Add support for the data option to the JS API (#159)

Also add renderString to the Dart API.

Partially addresses #7

CHANGELOG.md

@@ -8,9 +8,14 @@
 
 ### Node JS API
 
-* Add support for `lineFeed`, `indentWidth`, and `indentType` options to
+* Add support for `data`, `lineFeed`, `indentWidth`, and `indentType` options to
   `render()` and `renderSync()`.
 
+### Dart API
+
+* Add a `renderString()` method for rendering Sass source that's not in a file
+  on disk.
+
 ## 1.0.0-beta.1
 
 * Drop support for the reference combinator. This has been removed from the

lib/sass.dart

@@ -16,7 +16,34 @@ import 'src/sync_package_resolver.dart';
 ///
 /// [SyncPackageResolver]: https://www.dartdocs.org/documentation/package_resolver/latest/package_resolver/SyncPackageResolver-class.html
 ///
-/// Finally throws a [SassException] if conversion fails.
+/// Throws a [SassException] if conversion fails.
 String render(String path,
         {bool color: false, SyncPackageResolver packageResolver}) =>
     r.render(path, color: color, packageResolver: packageResolver);
+
+/// Converts [source] to CSS and returns the result.
+///
+/// If [indented] is `true`, this parses [source] using indented syntax;
+/// otherwise (and by default) it uses SCSS. If [color] is `true`, this will use
+/// terminal colors in warnings.
+///
+/// If [packageResolver] is provided, it's used to resolve `package:` imports.
+/// Otherwise, they aren't supported. It takes a [SyncPackageResolver][] from
+/// the `package_resolver` package.
+///
+/// [SyncPackageResolver]: https://www.dartdocs.org/documentation/package_resolver/latest/package_resolver/SyncPackageResolver-class.html
+///
+/// The [url] indicates the location from which [source] was loaded. It may may
+/// be a [String] or a [Uri].
+///
+/// Throws a [SassException] if conversion fails.
+String renderString(String source,
+        {bool indented: false,
+        bool color: false,
+        SyncPackageResolver packageResolver,
+        url}) =>
+    r.renderString(source,
+        indented: indented,
+        color: color,
+        packageResolver: packageResolver,
+        url: url);

lib/src/node.dart

@@ -39,14 +39,12 @@ void main() {
 void _render(RenderOptions options,
     void callback(RenderError error, RenderResult result)) {
   try {
-    var result = newRenderResult(render(options.file,
-        useSpaces: options.indentType != 'tab',
-        indentWidth: _parseIndentWidth(options.indentWidth),
-        lineFeed: _parseLineFeed(options.linefeed)));
-    callback(null, result);
+    callback(null, _doRender(options));
   } on SassException catch (error) {
     // TODO: populate the error more thoroughly if possible.
-    callback(newRenderError(message: error.message), null);
+    callback(newRenderError(error.message), null);
+  } catch (error) {
+    callback(newRenderError(error.toString()), null);
   }
 }
 
@@ -58,15 +56,42 @@ void _render(RenderOptions options,
 /// [render]: https://github.com/sass/node-sass#options
 RenderResult _renderSync(RenderOptions options) {
   try {
-    return newRenderResult(render(options.file,
-        useSpaces: options.indentType != 'tab',
-        indentWidth: _parseIndentWidth(options.indentWidth),
-        lineFeed: _parseLineFeed(options.linefeed)));
+    return _doRender(options);
   } on SassException catch (error) {
     // TODO: populate the error more thoroughly if possible.
-    jsThrow(newRenderError(message: error.message));
-    throw "unreachable";
+    jsThrow(newRenderError(error.message));
+  } catch (error) {
+    jsThrow(newRenderError(error.toString()));
   }
+  throw "unreachable";
+}
+
+/// Converts Sass to CSS.
+///
+/// Unlike [_render] and [_renderSync], this doesn't do any special handling for
+/// Dart exceptions.
+RenderResult _doRender(RenderOptions options) {
+  String output;
+  if (options.data != null) {
+    if (options.file != null) {
+      throw new ArgumentError(
+          "options.data and options.file may not both be set.");
+    }
+
+    output = renderString(options.data,
+        useSpaces: options.indentType != 'tab',
+        indentWidth: _parseIndentWidth(options.indentWidth),
+        lineFeed: _parseLineFeed(options.linefeed));
+  } else if (options.file != null) {
+    output = render(options.file,
+        useSpaces: options.indentType != 'tab',
+        indentWidth: _parseIndentWidth(options.indentWidth),
+        lineFeed: _parseLineFeed(options.linefeed));
+  } else {
+    throw new ArgumentError("Either options.data or options.file must be set.");
+  }
+
+  return newRenderResult(output);
 }
 
