diff --git a/.travis.yml b/.travis.yml
index c49062a..6f323b1 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,6 +6,6 @@ python:
   - "3.6"
   - "pypy"  # PyPy2 5.8.0
   - "pypy3" # Pypy3 5.8.0-beta0
+install: pip install tox-travis
 script:
-  - pip install -r nearley-requirements.txt
-  - python -m tests
+  - tox
diff --git a/README.md b/README.md
index 619be58..293ca1f 100644
--- a/README.md
+++ b/README.md
@@ -31,7 +31,7 @@ Most importantly, Lark will save you time and prevent you from getting parsing h
 
 Lark has no dependencies.
 
-[![Build Status](https://travis-ci.org/erezsh/lark.svg?branch=master)](https://travis-ci.org/erezsh/lark)
+[![Build Status](https://travis-ci.org/lark-parser/lark.svg?branch=master)](https://travis-ci.org/lark-parser/lark)
 
 ### Hello World
 
diff --git a/examples/README.md b/examples/README.md
index 3fbe3ea..0951c86 100644
--- a/examples/README.md
+++ b/examples/README.md
@@ -7,6 +7,7 @@
 - [indented\_tree.py](indented\_tree.py) - A demonstration of parsing indentation ("whitespace significant" language)
 - [fruitflies.py](fruitflies.py) - A demonstration of ambiguity
 - [turtle\_dsl.py](turtle_dsl.py) - Implements a LOGO-like toy language for Python's turtle, with interpreter.
+- [lark\_grammar.py](lark_grammar.py) + [lark.g](lark.g) - A reference implementation of the Lark grammar (using LALR(1) + standard lexer)
 
