Fix typo

Issue #16: Added regex support for matching headers

Issue #16 : Addressed code review and refactored support for regex into
a separate function

Added compiled regex to route matcher

doc.go

@@ -172,6 +172,13 @@ conform to the corresponding patterns. These requirements guarantee that a
 generated URL will always match a registered route -- the only exception is
 for explicitly defined "build-only" routes which never match.
 
+Regex support also exists for matching Headers within a route. For example, we could do:
+
+	r.HeadersRegexp("Content-Type", "application/(text|json)")
+
+...and the route will match both requests with a Content-Type of `application/json` as well as
+`application/text`
+
 There's also a way to build only the URL host or path for a route:
 use the methods URLHost() or URLPath() instead. For the previous route,
 we would do:

mux.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"net/http"
 	"path"
+	"regexp"
 
 	"github.com/gorilla/context"
 )
@@ -313,13 +314,21 @@ func uniqueVars(s1, s2 []string) error {
 	return nil
 }
 
-// mapFromPairs converts variadic string parameters to a string map.
-func mapFromPairs(pairs ...string) (map[string]string, error) {
+func checkPairs(pairs ...string) (int, error) {
 	length := len(pairs)
 	if length%2 != 0 {
-		return nil, fmt.Errorf(
+		return length, fmt.Errorf(
 			"mux: number of parameters must be multiple of 2, got %v", pairs)
 	}
+	return length, nil
+}
+
+// mapFromPairs converts variadic string parameters to a string map.
+func mapFromPairsToString(pairs ...string) (map[string]string, error) {
+	length, err := checkPairs(pairs...)
+	if err != nil {
+		return nil, err
+	}
 	m := make(map[string]string, length/2)
 	for i := 0; i < length; i += 2 {
 		m[pairs[i]] = pairs[i+1]
@@ -327,6 +336,19 @@ func mapFromPairs(pairs ...string) (map[string]string, error) {
 	return m, nil
 }
 
+func mapFromPairsToRegex(pairs ...string) (map[string]*regexp.Regexp, error) {
+	length, err := checkPairs(pairs...)
+	if err != nil {
+		return nil, err
+	}
+	m := make(map[string]*regexp.Regexp, length/2)
+	for i := 0; i < length; i += 2 {
+		regex, _ := regexp.Compile(pairs[i+1])
+		m[pairs[i]] = regex
+	}
+	return m, nil
+}
+
 // matchInArray returns true if the given string value is in the array.
 func matchInArray(arr []string, value string) bool {
 	for _, v := range arr {
@@ -337,9 +359,10 @@ func matchInArray(arr []string, value string) bool {
 	return false
 }
 
+type equals func(interface{}, interface{}) bool
+
 // matchMap returns true if the given key/value pairs exist in a given map.
-func matchMap(toCheck map[string]string, toMatch map[string][]string,
-	canonicalKey bool) bool {
+func matchMapWithString(toCheck map[string]string, toMatch map[string][]string, canonicalKey bool) bool {
 	for k, v := range toCheck {
 		// Check if key exists.
 		if canonicalKey {
@@ -364,3 +387,30 @@ func matchMap(toCheck map[string]string, toMatch map[string][]string,
 	}
 	return true
 }
+
+// matchMap returns true if the given key/value pairs exist in a given map.
+func matchMapWithRegex(toCheck map[string]*regexp.Regexp, toMatch map[string][]string, canonicalKey bool) bool {
+	for k, v := range toCheck {
+		// Check if key exists.
+		if canonicalKey {
+			k = http.CanonicalHeaderKey(k)
+		}
+		if values := toMatch[k]; values == nil {
+			return false
+		} else if v != nil {
+			// If value was defined as an empty string we only check that the
+			// key exists. Otherwise we also check for equality.
+			valueExists := false
+			for _, value := range values {
+				if v.MatchString(value) {
+					valueExists = true
+					break
+				}
+			}
+			if !valueExists {
+				return false
+			}
+		}
+	}
+	return true
+}

mux_test.go

@@ -434,6 +434,24 @@ func TestHeaders(t *testing.T) {
 			path:        "",
 			shouldMatch: false,
 		},
+		{
+			title:       "Headers route, regex header values to match",
+			route:       new(Route).Headers("foo", "ba[zr]"),
+			request:     newRequestHeaders("GET", "http://localhost", map[string]string{"foo": "bar"}),
+			vars:        map[string]string{},
+			host:        "",
+			path:        "",
+			shouldMatch: false,
+		},
+		{
+			title:       "Headers route, regex header values to match",
+			route:       new(Route).HeadersRegexp("foo", "ba[zr]"),
+			request:     newRequestHeaders("GET", "http://localhost", map[string]string{"foo": "baz"}),
+			vars:        map[string]string{},
+			host:        "",
+			path:        "",
+			shouldMatch: true,
+		},
 	}
 
 	for _, test := range tests {

route.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"net/http"
 	"net/url"
+	"regexp"
 	"strings"
 )
 
