""" simpleTALES Implementation Copyright (c) 2009 Colin Stewart (http://www.owlfish.com/) All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. The name of the author may not be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. If you make any bug fixes or feature enhancements please let me know! The classes in this module implement the TALES specification, used by the simpleTAL module. Module Dependencies: logging """ import types, sys import logging import simpletal __version__ = simpletal.__version__ DEFAULTVALUE = "This represents a Default value." class PathNotFoundException (Exception): pass class ContextContentException (Exception): """ This is raised when invalid content has been placed into the Context object. For example using non-ascii characters instead of Unicode strings. """ pass PATHNOTFOUNDEXCEPTION = PathNotFoundException() class ContextVariable (BaseException): def __init__ (self, value = None): self.ourValue = value def value (self, currentPath=None): if (hasattr (self.ourValue, "__call__")): return self.ourValue() return self.ourValue def rawValue (self): return self.ourValue def __str__ (self): return repr (self.ourValue) class RepeatVariable (ContextVariable): """ To be written""" def __init__ (self, sequence): ContextVariable.__init__ (self, 1) self.sequence = sequence self.position = 0 self.map = None def __getattr__(self, name): # to be used from python eval if (self.map is None): self.createMap() return self.map[name] def value (self, currentPath=None): if (self.map is None): self.createMap() return self.map def rawValue (self): return self.value() def getCurrentValue (self): return self.sequence [self.position] def increment (self): self.position += 1 if (self.position == len (self.sequence)): raise IndexError ("Repeat Finished") def createMap (self): self.map = {} self.map ['index'] = self.getIndex self.map ['number'] = self.getNumber self.map ['even'] = self.getEven self.map ['odd'] = self.getOdd self.map ['start'] = self.getStart self.map ['end'] = self.getEnd # TODO: first and last need to be implemented. self.map ['length'] = len (self.sequence) self.map ['letter'] = self.getLowerLetter self.map ['Letter'] = self.getUpperLetter self.map ['roman'] = self.getLowerRoman self.map ['Roman'] = self.getUpperRoman # Repeat implementation goes here def getIndex (self): return self.position def getNumber (self): return self.position + 1 def getEven (self): if ((self.position % 2) != 0): return 0 return 1 def getOdd (self): if ((self.position % 2) == 0): return 0 return 1 def getStart (self): if (self.position == 0): return 1 return 0 def getEnd (self): if (self.position == len (self.sequence) - 1): return 1 return 0 def getLowerLetter (self): result = "" nextCol = self.position if (nextCol == 0): return 'a' while (nextCol > 0): nextCol, thisCol = divmod (nextCol, 26) result = chr (ord ('a') + thisCol) + result return result def getUpperLetter (self): return self.getLowerLetter().upper() def getLowerRoman (self): romanNumeralList = (('m', 1000) ,('cm', 900) ,('d', 500) ,('cd', 400) ,('c', 100) ,('xc', 90) ,('l', 50) ,('xl', 40) ,('x', 10) ,('ix', 9) ,('v', 5) ,('iv', 4) ,('i', 1) ) if (self.position > 3999): # Roman numbers only supported up to 4000 return ' ' num = self.position + 1 result = "" for roman, integer in romanNumeralList: while (num >= integer): result += roman num -= integer return result def getUpperRoman (self): return self.getLowerRoman().upper() class IteratorRepeatVariable (RepeatVariable): def __init__ (self, sequence): RepeatVariable.