Cleaned up the object model. Added some extra checks.

.codeclimate.yml

@@ -0,0 +1,8 @@
+engines:
+  phpmd:
+    enabled: true
+    checks:
+      Controversial/CamelCasePropertyName:
+        enabled: false
+      Naming/ShortVariable:
+        enabled: false

.gitignore

@@ -1,3 +1,4 @@
 composer.phar
 /vendor/
-composer.lock
+/composer.lock
+/.php_cs.cache

.php_cs.dist

@@ -0,0 +1,60 @@
+<?php
+$header = <<<EOF
+This file is part of JSON:API implementation for PHP.
+
+(c) Alexey Karapetov <karapetov@gmail.com>
+
+For the full copyright and license information, please view the LICENSE
+file that was distributed with this source code.
+EOF;
+$finder = PhpCsFixer\Finder::create()
+    ->files()
+    ->name('*.php')
+    ->in(__DIR__ . '/src')
+    ->in(__DIR__ . '/test');
+return PhpCsFixer\Config::create()
+    ->setUsingCache(true)
+    ->setRiskyAllowed(true)
+    ->setRules([
+        '@PSR2' => true,
+        'array_syntax' => ['syntax' => 'short'],
+        'binary_operator_spaces' => true,
+        'cast_spaces' => true,
+        'concat_space' => true,
+        'declare_strict_types' => true,
+        'header_comment' => array('header' => $header),
+        'include' => true,
+        'is_null' => true,
+        'lowercase_cast' => true,
+        'mb_str_functions' => true,
+        'method_separation' => true,
+        'native_function_casing' => true,
+        'no_blank_lines_after_class_opening' => true,
+        'no_blank_lines_after_phpdoc' => true,
+        'no_empty_statement' => true,
+        'no_extra_consecutive_blank_lines' => true,
+        'no_leading_import_slash' => true,
+        'no_leading_namespace_whitespace' => true,
+        'no_trailing_comma_in_singleline_array' => true,
+        'no_unused_imports' => true,
+        'no_whitespace_in_blank_line' => true,
+        'object_operator_without_whitespace' => true,
+        'ordered_imports' => true,
+        'phpdoc_align' => true,
+        'phpdoc_indent' => true,
+        'phpdoc_no_access' => true,
+        'phpdoc_no_package' => true,
+        'phpdoc_order' => true,
+        'phpdoc_scalar' => true,
+        'phpdoc_trim' => true,
+        'phpdoc_types' => true,
+        'psr0' => true,
+        'short_scalar_cast' => true,
+        'single_blank_line_before_namespace' => true,
+        'standardize_not_equals' => true,
+        'strict_comparison' => true,
+        'ternary_operator_spaces' => true,
+        'trailing_comma_in_multiline_array' => true,
+        'whitespace_after_comma_in_array' => true,
+    ])
+    ->setFinder($finder);

.travis.yml

@@ -2,11 +2,10 @@ language: php
 php:
   - '7.0'
   - '7.1'
-  - nightly
 
 before_script:
   - composer install
 
 script:
-  - vendor/bin/phpcs
+  - vendor/bin/php-cs-fixer fix -v --dry-run
   - phpunit --coverage-clover build/logs/clover.xml

composer.json

@@ -15,11 +15,19 @@
   },
   "require-dev": {
     "phpunit/phpunit": "^6.0",
-    "squizlabs/php_codesniffer": "2.8.*"
+    "friendsofphp/php-cs-fixer": "^2.2"
   },
   "autoload": {
     "psr-4": {
       "JsonApiPhp\\JsonApi\\": "src/"
     }
+  },
+  "autoload-dev": {
+    "psr-4": {
+      "JsonApiPhp\\JsonApi\\Test\\": "test/"
+    }
+  },
+  "scripts": {
+    "test": "php-cs-fixer fix -v --dry-run --ansi && phpunit --colors=always"
   }
 }

phpunit.xml.dist

@@ -9,7 +9,7 @@
   -->
 
 <phpunit
-        bootstrap="test/bootstrap.php"
+        bootstrap="vendor/autoload.php"
         stopOnFailure="false"
         verbose="true"
         colors="true"

src/Document/Document.php

@@ -1,32 +1,31 @@
 <?php
-/**
- *  This file is part of JSON:API implementation for PHP.
+declare(strict_types=1);
+
+/*
+ * This file is part of JSON:API implementation for PHP.
  *
- *  (c) Alexey Karapetov <karapetov@gmail.com>
+ * (c) Alexey Karapetov <karapetov@gmail.com>
  *
- *  For the full copyright and license information, please view the LICENSE
- *  file that was distributed with this source code.
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
  */
 
-declare(strict_types=1);
-
 namespace JsonApiPhp\JsonApi\Document;
 
-use JsonApiPhp\JsonApi\Document\Resource\IdentifiableResource;
-use JsonApiPhp\JsonApi\HasLinksAndMeta;
+use JsonApiPhp\JsonApi\Document\Resource\ResourceInterface;
+use JsonApiPhp\JsonApi\Document\Resource\ResourceObject;
 
 final class Document implements \JsonSerializable
 {
     const MEDIA_TYPE = 'application/vnd.api+json';
     const DEFAULT_API_VERSION = '1.0';
 
-    use HasLinksAndMeta;
+    use LinksTrait;
+    use MetaTrait;
 
     private $data;
     private $errors;
-    private $meta;
-    private $json_api;
-    private $links;
+    private $api;
     private $included;
     private $is_sparse = false;
 