 ### Advanced
 
diff --git a/examples/lark.g b/examples/lark.g
new file mode 100644
index 0000000..1fbf592
--- /dev/null
+++ b/examples/lark.g
@@ -0,0 +1,49 @@
+start: (_item | _NL)*
+
+_item: rule
+     | token
+     | statement
+
+rule: RULE priority? ":" expansions _NL
+token: TOKEN priority? ":" expansions _NL
+
+priority: "." NUMBER
+
+statement: "%ignore" expansions _NL                -> ignore
+         | "%import" import_args ["->" TOKEN] _NL  -> import
+
+import_args: name ("." name)*
+
+?expansions: alias (_VBAR alias)*
+
+?alias: expansion ["->" RULE]
+
+?expansion: expr*
+
+?expr: atom [OP | "~" NUMBER [".." NUMBER]]
+
+?atom: "(" expansions ")"
+     | "[" expansions "]" -> maybe
+     | STRING ".." STRING -> literal_range
+     | name
+     | (REGEXP | STRING) -> literal
+
+name: RULE
+    | TOKEN
+
+_VBAR: _NL? "|"
+OP: /[+*][?]?|[?](?![a-z])/
+RULE: /!?[_?]?[a-z][_a-z0-9]*/
+TOKEN: /_?[A-Z][_A-Z0-9]*/
+STRING: _STRING "i"?
+REGEXP: /\/(?!\/)(\\\/|\\\\|[^\/\n])*?\/[imslux]*/
+_NL: /(\r?\n)+\s*/
+
+%import common.ESCAPED_STRING -> _STRING
+%import common.INT -> NUMBER
+%import common.WS_INLINE
+
+COMMENT: "//" /[^\n]/*
+
+%ignore WS_INLINE
+%ignore COMMENT
diff --git a/examples/lark_grammar.py b/examples/lark_grammar.py
new file mode 100644
index 0000000..88fc4cf
--- /dev/null
+++ b/examples/lark_grammar.py
@@ -0,0 +1,18 @@
+from lark import Lark
+
+parser = Lark(open('examples/lark.g'), parser="lalr")
+
+grammar_files = [
+    'examples/python2.g',
+    'examples/python3.g',
+    'examples/lark.g',
+    'lark/grammars/common.g',
+]
+
+def test():
+    for grammar_file in grammar_files:
+        tree = parser.parse(open(grammar_file).read())
+    print("All grammars parsed successfully")
+
+if __name__ == '__main__':
+    test()
diff --git a/examples/qscintilla_json.py b/examples/qscintilla_json.py
new file mode 100644
index 0000000..e7c4b7f
--- /dev/null
+++ b/examples/qscintilla_json.py
@@ -0,0 +1,201 @@
+#
+# This example shows how to write a syntax-highlighted editor with Qt and Lark
+#
+# Requirements:
+#
+#   PyQt5==5.10.1
+#   QScintilla==2.10.4
+
+import sys
+import textwrap
+
+from PyQt5.Qt import *  # noqa
+
+from PyQt5.Qsci import QsciScintilla
+from PyQt5.Qsci import QsciLexerCustom
+
+from lark import Lark
+
+
+class LexerJson(QsciLexerCustom):
+
+    def __init__(self, parent=None):
+        super().__init__(parent)
+        self.create_parser()
+        self.create_styles()
+
+    def create_styles(self):
+        deeppink = QColor(249, 38, 114)
+        khaki = QColor(230, 219, 116)
+        mediumpurple = QColor(174, 129, 255)
+        mediumturquoise = QColor(81, 217, 205)
+        yellowgreen = QColor(166, 226, 46)
+        lightcyan = QColor(213, 248, 232)
+        darkslategrey = QColor(39, 40, 34)
+
+        styles = {
+            0: mediumturquoise,
+            1: mediumpurple,
+            2: yellowgreen,
+            3: deeppink,
+            4: khaki,
+            5: lightcyan
+        }
+
+        for style, color in styles.items():
+            self.setColor(color, style)
+            self.setPaper(darkslategrey, style)
+            self.setFont(self.parent().font(), style)
+
+        self.token_styles = {
+            "__COLON": 5,
+            "__COMMA": 5,
+            "__LBRACE": 5,
+            "__LSQB": 5,
+            "__RBRACE": 5,
+            "__RSQB": 5,
+            "FALSE": 0,
+            "NULL": 0,
+            "TRUE": 0,
+            "STRING": 4,
+            "NUMBER": 1,
+        }
+
+    def create_parser(self):
+        grammar = '''
+            anons: ":" "{" "}" "," "[" "]"
+            TRUE: "true"
+            FALSE: "false"
+            NULL: "NULL"
+            %import common.ESCAPED_STRING -> STRING
+            %import common.SIGNED_NUMBER  -> NUMBER
+            %import common.WS
+            %ignore WS
+        '''
+
+        self.lark = Lark(grammar, parser=None, lexer='standard')
+        # All tokens: print([t.name for t in self.lark.parser.lexer.tokens])
+
+    def defaultPaper(self, style):
+        return QColor(39, 40, 34)
+
+    def language(self):
+        return "Json"
+
+    def description(self, style):
+        return {v: k for k, v in self.token_styles.items()}.get(style, "")
+
+    def styleText(self, start, end):
+        self.startStyling(start)
+        text = self.parent().text()[start:end]
+        last_pos = 0
+
+        try:
+            for token in self.lark.lex(text):
+                ws_len = token.pos_in_stream - last_pos
+                if ws_len:
+                    self.setStyling(ws_len, 0)    # whitespace
+
+                token_len = len(bytearray(token, "utf-8"))
+                self.setStyling(
+                    token_len, self.token_styles.get(token.type, 0))
+
+                last_pos = token.pos_in_stream + token_len
+        except Exception as e:
+            print(e)
+
+
+class EditorAll(QsciScintilla):
+
+    def __init__(self, parent=None):
+        super().__init__(parent)
+
+        # Set font defaults
+        font = QFont()
+        font.setFamily('Consolas')
+        font.setFixedPitch(True)
+        font.setPointSize(8)
+        font.setBold(True)
+        self.setFont(font)
+
+        # Set margin defaults
+        fontmetrics = QFontMetrics(font)
+        self.setMarginsFont(font)
+        self.setMarginWidth(0, fontmetrics.width("000") + 6)
+        self.setMarginLineNumbers(0, True)
+        self.setMarginsForegroundColor(QColor(128, 128, 128))
+        self.setMarginsBackgroundColor(QColor(39, 40, 34))
+        self.setMarginType(1, self.SymbolMargin)
+        self.setMarginWidth(1, 12)
+
+        # Set indentation defaults
+        self.setIndentationsUseTabs(False)
+        self.setIndentationWidth(4)
+        self.setBackspaceUnindents(True)
+        self.setIndentationGuides(True)
+
+        # self.setFolding(QsciScintilla.CircledFoldStyle)
+
+        # Set caret defaults
+        self.setCaretForegroundColor(QColor(247, 247, 241))
+        self.setCaretWidth(2)
+
+        # Set selection color defaults
+        self.setSelectionBackgroundColor(QColor(61, 61, 52))
+        self.resetSelectionForegroundColor()
+
+        # Set multiselection defaults
+        self.SendScintilla(QsciScintilla.SCI_SETMULTIPLESELECTION, True)
+        self.SendScintilla(QsciScintilla.SCI_SETMULTIPASTE, 1)
+        self.SendScintilla(
+            QsciScintilla.SCI_SETADDITIONALSELECTIONTYPING, True)
+
+        lexer = LexerJson(self)
+        self.setLexer(lexer)
+
+
+EXAMPLE_TEXT = textwrap.dedent("""\
+        {
+            "_id": "5b05ffcbcf8e597939b3f5ca",
+            "about": "Excepteur consequat commodo esse voluptate aute aliquip ad sint deserunt commodo eiusmod irure. Sint aliquip sit magna duis eu est culpa aliqua excepteur ut tempor nulla. Aliqua ex pariatur id labore sit. Quis sit ex aliqua veniam exercitation laboris anim adipisicing. Lorem nisi reprehenderit ullamco labore qui sit ut aliqua tempor consequat pariatur proident.",
+            "address": "665 Malbone Street, Thornport, Louisiana, 243",
+            "age": 23,
+            "balance": "$3,216.91",
+            "company": "BULLJUICE",
+            "email": "elisekelley@bulljuice.com",
+            "eyeColor": "brown",
+            "gender": "female",
+            "guid": "d3a6d865-0f64-4042-8a78-4f53de9b0707",
+            "index": 0,
+            "isActive": false,
+            "isActive2": true,
+            "latitude": -18.660714,
+            "longitude": -85.378048,
+            "name": "Elise Kelley",
+            "phone": "+1 (808) 543-3966",
+            "picture": "http://placehold.it/32x32",
+            "registered": "2017-09-30T03:47:40 -02:00",
+            "tags": [
+                "et",
+                "nostrud",
+                "in",
+                "fugiat",
+                "incididunt",
+                "labore",
+                "nostrud"
+            ]
+        }\
+    """)
+
+def main():
+    app = QApplication(sys.argv)
+    ex = EditorAll()
+    ex.setWindowTitle(__file__)
+    ex.setText(EXAMPLE_TEXT)
+    ex.resize(800, 600)
+    ex.show()
+    sys.exit(app.exec_())
+
+
+if __name__ == "__main__":
+    main()
diff --git a/lark/grammars/common.g b/lark/grammars/common.g
index 2bd02d0..8bc8079 100644
--- a/lark/grammars/common.g
+++ b/lark/grammars/common.g
@@ -20,6 +20,7 @@ SIGNED_NUMBER: ["+"|"-"] NUMBER
 //
 // Strings
 //
+//STRING: /"(\\\"|\\\\|[^"\n])*?"i?/
 STRING_INNER: ("\\\""|/[^"]/)
 ESCAPED_STRING: "\"" STRING_INNER* "\""
 
