bug #21722 [ExpressionLanguage] Registering functions after calling e…

…valuate(), compile() or parse() is not supported (maidmaid)

This PR was squashed before being merged into the 2.7 branch (closes #21722).

Discussion
----------

[ExpressionLanguage] Registering functions after calling evaluate(), compile() or parse() is not supported

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

If we add expr. function after first eval/compile like this:

```php
$el = new ExpressionLanguage();
$el->evaluate('1 + 1');
$el->addFunction(new ExpressionFunction('fn', function () {}, function () {}));
$el->evaluate('fn()');
```
A ``SyntaxError`` is thrown that says ``The function "fn" does not exist around position 1.``. It's the same bug with ``$el->compile('fn()')``.

This PR fixes this (duplicate of #21098 that was closed).

Commits
-------

e305369 [ExpressionLanguage] Registering functions after calling evaluate(), compile() or parse() is not supported

src/Symfony/Component/ExpressionLanguage/ExpressionLanguage.php

@@ -110,10 +110,16 @@ public function parse($expression, $names)
      * @param callable $compiler  A callable able to compile the function
      * @param callable $evaluator A callable able to evaluate the function
      *
+     * @throws \LogicException when registering a function after calling evaluate(), compile() or parse()
+     *
      * @see ExpressionFunction
      */
     public function register($name, $compiler, $evaluator)
     {
+        if (null !== $this->parser) {
+            throw new \LogicException('Registering functions after calling evaluate(), compile() or parse() is not supported.');
+        }
+
         $this->functions[$name] = array('compiler' => $compiler, 'evaluator' => $evaluator);
     }
 

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

@@ -11,6 +11,7 @@
 
 namespace Symfony\Component\ExpressionLanguage\Tests;
 
+use Symfony\Component\ExpressionLanguage\ExpressionFunction;
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\ExpressionLanguage\ExpressionLanguage;
 use Symfony\Component\ExpressionLanguage\Tests\Fixtures\TestProvider;
@@ -139,4 +140,58 @@ public function testCachingWithDifferentNamesOrder()
         $expressionLanguage->compile($expression, array('a', 'B' => 'b'));
         $expressionLanguage->compile($expression, array('B' => 'b', 'a'));
     }
+
+    /**
+     * @dataProvider getRegisterCallbacks
+     * @expectedException \LogicException
+     */
+    public function testRegisterAfterParse($registerCallback)
+    {
+        $el = new ExpressionLanguage();
+        $el->parse('1 + 1', array());
+        $registerCallback($el);
+    }
+
+    /**
+     * @dataProvider getRegisterCallbacks
+     * @expectedException \LogicException
+     */
+    public function testRegisterAfterEval($registerCallback)
+    {
+        $el = new ExpressionLanguage();
+        $el->evaluate('1 + 1');
+        $registerCallback($el);
+    }
+
+    /**
+     * @dataProvider getRegisterCallbacks
+     * @expectedException \LogicException
+     */
+    public function testRegisterAfterCompile($registerCallback)
+    {
+        $el = new ExpressionLanguage();
+        $el->compile('1 + 1');
+        $registerCallback($el);
+    }
+
+    public function getRegisterCallbacks()
+    {
+        return array(
+            array(
+                function (ExpressionLanguage $el) {
+                    $el->register('fn', function () {}, function () {});
+                },
+            ),
+            array(
+                function (ExpressionLanguage $el) {
+                    $el->addFunction(new ExpressionFunction('fn', function () {}, function () {}));
+                },
+            ),
+            array(
+                function (ExpressionLanguage $el) {
+                    $el->registerProvider(new TestProvider());
+                },
+            ),
+        );
+    }
 }