Improve the conversion of Callable to a string (#259)

* Improve the conversion of `Callable` to a string

* Fix CS

* Refactor `CallableParameter`

* Revert "Refactor `CallableParameter`"

This reverts commit dfed23f.

Author: mspirkov

src/Types/CallableParameter.php

@@ -14,6 +14,8 @@
 
 use phpDocumentor\Reflection\Type;
 
+use function trim;
+
 /**
  * Value Object representing a Callable parameters.
  *
@@ -74,4 +76,14 @@ public function isOptional(): bool
     {
         return $this->isOptional;
     }
+
+    public function __toString(): string
+    {
+        $reference = $this->isReference ? '&' : '';
+        $variadic = $this->isVariadic ? '...' : '';
+        $optional = $this->isOptional ? '=' : '';
+        $name = $this->name !== null ? '$' . $this->name : '';
+
+        return trim($this->type . ' ' . $reference . $variadic . $name . $optional);
+    }
 }

src/Types/Callable_.php

@@ -15,6 +15,8 @@
 
 use phpDocumentor\Reflection\Type;
 
+use function implode;
+
 /**
  * Value Object representing a Callable type.
  *
@@ -63,6 +65,16 @@ public function getReturnType(): ?Type
      */
     public function __toString(): string
     {
-        return $this->identifier;
+        if (!$this->parameters && $this->returnType === null) {
+            return $this->identifier;
+        }
+
+        if ($this->returnType instanceof self) {
+            $returnType = '(' . (string) $this->returnType . ')';
+        } else {
+            $returnType = (string) $this->returnType;
+        }
+
+        return $this->identifier . '(' . implode(', ', $this->parameters) . '): ' . $returnType;
     }
 }

tests/unit/TypeResolverTest.php

@@ -1192,6 +1192,34 @@ public function callableProvider(): array
                     new Object_(new Fqsen('\\phpDocumentor\\Foo'))
                 ),
             ],
+            [
+                'Closure(mixed): (callable(mixed): mixed)',
+                new Callable_(
+                    'Closure',
+                    [
+                        new CallableParameter(
+                            new Mixed_(),
+                            null,
+                            false,
+                            false,
+                            false
+                        ),
+                    ],
+                    new Callable_(
+                        'callable',
+                        [
+                            new CallableParameter(
+                                new Mixed_(),
+                                null,
+                                false,
+                                false,
+                                false
+                            ),
+                        ],
+                        new Mixed_()
+                    )
+                ),
+            ],
         ];
     }
 

tests/unit/Types/CallableTest.php

@@ -76,6 +76,65 @@ public static function provideToStringData(): array
                 '\Closure',
                 new Callable_('\Closure'),
             ],
+            'with different types' => [
+                'callable(\\phpDocumentor\\C, \\phpDocumentor\\A &...$a=, \\phpDocumentor\\B &...=): '
+                    . '\\phpDocumentor\\Foo',
+                new Callable_(
+                    'callable',
+                    [
+                        new CallableParameter(
+                            new Object_(new Fqsen('\\phpDocumentor\\C')),
+                            null,
+                            false,
+                            false,
+                            false
+                        ),
+                        new CallableParameter(
+                            new Object_(new Fqsen('\\phpDocumentor\\A')),
+                            'a',
+                            true,
+                            true,
+                            true
+                        ),
+                        new CallableParameter(
+                            new Object_(new Fqsen('\\phpDocumentor\\B')),
+                            null,
+                            true,
+                            true,
+                            true
+                        ),
+                    ],
+                    new Object_(new Fqsen('\\phpDocumentor\\Foo'))
+                ),
+            ],
+            'return callable' => [
+                'Closure(mixed): (callable(mixed): mixed)',
+                new Callable_(
+                    'Closure',
+                    [
+                        new CallableParameter(
+                            new Mixed_(),
+                            null,
+                            false,
+                            false,
+                            false
+                        ),
+                    ],
+                    new Callable_(
+                        'callable',
+                        [
+                            new CallableParameter(
+                                new Mixed_(),
+                                null,
+                                false,
+                                false,
+                                false
+                            ),
+                        ],
+                        new Mixed_()
+                    )
+                ),
+            ],
         ];
     }
 }