[FEATURE] Add compatibility layer to basically all ViewHelpers

Adds a massive number of backwards/cross compatibility
handlers, because Fluid decided to introduce a large number
of completely unnecessary breaking changes in v4, because
"it's cleaner" and apparently nobody cares about devs anymore.

Classes/Traits/ArgumentOverride.php

@@ -0,0 +1,28 @@
+<?php
+namespace FluidTYPO3\Vhs\Traits;
+
+/*
+ * This file is part of the FluidTYPO3/Vhs project under GPLv2 or later.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.md file that was distributed with this source code.
+ */
+
+use TYPO3\CMS\Core\Utility\VersionNumberUtility;
+
+trait ArgumentOverride
+{
+    protected function overrideArgument(
+        $name,
+        $type,
+        $description,
+        $required = false,
+        $defaultValue = null,
+        $escape = null
+    ) {
+        if (version_compare(VersionNumberUtility::getCurrentTypo3Version(), '13.4', '>=')) {
+            return parent::registerArgument($name, $type, $description, $required, $defaultValue, $escape);
+        }
+        return parent::overrideArgument($name, $type, $description, $required, $defaultValue, $escape);
+    }
+}

Classes/Traits/CompileWithContentArgumentAndRenderStatic.php

@@ -0,0 +1,184 @@
+<?php
+namespace FluidTYPO3\Vhs\Traits;
+
+/*
+ * This file is part of the FluidTYPO3/Vhs project under GPLv2 or later.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.md file that was distributed with this source code.
+ */
+
+use TYPO3Fluid\Fluid\Core\Compiler\TemplateCompiler;
+use TYPO3Fluid\Fluid\Core\Compiler\ViewHelperCompiler;
+use TYPO3Fluid\Fluid\Core\Exception;
+use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\ViewHelperNode;
+
+/**
+ * Class CompilableWithContentArgumentAndRenderStatic
+ *
+ * Provides default methods for rendering and compiling
+ * any ViewHelper that conforms to the `renderStatic`
+ * method pattern but has the added common use case that
+ * an argument value must be checked and used instead of
+ * the normal render children closure, if that named
+ * argument is specified and not empty.
+ */
+trait CompileWithContentArgumentAndRenderStatic
+{
+    /**
+     * Name of variable that contains the value to use
+     * instead of render children closure, if specified.
+     * If no name is provided here, the first variable
+     * registered in `initializeArguments` of the ViewHelper
+     * will be used.
+     *
+     * Note: it is significantly better practice defining
+     * this property in your ViewHelper class and so fix it
+     * to one particular argument instead of resolving,
+     * especially when your ViewHelper is called multiple
+     * times within an uncompiled template!
+     *
+     * This property cannot be directly set in consuming
+     * ViewHelper, instead set the property in ViewHelper
+     * constructor '__construct()', for example with
+     * $this->contentArgumentName = 'explicitlyToUseArgumentName';
+     *
+     * Another possible way would be to override the method
+     * 'resolveContentArgumentName()' and return the name.
+     *
+     * public function resolveContentArgumentName()
+     * {
+     *     return 'explicitlyToUseArgumentName';
+     * }
+     *
+     * Note: Setting this through 'initializeArguments()' will
+     *       not work as expected, and other methods should be
+     *       avoided to override this.
+     *
+     * Following test ViewHelpers are tested and demonstrates
+     * that the setting posibillities works.
+     *
+     * @var string
+     */
+    protected $contentArgumentName;
+
+    /**
+     * Default render method to render ViewHelper with
+     * first defined optional argument as content.
+     *
