selinux-policy/refpolicy/support/pyplate.py

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2005-06-07 18:23:00 +00:00
"""PyPlate : a simple Python-based templating program
PyPlate parses a file and replaces directives (in double square brackets [[ ... ]])
by various means using a given dictionary of variables. Arbitrary Python code
can be run inside many of the directives, making this system highly flexible.
Usage:
# Load and parse template file
template = pyplate.Template("output") (filename or string)
# Execute it with a dictionary of variables
template.execute_file(output_stream, locals())
PyPlate defines the following directives:
[[...]] evaluate the arbitrary Python expression and insert the
result into the output
[[# ... #]] comment.
[[exec ...]] execute arbitrary Python code in the sandbox namespace
[[if ...]] conditional expressions with usual Python semantics
[[elif ...]]
[[else]]
[[end]]
[[for ... in ...]] for-loop with usual Python semantics
[[end]]
[[def ...(...)]] define a "function" out of other templating elements
[[end]]
[[call ...]] call a templating function (not a regular Python function)
"""
#
# Copyright (C) 2002 Michael Droettboom
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#
from __future__ import nested_scopes
import sys, string, re, cStringIO
re_directive = re.compile("\[\[(.*)\]\]")
re_for_loop = re.compile("for (.*) in (.*)")
re_if = re.compile("if (.*)")
re_elif = re.compile("elif (.*)")
re_def = re.compile("def (.*?)\((.*)\)")
re_call = re.compile("call (.*?)\((.*)\)")
re_exec = re.compile("exec (.*)")
re_comment = re.compile("#(.*)#")
############################################################
# Template parser
class ParserException(Exception):
def __init__(self, lineno, s):
Exception.__init__(self, "line %d: %s" % (lineno, s))
class Template:
def __init__(self, filename=None):
if filename != None:
try:
self.parse_file(filename)
except:
self.parse_string(filename)
def parse_file(self, filename):
file = open(filename, 'r')
self.parse(file)
file.close()
def parse_string(self, template):
file = cStringIO.StringIO(template)
self.parse(file)
file.close()
def parse(self, file):
self.file = file
self.line = self.file.read()
self.lineno = 0
self.functions = {}
self.tree = TopLevelTemplateNode(self)
def parser_get(self):
if self.line == '':
return None
return self.line
def parser_eat(self, chars):
self.lineno = self.lineno + self.line[:chars].count("\n")
self.line = self.line[chars:]
def parser_exception(self, s):
raise ParserException(self.lineno, s)
def execute_file(self, filename, data):
file = open(filename, 'w')
self.execute(file, data)
file.close()
def execute_string(self, data):
s = cStringIO.StringIO()
self.execute(s, data)
return s.getvalue()
def execute_stdout(self, data):
self.execute(sys.stdout, data)
def execute(self, stream=sys.stdout, data={}):
self.tree.execute(stream, data)
def __repr__(self):
return repr(self.tree)
############################################################
# NODES
class TemplateNode:
def __init__(self, parent, s):
self.parent = parent
self.s = s
self.node_list = []
while 1:
new_node = TemplateNodeFactory(parent)
if self.add_node(new_node):
break
def add_node(self, node):
if node == 'end':
return 1
elif node != None:
self.node_list.append(node)
else:
raise self.parent.parser_exception(
"[[%s]] does not have a matching [[end]]" % self.s)
def execute(self, stream, data):
for node in self.node_list:
node.execute(stream, data)
def __repr__(self):
r = "<" + self.__class__.__name__ + " "
for i in self.node_list:
r = r + repr(i)
r = r + ">"
return r
class TopLevelTemplateNode(TemplateNode):
def __init__(self, parent):
TemplateNode.__init__(self, parent, '')
def add_node(self, node):
if node != None:
self.node_list.append(node)
else:
return 1
class ForTemplateNode(TemplateNode):
def __init__(self, parent, s):
TemplateNode.__init__(self, parent, s)
match = re_for_loop.match(s)
if match == None:
raise self.parent.parser_exception(
"[[%s]] is not a valid for-loop expression" % self.s)
else:
self.vars_temp = match.group(1).split(",")
self.vars = []
for v in self.vars_temp:
self.vars.append(v.strip())
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#print self.vars
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self.expression = match.group(2)
def execute(self, stream, data):
remember_vars = {}
for var in self.vars:
if data.has_key(var):
remember_vars[var] = data[var]
for list in eval(self.expression, globals(), data):
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if is_sequence(list):
for index, value in enumerate(list):
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data[self.vars[index]] = value
