NEW: Variadic URL parameter matches for url_handlers (#9438)

* Add wildcard URL parameter matches for url_handlers

* Extra tests for wildcard parameters

* Add a PHP warning if more params appear after wildcard param

docs/en/02_Developer_Guides/02_Controllers/02_Routing.md

@@ -142,6 +142,51 @@ the `TeamController`.
 Match an url starting with `/admin/help/`, but don't include `/help/` as part of the action (the shift point is set to 
 start parsing variables and the appropriate controller action AFTER the `//`).
 
+### Wildcard URL Patterns
+
+As of SilverStripe 4.6 there are two wildcard patterns that can be used. `$@` and `$*`. These parameters can only be used
+at the end of a URL pattern, any further rules are ignored.
+
+Inspired by bash variadic variable syntax there are two ways to capture all URL parameters without having to explicitly
+specify them in the URL rule.
+
+Using `$@` will split the URL into numbered parameters (`$1`, `$2`, ..., `$n`). For example:
+
+```php
+<?php
+class StaffController extends \SilverStripe\Control\Controller
+{
+    private static $url_handlers = [
+        'staff/$@' => 'index',
+    ];
+
+    public function index($request)
+    {
+        // GET /staff/managers/bob
+        $request->latestParam('$1'); // managers
+        $request->latestParam('$2'); // bob
+    }
+}
+```
+
+Alternatively, if access to the parameters is not required in this way then it is possible to use `$*` to match all
+URL parameters but not collect them in the same way:
+
+```php
+<?php
+class StaffController extends \SilverStripe\Control\Controller
+{
+    private static $url_handlers = [
+        'staff/$*' => 'index',
+    ];
+
+    public function index($request)
+    {
+        // GET /staff/managers/bob
+        $request->remaining(); // managers/bob
+    }
+}
+```
 
 ## URL Handlers
 

src/Control/HTTPRequest.php

@@ -564,7 +564,28 @@ class HTTPRequest implements ArrayAccess
 
                 /** @skipUpgrade */
                 $key = "Controller";
-                $arguments[$varName] = isset($this->dirParts[$i]) ? $this->dirParts[$i] : null;
+                if ($varName === '*' || $varName === '@') {
+                    if (isset($patternParts[$i + 1])) {
+                        user_error(sprintf('All URL params after wildcard parameter $%s will be ignored', $varName), E_USER_WARNING);
+                    }
+                    if ($varName === '*') {
+                        array_pop($patternParts);
+                        $shiftCount = sizeof($patternParts);
+                        $patternParts = array_merge($patternParts, array_slice($this->dirParts, $i));
+                        break;
+                    } else {
+                        array_pop($patternParts);
+                        $shiftCount = sizeof($patternParts);
+                        $remaining = count($this->dirParts) - $i;
+                        for ($j = 1; $j <= $remaining; $j++) {
+                            $arguments["$${j}"] = $this->dirParts[$j + $i - 1];
+                        }
+                        $patternParts = array_merge($patternParts, array_keys($arguments));
+                        break;
+                    }
+                } else {
+                    $arguments[$varName] = $this->dirParts[$i] ?? null;
+                }
                 if ($part == '$Controller'
                     && (
                         !ClassInfo::exists($arguments[$key])

tests/php/Control/HTTPRequestTest.php

@@ -25,6 +25,43 @@ class HTTPRequestTest extends SapphireTest
         $this->assertEquals(array("_matched" => true), $request->match('add', true));
     }
 
+    /**
+     * @useDatabase false
+     */
+    public function testWildCardMatch()
+    {
+        $request = new HTTPRequest('GET', 'admin/crm/test');
+        $this->assertEquals(['$1' => 'crm', '$2' => 'test'], $request->match('admin/$@', true));
+        $this->assertTrue($request->allParsed());
+
+        $request = new HTTPRequest('GET', 'admin/crm/test');
+        $this->assertEquals(['_matched' => true], $request->match('admin/$*', true));
+        $this->assertTrue($request->allParsed());
+        $this->assertEquals('crm/test', $request->remaining());
+
+        $request = new HTTPRequest('GET', 'admin/crm/test/part1/part2');
+        $this->assertEquals(['Action' => 'crm', '$1' => 'test', '$2' => 'part1', '$3' => 'part2'], $request->match('admin/$Action/$@', true));
+        $this->assertTrue($request->allParsed());
+
+        $request = new HTTPRequest('GET', 'admin/crm/test/part1/part2');
+        $this->assertEquals(['Action' => 'crm'], $request->match('admin/$Action/$*', true));
+        $this->assertTrue($request->allParsed());
+        $this->assertEquals('test/part1/part2', $request->remaining());
+    }
+
+    /**
+     * This test just asserts a warning is given if there is more than one wildcard parameter. Note that this isn't an
+     * enforcement of an API and we an add new behaviour in the future to allow many wildcard params if we want to
+     *
+     * @expectedException \PHPUnit_Framework_Error_Warning
+     */
+    public function testWildCardWithFurtherParams()
+    {
+        $request = new HTTPRequest('GET', 'admin/crm/test');
+        // all parameters after the first wildcard parameter are ignored
+        $request->match('admin/$Action/$@/$Other/$*', true);
+    }
+
     public function testHttpMethodOverrides()
     {
         $request = new HTTPRequest(