append([]string{method}, strings.Split(path[1:], "/")...)
+	params := make(map[string]string)
+	node := this
+
+	for _, p := range parts {
+		n, ok := node.children[p]
+
+		if !ok && node.varName != "" {
+			n = node.children[":"]
+			params[node.varName] = p
+		} else if !ok {
+			return nil, nil
+		}
+
+		node = n
+	}
+
+	return node.handler, params
+}