TL-40011: Adding in webkit-style transformation support

src/Compiler.php

@@ -37,6 +37,7 @@
 use ScssPhp\ScssPhp\Logger\StreamLogger;
 use ScssPhp\ScssPhp\Node\Number;
 use ScssPhp\ScssPhp\SourceMap\SourceMapGenerator;
+use ScssPhp\ScssPhp\Transforms\Transformer;
 use ScssPhp\ScssPhp\Util\Path;
 
 /**
@@ -326,10 +327,8 @@ class Compiler
      * The directory of the currently processed file
      *
      * @var string|null
-     * 
-     * Changed to protected by Totara
      */
-    protected $currentDirectory;
+    private $currentDirectory;
 
     /**
      * The directory of the input file
@@ -353,6 +352,20 @@ class Compiler
      */
     private $warnedChildFunctions = [];
 
+    /**
+     * Optional file loader
+     *
+     * @var callable|null
+     */
+    private $fileLoader = null;
+
+    /**
+     * Used to handle transformations of the tree.
+     *
+     * @var Transformer
+     */
+    private Transformer $transformer;
+
     /**
      * Constructor
      *
@@ -371,6 +384,7 @@ public function __construct($cacheOptions = null)
         }
 
         $this->logger = new StreamLogger(fopen('php://stderr', 'w'), true);
+        $this->transformer = new Transformer();
     }
 
     /**
@@ -5750,6 +5764,8 @@ public function addFeature($name)
      */
     protected function importFile($path, OutputBlock $out)
     {
+        [$path, $transforms] = $this->transformer->extractTransformsFromPath($path);
+
         $this->pushCallStack('import ' . $this->getPrettyPath($path));
         // see if tree is cached
         $realPath = realpath($path);
@@ -5758,6 +5774,8 @@ protected function importFile($path, OutputBlock $out)
             $realPath = $path;
         }
 
+        $cacheKey = ($transforms ? implode('!', $transforms) : '') . $realPath;
+
         if (substr($path, -5) === '.sass') {
             $this->sourceIndex = \count($this->sourceNames);
             $this->sourceNames[] = $path;
@@ -5767,16 +5785,28 @@ protected function importFile($path, OutputBlock $out)
             throw $this->error('The Sass indented syntax is not implemented.');
         }
 
-        if (isset($this->importCache[$realPath])) {
+        if (isset($this->importCache[$cacheKey])) {
             $this->handleImportLoop($realPath);
 
-            $tree = $this->importCache[$realPath];
+            $tree = $this->importCache[$cacheKey];
         } else {
-            $code   = file_get_contents($path);
+            // Allow the custom file loaders
+            if ($this->fileLoader !== null) {
+                $code = call_user_func($this->fileLoader, $path);
+            } else {
+                $code = file_get_contents($path);
+            }
+
             $parser = $this->parserFactory($path);
             $tree   = $parser->parse($code);
 
-            $this->importCache[$realPath] = $tree;
+            // Apply webpack-style transforms to the tree
+            if ($transforms) {
+                // Apply the named transformations
+                $tree = $this->transformer->applyTransformations($transforms, $path, $tree);
+            }
+
+            $this->importCache[$cacheKey] = $tree;
         }
 
         $currentDirectory = $this->currentDirectory;
@@ -5819,7 +5849,9 @@ public static function isCssImport($url)
     }
 
     /**
-     * Return the file path for an import url if it exists
+     * Return the file path for an import url if it exists.
+     *
+     * This includes an override supporting webkit transformations.
      *
      * @internal
      *
@@ -5830,6 +5862,16 @@ public static function isCssImport($url)
      */
     public function findImport($url, $currentDir = null)
     {
+        $pos = strrpos($url, '!');
+        if ($pos !== false) {
+            [$path, $transforms] = $this->transformer->extractTransformsFromPath($url);
+            $result = $this->findImport($path, $currentDir);
+            if ($result === null) {
+                throw $this->error("`$path` file not found for @import");
+            }
+            return implode('!', $transforms) . "!$result";
+        }
+
         // Vanilla css and external requests. These are not meant to be Sass imports.
         // Callback importers are still called for BC.
         if (self::isCssImport($url)) {
@@ -6252,7 +6294,7 @@ protected function handleImportLoop($name)
                 continue;
             }
 
