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package restful
// Copyright 2013 Ernest Micklei. All rights reserved.
// Use of this source code is governed by a license
// that can be found in the LICENSE file.
import (
"net/http"
"regexp"
"sort"
"strings"
)
// CurlyRouter expects Routes with paths that contain zero or more parameters in curly brackets.
type CurlyRouter struct{}
// SelectRoute is part of the Router interface and returns the best match
// for the WebService and its Route for the given Request.
func (c CurlyRouter) SelectRoute(
webServices []*WebService,
httpRequest *http.Request) (selectedService *WebService, selected *Route, err error) {
requestTokens := tokenizePath(httpRequest.URL.Path)
detectedService := c.detectWebService(requestTokens, webServices)
if detectedService == nil {
if trace {
traceLogger.Printf("no WebService was found to match URL path:%s\n", httpRequest.URL.Path)
}
return nil, nil, NewError(http.StatusNotFound, "404: Page Not Found")
}
candidateRoutes := c.selectRoutes(detectedService, requestTokens)
if len(candidateRoutes) == 0 {
if trace {
traceLogger.Printf("no Route in WebService with path %s was found to match URL path:%s\n", detectedService.rootPath, httpRequest.URL.Path)
}
return detectedService, nil, NewError(http.StatusNotFound, "404: Page Not Found")
}
selectedRoute, err := c.detectRoute(candidateRoutes, httpRequest)
if selectedRoute == nil {
return detectedService, nil, err
}
return detectedService, selectedRoute, nil
}
// selectRoutes return a collection of Route from a WebService that matches the path tokens from the request.
func (c CurlyRouter) selectRoutes(ws *WebService, requestTokens []string) sortableCurlyRoutes {
candidates := sortableCurlyRoutes{}
for _, each := range ws.routes {
matches, paramCount, staticCount := c.matchesRouteByPathTokens(each.pathParts, requestTokens)
if matches {
candidates.add(curlyRoute{each, paramCount, staticCount}) // TODO make sure Routes() return pointers?
}
}
sort.Sort(sort.Reverse(candidates))
return candidates
}
// matchesRouteByPathTokens computes whether it matches, howmany parameters do match and what the number of static path elements are.
func (c CurlyRouter) matchesRouteByPathTokens(routeTokens, requestTokens []string) (matches bool, paramCount int, staticCount int) {
if len(routeTokens) < len(requestTokens) {
// proceed in matching only if last routeToken is wildcard
count := len(routeTokens)
if count == 0 || !strings.HasSuffix(routeTokens[count-1], "*}") {
return false, 0, 0
}
// proceed
}
for i, routeToken := range routeTokens {
if i == len(requestTokens) {
// reached end of request path
return false, 0, 0
}
requestToken := requestTokens[i]
if strings.HasPrefix(routeToken, "{") {
paramCount++
if colon := strings.Index(routeToken, ":"); colon != -1 {
// match by regex
matchesToken, matchesRemainder := c.regularMatchesPathToken(routeToken, colon, requestToken)
if !matchesToken {
return false, 0, 0
}
if matchesRemainder {
break
}
}
} else { // no { prefix
if requestToken != routeToken {
return false, 0, 0
}
staticCount++
}
}
return true, paramCount, staticCount
}
// regularMatchesPathToken tests whether the regular expression part of routeToken matches the requestToken or all remaining tokens
// format routeToken is {someVar:someExpression}, e.g. {zipcode:[\d][\d][\d][\d][A-Z][A-Z]}
func (c CurlyRouter) regularMatchesPathToken(routeToken string, colon int, requestToken string) (matchesToken bool, matchesRemainder bool) {
regPart := routeToken[colon+1 : len(routeToken)-1]
if regPart == "*" {
if trace {
traceLogger.Printf("wildcard parameter detected in route token %s that matches %s\n", routeToken, requestToken)
}
return true, true
}
matched, err := regexp.MatchString(regPart, requestToken)
return (matched && err == nil), false
}
var jsr311Router = RouterJSR311{}
// detectRoute selectes from a list of Route the first match by inspecting both the Accept and Content-Type
// headers of the Request. See also RouterJSR311 in jsr311.go
func (c CurlyRouter) detectRoute(candidateRoutes sortableCurlyRoutes, httpRequest *http.Request) (*Route, error) {
// tracing is done inside detectRoute
return jsr311Router.detectRoute(candidateRoutes.routes(), httpRequest)
}
// detectWebService returns the best matching webService given the list of path tokens.
// see also computeWebserviceScore
func (c CurlyRouter) detectWebService(requestTokens []string, webServices []*WebService) *WebService {
var best *WebService
score := -1
for _, each := range webServices {
matches, eachScore := c.computeWebserviceScore(requestTokens, each.pathExpr.tokens)
if matches && (eachScore > score) {
best = each
score = eachScore
}
}
return best
}
// computeWebserviceScore returns whether tokens match and
// the weighted score of the longest matching consecutive tokens from the beginning.
func (c CurlyRouter) computeWebserviceScore(requestTokens []string, tokens []string) (bool, int) {
if len(tokens) > len(requestTokens) {
return false, 0
}
score := 0
for i := 0; i < len(tokens); i++ {
each := requestTokens[i]
other := tokens[i]
if len(each) == 0 && len(other) == 0 {
score++
continue
}
if len(other) > 0 && strings.HasPrefix(other, "{") {
// no empty match
if len(each) == 0 {
return false, score
}
score += 1
} else {
// not a parameter
if each != other {
return false, score
}
score += (len(tokens) - i) * 10 //fuzzy
}
}
return true, score
}