Removed some of the Python2 compatibility code

lark/exceptions.py

@@ -1,6 +1,6 @@
 from warnings import warn
 
-from .utils import STRING_TYPE, logger, NO_VALUE
+from .utils import logger, NO_VALUE
 
 
 ###{standalone
@@ -90,7 +90,7 @@ class UnexpectedInput(LarkError):
 
         candidate = (None, False)
         for i, (label, example) in enumerate(examples):
-            assert not isinstance(example, STRING_TYPE)
+            assert not isinstance(example, str), "Expecting a list"
 
             for j, malformed in enumerate(example):
                 try:

lark/lark.py

@@ -1,14 +1,13 @@
 from __future__ import absolute_import
 
-
-from lark.exceptions import ConfigurationError, assert_config
-
+from abc import ABC, abstractmethod
 import sys, os, pickle, hashlib
 from io import open
 import tempfile
 from warnings import warn
 
-from .utils import STRING_TYPE, Serialize, SerializeMemoizer, FS, isascii, logger, ABC, abstractmethod
+from .exceptions import ConfigurationError, assert_config
+from .utils import Serialize, SerializeMemoizer, FS, isascii, logger
 from .load_grammar import load_grammar, FromPackageLoader, Grammar, verify_used_files
 from .tree import Tree
 from .common import LexerConf, ParserConf
@@ -153,7 +152,7 @@ class LarkOptions(Serialize):
 
             options[name] = value
 
-        if isinstance(options['start'], STRING_TYPE):
+        if isinstance(options['start'], str):
             options['start'] = [options['start']]
 
         self.__dict__['options'] = options
@@ -247,14 +246,11 @@ class Lark(Serialize):
 
         cache_fn = None
         cache_md5 = None
-        if isinstance(grammar, STRING_TYPE):
+        if isinstance(grammar, str):
             self.source_grammar = grammar
             if self.options.use_bytes:
                 if not isascii(grammar):
                     raise ConfigurationError("Grammar must be ascii only, when use_bytes=True")
-                if sys.version_info[0] == 2 and self.options.use_bytes != 'force':
-                    raise ConfigurationError("`use_bytes=True` may have issues on python2."
-                                              "Use `use_bytes='force'` to use it at your own risk.")
 
             if self.options.cache:
                 if self.options.parser != 'lalr':
@@ -266,7 +262,7 @@ class Lark(Serialize):
                 s = grammar + options_str + __version__ + str(sys.version_info[:2])
                 cache_md5 = hashlib.md5(s.encode('utf8')).hexdigest()
 
-                if isinstance(self.options.cache, STRING_TYPE):
+                if isinstance(self.options.cache, str):
                     cache_fn = self.options.cache
                 else:
                     if self.options.cache is not True:

lark/lexer.py

@@ -1,8 +1,9 @@
 # Lexer Implementation
 
 import re
+from contextlib import suppress
 
-from .utils import Str, classify, get_regexp_width, Py36, Serialize, suppress
+from .utils import classify, get_regexp_width, Py36, Serialize
 from .exceptions import UnexpectedCharacters, LexError, UnexpectedToken
 
 ###{standalone
@@ -110,7 +111,7 @@ class TerminalDef(Serialize):
             return self.name
 
 
-class Token(Str):
+class Token(str):
     """A string with meta-information, that is produced by the lexer.
 
     When parsing text, the resulting chunks of the input that haven't been discarded,
@@ -177,9 +178,9 @@ class Token(Str):
         if isinstance(other, Token) and self.type != other.type:
             return False
 
-        return Str.__eq__(self, other)
+        return str.__eq__(self, other)
 
-    __hash__ = Str.__hash__
+    __hash__ = str.__hash__
 
 
 class LineCounter:

lark/load_grammar.py

@@ -8,6 +8,7 @@ from io import open
 import pkgutil
 from ast import literal_eval
 from numbers import Integral
+from contextlib import suppress
 
 from .utils import bfs, Py36, logger, classify_bool, is_id_continue, is_id_start, bfs_all_unique
 from .lexer import Token, TerminalDef, PatternStr, PatternRE
@@ -16,7 +17,7 @@ from .parse_tree_builder import ParseTreeBuilder
 from .parser_frontends import ParsingFrontend
 from .common import LexerConf, ParserConf
 from .grammar import RuleOptions, Rule, Terminal, NonTerminal, Symbol
-from .utils import classify, suppress, dedup_list, Str
+from .utils import classify, dedup_list
 from .exceptions import GrammarError, UnexpectedCharacters, UnexpectedToken, ParseError
 
 from .tree import Tree, SlottedTree as ST
@@ -539,9 +540,9 @@ class PrepareSymbols(Transformer_InPlace):
         if isinstance(v, Tree):
             return v
         elif v.type == 'RULE':
-            return NonTerminal(Str(v.value))
+            return NonTerminal(str(v.value))
         elif v.type == 'TERMINAL':
-            return Terminal(Str(v.value), filter_out=v.startswith('_'))
+            return Terminal(str(v.value), filter_out=v.startswith('_'))
         assert False
 
 

lark/tools/standalone.py

@@ -27,6 +27,7 @@ from __future__ import print_function
 #
 
 from io import open
+from abc import ABC, abstractmethod
 ###}
 
 import sys

lark/utils.py

@@ -1,4 +1,3 @@
-import hashlib
 import unicodedata
 import os
 from functools import reduce
@@ -14,14 +13,6 @@ logger.addHandler(logging.StreamHandler())
 # By default, we should not output any log messages
 logger.setLevel(logging.CRITICAL)
 
-if sys.version_info[0]>2:
-    from abc import ABC, abstractmethod
-else:
-    from abc import ABCMeta, abstractmethod
-    class ABC(object): # Provide Python27 compatibility
-        __slots__ = ()
-        __metclass__ = ABCMeta
-
 
 Py36 = (sys.version_info[:2] >= (3, 6))
 
@@ -120,28 +111,16 @@ class SerializeMemoizer(Serialize):
         return _deserialize(data, namespace, memo)
 
 
-try:
-    STRING_TYPE = basestring
-except NameError:   # Python 3
-    STRING_TYPE = str
-
 
 import types
 from functools import wraps, partial
-from contextlib import contextmanager
-
-Str = type(u'')
-try:
-    classtype = types.ClassType  # Python2
-except AttributeError:
-    classtype = type    # Python3
 
 
 def smart_decorator(f, create_decorator):
     if isinstance(f, types.FunctionType):
         return wraps(f)(create_decorator(f, True))
 
-    elif isinstance(f, (classtype, type, types.BuiltinFunctionType)):
+    elif isinstance(f, (type, types.BuiltinFunctionType)):
         return wraps(f)(create_decorator(f, False))
 
     elif isinstance(f, types.MethodType):
@@ -222,34 +201,12 @@ def dedup_list(l):
     return [x for x in l if not (x in dedup or dedup.add(x))]
 
 
-try:
-    from contextlib import suppress     # Python 3
-except ImportError:
-    @contextmanager
-    def suppress(*excs):
-        '''Catch and dismiss the provided exception
-
-        >>> x = 'hello'
-        >>> with suppress(IndexError):
-        ...     x = x[10]
-        >>> x
-        'hello'
-        '''
-        try:
-            yield
-        except excs:
-            pass
-
-
-try:
-    compare = cmp
-except NameError:
-    def compare(a, b):
-        if a == b:
-            return 0
-        elif a > b:
-            return 1
-        return -1
+def compare(a, b):
+    if a == b:
+        return 0
+    elif a > b:
+        return 1
+    return -1
 
 
 class Enumerator(Serialize):