1 ##############################################################################
2 #
3 # Copyright (c) 2001 Zope Corporation and Contributors. All Rights Reserved.
4 #
5 # This software is subject to the provisions of the Zope Public License,
6 # Version 2.0 (ZPL). A copy of the ZPL should accompany this distribution.
7 # THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
8 # WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
9 # WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
10 # FOR A PARTICULAR PURPOSE
11 #
12 ##############################################################################
14 """Generic Python Expression Handler
16 Modified for Roundup 0.5 release:
18 - more informative traceback info
20 """
21 __docformat__ = 'restructuredtext'
23 __version__='$Revision: 1.5 $'[11:-2]
25 from TALES import CompilerError
26 from string import strip, split, join, replace, lstrip
27 from sys import exc_info
29 class getSecurityManager:
30 '''Null security manager'''
31 def validate(self, *args, **kwargs):
32 return 1
33 addContext = removeContext = validateValue = validate
35 class PythonExpr:
36 def __init__(self, name, expr, engine):
37 self.expr = expr = replace(strip(expr), '\n', ' ')
38 try:
39 d = {}
40 exec 'def f():\n return %s\n' % strip(expr) in d
41 self._f = d['f']
42 except:
43 raise CompilerError, ('Python expression error:\n'
44 '%s: %s') % exc_info()[:2]
45 self._get_used_names()
47 def _get_used_names(self):
48 self._f_varnames = vnames = []
49 for vname in self._f.func_code.co_names:
50 if vname[0] not in '$_':
51 vnames.append(vname)
53 def _bind_used_names(self, econtext):
54 # Bind template variables
55 names = {}
56 vars = econtext.vars
57 getType = econtext.getCompiler().getTypes().get
58 for vname in self._f_varnames:
59 has, val = vars.has_get(vname)
60 if not has:
61 has = val = getType(vname)
62 if has:
63 val = ExprTypeProxy(vname, val, econtext)
64 if has:
65 names[vname] = val
66 return names
68 def __call__(self, econtext):
69 __traceback_info__ = 'python expression "%s"'%self.expr
70 f = self._f
71 f.func_globals.update(self._bind_used_names(econtext))
72 return f()
74 def __str__(self):
75 return 'Python expression "%s"' % self.expr
76 def __repr__(self):
77 return '<PythonExpr %s>' % self.expr
79 class ExprTypeProxy:
80 '''Class that proxies access to an expression type handler'''
81 def __init__(self, name, handler, econtext):
82 self._name = name
83 self._handler = handler
84 self._econtext = econtext
85 def __call__(self, text):
86 return self._handler(self._name, text,
87 self._econtext.getCompiler())(self._econtext)