__init__ (self, sequence) self.curValue = None self.iterStatus = 0 def getCurrentValue (self): if (self.iterStatus == 0): self.iterStatus = 1 try: self.curValue = next(self.sequence) except StopIteration as e: self.iterStatus = 2 raise IndexError ("Repeat Finished") return self.curValue def increment (self): # Need this for the repeat variable functions. self.position += 1 try: self.curValue = next(self.sequence) except StopIteration as e: self.iterStatus = 2 raise IndexError ("Repeat Finished") def createMap (self): self.map = {} self.map ['index'] = self.getIndex self.map ['number'] = self.getNumber self.map ['even'] = self.getEven self.map ['odd'] = self.getOdd self.map ['start'] = self.getStart self.map ['end'] = self.getEnd # TODO: first and last need to be implemented. self.map ['length'] = sys.maxsize self.map ['letter'] = self.getLowerLetter self.map ['Letter'] = self.getUpperLetter self.map ['roman'] = self.getLowerRoman self.map ['Roman'] = self.getUpperRoman def getEnd (self): if (self.iterStatus == 2): return 1 return 0 class PathFunctionVariable (ContextVariable): def __init__ (self, func): ContextVariable.__init__ (self, value = func) self.func = func def value (self, currentPath=None): if (currentPath is not None): index, paths = currentPath result = ContextVariable (self.func ('/'.join (paths[index:]))) # Fast track the result raise result class CachedFuncResult (ContextVariable): def value (self, currentPath=None): try: return self.cachedValue except: self.cachedValue = ContextVariable.value (self) return self.cachedValue def clearCache (self): try: del self.cachedValue except: pass class PythonPathFunctions: def __init__ (self, context): self.context = context def path (self, expr): return self.context.evaluatePath (expr) def string (self, expr): return self.context.evaluateString (expr) def exists (self, expr): return self.context.evaluateExists (expr) def nocall (self, expr): return self.context.evaluateNoCall (expr) def test (self, *arguments): if (len (arguments) % 2): # We have an odd number of arguments - which means the last one is a default pairs = arguments[:-1] defaultValue = arguments[-1] else: # No default - so use None pairs = arguments defaultValue = None index = 0 while (index < len (pairs)): test = pairs[index] index += 1 value = pairs[index] index += 1 if (test): return value return defaultValue class Context: def __init__ (self, options=None, allowPythonPath=0): self.allowPythonPath = allowPythonPath self.globals = {} self.locals = {} self.localStack = [] self.repeatStack = [] self.populateDefaultVariables (options) self.log = logging.getLogger ("simpleTALES.Context") self.true = 1 self.false = 0 self.pythonPathFuncs = PythonPathFunctions (self) def addRepeat (self, name, var, initialValue): # Pop the current repeat map onto the stack self.repeatStack.append (self.repeatMap) self.repeatMap = self.repeatMap.copy() self.repeatMap [name] = var # Map this repeatMap into the global space self.addGlobal ('repeat', self.repeatMap) # Add in the locals self.pushLocals() self.setLocal (name, initialValue) def removeRepeat (self, name): # Bring the old repeat map back self.repeatMap = self.repeatStack.pop() # Map this repeatMap into the global space self.addGlobal ('repeat', self.repeatMap) def addGlobal (self, name, value): self.globals[name] = value def pushLocals (self): # Push the current locals onto a stack so that we can safely over-ride them. self.localStack.append (self.locals) self.locals = self.locals.copy() def setLocal (self, name, value): # Override the current local if present with the new one self.locals [name] = value def popLocals (self): self.locals = self.localStack.pop() def evaluate (self, expr, originalAtts = None): # Returns a ContextVariable #self.log.debug ("Evaluating %s" % expr) if (originalAtts is not None): # Call from outside self.globals['attrs'] = originalAtts suppressException = 1 else: suppressException = 0 # Supports path, exists, nocall, not, and string expr = expr.strip () try: if expr.startswith ('path:'): return self.evaluatePath (expr[5:].lstrip ()) elif expr.startswith ('exists:'): return self.evaluateExists (expr[7:].lstrip()) elif expr.startswith ('nocall:'): return self.evaluateNoCall (expr[7:].lstrip()) elif expr.startswith ('not:'): return self.evaluateNot (expr[4:].lstrip()) elif expr.startswith ('string:'): return