add URL pattern template replacement function, per #3

Author: mindplay-dk

src/UrlHelper.php

@@ -71,4 +71,30 @@ protected function slug($value, $max_length = null) {
 
         return substr($clean, 0, $max_length ?: $this->slug_max_length);
     }
+
+    /**
+     * Replaces a route template, with placeholders such as "<foo>" or "<foo:bar>", with
+     * a set of replacement values.
+     *
+     * @param string $template route template
+     * @param array  $values   map where token name => replacement value
+     *
+     * @return string
+     */
+    protected function replace($template, $values)
+    {
+        return preg_replace_callback(
+            Router::PARAM_PATTERN,
+            function ($matches) use ($values) {
+                $name = $matches[1];
+
+                if (!isset($values[$name])) {
+                    throw new InvalidArgumentException("missing replacement value for token: {$name}");
+                }
+
+                return $values[$name];
+            },
+            $template
+        );
+    }
 }

test/test.php

@@ -22,6 +22,21 @@ public function test($input, $expected)
     }
 }
 
+class ReplaceTester extends UrlHelper
+{
+    /**
+     * @param string $template
+     * @param array  $tokens
+     * @param string $expected
+     *
+     * @return string
+     */
+    public function test($template, $tokens, $expected)
+    {
+        eq($this->replace($template, $tokens), $expected);
+    }
+}
+
 class SampleUrlHelper extends UrlHelper
 {
     /**
@@ -40,7 +55,7 @@ class SampleController implements Controller
 {
     public function run($id, $title)
     {
-        return array($id, $title);
+        return [$id, $title];
     }
 }
 
@@ -168,7 +183,7 @@ function () {
             function () use ($router) {
                 $router->resolve('GET', '/users/bob?crazy-yo');
             },
-            '#^'.preg_quote('unexpected query string in $url: /users/bob?crazy-yo').'$#'
+            '#^' . preg_quote('unexpected query string in $url: /users/bob?crazy-yo') . '$#'
         );
     }
 );
@@ -331,6 +346,28 @@ function () use ($url) {
     }
 );
 
+test(
+    'can replace tokens in templates',
+    function () {
+        $replace = new ReplaceTester();
+
+        $replace->test('foo/<bar>', ['bar' => 'hello'], 'foo/hello');
+
+        $replace->test('foo/<bar:slug>', ['bar' => 'hello'], 'foo/hello');
+
+        $replace->test('foo/<bar:slug>/<baz:\w+>', ['bar' => 'hello', 'baz' => 'world'], 'foo/hello/world');
+
+        expect(
+            'InvalidArgumentException',
+            'should throw for missing replacements token',
+            function () use ($replace) {
+                $replace->test('foo/<bar>/<baz>', ['bar' => 'hello'], 'foo/hello/');
+            },
+            '/for token: baz/'
+        );
+    }
+);
+
 test(
     'can use wildcard in patterns',
     function () {