 /// Parses the indentation width into an [int].

lib/src/node/render_error.dart

@@ -19,8 +19,8 @@ class RenderError {
       {String message, int line, int column, int status, String file});
 }
 
-RenderError newRenderError(
-    {String message, int line, int column, int status, String file}) {
+RenderError newRenderError(String message,
+    {int line, int column, int status, String file}) {
   var error = new RenderError._(
       message: message, line: line, column: column, status: status, file: file);
   setToString(error, () => "Error: $message");

lib/src/node/render_options.dart

@@ -8,10 +8,15 @@ import 'package:js/js.dart';
 @anonymous
 class RenderOptions {
   external String get file;
+  external String get data;
   external String get indentType;
   external dynamic get indentWidth;
   external String get linefeed;
 
   external factory RenderOptions(
-      {String file, String indentType, indentWidth, String linefeed});
+      {String file,
+      String data,
+      String indentType,
+      indentWidth,
+      String linefeed});
 }

lib/src/render.dart

@@ -12,16 +12,33 @@ import 'visitor/serialize.dart';
 /// Like [render] in `lib/sass.dart`, but provides more options to support the
 /// node-sass compatible API.
 String render(String path,
-    {bool color: false,
+        {bool color: false,
+        SyncPackageResolver packageResolver,
+        bool useSpaces: true,
+        int indentWidth,
+        LineFeed lineFeed}) =>
+    renderString(readFile(path),
+        indented: p.extension(path) == '.sass',
+        color: color,
+        packageResolver: packageResolver,
+        useSpaces: useSpaces,
+        indentWidth: indentWidth,
+        lineFeed: lineFeed,
+        url: p.toUri(path));
+
+/// Like [renderString] in `lib/sass.dart`, but provides more options to support
+/// the node-sass compatible API.
+String renderString(String source,
+    {bool indented: false,
+    bool color: false,
     SyncPackageResolver packageResolver,
     bool useSpaces: true,
     int indentWidth,
-    LineFeed lineFeed}) {
-  var contents = readFile(path);
-  var url = p.toUri(path);
-  var sassTree = p.extension(path) == '.sass'
-      ? new Stylesheet.parseSass(contents, url: url, color: color)
-      : new Stylesheet.parseScss(contents, url: url, color: color);
+    LineFeed lineFeed,
+    url}) {
+  var sassTree = indented
+      ? new Stylesheet.parseSass(source, url: url, color: color)
+      : new Stylesheet.parseScss(source, url: url, color: color);
   var cssTree =
       evaluate(sassTree, color: color, packageResolver: packageResolver);
   return toCss(cssTree,

test/node_api_test.dart

@@ -41,6 +41,42 @@ a {
 }'''));
     });
 
+    test("supports relative imports for a file", () async {
+      var importerPath = p.join(sandbox, 'importer.scss');
+      await writeTextFile(importerPath, '@import "test"');
+      expect(_renderSync(new RenderOptions(file: importerPath)), equals('''
+a {
+  b: c;
+}'''));
+    });
+
+    test("renders a string", () {
+      expect(_renderSync(new RenderOptions(data: "a {b: c}")), equals('''
+a {
+  b: c;
+}'''));
+    });
+
+    test("data and file may not both be set", () {
+      var error =
+          _renderSyncError(new RenderOptions(data: "x {y: z}", file: sassPath));
+      expect(error.toString(),
+          contains('options.data and options.file may not both be set.'));
+    });
+
+    test("one of data and file must be set", () {
+      var error = _renderSyncError(new RenderOptions());
+      expect(error.toString(),
+          contains('Either options.data or options.file must be set.'));
+    });
+
+    test("rejects both a file and a string", () {
+      expect(_renderSync(new RenderOptions(data: "a {b: c}")), equals('''
+a {
+  b: c;
+}'''));
+    });
+
     test("allows tab indentation", () {
       expect(_renderSync(new RenderOptions(file: sassPath, indentType: 'tab')),
           equals('''