Emit LogEvents (#6)

bin/dart_sass_embedded.dart

@@ -7,12 +7,11 @@ import 'dart:convert';
 
 import 'package:sass/sass.dart' as sass;
 import 'package:source_maps/source_maps.dart' as source_maps;
-import 'package:source_span/source_span.dart';
 import 'package:stream_channel/stream_channel.dart';
 
 import 'package:sass_embedded/src/dispatcher.dart';
-import 'package:sass_embedded/src/embedded_sass.pb.dart' as proto;
+import 'package:sass_embedded/src/embedded_sass.pb.dart';
-import 'package:sass_embedded/src/embedded_sass.pb.dart' hide SourceSpan;
+import 'package:sass_embedded/src/logger.dart';
 import 'package:sass_embedded/src/util/length_delimited_transformer.dart';
 import 'package:sass_embedded/src/utils.dart';
 
@@ -35,6 +34,7 @@ void main(List<String> args) {
         request.style == InboundMessage_CompileRequest_OutputStyle.COMPRESSED
             ? sass.OutputStyle.compressed
             : sass.OutputStyle.expanded;
+    var logger = Logger(dispatcher, request.id);
 
     try {
       String result;
@@ -46,6 +46,7 @@ void main(List<String> args) {
         case InboundMessage_CompileRequest_Input.string:
           var input = request.string;
           result = sass.compileString(input.source,
+              logger: logger,
               syntax: _syntaxToSyntax(input.syntax),
               style: style,
               url: input.url.isEmpty ? null : input.url,
@@ -55,7 +56,7 @@ void main(List<String> args) {
         case InboundMessage_CompileRequest_Input.path:
           try {
             result = sass.compile(request.path,
-                style: style, sourceMap: sourceMapCallback);
+                logger: logger, style: style, sourceMap: sourceMapCallback);
           } on FileSystemException catch (error) {
             return OutboundMessage_CompileResponse()
               ..failure = (OutboundMessage_CompileResponse_CompileFailure()
@@ -79,7 +80,7 @@ void main(List<String> args) {
       return OutboundMessage_CompileResponse()
         ..failure = (OutboundMessage_CompileResponse_CompileFailure()
           ..message = error.message
-          ..span = _protofySpan(error.span)
+          ..span = protofySpan(error.span)
           ..stackTrace = error.trace.toString());
     }
   });
@@ -98,18 +99,3 @@ sass.Syntax _syntaxToSyntax(InboundMessage_Syntax syntax) {
       throw "Unknown syntax $syntax.";
   }
 }
-
-/// Converts a Dart source span to a protocol buffer source span.
-proto.SourceSpan _protofySpan(SourceSpanWithContext span) => proto.SourceSpan()
-  ..text = span.text
-  ..start = _protofyLocation(span.start)
-  ..end = _protofyLocation(span.end)
-  ..url = span.sourceUrl?.toString() ?? ""
-  ..context = span.context;
-
-/// Converts a Dart source location to a protocol buffer source location.
-SourceSpan_SourceLocation _protofyLocation(SourceLocation location) =>
-    SourceSpan_SourceLocation()
-      ..offset = location.offset
-      ..line = location.line
-      ..column = location.column;

lib/src/dispatcher.dart

@@ -90,6 +90,10 @@ class Dispatcher {
     });
   }
 
+  /// Sends [event] to the host.
+  void sendLog(OutboundMessage_LogEvent event) =>
+      _send(OutboundMessage()..logEvent = event);
+
   /// Sends [message] to the host.
   void _send(OutboundMessage message) =>
       _channel.sink.add(message.writeToBuffer());

