Add initial support for introspection

Resources/introspection.graphql

@@ -0,0 +1,91 @@
+query IntrospectionQuery {
+    __schema {
+        queryType { name }
+        mutationType { name }
+        subscriptionType { name }
+        types {
+            ...FullType
+        }
+        directives {
+            name
+            description
+            locations
+            args {
+                ...InputValue
+            }
+        }
+    }
+}
+
+fragment FullType on __Type {
+    kind
+    name
+    description
+    fields(includeDeprecated: true) {
+        name
+        description
+        args {
+            ...InputValue
+        }
+        type {
+            ...TypeRef
+        }
+        isDeprecated
+        deprecationReason
+    }
+    inputFields {
+        ...InputValue
+    }
+    interfaces {
+        ...TypeRef
+    }
+    enumValues(includeDeprecated: true) {
+        name
+        description
+        isDeprecated
+        deprecationReason
+    }
+    possibleTypes {
+        ...TypeRef
+    }
+}
+
+fragment InputValue on __InputValue {
+    name
+    description
+    type { ...TypeRef }
+    defaultValue
+}
+
+fragment TypeRef on __Type {
+    kind
+    name
+    ofType {
+        kind
+        name
+        ofType {
+            kind
+            name
+            ofType {
+                kind
+                name
+                ofType {
+                    kind
+                    name
+                    ofType {
+                        kind
+                        name
+                        ofType {
+                            kind
+                            name
+                            ofType {
+                                kind
+                                name
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

src/Execution/ExecutionResult.php

@@ -2,10 +2,13 @@
 
 namespace Digia\GraphQL\Execution;
 
+use function Digia\GraphQL\Util\jsonEncode;
+use Digia\GraphQL\Util\SerializationInterface;
 use Digia\GraphQL\Error\GraphQLError;
 
-class ExecutionResult
+class ExecutionResult implements SerializationInterface
 {
+
     /**
      * @var GraphQLError[]
      */
@@ -18,10 +21,11 @@ class ExecutionResult
 
     /**
      * ExecutionResult constructor.
-     * @param mixed[] $data
+     *
+     * @param mixed[]        $data
      * @param GraphQLError[] $errors
      */
-    public function __construct(array $data, array $errors)
+    public function __construct(?array $data, ?array $errors)
     {
         $this->errors = $errors;
         $this->data   = $data;
@@ -44,4 +48,23 @@ public function addError(GraphQLError $error): ExecutionResult
         $this->errors[] = $error;
         return $this;
     }
+
+    /**
+     * @inheritdoc
+     */
+    public function toArray(): array
+    {
+        return [
+            'data'   => $this->data,
+            'errors' => $this->errors,
+        ];
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function toJSON(): string
+    {
+        return jsonEncode($this->toArray());
+    }
 }

src/Type/Definition/FieldsTrait.php

@@ -26,32 +26,6 @@ trait FieldsTrait
      */
     private $_isFieldMapDefined = false;
 
-    /**
-     * @param Field $field
-     * @return $this
-     * @throws \Exception
-     */
-    public function addField(Field $field)
-    {
-        $this->_fieldMap[$field->getName()] = $field;
-
-        return $this;
-    }
-
-    /**
-     * @param array $fields
-     * @return $this
-     * @throws \Exception
-     */
-    public function addFields(array $fields)
-    {
-        foreach ($fields as $field) {
-            $this->addField($field);
-        }
-
-        return $this;
-    }
-
     /**
      * @return Field[]
      * @throws \Exception

src/Type/TypeKindEnum.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace Digia\GraphQL\Type;
+
+class TypeKindEnum
+{
+
+    const SCALAR       = 'SCALAR';
+    const OBJECT       = 'OBJECT';
+    const INTERFACE    = 'INTERFACE';
+    const UNION        = 'UNION';
+    const ENUM         = 'ENUM';
+    const INPUT_OBJECT = 'INPUT_OBJECT';
+    const LIST         = 'LIST';
+    const NON_NULL     = 'NON_NULL';
+
+    /**
+     * @return array
+     * @throws \ReflectionException
+     */
+    public static function values(): array
+    {
+        return array_values((new \ReflectionClass(__CLASS__))->getConstants());
+    }
+}

src/Type/definition.php

@@ -6,6 +6,7 @@
 use Digia\GraphQL\Type\Definition\CompositeTypeInterface;
 use Digia\GraphQL\Type\Definition\Directive;
 use Digia\GraphQL\Type\Definition\EnumType;
+use Digia\GraphQL\Type\Definition\Field;
 use Digia\GraphQL\Type\Definition\InputObjectType;
 use Digia\GraphQL\Type\Definition\InputTypeInterface;
 use Digia\GraphQL\Type\Definition\InterfaceType;