add: ReadWritePropertiesExtension (#2)

Author: mleutenegger

phpstan.neon

@@ -86,3 +86,8 @@ services:
         class: Symbiote\SilverstripePHPStan\Type\HasMethodTypeSpecifyingExtension
         tags:
             - phpstan.typeSpecifier.methodTypeSpecifyingExtension
+    # Special handling for configuration properties
+    -
+        class: Symbiote\SilverstripePHPStan\Reflection\ReadWritePropertiesExtension
+        tags:
+            - phpstan.properties.readWriteExtension

src/Reflection/ReadWritePropertiesExtension.php

@@ -0,0 +1,82 @@
+<?php
+
+namespace Symbiote\SilverstripePHPStan\Reflection;
+
+use PHPStan\Reflection\PropertyReflection;
+use SilverStripe\Core\Config\Configurable;
+
+/**
+ * Adds information about configuration properties, which are always read,
+ * written and initialized. We check for the presence of the '@config'
+ * docblock as described in the official silverstripe docs
+ * (https://docs.silverstripe.org/en/4/developer_guides/configuration/configuration/#configuration-properties)
+ * and wether or not the class defining the property uses the 'Configurable' trait.
+ */
+class ReadWritePropertiesExtension implements \PHPStan\Rules\Properties\ReadWritePropertiesExtension
+{
+
+    /**
+     * isAlwaysRead - see https://phpstan.org/developing-extensions/always-read-written-properties
+     *
+     * @param  PropertyReflection $property     the reflection from the static analysis
+     * @param  string             $propertyName the name of the property
+     * @return bool
+     */
+    public function isAlwaysRead(PropertyReflection $property, string $propertyName): bool
+    {
+        return
+            $this->containsConfigBlock($property) &&
+            $this->classUsesConfigTrait($property);
+    }
+
+    /**
+     * isAlwaysWritten - see https://phpstan.org/developing-extensions/always-read-written-properties
+     *
+     * @param  PropertyReflection $property     the reflection from the static analysis
+     * @param  string             $propertyName the name of the property
+     * @return bool
+     */
+    public function isAlwaysWritten(PropertyReflection $property, string $propertyName): bool
+    {
+        return
+            $this->containsConfigBlock($property) &&
+            $this->classUsesConfigTrait($property);
+    }
+
+    /**
+     * isInitialized - see https://phpstan.org/developing-extensions/always-read-written-properties
+     *
+     * @param  PropertyReflection $property     the reflection from the static analysis
+     * @param  string             $propertyName the name of the property
+     * @return bool
+     */
+    public function isInitialized(PropertyReflection $property, string $propertyName): bool
+    {
+        return
+            $this->containsConfigBlock($property) &&
+            $this->classUsesConfigTrait($property);
+    }
+
+    /**
+     * containsConfigBlock - check if the @config docblock is present
+     *
+     * @param  PropertyReflection $property the property to check
+     * @return bool
+     */
+    public function containsConfigBlock(PropertyReflection $property): bool
+    {
+        return !!strpos($property->getDocComment(), '@config');
+    }
+
+    /**
+     * classUsesConfigTrait - check if the class defining the property is using
+     * the configurable trait
+     *
+     * @param  PropertyReflection $property the property to check
+     * @return bool
+     */
+    public function classUsesConfigTrait(PropertyReflection $property): bool
+    {
+        return $property->getDeclaringClass()->hasTraitUse(Configurable::class);
+    }
+}