@@ -188,7 +189,7 @@ func (r *Route) addRegexpMatcher(tpl string, matchHost, matchPrefix, matchQuery
 type headerMatcher map[string]string
 
 func (m headerMatcher) Match(r *http.Request, match *RouteMatch) bool {
-	return matchMap(m, r.Header, true)
+	return matchMapWithString(m, r.Header, true)
 }
 
 // Headers adds a matcher for request header values.
@@ -199,22 +200,53 @@ func (m headerMatcher) Match(r *http.Request, match *RouteMatch) bool {
 //               "X-Requested-With", "XMLHttpRequest")
 //
 // The above route will only match if both request header values match.
+// Alternatively, you can provide a regular expression and match the header as follows:
+//
+//     r.Headers("Content-Type", "application/(text|json)",
+//               "X-Requested-With", "XMLHttpRequest")
+//
+// The above route will the same as the previous example, with the addition of matching
+// application/text as well.
 //
 // It the value is an empty string, it will match any value if the key is set.
 func (r *Route) Headers(pairs ...string) *Route {
 	if r.err == nil {
 		var headers map[string]string
-		headers, r.err = mapFromPairs(pairs...)
+		headers, r.err = mapFromPairsToString(pairs...)
 		return r.addMatcher(headerMatcher(headers))
 	}
 	return r
 }
 
+// headerRegexMatcher matches the request against the route given a regex for the header
+type headerRegexMatcher map[string]*regexp.Regexp
+
+func (m headerRegexMatcher) Match(r *http.Request, match *RouteMatch) bool {
+	return matchMapWithRegex(m, r.Header, true)
+}
+
+// Regular expressions can be used with headers as well.
+// It accepts a sequence of key/value pairs, where the value has regex support. For example
+//     r := mux.NewRouter()
+//     r.HeadersRegexp("Content-Type", "application/(text|json)",
+//               "X-Requested-With", "XMLHttpRequest")
+//
+// The above route will only match if both the request header matches both regular expressions.
+// It the value is an empty string, it will match any value if the key is set.
+func (r *Route) HeadersRegexp(pairs ...string) *Route {
+	if r.err == nil {
+		var headers map[string]*regexp.Regexp
+		headers, r.err = mapFromPairsToRegex(pairs...)
+		return r.addMatcher(headerRegexMatcher(headers))
+	}
+	return r
+}
+
 // Host -----------------------------------------------------------------------
 
 // Host adds a matcher for the URL host.
 // It accepts a template with zero or more URL variables enclosed by {}.
-// Variables can define an optional regexp pattern to me matched:
+// Variables can define an optional regexp pattern to be matched:
 //
 // - {name} matches anything until the next dot.
 //
@@ -272,7 +304,7 @@ func (r *Route) Methods(methods ...string) *Route {
 // Path adds a matcher for the URL path.
 // It accepts a template with zero or more URL variables enclosed by {}. The
 // template must start with a "/".
-// Variables can define an optional regexp pattern to me matched:
+// Variables can define an optional regexp pattern to be matched:
 //
 // - {name} matches anything until the next slash.
 //
@@ -323,7 +355,7 @@ func (r *Route) PathPrefix(tpl string) *Route {
 //
 // It the value is an empty string, it will match any value if the key is set.
 //
-// Variables can define an optional regexp pattern to me matched:
+// Variables can define an optional regexp pattern to be matched:
 //
 // - {name} matches anything until the next slash.
 //
@@ -511,7 +543,7 @@ func (r *Route) URLPath(pairs ...string) (*url.URL, error) {
 // prepareVars converts the route variable pairs into a map. If the route has a
 // BuildVarsFunc, it is invoked.
 func (r *Route) prepareVars(pairs ...string) (map[string]string, error) {
-	m, err := mapFromPairs(pairs...)
+	m, err := mapFromPairsToString(pairs...)
 	if err != nil {
 		return nil, err
 	}