diff --git a/lark/load_grammar.py b/lark/load_grammar.py
index 43d1bf5..13aeff0 100644
--- a/lark/load_grammar.py
+++ b/lark/load_grammar.py
@@ -122,7 +122,7 @@ RULES = {
     'statement': ['ignore', 'import'],
     'ignore': ['_IGNORE expansions _NL'],
     'import': ['_IMPORT import_args _NL',
-               '_IMPORT import_args _TO TOKEN'],
+               '_IMPORT import_args _TO TOKEN _NL'],
     'import_args': ['_import_args'],
     '_import_args': ['name', '_import_args _DOT name'],
 
@@ -375,6 +375,7 @@ class TokenTreeToPattern(Transformer):
         return p
 
     def expansion(self, items):
+        assert items
         if len(items) == 1:
             return items[0]
         if len({i.flags for i in items}) > 1:
@@ -486,6 +487,11 @@ class Grammar:
 
         # Convert token-trees to strings/regexps
         transformer = PrepareLiterals() * TokenTreeToPattern()
+        for name, (token_tree, priority) in token_defs:
+            for t in token_tree.find_data('expansion'):
+                if not t.children:
+                    raise GrammarError("Tokens cannot be empty (%s)" % name)
+
         tokens = [TokenDef(name, transformer.transform(token_tree), priority)
                   for name, (token_tree, priority) in token_defs]
 
diff --git a/tox.ini b/tox.ini
new file mode 100644
index 0000000..2c92629
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,24 @@
+[tox]
+envlist = py27, py34, py35, py36, pypy, pypy3
+skip_missing_interpreters=true
+
+[travis]
+2.7 = py27
+3.4 = py34
+3.5 = py35
+3.6 = py36
+pypy = pypy
+pypy3 = pypy3
+
+[testenv]
+whitelist_externals = git
+deps =
+    -rnearley-requirements.txt
+
+# to always force recreation and avoid unexpected side effects
+recreate=True
+
+commands=
+    git submodule sync -q
+    git submodule update --init
+    python -m tests
\ No newline at end of file