Add dummy AST printer

composer.json

@@ -20,6 +20,7 @@
             "./src/Language/blockStringValue.php",
             "./src/Language/helpers.php",
             "./src/Language/parse.php",
+            "./src/Language/print.php",
             "./src/Type/definition.php",
             "./src/Type/directives.php",
             "./src/Type/scalars.php",
@@ -34,6 +35,7 @@
             "./src/Language/blockStringValue.php",
             "./src/Language/helpers.php",
             "./src/Language/parse.php",
+            "./src/Language/print.php",
             "./src/Type/definition.php",
             "./src/Type/directives.php",
             "./src/Type/scalars.php",

src/Language/AST/Node/Contract/NodeInterface.php

@@ -16,4 +16,9 @@ public function getKind(): string;
      * @return Location|null
      */
     public function getLocation(): ?Location;
+
+    /**
+     * @return string
+     */
+    public function toJSON(): string;
 }

src/Language/Contract/PrinterInterface.php

@@ -1,14 +1,15 @@
 <?php
-/**
- * Created by PhpStorm.
- * User: chris
- * Date: 27/02/2018
- * Time: 9.53
- */
 
 namespace Digia\GraphQL\Language\Contract;
 
+use Digia\GraphQL\Language\AST\Node\Contract\NodeInterface;
+
 interface PrinterInterface
 {
 
+    /**
+     * @param NodeInterface $node
+     * @return string
+     */
+    public function print(NodeInterface $node): string;
 }

src/Language/Printer.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace Digia\GraphQL\Language;
+
+use Digia\GraphQL\Language\AST\Node\Contract\NodeInterface;
+use Digia\GraphQL\Language\Contract\PrinterInterface;
+
+class Printer implements PrinterInterface
+{
+
+    /**
+     * @inheritdoc
+     */
+    public function print(NodeInterface $node): string
+    {
+        // TODO: Implement proper printing of AST trees
+        return $node->toJSON();
+    }
+}

src/Language/print.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace Digia\GraphQL\Language;
+
+use Digia\GraphQL\Language\AST\Node\Contract\NodeInterface;
+
+/**
+ * @param NodeInterface $node
+ * @return string
+ */
+function printNode(NodeInterface $node): string
+{
+    static $instance = null;
+
+    if (null === $instance) {
+        $instance = new Printer();
+    }
+
+    return $instance->print($node);
+}

tests/Functional/Language/SchemaPrinterTest.php

@@ -5,6 +5,7 @@
 use Digia\GraphQL\Language\AST\Node\DocumentNode;
 use Digia\GraphQL\Test\TestCase;
 use function Digia\GraphQL\Language\parse;
+use function Digia\GraphQL\Language\printNode;
 use function Digia\GraphQL\Util\readFile;
 
 class SchemaPrinterTest extends TestCase
@@ -25,7 +26,7 @@ public function testDoesNotAlterAST()
         $ast       = parse($kitchenSink);
         $astBefore = $ast->toJSON();
 
-        // TODO: Print the schema once the Printer is implemented
+        printNode($ast);
 
         $this->assertEquals($ast->toJSON(), $astBefore);
     }