Remove trailing parent argument to matchPath

Also, be more explicit about the options we pass to matchPath. Instead
of allowing both `path` and `from`, do the coercion ahead of time in
<Switch>.

Author: mjackson

packages/react-router/modules/Route.js

@@ -48,7 +48,7 @@ class Route extends React.Component {
 
     const pathname = (location || route.location).pathname
 
-    return matchPath(pathname, { path, strict, exact }, route.match)
+    return path ? matchPath(pathname, { path, strict, exact }) : route.match
   }
 
   componentWillReceiveProps(nextProps, nextContext) {

packages/react-router/modules/Switch.js

@@ -28,14 +28,18 @@ class Switch extends React.Component {
   }
 
   render() {
+    const { route } = this.context
     const { children } = this.props
-    const location = this.props.location || this.context.route.location
-    const parent = this.context.route.match
+    const location = this.props.location || route.location
+
     let match, child
     React.Children.forEach(children, element => {
+      const { path: pathProp, exact, strict, from } = element.props
+      const path = pathProp || from
+
       if (match == null) {
         child = element
-        match = matchPath(location.pathname, element.props, parent)
+        match = path ? matchPath(location.pathname, { path, exact, strict }) : route.match
       }
     })
 

packages/react-router/modules/__tests__/matchPath-test.js

@@ -34,25 +34,15 @@ describe('matchPath', () => {
     })
   })
 
-  describe("with no path", () => {
-    it("returns parent match", () => {
-      const parentMatch = {
-        url: '/test-location/7',
-        path: '/test-location/:number',
-        params: { number: 7 },
-        isExact: true
-      }
-      const match = matchPath('/test-location/7', {}, parentMatch)
-      expect(match).toBe(parentMatch)
-    })
-
-    it('returns match with default values when parent match is null', () => {
-      const pathname = '/some/path'
-      const match = matchPath(pathname, {}, null)
-      expect(match.url).toBe(pathname)
-      expect(match.path).toBe(undefined)
-      expect(match.params).toEqual({})
-      expect(match.isExact).toBe(true)
+  describe('with no path', () => {
+    it('matches the root URL', () => {
+      const match = matchPath('/test-location/7', {})
+      expect(match).toMatch({
+        url: '/',
+        path: '/',
+        params: {},
+        isExact: false
+      })
     })
   })
 

packages/react-router/modules/matchPath.js

@@ -26,16 +26,11 @@ const compilePath = (pattern, options) => {
 /**
  * Public API for matching a URL pathname to a path pattern.
  */
-const matchPath = (pathname, options = {}, parent) => {
+const matchPath = (pathname, options = {}) => {
   if (typeof options === 'string')
     options = { path: options }
 
-  const { exact = false, strict = false } = options
-  const path = options.path || options.from
-
-  if (!path)
-    return parent != null ? parent : { url: pathname, isExact: true, params: {} }
-
+  const { path = '/', exact = false, strict = false } = options
   const { re, keys } = compilePath(path, { end: exact, strict })
   const match = re.exec(pathname)