Support ES6 modules in setting url-pattern compiler

Author: STRML

docs/override-url-pattern.md

@@ -8,6 +8,7 @@ The author of `url-pattern`, which does the underlying conversion in RRC from ro
 For example:
 
     var Router = require('react-router-component');
+    var URLPattern = require('url-pattern');
 
     // Create a compiler that only matches alphabetical characters in urls.
     //
@@ -24,3 +25,14 @@ Overriding the compiler allows you to write very powerful route definitions.
 Note that this override is global. At this time, there is no way to define a compiler per Router. If you have
 more advanced needs, we recommend using `url-pattern` directly to generate regular expressions to use as route paths,
 or using regular expressions directly.
+
+A note on ES6; ES6 modules can't modify `module.exports` directly. Instead, use `setCreateURLPatternCompilerFactory`:
+
+    import * as Router from 'react-router-component';
+    import * as URLPattern from 'url-pattern';
+
+    Router.setCreateURLPatternCompilerFactory((routeProps) => {
+      var compiler = new URLPattern.Compiler();
+      compiler.segmentValueCharset = 'a-zA-Z';
+      return compiler;
+    })

index.js

@@ -38,5 +38,10 @@ module.exports = {
   // The fn used to create a compiler for "/user/:id"-style routes is exposed here so it can be overridden.
   createURLPatternCompiler: function() {
     return new URLPattern.Compiler();
+  },
+
+  // For ES6 imports, which can't modify module.exports directly
+  setCreateURLPatternCompilerFactory: function(fn) {
+    this.createURLPatternCompiler = fn;
   }
 };

tests/matchRoutes.js

@@ -88,7 +88,7 @@ describe('matchRoutes', function() {
                           handler: React.createElement('div', {name: 'parseDomain'})});
 
     // Lifted from url-pattern docs
-    Router.createURLPatternCompiler = function(routeProps) {
+    Router.setCreateURLPatternCompilerFactory(function(routeProps) {
       // Somebody might use this, make sure it works.
       assert.strictEqual(routeProps.path, route.props.path);
 
@@ -102,7 +102,7 @@ describe('matchRoutes', function() {
       compiler.optionalSegmentEndChar = ']';
       compiler.wildcardChar = '?';
       return compiler;
-    };
+    });
 
     var match = matchRoutes([route], 'https://www.github.com/strml/react-router-component');
     assert(match.route);