-            $file = $this->sourceNames[$env->block->sourceIndex] ?? '';
+            $file = $this->sourceNames[$env->block->sourceIndex] ?? null;
 
             if ($file === null) {
                 continue;
@@ -10472,4 +10514,24 @@ protected function libScssphpGlob($args)
 
         return [Type::T_LIST, ',', $listParts];
     }
+
+    /**
+     * Set the file loader.
+     *
+     * @param callable|null $fileLoader
+     * @return void
+     */
+    public function setFileLoader(?callable $fileLoader): void
+    {
+        $this->fileLoader = $fileLoader;
+    }
+
+    /**
+     * @param Transformer $transformer
+     * @return void
+     */
+    public function setTransformer(Transformer $transformer): void
+    {
+        $this->transformer = $transformer;
+    }
 }

src/Transforms/Resource.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace ScssPhp\ScssPhp\Transforms;
+
+use ScssPhp\ScssPhp\Block;
+
+/**
+ * A resource represents the scss file that is in the process of transforming.
+ */
+class Resource
+{
+    private bool $modified = false;
+
+    public function __construct(protected string $path, protected Block $ast)
+    {
+    }
+
+    /**
+     * Return the modified Tree
+     *
+     * @return Block
+     */
+    public function getAst(): Block
+    {
+        return $this->ast;
+    }
+
+    /**
+     * Marks the AST has been modified
+     *
+     * @return void
+     */
+    public function markASTModified(): void
+    {
+        $this->modified = true;
+    }
+
+    /**
+     * Indicates if the resource AST has been modified or not.
+     *
+     * @return bool
+     */
+    public function isASTOnly(): bool
+    {
+        return $this->modified;
+    }
+}

src/Transforms/ResourceFactory.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace ScssPhp\ScssPhp\Transforms;
+
+use ScssPhp\ScssPhp\Block;
+
+class ResourceFactory
+{
+    /**
+     * Create a new resource instance to be used in transformations.
+     *
+     * @return Resource
+     */
+    public function createResource(string $path, Block $ast): Resource
+    {
+        return new Resource($path, $ast);
+    }
+}

src/Transforms/Transform.php

@@ -0,0 +1,12 @@
+<?php
+
+namespace ScssPhp\ScssPhp\Transforms;
+
+interface Transform
+{
+    /**
+     * @param Resource $resource
+     * @return void
+     */
+    public function execute(\ScssPhp\ScssPhp\Transforms\Resource $resource): void;
+}

src/Transforms/Transformer.php

@@ -0,0 +1,66 @@
+<?php
+
+namespace ScssPhp\ScssPhp\Transforms;
+
+use ScssPhp\ScssPhp\Block;
+
+class Transformer
+{
+    /**
+     * @param ResourceFactory|null $factory
+     * @param array<string, Transform> $transforms
+     */
+    public function __construct(protected ?ResourceFactory $factory = null, protected array $transforms = [])
+    {
+    }
+
+    public function setResourceFactory(?ResourceFactory $factory): void
+    {
+        $this->factory = $factory;
+    }
+
+    public function registerTransform(string $name, Transform $transform): void
+    {
+        $this->transforms[$name] = $transform;
+    }
+
+    /**
+     * @param string[] $transforms
+     * @param string $path
+     * @param Block $tree
+     * @return Block
+     */
+    public function applyTransformations(array $transforms, string $path, Block $tree): Block
+    {
+        // Make the resource
+        $resource = ($this->factory ?? new ResourceFactory())->createResource($path, $tree);
+
+        // transforms execute from right to left (like webpack)
+        $transforms = array_reverse($transforms, true);
+        foreach ($transforms as $name) {
+            if (!isset($this->transforms[$name])) {
+                throw new \Exception('Unknown transform "' . $name . '"');
+            }
+            $this->transforms[$name]->execute($resource);
+        }
+
+        return $resource->getAst();
+    }
+
+    /**
+     * @param string $path
+     * @return array{0: string, 1: string[]}
+     */
+    public function extractTransformsFromPath(string $path): array
+    {
+        $pos = strrpos($path, '!');
+        $transforms = [];
+
+        if ($pos !== false) {
+            $pathTransforms = substr($path, 0, $pos);
+            $transforms = !empty($pathTransforms) ? explode('!', $pathTransforms) : [];
+            $path = substr($path, $pos + 1);
+        }
+        return [$path, $transforms];
+    }
+}