##############################################################################
#
# Copyright (c) 2001 Zope Corporation and Contributors. All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.0 (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
#
##############################################################################
"""TALES
An implementation of a generic TALES engine
"""
__version__='$Revision: 1.31.6.7 $'[11:-2]
import re, sys, ZTUtils
from MultiMapping import MultiMapping
from DocumentTemplate.DT_Util import ustr
from GlobalTranslationService import getGlobalTranslationService
StringType = type('')
NAME_RE = r"[a-zA-Z][a-zA-Z0-9_]*"
_parse_expr = re.compile(r"(%s):" % NAME_RE).match
_valid_name = re.compile('%s$' % NAME_RE).match
class TALESError(Exception):
"""Error during TALES expression evaluation"""
class Undefined(TALESError):
'''Exception raised on traversal of an undefined path'''
class RegistrationError(Exception):
'''TALES Type Registration Error'''
class CompilerError(Exception):
'''TALES Compiler Error'''
class Default:
'''Retain Default'''
Default = Default()
class SafeMapping(MultiMapping):
'''Mapping with security declarations and limited method exposure.
Since it subclasses MultiMapping, this class can be used to wrap
one or more mapping objects. Restricted Python code will not be
able to mutate the SafeMapping or the wrapped mappings, but will be
able to read any value.
'''
__allow_access_to_unprotected_subobjects__ = 1
push = pop = None
_push = MultiMapping.push
_pop = MultiMapping.pop
class Iterator(ZTUtils.Iterator):
def __init__(self, name, seq, context):
ZTUtils.Iterator.__init__(self, seq)
self.name = name
self._context = context
def next(self):
if ZTUtils.Iterator.next(self):
self._context.setLocal(self.name, self.item)
return 1
return 0
class ErrorInfo:
"""Information about an exception passed to an on-error handler."""
__allow_access_to_unprotected_subobjects__ = 1
def __init__(self, err, position=(None, None)):
if isinstance(err, Exception):
self.type = err.__class__
self.value = err
else:
self.type = err
self.value = None
self.lineno = position[0]
self.offset = position[1]
class Engine:
'''Expression Engine
An instance of this class keeps a mutable collection of expression
type handlers. It can compile expression strings by delegating to
these handlers. It can provide an expression Context, which is
capable of holding state and evaluating compiled expressions.
'''
Iterator = Iterator
def __init__(self, Iterator=None):
self.types = {}
if Iterator is not None:
self.Iterator = Iterator
def registerType(self, name, handler):
if not _valid_name(name):
raise RegistrationError, 'Invalid Expression type "%s".' % name
types = self.types
if types.has_key(name):
raise RegistrationError, (
'Multiple registrations for Expression type "%s".' %
name)
types[name] = handler
def getTypes(self):
return self.types
def compile(self, expression):
m = _parse_expr(expression)
if m:
type = m.group(1)
expr = expression[m.end():]
else:
type = "standard"
expr = expression
try:
handler = self.types[type]
except KeyError:
raise CompilerError, (
'Unrecognized expression type "%s".' % type)
return handler(type, expr, self)
def getContext(self, contexts=None, **kwcontexts):
if contexts is not None:
if kwcontexts:
kwcontexts.update(contexts)
else:
kwcontexts = contexts
return Context(self, kwcontexts)
def getCompilerError(self):
return CompilerError
class Context:
'''Expression Context
An instance of this class holds context information that it can
use to evaluate compiled expressions.
'''
_context_class = SafeMapping
position = (None, None)
source_file = None
def __init__(self, compiler, contexts):
self._compiler = compiler
self.contexts = contexts
contexts['nothing'] = None
contexts['default'] = Default
self.repeat_vars = rv = {}
# Wrap this, as it is visible to restricted code
contexts['repeat'] = rep = self._context_class(rv)
contexts['loop'] = rep # alias
self.global_vars = gv = contexts.copy()
self.local_vars = lv = {}
self.vars = self._context_class(gv, lv)
# Keep track of what needs to be popped as each scope ends.
self._scope_stack = []
def getCompiler(self):
return self._compiler
def beginScope(self):
self._scope_stack.append([self.local_vars.copy()])
def endScope(self):
scope = self._scope_stack.pop()
self.local_vars = lv = scope[0]
v = self.vars
v._pop()
v._push(lv)
# Pop repeat variables, if any
i = len(scope) - 1
while i:
name, value = scope[i]
if value is None:
del self.repeat_vars[name]
else:
self.repeat_vars[name] = value
i = i - 1
def setLocal(self, name, value):
self.local_vars[name] = value
def setGlobal(self, name, value):
self.global_vars[name] = value
def setRepeat(self, name, expr):
expr = self.evaluate(expr)
if not expr:
return self._compiler.Iterator(name, (), self)
it = self._compiler.Iterator(name, expr, self)
old_value = self.repeat_vars.get(name)
self._scope_stack[-1].append((name, old_value))
self.repeat_vars[name] = it
return it
def evaluate(self, expression,
isinstance=isinstance, StringType=StringType):
if isinstance(expression, StringType):
expression = self._compiler.compile(expression)
__traceback_supplement__ = (
TALESTracebackSupplement, self, expression)
return expression(self)
evaluateValue = evaluate
evaluateBoolean = evaluate
def evaluateText(self, expr):
text = self.evaluate(expr)
if text is Default or text is None:
return text
return ustr(text)
def evaluateStructure(self, expr):
return self.evaluate(expr)
evaluateStructure = evaluate
def evaluateMacro(self, expr):
# XXX Should return None or a macro definition
return self.evaluate(expr)
evaluateMacro = evaluate
def createErrorInfo(self, err, position):
return ErrorInfo(err, position)
def getDefault(self):
return Default
def setSourceFile(self, source_file):
self.source_file = source_file
def setPosition(self, position):
self.position = position
def translate(self, domain, msgid, mapping=None,
context=None, target_language=None):
if context is None:
context = self.contexts.get('here')
return getGlobalTranslationService().translate(
domain, msgid, mapping=mapping,
context=context, target_language=target_language)
class TALESTracebackSupplement:
"""Implementation of ITracebackSupplement"""
def __init__(self, context, expression):
self.context = context
self.source_url = context.source_file
self.line = context.position[0]
self.column = context.position[1]
self.expression = repr(expression)
def getInfo(self, as_html=0):
import pprint
data = self.context.contexts.copy()
s = pprint.pformat(data)
if not as_html:
return ' - Names:\n %s' % s.replace('\n', '\n ')
else:
from cgi import escape
return '<b>Names:</b><pre>%s</pre>' % (escape(s))
class SimpleExpr:
'''Simple example of an expression type handler'''
def __init__(self, name, expr, engine):
self._name = name
self._expr = expr
def __call__(self, econtext):
return self._name, self._expr
def __repr__(self):
return '<SimpleExpr %s %s>' % (self._name, `self._expr`)
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