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\TransformCompiler;
 use ScssPhp\ScssPhp\Util\Path;
 
 /**
@@ -351,6 +352,20 @@ class Compiler
      */
     private $warnedChildFunctions = [];
 
+    /**
+     * Optional file loader
+     *
+     * @var callable|null
+     */
+    protected $fileLoader = null;
+
+    /**
+     * Used to handle transformations of the tree.
+     *
+     * @var TransformCompiler
+     */
+    protected TransformCompiler $transformer;
+
     /**
      * Constructor
      *
@@ -369,6 +384,7 @@ public function __construct($cacheOptions = null)
         }
 
         $this->logger = new StreamLogger(fopen('php://stderr', 'w'), true);
+        $this->transformer = new TransformCompiler();
     }
 
     /**
@@ -5748,6 +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);
@@ -5756,6 +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[] = $path;
@@ -5765,16 +5785,28 @@ protected function importFile($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);
-            $parser = $this->parserFactory($path);
-            $tree   = $parser->parse($code);
+            // Allow the custom file loaders
+            if ($this->fileLoader !== null) {
+                $code = call_user_func($this->fileLoader, $path);
+            } else {
+                $code = file_get_contents($path);
+            }
 
-            $this->importCache[$realPath] = $tree;
+            // Apply webpack-style transforms to the tree
+            if ($transforms) {
+                // Apply the named transformations
+                $tree = $this->transformer->applyTransformations($transforms, $path, $code, fn($path, $code) => $this->parserFactory($path)->parse($code));
+            } else {
+                $parser = $this->parserFactory($path);
+                $tree = $parser->parse($code);
+            }
+
+            $this->importCache[$cacheKey] = $tree;
         }
 
         $currentDirectory = $this->currentDirectory;
@@ -5817,7 +5849,9 @@ public static function isCssImport($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
      *
@@ -5828,6 +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($url)) {
@@ -6250,7 +6294,7 @@ protected function handleImportLoop($name)
                 continue;
             }
 
-            $file = $this->sourceNames[$env->block->sourceIndex] ?? '';
+            $file = $this->sourceNames[$env->block->sourceIndex] ?? null;
 
             if ($file === null) {
                 continue;
@@ -10470,4 +10514,24 @@ protected function libScssphpGlob($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 TransformCompiler $compiler
+     * @return void
+     */
+    public function setTransformer(TransformCompiler $compiler): void
+    {
+        $this->transformer = $compiler;
+    }
 }

src/Transforms/Resource.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace ScssPhp\ScssPhp\Transforms;
+
+use ScssPhp\ScssPhp\Block;
+
+/**
+ * A resource represents the scss file that is in the process of transforming.
+ */
+interface Resource
+{
+    /**
+     * Reads back the specific code if it's still in a readable state.
+     * If the AST has been generated an exception will be thrown instead.
+     */
+    public function getCode(): string;
+
+    /**
+     * Set the CSS code to transform. This will delete the internal AST tree, marking it ready for parsing again.
+     */
+    public function setCode(string $code): void;
+
+    /**
+     * Load the compiled tree.
+     */
+    public function getAst(): Block;
+
+    public function setAst(Block $ast): void;
+
+    public function markASTModified(): void;
+
+    public function isASTOnly(): bool;
+}

src/Transforms/ResourceFactory.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace ScssPhp\ScssPhp\Transforms;
+
+/**
+ * A resource represents the scss file that is in the process of transforming.
+ * This factory can be used to replace specific instances of resources.
+ */
+interface ResourceFactory
+{
+    /**
+     * Create a new instance of the resource based on the code & path provided.
+     *
+     * @param string $path
+     * @param string $code
+     * @param callable $astParserFactory
+     * @return Resource
+     */
+    public function createResource(string $path, string $code, callable $astParserFactory): Resource;
+}

src/Transforms/Transform.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace ScssPhp\ScssPhp\Transforms;
+
+/**
+ * Contract for a transform action. Provided with the resource the transform can modify it in a chain.
+ */
+interface Transform
+{
+    public function execute(Resource $resource): void;
+}

src/Transforms/TransformCompiler.php

@@ -0,0 +1,67 @@
+<?php
+
+namespace ScssPhp\ScssPhp\Transforms;
+
+use ScssPhp\ScssPhp\Block;
+
+/**
+ * Base class that applies the transformation actions, an extension to the compiler.
+ */
+class TransformCompiler
+{
+    protected ResourceFactory $resourceFactory;
+
+    /**
+     * @param array<string, Transform> $transforms
+     */
+    public function __construct(protected array $transforms = [], ?ResourceFactory $resourceFactory = null)
+    {
+        $this->resourceFactory = $resourceFactory ?? new TransformResourceFactory();
+    }
+
+    public function registerTransform(string $name, Transform $transform): void
+    {
+        $this->transforms[$name] = $transform;
+    }
+
+    /**
+     * @param string[] $transforms
+     * @param string $path
+     * @param string $code
+     * @param callable $astParserFactory
+     * @return Block
+     */
+    public function applyTransformations(array $transforms, string $path, string $code, callable $astParserFactory): Block
+    {
+        // Make the resource
+        $resource = $this->resourceFactory->createResource($path, $code, $astParserFactory);
+
+        // 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];
+    }
+}

src/Transforms/TransformResource.php

@@ -0,0 +1,83 @@
+<?php
+
+namespace ScssPhp\ScssPhp\Transforms;
+
+use ScssPhp\ScssPhp\Block;
+
+/**
+ * A resource represents the scss file that is in the process of transforming.
+ */
+class TransformResource implements Resource
+{
+    private bool $modified = false;
+    protected ?Block $ast = null;
+
+    /**
+     * @var callable
+     */
+    protected $parserFactory;
+
+    public function __construct(protected string $path, protected string $code, callable $parserFactory)
+    {
+        $this->parserFactory = $parserFactory;
+    }
+
+    public function getCode(): string
+    {
+        if ($this->modified) {
+            throw new \Exception('Cannot access code as it is in AST only mode');
+        }
+
+        return $this->code;
+    }
+
+    public function setCode(string $code): void
+    {
+        $this->code = $code;
+        $this->ast = null;
+        $this->modified = false;
+    }
+
+    /**
+     * Return the modified Tree
+     *
+     * @return Block
+     */
+    public function getAst(): Block
+    {
+        if ($this->ast === null) {
+            if (empty($this->code)) {
+                throw new \Exception('AST and source are both unavailable for this resource');
+            }
+
+            $this->ast = ($this->parserFactory)($this->path, $this->code);
+        }
+        return $this->ast;
+    }
+
+    public function setAst(Block $ast): void
+    {
+        $this->ast = $ast;
+        $this->markASTModified();
+    }
+
+    /**
+     * 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/TransformResourceFactory.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace ScssPhp\ScssPhp\Transforms;
+
+/**
+ * Default factory to create a resource.
+ */
+class TransformResourceFactory implements ResourceFactory
+{
+    /**
+     * Create a new instance of the resource based on the code & path provided.
+     * @param string $path
+     * @param string $code
+     * @param callable $astParserFactory
+     * @return Resource
+     */
+    public function createResource(string $path, string $code, callable $astParserFactory): Resource
+    {
+        return new TransformResource($path, $code, $astParserFactory);
+    }
+}