route: add GetHeaders and GetHeadersRegexp

mux_test.go

@@ -16,6 +16,7 @@ import (
 	"net/http/httptest"
 	"net/url"
 	"reflect"
+	"regexp"
 	"strings"
 	"testing"
 	"time"
@@ -2009,6 +2010,66 @@ func testQueriesTemplates(t *testing.T, test routeTest) {
 	}
 }
 
+func TestGetHeaders(t *testing.T) {
+	r := NewRouter()
+	route := r.NewRoute().Path("/v1/conversations").Headers(
+		"Content-Type", "application/json",
+		"X-Requested-With", "XMLHttpRequest",
+	)
+	got, err := route.GetHeaders()
+	if err != nil {
+		t.Fatalf("GetHeaders: %v", err)
+	}
+	want := map[string]string{
+		"Content-Type":     "application/json",
+		"X-Requested-With": "XMLHttpRequest",
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("GetHeaders = %#v, want %#v", got, want)
+	}
+
+	if _, err := r.NewRoute().Path("/no-headers").GetHeaders(); err == nil {
+		t.Fatal("GetHeaders: expected error for route without headers")
+	}
+
+	if _, err := r.NewRoute().Path("/regexp-only").HeadersRegexp("Accept", "html").GetHeaders(); err == nil {
+		t.Fatal("GetHeaders: expected error for HeadersRegexp-only route")
+	}
+}
+
+func TestGetHeadersRegexp(t *testing.T) {
+	r := NewRouter()
+	route := r.NewRoute().Path("/v1").HeadersRegexp(
+		"Content-Type", "application/(text|json)",
+		"X-Requested-With", "XMLHttpRequest",
+	)
+	got, err := route.GetHeadersRegexp()
+	if err != nil {
+		t.Fatalf("GetHeadersRegexp: %v", err)
+	}
+	if len(got) != 2 {
+		t.Fatalf("GetHeadersRegexp len = %d, want 2: %#v", len(got), got)
+	}
+	re, err := regexp.Compile(got["Content-Type"])
+	if err != nil {
+		t.Fatalf("GetHeadersRegexp Content-Type: %v", err)
+	}
+	if !re.MatchString("application/json") || re.MatchString("application/xml") {
+		t.Fatalf("GetHeadersRegexp Content-Type %q did not match as registered", got["Content-Type"])
+	}
+	if got["X-Requested-With"] == "" {
+		t.Fatalf("GetHeadersRegexp missing X-Requested-With: %#v", got)
+	}
+
+	if _, err := r.NewRoute().Path("/no-headers").GetHeadersRegexp(); err == nil {
+		t.Fatal("GetHeadersRegexp: expected error for route without header regexps")
+	}
+
+	if _, err := r.NewRoute().Path("/exact-only").Headers("Accept", "text/html").GetHeadersRegexp(); err == nil {
+		t.Fatal("GetHeadersRegexp: expected error for Headers-only route")
+	}
+}
+
 type TestA301ResponseWriter struct {
 	hh     http.Header
 	status int

route.go

@@ -776,6 +776,54 @@ func (r *Route) GetMethods() ([]string, error) {
 	return nil, errors.New("mux: route doesn't have methods")
 }
 
+// GetHeaders returns the exact header name/value pairs the route matches against.
+// This is useful for building simple REST API documentation and for instrumentation
+// against third-party services.
+// An error will be returned if the route does not have headers.
+func (r *Route) GetHeaders() (map[string]string, error) {
+	if r.err != nil {
+		return nil, r.err
+	}
+	out := make(map[string]string)
+	found := false
+	for _, m := range r.matchers {
+		if headers, ok := m.(headerMatcher); ok {
+			found = true
+			for k, v := range headers {
+				out[k] = v
+			}
+		}
+	}
+	if !found {
+		return nil, errors.New("mux: route doesn't have headers")
+	}
+	return out, nil
+}
+
+// GetHeadersRegexp returns the header name/regexp pairs the route matches against.
+// This is useful for building simple REST API documentation and for instrumentation
+// against third-party services.
+// An error will be returned if the route does not have header regular expressions.
+func (r *Route) GetHeadersRegexp() (map[string]string, error) {
+	if r.err != nil {
+		return nil, r.err
+	}
+	out := make(map[string]string)
+	found := false
+	for _, m := range r.matchers {
+		if headers, ok := m.(headerRegexMatcher); ok {
+			found = true
+			for k, v := range headers {
+				out[k] = v.String()
+			}
+		}
+	}
+	if !found {
+		return nil, errors.New("mux: route doesn't have header regexps")
+	}
+	return out, nil
+}
+
 // GetHostTemplate returns the template used to build the
 // route match.
 // This is useful for building simple REST API documentation and for instrumentation