+     * @return mixed Rendered result
+     * @api
+     */
+    public function render()
+    {
+        return static::renderStatic(
+            $this->arguments,
+            $this->buildRenderChildrenClosure(),
+            $this->renderingContext,
+        );
+    }
+
+    /**
+     * @param string $argumentsName
+     * @param string $closureName
+     * @param string $initializationPhpCode
+     * @param ViewHelperNode $node
+     * @param TemplateCompiler $compiler
+     * @return string
+     */
+    public function compile(
+        $argumentsName,
+        $closureName,
+        &$initializationPhpCode,
+        ViewHelperNode $node,
+        TemplateCompiler $compiler
+    ) {
+        [$initialization, $execution] = ViewHelperCompiler::getInstance()->compileWithCallToStaticMethod(
+            $this,
+            $argumentsName,
+            $closureName,
+            ViewHelperCompiler::RENDER_STATIC,
+            static::class
+        );
+        $contentArgumentName = $this->resolveContentArgumentName();
+        $initializationPhpCode .= sprintf(
+            '%s = (%s[\'%s\'] !== null) ? function() use (%s) { return %s[\'%s\']; } : %s;',
+            $closureName,
+            $argumentsName,
+            $contentArgumentName,
+            $argumentsName,
+            $argumentsName,
+            $contentArgumentName,
+            $closureName
+        );
+        $initializationPhpCode .= $initialization;
+        return $execution;
+    }
+
+    /**
+     * Helper which is mostly needed when calling renderStatic() from within
+     * render().
+     *
+     * No public API yet.
+     *
+     * @return \Closure
+     */
+    protected function buildRenderChildrenClosure()
+    {
+        $argumentName = $this->resolveContentArgumentName();
+        $arguments = $this->arguments;
+        if (!empty($argumentName) && isset($arguments[$argumentName])) {
+            $renderChildrenClosure = function () use ($arguments, $argumentName) {
+                return $arguments[$argumentName];
+            };
+        } else {
+            $self = clone $this;
+            $renderChildrenClosure = function () use ($self) {
+                return $self->renderChildren();
+            };
+        }
+        return $renderChildrenClosure;
+    }
+
+    /**
+     * Helper method which triggers the rendering of everything between the
+     * opening and the closing tag.
+     *
+     * @return mixed The finally rendered child nodes.
+     * @api
+     */
+    public function renderChildren()
+    {
+        if ($this->renderChildrenClosure !== null) {
+            $closure = $this->renderChildrenClosure;
+            return $closure();
+        }
+        return $this->viewHelperNode->evaluateChildNodes($this->renderingContext);
+    }
+
+    /**
+     * @return string
+     */
+    public function resolveContentArgumentName()
+    {
+        if (empty($this->contentArgumentName)) {
+            $registeredArguments = $this->prepareArguments();
+            foreach ($registeredArguments as $registeredArgument) {
+                if (!$registeredArgument->isRequired()) {
+                    $this->contentArgumentName = $registeredArgument->getName();
+                    return $this->contentArgumentName;
+                }
+            }
+            throw new Exception(
+                sprintf('Attempting to compile %s failed. Chosen compile method requires that ViewHelper has ' .
+                    'at least one registered and optional argument', __CLASS__)
+            );
+        }
+        return $this->contentArgumentName;
+    }
+
+    public function getContentArgumentName(): ?string
+    {
+        return $this->resolveContentArgumentName();
+    }
+}

