Handle lexer errors.

Fixes #105.

Author: RubenVerborgh

lib/N3Lexer.js

@@ -410,6 +410,7 @@ N3Lexer.prototype = {
         if (self._input !== null)
           self._tokenizeToEnd(callback, true);
       });
+      input.on('error', callback);
     }
   },
 };

lib/N3StreamParser.js

@@ -14,13 +14,19 @@ function N3StreamParser(options) {
 
   // Set up parser
   var self = this, parser = new N3Parser(options), onData, onEnd;
-  parser.parse(
-    // Pass dummy stream to obtain `data` and `end` callbacks
-    { on: function (event, cb) { event === 'data' ? (onData = cb) : (onEnd = cb); } },
-    // Handle triples by pushing them down the pipeline
-    function (error, t) { error && self.emit('error', error) || t && self.push(t); },
-    // Emit prefixes through the `prefix` event
-    function (prefix, uri) { self.emit('prefix', prefix, uri); });
+  // Pass dummy stream to obtain `data` and `end` callbacks
+  parser.parse({
+    on: function (event, cb) {
+      switch (event) {
+      case 'data': onData = cb; break;
+      case 'end':   onEnd = cb; break;
+      }
+    },
+  },
+  // Handle triples by pushing them down the pipeline
+  function (error, t) { error && self.emit('error', error) || t && self.push(t); },
+  // Emit prefixes through the `prefix` event
+  function (prefix, uri) { self.emit('prefix', prefix, uri); });
 
   // Implement Transform methods through parser callbacks
   this._transform = function (chunk, encoding, done) { onData(chunk); done(); };

test/N3Lexer-test.js

@@ -730,30 +730,74 @@ describe('N3Lexer', function () {
     });
 
     describe('passing data after the stream has been finished', function () {
-      var tokens = [], stream = new EventEmitter(), lexer = new N3Lexer();
-      lexer.tokenize(stream, function (error, token) { !error && tokens.push(token); });
-      stream.emit('data', '<a> ');
-      stream.emit('end');
-      stream.emit('data', '<b> ');
-      stream.emit('end');
+      var tokens = [], error;
+      before(function () {
+        var stream = new EventEmitter(), lexer = new N3Lexer();
+        lexer.tokenize(stream, function (err, token) {
+          if (err)
+            error = err;
+          else
+            tokens.push(token);
+        });
+        stream.emit('data', '<a> ');
+        stream.emit('end');
+        stream.emit('data', '<b> ');
+        stream.emit('end');
+      });
 
       it('parses only the first chunk (plus EOF)', function () {
         tokens.should.have.length(2);
       });
+
+      it('does not emit an error', function () {
+        expect(error).to.not.exist;
+      });
     });
 
-    describe('passing data after an error has occurred', function () {
-      var tokens = [], stream = new EventEmitter(), lexer = new N3Lexer();
-      lexer.tokenize(stream, function (error, token) { !error && tokens.push(token); });
-      stream.emit('data', '<a> ');
-      stream.emit('data', ' error ');
-      stream.emit('end');
-      stream.emit('data', '<b> ');
-      stream.emit('end');
+    describe('passing data after a syntax error', function () {
+      var tokens = [], error;
+      before(function () {
+        var stream = new EventEmitter(), lexer = new N3Lexer();
+        lexer.tokenize(stream, function (err, token) {
+          if (err)
+            error = err;
+          else
+            tokens.push(token);
+        });
+        stream.emit('data', '<a> ');
+        stream.emit('data', ' error ');
+        stream.emit('end');
+        stream.emit('data', '<b> ');
+        stream.emit('end');
+      });
 
       it('parses only the first chunk', function () {
         tokens.should.have.length(1);
       });
+
+      it('emits the error', function () {
+        expect(error).to.exist;
+        expect(error).to.have.property('message', 'Unexpected "error" on line 1.');
+      });
+    });
+
+    describe('when the stream errors', function () {
+      var tokens = [], error;
+      before(function () {
+        var stream = new EventEmitter(), lexer = new N3Lexer();
+        lexer.tokenize(stream, function (err, token) {
+          if (err)
+            error = err;
+          else
+            tokens.push(token);
+        });
+        stream.emit('error', new Error('my error'));
+      });
+
+      it('passes the error', function () {
+        expect(error).to.exist;
+        expect(error).to.have.property('message', 'my error');
+      });
     });
 
     describe('called with a string and without callback', function () {