From 9ac2e741eca3f6a4e081ccb7afdaa3f3627f003d Mon Sep 17 00:00:00 2001
From: David Sferruzza <david.sferruzza@gmail.com>
Date: Fri, 29 Nov 2013 00:14:11 +0100
Subject: [PATCH] Add loader system for @import

---
 docs/docs.md  | 24 ++++++++++++++++++++++++
 lessc.inc.php | 29 +++++++++++++++++++++--------
 2 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/docs/docs.md b/docs/docs.md
index 797b0f1a..f88c2b0d 100644
--- a/docs/docs.md
+++ b/docs/docs.md
@@ -1003,6 +1003,8 @@ Methods:
 
 * [`addImportDir($dir)`](#import_directory) -- Append directory to search path for imports
 
+* [`setLoader($callback)`](#loader) -- Register a callback use to fetch imported files
+
 
 ### Compiling
 
@@ -1277,6 +1279,28 @@ overwriting the whole thing.
     $less->addImportDir("public/stylesheets");
     ```
 
+### Loader
+
+It is possible to register a callback that will be called to fetch imported files (using `@import`).
+This can be useful when LESS files are not in a directory on the filesystem.
+
+The callback takes one parameter, which is the name of the file (as specified in the `@import` directive).
+
+It will return either `false` or a string of LESS code to be parsed.
+If it returns `false`, the `@import` directive will stay.
+
+    ```php
+    $less->loader(function($name) {
+      // Use $name to do whatever you want to fetch your LESS code
+
+      // return $content; <- will use the $content you just fetched
+      // return false; <- will let the `@import` directive untouched
+      // return ''; <- will import nothing and remove the `@import` directive
+    });
+    ```
+
+If no callback is registered, the `@import` directives will be resolved using the classic behaviour (see **Import Directory**).
+
 ### Custom Functions
 
 **lessphp** has a simple extension interface where you can implement user
diff --git a/lessc.inc.php b/lessc.inc.php
index 6ad6c649..ba26e880 100644
--- a/lessc.inc.php
+++ b/lessc.inc.php
@@ -54,6 +54,8 @@ class lessc {
 	public $importDisabled = false;
 	public $importDir = '';
 
+	public $loader = null;
+
 	protected $numberPrecision = null;
 
 	protected $allParsedFiles = array();
@@ -90,6 +92,10 @@ static public function preg_quote($what) {
 		return preg_quote($what, '/');
 	}
 
+	public function setLoader($callback) {
+		$this->loader = $callback;
+	}
+
 	protected function tryImport($importPath, $parentBlock, $out) {
 		if ($importPath[0] == "function" && $importPath[1] == "url") {
 			$importPath = $this->flattenList($importPath[2]);
@@ -100,13 +106,21 @@ protected function tryImport($importPath, $parentBlock, $out) {
 
 		$url = $this->compileValue($this->lib_e($str));
 
-		// don't import if it ends in css
-		if (substr_compare($url, '.css', -4, 4) === 0) return false;
-
-		$realPath = $this->findImport($url);
-
-		if ($realPath === null) return false;
+		if (is_callable($this->loader)) {
+			$realPath = $url;
+			$content = call_user_func($this->loader, $realPath);
+			if ($content === false) return false;
+		}
+		else {
+			// don't import if it ends in css
+			if (substr_compare($url, '.css', -4, 4) === 0) return false;
 
+			$realPath = $this->findImport($url);
+			if ($realPath === null) return false;
+			$content = file_get_contents($realPath);
+			$this->addParsedFile($realPath);
+		}
+		
 		if ($this->importDisabled) {
 			return array(false, "/* import disabled */");
 		}
@@ -115,9 +129,8 @@ protected function tryImport($importPath, $parentBlock, $out) {
 			return array(false, null);
 		}
 
-		$this->addParsedFile($realPath);
 		$parser = $this->makeParser($realPath);
-		$root = $parser->parse(file_get_contents($realPath));
+		$root = $parser->parse($content);
 
 		// set the parents of all the block props
 		foreach ($root->props as $prop) {