add processResource option to control if resource is added as dependency

README.md

@@ -14,24 +14,35 @@ runLoaders({
 	context: { minimize: true },
 	// Additional loader context which is used as base context
 
+	processResource: (loaderContext, resourcePath, callback) => { ... },
+	// Optional: A function to process the resource
+	// Must have signature function(context, path, function(err, buffer))
+	// By default readResource is used and the resource is added a fileDependency
+
 	readResource: fs.readFile.bind(fs)
-	// A function to read the resource
+	// Optional: A function to read the resource
+	// Only used when 'processResource' is not provided
 	// Must have signature function(path, function(err, buffer))
-
+	// By default fs.readFile is used
 }, function(err, result) {
 	// err: Error?
 
 	// result.result: Buffer | String
 	// The result
+	// only available when no error occured
 
 	// result.resourceBuffer: Buffer
 	// The raw resource as Buffer (useful for SourceMaps)
+	// only available when no error occured
 
 	// result.cacheable: Bool
 	// Is the result cacheable or do it require reexecution?
 
 	// result.fileDependencies: String[]
-	// An array of paths (files) on which the result depends on
+	// An array of paths (existing files) on which the result depends on
+
+	// result.missingDependencies: String[]
+	// An array of paths (not existing files) on which the result depends on
 
 	// result.contextDependencies: String[]
 	// An array of paths (directories) on which the result depends on

lib/LoaderRunner.js

@@ -217,8 +217,7 @@ function processResource(options, loaderContext, callback) {
 
 	var resourcePath = loaderContext.resourcePath;
 	if(resourcePath) {
-		loaderContext.addDependency(resourcePath);
-		options.readResource(resourcePath, function(err, buffer) {
+		options.processResource(loaderContext, resourcePath, function(err, buffer) {
 			if(err) return callback(err);
 			options.resourceBuffer = buffer;
 			iterateNormalLoaders(options, loaderContext, [buffer], callback);
@@ -266,7 +265,10 @@ exports.runLoaders = function runLoaders(options, callback) {
 	var resource = options.resource || "";
 	var loaders = options.loaders || [];
 	var loaderContext = options.context || {};
-	var readResource = options.readResource || readFile;
+	var processResource = options.processResource || ((readResource, context, resource, callback) => {
+		context.addDependency(resource);
+		readResource(resource, callback);
+	}).bind(null, options.readResource || readFile);
 
 	//
 	var splittedResource = resource && parsePathQueryFragment(resource);
@@ -390,7 +392,7 @@ exports.runLoaders = function runLoaders(options, callback) {
 
 	var processOptions = {
 		resourceBuffer: null,
-		readResource: readResource
+		processResource: processResource
 	};
 	iteratePitchingLoaders(processOptions, loaderContext, function(err, result) {
 		if(err) {