Refactor the parser code

Author: zeroSteiner

lib/rule_engine/ast.py

@@ -38,7 +38,7 @@
 import re
 
 from . import errors
-from ._utils import parse_datetime, parse_float, parse_timedelta
+from .parser.utilities import parse_datetime, parse_float, parse_timedelta
 from .suggestions import suggest_symbol
 from .types import *
 

lib/rule_engine/builtins.py

@@ -38,10 +38,10 @@
 import math
 import random
 
-from ._utils import parse_datetime, parse_float, parse_timedelta
 from . import ast
 from . import errors
 from . import types
+from .parser.utilities import parse_datetime, parse_float, parse_timedelta
 
 import dateutil.tz
 

lib/rule_engine/parser.py renamed to lib/rule_engine/parser/__init__.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 #
-#  rule_engine/parser.py
+#  rule_engine/parser/__init__.py
 #
 #  Redistribution and use in source and binary forms, with or without
 #  modification, are permitted provided that the following conditions are
@@ -32,15 +32,12 @@
 
 import ast as pyast
 import collections
-import threading
 import types as pytypes
 
-from . import ast
-from . import errors
-from ._utils import timedelta_regex
-
-import ply.lex as lex
-import ply.yacc as yacc
+from .. import ast
+from .. import errors
+from .base import ParserBase
+from .utilities import timedelta_regex
 
 literal_eval = pyast.literal_eval
 
@@ -58,52 +55,6 @@ def build(self):
 		constructor = getattr(self.cls, self.method)
 		return constructor(*self.args, **self.kwargs)
 
-class ParserBase(object):
-	"""
-	A base class for parser objects to inherit from. This does not provide any
-	grammar related definitions.
-	"""
-	precedence = ()
-	"""The precedence for operators."""
-	tokens = ()
-	reserved_words = {}
-	"""
-	A mapping of literal words which are reserved to their corresponding grammar
-	names.
-	"""
-	__mutex = threading.Lock()
-	def __init__(self, debug=False):
-		"""
-		:param bool debug: Whether or not to enable debugging features when
-			using the ply API.
-		"""
-		self.debug = debug
-		self.context = None
-		# Build the lexer and parser
-		self._lexer = lex.lex(module=self, debug=self.debug)
-		self._parser = yacc.yacc(module=self, debug=self.debug, write_tables=self.debug)
-
-	def parse(self, text, context, **kwargs):
-		"""
-		Parse the specified text in an abstract syntax tree of nodes that can later be evaluated. This is done in two
-		phases. First, the syntax is parsed and a tree of deferred / uninitialized AST nodes are constructed. Next each
-		node is built recursively using it's respective :py:meth:`rule_engine.ast.ASTNodeBase.build`.
-
-		:param str text: The grammar text to parse into an AST.
-		:param context: A context for specifying parsing and evaluation options.
-		:type context: :py:class:`~rule_engine.engine.Context`
-		:return: The parsed AST statement.
-		:rtype: :py:class:`~rule_engine.ast.Statement`
-		"""
-		kwargs['lexer'] = kwargs.pop('lexer', self._lexer)
-		with self.__mutex:
-			self.context = context
-			# phase 1: parse the string into a tree of deferred nodes
-			result = self._parser.parse(text, **kwargs)
-			self.context = None
-		# phase 2: initialize each AST node recursively, providing them with an opportunity to define assignments
-		return result.build()
-
 class Parser(ParserBase):
 	"""
 	The parser class for the rule grammar. This class contains many ply specific

lib/rule_engine/parser/base.py

@@ -0,0 +1,82 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#
+#  rule_engine/parser/base.py
+#
+#  Redistribution and use in source and binary forms, with or without
+#  modification, are permitted provided that the following conditions are
+#  met:
+#
+#  * Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+#  * Redistributions in binary form must reproduce the above
+#    copyright notice, this list of conditions and the following disclaimer
+#    in the documentation and/or other materials provided with the
+#    distribution.
+#  * Neither the name of the project nor the names of its
+#    contributors may be used to endorse or promote products derived from
+#    this software without specific prior written permission.
+#
+#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+#  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+#  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+#  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+#  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+#  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+#  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+#  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+#  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+#  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+#  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+
+import threading
+
+import ply.lex as lex
+import ply.yacc as yacc
+
+class ParserBase(object):
+	"""
+	A base class for parser objects to inherit from. This does not provide any
+	grammar related definitions.
+	"""
+	precedence = ()
+	"""The precedence for operators."""
+	tokens = ()
+	reserved_words = {}
+	"""
+	A mapping of literal words which are reserved to their corresponding grammar
+	names.
+	"""
+	__mutex = threading.Lock()
+	def __init__(self, debug=False):
+		"""
+		:param bool debug: Whether or not to enable debugging features when
+			using the ply API.
+		"""
+		self.debug = debug
+		self.context = None
+		# Build the lexer and parser
+		self._lexer = lex.lex(module=self, debug=self.debug)
+		self._parser = yacc.yacc(module=self, debug=self.debug, write_tables=self.debug)
+
+	def parse(self, text, context, **kwargs):
+		"""
+		Parse the specified text in an abstract syntax tree of nodes that can later be evaluated. This is done in two
+		phases. First, the syntax is parsed and a tree of deferred / uninitialized AST nodes are constructed. Next each
+		node is built recursively using it's respective :py:meth:`rule_engine.ast.ASTNodeBase.build`.
+
+		:param str text: The grammar text to parse into an AST.
+		:param context: A context for specifying parsing and evaluation options.
+		:type context: :py:class:`~rule_engine.engine.Context`
+		:return: The parsed AST statement.
+		:rtype: :py:class:`~rule_engine.ast.Statement`
+		"""
+		kwargs['lexer'] = kwargs.pop('lexer', self._lexer)
+		with self.__mutex:
+			self.context = context
+			# phase 1: parse the string into a tree of deferred nodes
+			result = self._parser.parse(text, **kwargs)
+			self.context = None
+		# phase 2: initialize each AST node recursively, providing them with an opportunity to define assignments
+		return result.build()