else:
data[self.vars[0]] = list
TemplateNode.execute(self, stream, data)
for key, value in remember_vars.items():
data[key] = value
class IfTemplateNode(TemplateNode):
def __init__(self, parent, s):
self.else_node = None
TemplateNode.__init__(self, parent, s)
match = re_if.match(s)
if match == None:
raise self.parent.parser_exception(
"[[%s]] is not a valid if expression" % self.s)
else:
self.expression = match.group(1)
def add_node(self, node):
if node == 'end':
return 1
elif isinstance(node, ElseTemplateNode):
self.else_node = node
return 1
elif isinstance(node, ElifTemplateNode):
self.else_node = node
return 1
elif node != None:
self.node_list.append(node)
else:
raise self.parent.parser_exception(
"[[%s]] does not have a matching [[end]]" % self.s)
def execute(self, stream, data):
if eval(self.expression, globals(), data):
TemplateNode.execute(self, stream, data)
elif self.else_node != None:
self.else_node.execute(stream, data)
class ElifTemplateNode(IfTemplateNode):
def __init__(self, parent, s):
self.else_node = None
TemplateNode.__init__(self, parent, s)
match = re_elif.match(s)
if match == None:
self.parent.parser_exception(
"[[%s]] is not a valid elif expression" % self.s)
else:
self.expression = match.group(1)
class ElseTemplateNode(TemplateNode):
pass
class FunctionTemplateNode(TemplateNode):
def __init__(self, parent, s):
TemplateNode.__init__(self, parent, s)
match = re_def.match(s)
if match == None:
self.parent.parser_exception(
"[[%s]] is not a valid function definition" % self.s)
self.function_name = match.group(1)
self.vars_temp = match.group(2).split(",")
self.vars = []
for v in self.vars_temp:
self.vars.append(v.strip())
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#print self.vars
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self.parent.functions[self.function_name] = self
def execute(self, stream, data):
pass
def call(self, args, stream, data):
remember_vars = {}
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for index, var in enumerate(self.vars):
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if data.has_key(var):
remember_vars[var] = data[var]
data[var] = args[index]
TemplateNode.execute(self, stream, data)
for key, value in remember_vars.items():
data[key] = value
class LeafTemplateNode(TemplateNode):
def __init__(self, parent, s):
self.parent = parent
self.s = s
def execute(self, stream, data):
stream.write(self.s)
def __repr__(self):
return "<" + self.__class__.__name__ + ">"
class CommentTemplateNode(LeafTemplateNode):
def execute(self, stream, data):
pass
class ExpressionTemplateNode(LeafTemplateNode):
def execute(self, stream, data):
stream.write(str(eval(self.s, globals(), data)))
class ExecTemplateNode(LeafTemplateNode):
def __init__(self, parent, s):
LeafTemplateNode.__init__(self, parent, s)
match = re_exec.match(s)
if match == None:
self.parent.parser_exception(
"[[%s]] is not a valid statement" % self.s)
self.s = match.group(1)
def execute(self, stream, data):
exec(self.s, globals(), data)
pass
class CallTemplateNode(LeafTemplateNode):
def __init__(self, parent, s):
LeafTemplateNode.__init__(self, parent, s)
match = re_call.match(s)
if match == None:
self.parent.parser_exception(
"[[%s]] is not a valid function call" % self.s)
self.function_name = match.group(1)
self.vars = "(" + match.group(2).strip() + ",)"
def execute(self, stream, data):
self.parent.functions[self.function_name].call(
eval(self.vars, globals(), data), stream, data)
############################################################
# Node factory
template_factory_type_map = {
'if' : IfTemplateNode,
'for' : ForTemplateNode,
'elif' : ElifTemplateNode,
'else' : ElseTemplateNode,
'def' : FunctionTemplateNode,
'call' : CallTemplateNode,
'exec' : ExecTemplateNode }
template_factory_types = template_factory_type_map.keys()
def TemplateNodeFactory(parent):
src = parent.parser_get()
if src == None:
return None
match = re_directive.search(src)
if match == None:
parent.parser_eat(len(src))
return LeafTemplateNode(parent, src)
elif src == '' or match.start() != 0:
parent.parser_eat(match.start())
return LeafTemplateNode(parent, src[:match.start()])
else:
directive = match.group()[2:-2].strip()
parent.parser_eat(match.end())
if directive == 'end':
return 'end'
elif re_comment.match(directive):
return CommentTemplateNode(parent, directive)
else:
for i in template_factory_types:
if directive[0:len(i)] == i:
return template_factory_type_map[i](parent, directive)
return ExpressionTemplateNode(parent, directive)
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def is_sequence(object):
try:
test = object[0:0]
except:
return False
else:
return True