Classes/Traits/CompileWithRenderStatic.php

@@ -0,0 +1,40 @@
+<?php
+namespace FluidTYPO3\Vhs\Traits;
+
+/*
+ * This file is part of the FluidTYPO3/Vhs project under GPLv2 or later.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.md file that was distributed with this source code.
+ */
+
+/**
+ * Class CompilableWithRenderStatic
+ *
+ * Provides default methods for rendering and compiling
+ * any ViewHelper that conforms to the `renderStatic`
+ * method pattern.
+ */
+trait CompileWithRenderStatic
+{
+    /**
+     * Default render method - simply calls renderStatic() with a
+     * prepared set of arguments.
+     *
+     * @return mixed Rendered result
+     * @api
+     */
+    public function render()
+    {
+        return static::renderStatic(
+            $this->arguments,
+            $this->buildRenderChildrenClosure(),
+            $this->renderingContext,
+        );
+    }
+
+    /**
+     * @return \Closure
+     */
+    abstract protected function buildRenderChildrenClosure();
+}

Classes/Traits/TagViewHelperCompatibility.php

@@ -0,0 +1,66 @@
+<?php
+namespace FluidTYPO3\Vhs\Traits;
+
+/*
+ * This file is part of the FluidTYPO3/Vhs project under GPLv2 or later.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.md file that was distributed with this source code.
+ */
+
+use TYPO3\CMS\Core\Utility\VersionNumberUtility;
+
+trait TagViewHelperCompatibility
+{
+    /**
+     * Register a new tag attribute. Tag attributes are all arguments which will be directly appended to a tag if you
+     * call $this->initializeTag()
+     *
+     * @param string $name Name of tag attribute
+     * @param string $type Type of the tag attribute
+     * @param string $description Description of tag attribute
+     * @param bool $required set to true if tag attribute is required. Defaults to false.
+     * @param mixed $defaultValue Optional, default value of attribute if one applies
+     * @return void
+     * @api
+     */
+    protected function registerTagAttribute($name, $type, $description, $required = false, $defaultValue = null)
+    {
+        if (version_compare(VersionNumberUtility::getCurrentTypo3Version(), '13.4', '>=')) {
+            $this->registerArgument($name, $type, $description, $required, $defaultValue);
+            return;
+        }
+        parent::registerTagAttribute($name, $type, $description, $required, $defaultValue);
+    }
+
+    /**
+     * Registers all standard HTML universal attributes.
+     * Should be used inside registerArguments();
+     *
+     * @return void
+     * @api
+     */
+    protected function registerUniversalTagAttributes()
+    {
+        if (version_compare(VersionNumberUtility::getCurrentTypo3Version(), '13.4', '>=')) {
+            return;
+        }
+        $this->registerTagAttribute('class', 'string', 'CSS class(es) for this element');
+        $this->registerTagAttribute(
+            'dir',
+            'string',
+            'Text direction for this HTML element. Allowed strings: "ltr" (left to right), "rtl" (right to left)'
+        );
+        $this->registerTagAttribute('id', 'string', 'Unique (in this file) identifier for this HTML element.');
+        $this->registerTagAttribute(
+            'lang',
+            'string',
+            'Language for this element. Use short names specified in RFC 1766'
+        );
+        $this->registerTagAttribute('style', 'string', 'Individual CSS styles for this element');
+        $this->registerTagAttribute('title', 'string', 'Tooltip text of element');
+        $this->registerTagAttribute('accesskey', 'string', 'Keyboard shortcut to access this element');
+        $this->registerTagAttribute('tabindex', 'integer', 'Specifies the tab order of this element');
+        $this->registerTagAttribute('onclick', 'string', 'JavaScript evaluated for the onclick event');
+    }
+}

Classes/Traits/TagViewHelperTrait.php

@@ -8,6 +8,8 @@
  * LICENSE.md file that was distributed with this source code.
  */
 
+use TYPO3\CMS\Core\Utility\VersionNumberUtility;
+
 /**
  * Class TagViewHelperTrait
  *
@@ -31,13 +33,51 @@ public function registerArguments(): void
         $this->registerUniversalTagAttributes();
     }
 
+    /**
+     * Register a new tag attribute. Tag attributes are all arguments which will be directly appended to a tag if you
+     * call $this->initializeTag()
+     *
+     * @param string $name Name of tag attribute
+     * @param string $type Type of the tag attribute
+     * @param string $description Description of tag attribute
+     * @param bool $required set to true if tag attribute is required. Defaults to false.
+     * @param mixed $defaultValue Optional, default value of attribute if one applies
+     * @return void
+     * @api
+     */
+    protected function registerTagAttribute($name, $type, $description, $required = false, $defaultValue = null)
+    {
+        if (version_compare(VersionNumberUtility::getCurrentTypo3Version(), '13.4', '>=')) {
+            $this->registerArgument($name, $type, $description, $required, $defaultValue);
+            return;
+        }
+        parent::registerTagAttribute($name, $type, $description, $required, $defaultValue);
+    }
+
     /**
      * Registers all standard and HTML5 universal attributes.
      * Should be used inside registerArguments();
      */
     protected function registerUniversalTagAttributes(): void
     {
-        parent::registerUniversalTagAttributes();
+        $this->registerTagAttribute('class', 'string', 'CSS class(es) for this element');
+        $this->registerTagAttribute(
+            'dir',
+            'string',
+            'Text direction for this HTML element. Allowed strings: "ltr" (left to right), "rtl" (right to left)'
+        );
+        $this->registerTagAttribute('id', 'string', 'Unique (in this file) identifier for this HTML element.');
+        $this->registerTagAttribute(
+            'lang',
+            'string',
+            'Language for this element. Use short names specified in RFC 1766'
+        );
+        $this->registerTagAttribute('style', 'string', 'Individual CSS styles for this element');
+        $this->registerTagAttribute('title', 'string', 'Tooltip text of element');
+        $this->registerTagAttribute('accesskey', 'string', 'Keyboard shortcut to access this element');
+        $this->registerTagAttribute('tabindex', 'integer', 'Specifies the tab order of this element');
+        $this->registerTagAttribute('onclick', 'string', 'JavaScript evaluated for the onclick event');
+
         $this->registerArgument(
             'forceClosingTag',
             'boolean',