@@ -48,14 +47,14 @@ public static function fromErrors(Error ...$errors): self
         return $doc;
     }
 
-    public static function fromResource(IdentifiableResource $data): self
+    public static function fromResource(ResourceInterface $data): self
     {
         $doc = new self;
         $doc->data = $data;
         return $doc;
     }
 
-    public static function fromResources(IdentifiableResource ...$data): self
+    public static function fromResources(ResourceInterface ...$data): self
     {
         $doc = new self;
         $doc->data = $data;
@@ -64,15 +63,15 @@ public static function fromResources(IdentifiableResource ...$data): self
 
     public function setApiVersion(string $version = self::DEFAULT_API_VERSION)
     {
-        $this->json_api['version'] = $version;
+        $this->api['version'] = $version;
     }
 
     public function setApiMeta(array $meta)
     {
-        $this->json_api['meta'] = $meta;
+        $this->api['meta'] = $meta;
     }
 
-    public function setIncluded(IdentifiableResource ...$included)
+    public function setIncluded(ResourceObject ...$included)
     {
         $this->included = $included;
     }
@@ -90,7 +89,7 @@ public function jsonSerialize()
                 'data' => $this->data,
                 'errors' => $this->errors,
                 'meta' => $this->meta,
-                'jsonapi' => $this->json_api,
+                'jsonapi' => $this->api,
                 'links' => $this->links,
                 'included' => $this->included,
             ],
@@ -113,9 +112,9 @@ private function enforceFullLinkage()
         }
     }
 
-    private function anotherIncludedResourceIdentifies(IdentifiableResource $resource): bool
+    private function anotherIncludedResourceIdentifies(ResourceObject $resource): bool
     {
-        /** @var IdentifiableResource $included_resource */
+        /** @var ResourceObject $included_resource */
         foreach ($this->included as $included_resource) {
             if ($included_resource !== $resource && $included_resource->identifies($resource)) {
                 return true;
@@ -124,9 +123,9 @@ private function anotherIncludedResourceIdentifies(IdentifiableResource $resourc
         return false;
     }
 
-    private function hasLinkTo(IdentifiableResource $resource): bool
+    private function hasLinkTo(ResourceObject $resource): bool
     {
-        /** @var IdentifiableResource $my_resource */
+        /** @var ResourceInterface $my_resource */
         foreach ($this->toResources() as $my_resource) {
             if ($my_resource->identifies($resource)) {
                 return true;
@@ -135,9 +134,9 @@ private function hasLinkTo(IdentifiableResource $resource): bool
         return false;
     }
 
-    private function toResources(): \Generator
+    private function toResources(): \Iterator
     {
-        if ($this->data instanceof IdentifiableResource) {
+        if ($this->data instanceof ResourceInterface) {
             yield $this->data;
         } elseif (is_array($this->data)) {
             foreach ($this->data as $datum) {

src/Document/Error.php

@@ -1,22 +1,20 @@
 <?php
-/**
- *  This file is part of JSON:API implementation for PHP.
+declare(strict_types=1);
+
+/*
+ * This file is part of JSON:API implementation for PHP.
  *
- *  (c) Alexey Karapetov <karapetov@gmail.com>
+ * (c) Alexey Karapetov <karapetov@gmail.com>
  *
- *  For the full copyright and license information, please view the LICENSE
- *  file that was distributed with this source code.
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
  */
 
-declare(strict_types=1);
-
 namespace JsonApiPhp\JsonApi\Document;
 
-use JsonApiPhp\JsonApi\HasMeta;
-
 final class Error implements \JsonSerializable
 {
-    use HasMeta;
+    use MetaTrait;
 
     private $id;
     private $links;
@@ -25,7 +23,6 @@ final class Error implements \JsonSerializable
     private $title;
     private $detail;
     private $source;
-    private $meta;
 
     public function setId(string $id)
     {
@@ -83,6 +80,6 @@ public function jsonSerialize()
             function ($v) {
                 return null !== $v;
             }
-        ) ?: (object)[];
+        ) ?: (object) [];
     }
 }

src/Document/LinksTrait.php

@@ -0,0 +1,23 @@
+<?php
+declare(strict_types=1);
+
+/*
+ * This file is part of JSON:API implementation for PHP.
+ *
+ * (c) Alexey Karapetov <karapetov@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JsonApiPhp\JsonApi\Document;
+
+trait LinksTrait
+{
+    protected $links;
+
+    public function setLink(string $name, string $value, array $meta = null)
+    {
+        $this->links[$name] = $meta ? ['href' => $value, 'meta' => $meta] : $value;
+    }
+}

src/HasMeta.php → src/Document/MetaTrait.php

@@ -1,19 +1,21 @@
 <?php
-/**
- *  This file is part of JSON:API implementation for PHP.
+declare(strict_types=1);
+
+/*
+ * This file is part of JSON:API implementation for PHP.
  *
- *  (c) Alexey Karapetov <karapetov@gmail.com>
+ * (c) Alexey Karapetov <karapetov@gmail.com>
  *
- *  For the full copyright and license information, please view the LICENSE
- *  file that was distributed with this source code.
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
  */
 
-declare(strict_types=1);
+namespace JsonApiPhp\JsonApi\Document;
 
-namespace JsonApiPhp\JsonApi;
-
-trait HasMeta
+trait MetaTrait
 {
+    protected $meta;
+
     public function setMeta(string $key, $val)
     {
         $this->meta[$key] = $val;