bug #15552 [ExpressionLanguage] Fixed expressions cache key generation (inso)

This PR was squashed before being merged into the 2.7 branch (closes #15552).

Discussion
----------

[ExpressionLanguage] Fixed expressions cache key generation

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Reworked version of #15537

Difference with original PR:
- sort $names array to ensure its order does not affect caching, added test for it
- minor tweaks for cache key format
- used `foreach` instead of `array_map`

P.S. I'm not proficient with tests so not sure if tests are correct.

Commits
-------

4114a2b [ExpressionLanguage] Fixed expressions cache key generation

src/Symfony/Component/ExpressionLanguage/ExpressionLanguage.php

@@ -84,7 +84,14 @@ class ExpressionLanguage
             return $expression;
         }
 
-        $key = $expression.'//'.implode('-', $names);
+        asort($names);
+        $cacheKeyItems = array();
+
+        foreach ($names as $nameKey => $name) {
+            $cacheKeyItems[] = is_int($nameKey) ? $name : $nameKey.':'.$name;
+        }
+
+        $key = $expression.'//'.implode('|', $cacheKeyItems);
 
         if (null === $parsedExpression = $this->cache->fetch($key)) {
             $nodes = $this->getParser()->parse($this->getLexer()->tokenize((string) $expression), $names);

src/Symfony/Component/ExpressionLanguage/Tests/ExpressionLanguageTest.php

@@ -104,4 +104,38 @@ class ExpressionLanguageTest extends \PHPUnit_Framework_TestCase
             array('true or foo', array('foo' => 'foo'), true),
         );
     }
+
+    public function testCachingForOverriddenVariableNames()
+    {
+        $expressionLanguage = new ExpressionLanguage();
+        $expression = 'a + b';
+        $expressionLanguage->evaluate($expression, array('a' => 1, 'b' => 1));
+        $result = $expressionLanguage->compile($expression, array('a', 'B' => 'b'));
+        $this->assertSame('($a + $B)', $result);
+    }
+
+    public function testCachingWithDifferentNamesOrder()
+    {
+        $cacheMock = $this->getMock('Symfony\Component\ExpressionLanguage\ParserCache\ParserCacheInterface');
+        $expressionLanguage = new ExpressionLanguage($cacheMock);
+        $savedParsedExpressions = array();
+        $cacheMock
+            ->expects($this->exactly(2))
+            ->method('fetch')
+            ->will($this->returnCallback(function ($key) use (&$savedParsedExpressions) {
+                return isset($savedParsedExpressions[$key]) ? $savedParsedExpressions[$key] : null;
+            }))
+        ;
+        $cacheMock
+            ->expects($this->exactly(1))
+            ->method('save')
+            ->will($this->returnCallback(function ($key, $expression) use (&$savedParsedExpressions) {
+                $savedParsedExpressions[$key] = $expression;
+            }))
+        ;
+
+        $expression = 'a + b';
+        $expressionLanguage->compile($expression, array('a', 'B' => 'b'));
+        $expressionLanguage->compile($expression, array('B' => 'b', 'a'));
+    }
 }