lib/src/logger.dart

@@ -0,0 +1,43 @@
+// Copyright 2019 Google Inc. Use of this source code is governed by an
+// MIT-style license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+import 'package:sass/sass.dart' as sass;
+import 'package:source_span/source_span.dart';
+import 'package:stack_trace/stack_trace.dart';
+
+import 'dispatcher.dart';
+import 'embedded_sass.pb.dart' hide SourceSpan;
+import 'utils.dart';
+
+/// A Sass logger that sends log messages as `LogEvent`s.
+class Logger implements sass.Logger {
+  /// The [Dispatcher] to which to send events.
+  final Dispatcher _dispatcher;
+
+  /// The ID of the compilation to which this logger is passed.
+  final int _compilationId;
+
+  Logger(this._dispatcher, this._compilationId);
+
+  void debug(String message, SourceSpan span) {
+    _dispatcher.sendLog(OutboundMessage_LogEvent()
+      ..compilationId = _compilationId
+      ..type = OutboundMessage_LogEvent_Type.DEBUG
+      ..message = message
+      ..span = protofySpan(span));
+  }
+
+  void warn(String message,
+      {FileSpan span, Trace trace, bool deprecation = false}) {
+    var event = OutboundMessage_LogEvent()
+      ..compilationId = _compilationId
+      ..type = deprecation
+          ? OutboundMessage_LogEvent_Type.DEPRECATION_WARNING
+          : OutboundMessage_LogEvent_Type.WARNING
+      ..message = message;
+    if (span != null) event.span = protofySpan(span);
+    if (trace != null) event.stackTrace = trace.toString();
+    _dispatcher.sendLog(event);
+  }
+}

lib/src/utils.dart

@@ -2,10 +2,31 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
-import 'embedded_sass.pb.dart';
+import 'package:source_span/source_span.dart';
+
+import 'embedded_sass.pb.dart' as proto;
+import 'embedded_sass.pb.dart' hide SourceSpan;
 
 /// Returns a [ProtocolError] indicating that a mandatory field with the givne
 /// [fieldName] was missing.
 ProtocolError mandatoryError(String fieldName) => ProtocolError()
   ..type = ProtocolError_ErrorType.PARAMS
   ..message = "Missing mandatory field $fieldName";
+
+/// Converts a Dart source span to a protocol buffer source span.
+proto.SourceSpan protofySpan(SourceSpan span) {
+  var protoSpan = proto.SourceSpan()
+    ..text = span.text
+    ..start = _protofyLocation(span.start)
+    ..end = _protofyLocation(span.end)
+    ..url = span.sourceUrl?.toString() ?? "";
+  if (span is SourceSpanWithContext) protoSpan.context = span.context;
+  return protoSpan;
+}
+
+/// Converts a Dart source location to a protocol buffer source location.
+SourceSpan_SourceLocation _protofyLocation(SourceLocation location) =>
+    SourceSpan_SourceLocation()
+      ..offset = location.offset
+      ..line = location.line
+      ..column = location.column;

test/protocol_test.dart

@@ -155,6 +155,85 @@ void main() {
     await process.kill();
   });
 
