Source Code for Module Products.ZenUtils.ZenTales

  1  ############################################################################## 
  2  #  
  3  # Copyright (C) Zenoss, Inc. 2007, all rights reserved. 
  4  #  
  5  # This content is made available according to terms specified in 
  6  # License.zenoss under the directory where your Zenoss product is installed. 
  7  #  
  8  ############################################################################## 
  9   
 10   
 11  import cgi 
 12  import re 
 13  import cStringIO 
 14  from Products.PageTemplates.Expressions import getEngine 
 15  from zope.tal.htmltalparser import HTMLTALParser 
 16  from zope.tal.talgenerator import TALGenerator 
 17  from zope.tales.engine import Engine 
 18  from zope.tal.talinterpreter import TALInterpreter 
 19  from DateTime import DateTime 
 20   
 21 -class InvalidTalesException(Exception): 
 22      pass 
 23   
 24   
 25  _compiled = {} 
 26   
 27 -def talesEvalStr(expression, context, extra=None): 
 28      return talesEval('string:%s' % expression, context, extra) 
 29   
 30   
 31 -def talesEval(express, context, extra=None): 
 32      """Perform a TALES eval on the express using context. 
 33      """ 
 34      compiled = talesCompile(express) 
 35      contextDict = { 'context':context, 
 36                      'here':context, 
 37                      'nothing':None, 
 38                      'now': DateTime(), 
 39                      } 
 40      if isinstance(extra, dict): 
 41          contextDict.update(extra) 
 42      try: 
 43          res = compiled(getEngine().getContext(contextDict)) 
 44      except Exception, e: 
 45          msg = "Error when processing tales expression %s on context %s : Exception Class %s Message: %s" % (express, 
 46                                                                                                              context, 
 47                                                                                                              type(e), e) 
 48          raise InvalidTalesException(msg) 
 49      if isinstance(res, Exception): 
 50          raise res 
 51      return res 
 52   
 53 -def talesCompile(express): 
 54      compiled = _compiled.get(express, None) 
 55      if not compiled: 
 56          _compiled[express] = compiled = getEngine().compile(express) 
 57      return compiled 
 58   
 59  TAG = re.compile(r'(<tal[^<>]>)') 
 60  TPLBLOCK = re.compile(r'\$\{(.*?)\}') 
 61   
 62 -def _chunk_repl(match): 
 63      """ 
 64      Need this to escape quotes and <> in expressions 
 65      """ 
 66      interior = cgi.escape(match.groups()[0], True) 
 67      return '<tal:block content="%s"/>' % interior 
 68   
 69 -def talEval(expression, context, extra=None): 
 70      """ 
 71      Perform a TAL eval on the expression. 
 72      """ 
 73      # First, account for the possibility that it is merely TALES; if there are 
 74      # no <tal> in it at all (nor the ${python:} you can do with this function), 
 75      # just send it to talesEval 
 76      isTales = '<tal' not in expression and '${python:' not in expression 
 77      if isTales: 
 78          return talesEvalStr(expression, context, extra) 
 79   
 80      # Next, as a convenience, replace all ${} blocks that aren't inside a <tal> 
 81      # with <tal:block content="..."/> equivalent 
 82      chunks = TAG.split(expression) 
 83      modified = [] 
 84      for chunk in chunks: 
 85          if chunk.startswith('<tal'): 
 86              modified.append(chunk) 
 87          else: 
 88              modified.append(TPLBLOCK.sub(_chunk_repl, chunk)) 
 89      expression = ''.join(modified) 
 90   
 91      # Finally, compile the expression and apply context 
 92      gen = TALGenerator(Engine, xml=0) 
 93      parser = HTMLTALParser(gen) 
 94      parser.parseString(expression) 
 95      program, macros = parser.getCode() 
 96      output = cStringIO.StringIO() 
 97      context = Engine.getContext(context) 
 98      TALInterpreter(program, macros, context, output, tal=True)() 
 99      return output.getvalue() 
100