Moving code to satellite.

1 files changed, 77 insertions, 0 deletions

diff --git a/src/zope/tales/pythonexpr.py b/src/zope/tales/pythonexpr.py
new file mode 100644
index 0000000..7fab3bb
--- /dev/null
+++ b/src/zope/tales/pythonexpr.py
@@ -0,0 +1,77 @@
+##############################################################################
+#
+# Copyright (c) 2001, 2002 Zope Corporation and Contributors.
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+##############################################################################
+"""Generic Python Expression Handler
+
+$Id$
+"""
+
+class PythonExpr(object):
+    def __init__(self, name, expr, engine):
+        text = '\n'.join(expr.splitlines()) # normalize line endings
+        text = '(' + text + ')' # Put text in parens so newlines don't matter
+        self.text = text
+        try:
+            code = self._compile(text, '<string>')
+        except SyntaxError, e:
+            raise engine.getCompilerError()(str(e))
+        self._code = code
+        self._varnames = code.co_names
+
+    def _compile(self, text, filename):
+        return compile(text, filename, 'eval')
+
+    def _bind_used_names(self, econtext, builtins):
+        # Construct a dictionary of globals with which the Python
+        # expression should be evaluated.
+        names = {}
+        vars = econtext.vars
+        marker = self
+        if not isinstance(builtins, dict):
+            builtins = builtins.__dict__
+        for vname in self._varnames:
+            val = vars.get(vname, marker)
+            if val is not marker:
+                names[vname] = val
+            elif vname not in builtins:
+                # Fall back to using expression types as variable values.
+                val = econtext._engine.getTypes().get(vname, marker)
+                if val is not marker:
+                    val = ExprTypeProxy(vname, val, econtext)
+                    names[vname] = val
+
+        names['__builtins__'] = builtins
+        return names
+
+    def __call__(self, econtext):
+        __traceback_info__ = self.text
+        vars = self._bind_used_names(econtext, __builtins__)
+        return eval(self._code, vars)
+
+    def __str__(self):
+        return 'Python expression "%s"' % self.text
+
+    def __repr__(self):
+        return '<PythonExpr %s>' % self.text
+
+
+class ExprTypeProxy(object):
+    '''Class that proxies access to an expression type handler'''
+    def __init__(self, name, handler, econtext):
+        self._name = name
+        self._handler = handler
+        self._econtext = econtext
+
+    def __call__(self, text):
+        return self._handler(self._name, text,
+                             self._econtext._engine)(self._econtext)