+  group("emits a log event", () {
+    test("for a @debug rule", () async {
+      process.inbound.add(compileString("a {@debug hello}"));
+
+      var logEvent = getLogEvent(await process.outbound.next);
+      expect(logEvent.compilationId, equals(0));
+      expect(logEvent.type, equals(OutboundMessage_LogEvent_Type.DEBUG));
+      expect(logEvent.message, equals("hello"));
+      expect(logEvent.span.text, equals("@debug hello"));
+      expect(logEvent.span.start, equals(location(3, 0, 3)));
+      expect(logEvent.span.end, equals(location(15, 0, 15)));
+      expect(logEvent.span.context, equals("a {@debug hello}"));
+      expect(logEvent.stackTrace, isEmpty);
+      await process.kill();
+    });
+
+    test("for a @warn rule", () async {
+      process.inbound.add(compileString("a {@warn hello}"));
+
+      var logEvent = getLogEvent(await process.outbound.next);
+      expect(logEvent.compilationId, equals(0));
+      expect(logEvent.type, equals(OutboundMessage_LogEvent_Type.WARNING));
+      expect(logEvent.message, equals("hello"));
+      expect(logEvent.span, equals(SourceSpan()));
+      expect(logEvent.stackTrace, equals("- 1:4  root stylesheet\n"));
+      await process.kill();
+    });
+
+    test("for a parse-time deprecation warning", () async {
+      process.inbound.add(compileString("@if true {} @elseif true {}"));
+
+      var logEvent = getLogEvent(await process.outbound.next);
+      expect(logEvent.compilationId, equals(0));
+      expect(logEvent.type,
+          equals(OutboundMessage_LogEvent_Type.DEPRECATION_WARNING));
+      expect(
+          logEvent.message,
+          equals(
+              '@elseif is deprecated and will not be supported in future Sass '
+              'versions.\n'
+              'Use "@else if" instead.'));
+      expect(logEvent.span.text, equals("@elseif"));
+      expect(logEvent.span.start, equals(location(12, 0, 12)));
+      expect(logEvent.span.end, equals(location(19, 0, 19)));
+      expect(logEvent.span.context, equals("@if true {} @elseif true {}"));
+      expect(logEvent.stackTrace, isEmpty);
+      await process.kill();
+    });
+
+    test("for a runtime deprecation warning", () async {
+      process.inbound.add(compileString("a {\$var: value !global}"));
+
+      var logEvent = getLogEvent(await process.outbound.next);
+      expect(logEvent.compilationId, equals(0));
+      expect(logEvent.type,
+          equals(OutboundMessage_LogEvent_Type.DEPRECATION_WARNING));
+      expect(
+          logEvent.message,
+          equals("As of Dart Sass 2.0.0, !global assignments won't be able to\n"
+              "declare new variables. Consider adding `\$var: null` at the "
+              "root of the\n"
+              "stylesheet."));
+      expect(logEvent.span.text, equals("\$var: value !global"));
+      expect(logEvent.span.start, equals(location(3, 0, 3)));
+      expect(logEvent.span.end, equals(location(22, 0, 22)));
+      expect(logEvent.span.context, equals("a {\$var: value !global}"));
+      expect(logEvent.stackTrace, "- 1:4  root stylesheet\n");
+      await process.kill();
+    });
+
+    test("with the same ID as the CompileRequest", () async {
+      process.inbound.add(compileString("@debug hello", id: 12345));
+
+      var logEvent = getLogEvent(await process.outbound.next);
+      expect(logEvent.compilationId, equals(12345));
+      await process.kill();
+    });
+  });
+
   group("gracefully handles an error", () {
     test("from invalid syntax", () async {
       process.inbound.add(compileString("a {b: }"));

test/utils.dart

@@ -90,7 +90,8 @@ void _ensureUpToDate(String path, String commandToRun) {
 /// Returns a [InboundMessage] that compiles the given plain CSS
 /// string.
 InboundMessage compileString(String css,
-    {InboundMessage_Syntax syntax,
+    {int id,
+    InboundMessage_Syntax syntax,
     InboundMessage_CompileRequest_OutputStyle style,
     String url,
     bool sourceMap}) {
@@ -99,6 +100,7 @@ InboundMessage compileString(String css,
   if (url != null) input.url = url;
 
   var request = InboundMessage_CompileRequest()..string = input;
+  if (id != null) request.id = id;
   if (style != null) request.style = style;
   if (sourceMap != null) request.sourceMap = sourceMap;
 
@@ -146,6 +148,16 @@ OutboundMessage_CompileResponse getCompileResponse(value) {
   return message.compileResponse;
 }
 
+/// Asserts that [message] is an [OutboundMessage] with a `LogEvent` and
+/// returns it.
+OutboundMessage_LogEvent getLogEvent(value) {
+  expect(value, isA<OutboundMessage>());
+  var message = value as OutboundMessage;
+  expect(message.hasLogEvent(), isTrue,
+      reason: "Expected $message to have a LogEvent");
+  return message.logEvent;
+}
+
 /// Asserts that an [OutboundMessage] is a `CompileResponse` with CSS that
 /// matches [css], with a source map that matches [sourceMap] (if passed).
 ///