Proper colon support in reverse (#2416)

* Adds support of the escaped colon in echo.Reverse

---------

Co-authored-by: Mihard <mihard@webird.ru>

echo_test.go

@@ -1517,6 +1517,83 @@ func TestEcho_OnAddRouteHandler(t *testing.T) {
 }
 
 func TestEchoReverse(t *testing.T) {
+	var testCases = []struct {
+		name          string
+		whenRouteName string
+		whenParams    []interface{}
+		expect        string
+	}{
+		{
+			name:          "ok,static with no params",
+			whenRouteName: "/static",
+			expect:        "/static",
+		},
+		{
+			name:          "ok,static with non existent param",
+			whenRouteName: "/static",
+			whenParams:    []interface{}{"missing param"},
+			expect:        "/static",
+		},
+		{
+			name:          "ok, wildcard with no params",
+			whenRouteName: "/static/*",
+			expect:        "/static/*",
+		},
+		{
+			name:          "ok, wildcard with params",
+			whenRouteName: "/static/*",
+			whenParams:    []interface{}{"foo.txt"},
+			expect:        "/static/foo.txt",
+		},
+		{
+			name:          "ok, single param without param",
+			whenRouteName: "/params/:foo",
+			expect:        "/params/:foo",
+		},
+		{
+			name:          "ok, single param with param",
+			whenRouteName: "/params/:foo",
+			whenParams:    []interface{}{"one"},
+			expect:        "/params/one",
+		},
+		{
+			name:          "ok, multi param without params",
+			whenRouteName: "/params/:foo/bar/:qux",
+			expect:        "/params/:foo/bar/:qux",
+		},
+		{
+			name:          "ok, multi param with one param",
+			whenRouteName: "/params/:foo/bar/:qux",
+			whenParams:    []interface{}{"one"},
+			expect:        "/params/one/bar/:qux",
+		},
+		{
+			name:          "ok, multi param with all params",
+			whenRouteName: "/params/:foo/bar/:qux",
+			whenParams:    []interface{}{"one", "two"},
+			expect:        "/params/one/bar/two",
+		},
+		{
+			name:          "ok, multi param + wildcard with all params",
+			whenRouteName: "/params/:foo/bar/:qux/*",
+			whenParams:    []interface{}{"one", "two", "three"},
+			expect:        "/params/one/bar/two/three",
+		},
+		{
+			name:          "ok, backslash is not escaped",
+			whenRouteName: "/backslash",
+			whenParams:    []interface{}{"test"},
+			expect:        `/a\b/test`,
+		},
+		{
+			name:          "ok, escaped colon verbs",
+			whenRouteName: "/params:customVerb",
+			whenParams:    []interface{}{"PATCH"},
+			expect:        `/params:PATCH`,
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
 			e := New()
 			dummyHandler := func(Context) error { return nil }
 
@@ -1525,18 +1602,12 @@ func TestEchoReverse(t *testing.T) {
 			e.GET("/params/:foo", dummyHandler).Name = "/params/:foo"
 			e.GET("/params/:foo/bar/:qux", dummyHandler).Name = "/params/:foo/bar/:qux"
 			e.GET("/params/:foo/bar/:qux/*", dummyHandler).Name = "/params/:foo/bar/:qux/*"
+			e.GET("/a\\b/:x", dummyHandler).Name = "/backslash"
+			e.GET("/params\\::customVerb", dummyHandler).Name = "/params:customVerb"
 
-	assert.Equal(t, "/static", e.Reverse("/static"))
+			assert.Equal(t, tc.expect, e.Reverse(tc.whenRouteName, tc.whenParams...))
-	assert.Equal(t, "/static", e.Reverse("/static", "missing param"))
+		})
-	assert.Equal(t, "/static/*", e.Reverse("/static/*"))
+	}
-	assert.Equal(t, "/static/foo.txt", e.Reverse("/static/*", "foo.txt"))
-
-	assert.Equal(t, "/params/:foo", e.Reverse("/params/:foo"))
-	assert.Equal(t, "/params/one", e.Reverse("/params/:foo", "one"))
-	assert.Equal(t, "/params/:foo/bar/:qux", e.Reverse("/params/:foo/bar/:qux"))
-	assert.Equal(t, "/params/one/bar/:qux", e.Reverse("/params/:foo/bar/:qux", "one"))
-	assert.Equal(t, "/params/one/bar/two", e.Reverse("/params/:foo/bar/:qux", "one", "two"))
-	assert.Equal(t, "/params/one/bar/two/three", e.Reverse("/params/:foo/bar/:qux/*", "one", "two", "three"))
 }
 
 func TestEchoReverseHandleHostProperly(t *testing.T) {

router.go

@@ -159,7 +159,12 @@ func (r *Router) Reverse(name string, params ...interface{}) string {
 	for _, route := range r.routes {
 		if route.Name == name {
 			for i, l := 0, len(route.Path); i < l; i++ {
-				if (route.Path[i] == ':' || route.Path[i] == '*') && n < ln {
+				hasBackslash := route.Path[i] == '\\'
+				if hasBackslash && i+1 < l && route.Path[i+1] == ':' {
+					i++ // backslash before colon escapes that colon. in that case skip backslash
+				}
+				if n < ln && (route.Path[i] == '*' || (!hasBackslash && route.Path[i] == ':')) {
+					// in case of `*` wildcard or `:` (unescaped colon) param we replace everything till next slash or end of path
 					for ; i < l && route.Path[i] != '/'; i++ {
 					}
 					uri.WriteString(fmt.Sprintf("%v", params[n]))