self.evaluateString (expr[7:].lstrip()) elif expr.startswith ('python:'): return self.evaluatePython (expr[7:].lstrip()) else: # Not specified - so it's a path return self.evaluatePath (expr) except PathNotFoundException as e: if (suppressException): return None raise e def evaluatePython (self, expr): if (not self.allowPythonPath): self.log.warning ("Parameter allowPythonPath is false. NOT Evaluating python expression %s" % expr) return self.false #self.log.debug ("Evaluating python expression %s" % expr) globals={} for name, value in list(self.globals.items()): if (isinstance (value, ContextVariable)): value = value.rawValue() globals [name] = value globals ['path'] = self.pythonPathFuncs.path globals ['string'] = self.pythonPathFuncs.string globals ['exists'] = self.pythonPathFuncs.exists globals ['nocall'] = self.pythonPathFuncs.nocall globals ['test'] = self.pythonPathFuncs.test locals={} for name, value in list(self.locals.items()): if (isinstance (value, ContextVariable)): value = value.rawValue() locals [name] = value try: result = eval(expr, globals, locals) if (isinstance (result, ContextVariable)): return result.value() return result except Exception as e: # An exception occured evaluating the template, return the exception as text self.log.warning ("Exception occurred evaluating python path, exception: " + str (e)) return "Exception: %s" % str (e) def evaluatePath (self, expr): #self.log.debug ("Evaluating path expression %s" % expr) allPaths = expr.split ('|') if (len (allPaths) > 1): for path in allPaths: # Evaluate this path try: return self.evaluate (path.strip ()) except PathNotFoundException as e: # Path didn't exist, try the next one pass # No paths evaluated - raise exception. raise PATHNOTFOUNDEXCEPTION else: # A single path - so let's evaluate it. # This *can* raise PathNotFoundException return self.traversePath (allPaths[0]) def evaluateExists (self, expr): #self.log.debug ("Evaluating %s to see if it exists" % expr) allPaths = expr.split ('|') # The first path is for us # Return true if this first bit evaluates, otherwise test the rest try: result = self.traversePath (allPaths[0], canCall = 0) return self.true except PathNotFoundException as e: # Look at the rest of the paths. pass for path in allPaths[1:]: # Evaluate this path try: pathResult = self.evaluate (path.strip ()) # If this is part of a "exists: path1 | exists: path2" path then we need to look at the actual result. if (pathResult): return self.true except PathNotFoundException as e: pass # If we get this far then there are *no* paths that exist. return self.false def evaluateNoCall (self, expr): #self.log.debug ("Evaluating %s using nocall" % expr) allPaths = expr.split ('|') # The first path is for us try: return self.traversePath (allPaths[0], canCall = 0) except PathNotFoundException as e: # Try the rest of the paths. pass for path in allPaths[1:]: # Evaluate this path try: return self.evaluate (path.strip ()) except PathNotFoundException as e: pass # No path evaluated - raise error raise PATHNOTFOUNDEXCEPTION def evaluateNot (self, expr): #self.log.debug ("Evaluating NOT value of %s" % expr) # Evaluate what I was passed try: pathResult = self.evaluate (expr) except PathNotFoundException as e: # In SimpleTAL the result of "not: no/such/path" should be TRUE not FALSE. return self.true if (pathResult is None): # Value was Nothing return self.true if (pathResult == DEFAULTVALUE): return self.false try: resultLen = len (pathResult) if (resultLen > 0): return self.false else: return self.true except: # Not a sequence object. pass if (not pathResult): return self.true # Everything else is true, so we return false! return self.false def evaluateString (self, expr): #self.log.debug ("Evaluating String %s" % expr) result = "" skipCount = 0 for position in range (0,len (expr)): if (skipCount > 0): skipCount -= 1 else: if (expr[position] == '$'): try: if (expr[position + 1] == '$'): # Escaped $ sign result += '$' skipCount = 1 elif (expr[position + 1] == '{'): # Looking for a path! endPos = expr.find ('}', position + 1) if (endPos > 0): path = expr[position + 2:endPos] # Evaluate the path - missing paths raise exceptions as normal. try: pathResult = self.evaluate (path) except PathNotFoundException as e: # This part of the path didn't evaluate to anything - leave blank pathResult = '' if (pathResult is not None): if (isinstance (pathResult, str)): result += pathResult else: # THIS IS NOT A BUG! # Use Unicode in Context if you aren't using Ascii! result += str (pathResult) skipCount = endPos - position else: # It's a variable endPos = expr.find (' ', position + 1) if (endPos == -1): endPos = len (expr) path = expr [position + 1:endPos] # Evaluate the variable - missing paths raise exceptions as normal. try: pathResult = self.traversePath (path) except PathNotFoundException as e: # This part of the path didn't evaluate to anything - leave blank pathResult = '' if (pathResult is not None): if (isinstance (pathResult, str)): result += pathResult else: # THIS IS NOT A BUG! # Use Unicode in Context if you aren't using Ascii! result += str (pathResult) skipCount = endPos - position - 1 except IndexError as e: # Trailing $ sign - just suppress it self.log.warning ("Trailing $ detected") pass else: result += expr[position] return result def traversePath (self, expr, canCall=1): # canCall only applies to the *final* path destination, not points down the path. # Check for and correct for trailing/leading quotes if (expr.startswith ('"') or expr.startswith ("'")): if (expr.endswith ('"') or expr.endswith ("'")): expr = expr [1:-1] else: expr = expr [1:] elif (expr.endswith ('"') or expr.endswith ("'")): expr = expr [0:-1] pathList = expr.split ('/') path = pathList[0] if path.startswith ('?'): path = path[1:] if path in self.locals: path = self.locals[path] if (isinstance (path, ContextVariable)): path = path.value() elif (hasattr (path, "__call__")):path = path() elif path in self.globals: path = self.globals[path] if (isinstance (path, ContextVariable)): path = path.value() elif (hasattr (path, "__call__")):path = path() #self.log.debug ("Dereferenced to %s" % path) if path in self.locals: val = self.locals[path] elif path in self.globals: val = self.globals[path] else: # If we can't find it then raise an exception raise PATHNOTFOUNDEXCEPTION index = 1 for path in pathList[1:]: #self.log.debug ("Looking for path element %s" % path) if path.startswith ('?'): path = path[1:] if path in self.locals: path = self.locals[path] if (isinstance (path, ContextVariable)): path = path.value() elif (hasattr (path, "__call__")):path = path() elif path in self.globals: path = self.globals[path] if (isinstance (path, ContextVariable)): path = path.value() elif (hasattr (path, "__call__")):path = path() #self.log.debug ("Dereferenced to %s" % path) try: if (isinstance (val, ContextVariable)): temp = val.value((index,pathList)) elif (hasattr (val, "__call__")):temp = val() else: temp = val except ContextVariable as e: # Fast path for those functions that return values return e.value() if (hasattr (temp, path)): val = getattr (temp, path) else: try: try: val = temp[path] except TypeError: val = temp[int(path)] except: #self.log.debug ("Not found.") raise PATHNOTFOUNDEXCEPTION index = index + 1 #self.log.debug ("Found value %s" % str (val)) if (canCall): try: if (isinstance (val, ContextVariable)): result = val.value((index,pathList)) elif (hasattr (val, "__call__")):result = val() else: result = val except ContextVariable as e: # Fast path for those functions that return values return e.value() else: if (isinstance (val, ContextVariable)): result = val.realValue else: result = val return result def __str__ (self): return "Globals: " + str (self.globals) + "Locals: " + str (self.locals) def populateDefaultVariables (self, options): vars = {} self.repeatMap = {} vars['nothing'] = None vars['default'] = DEFAULTVALUE vars['options'] = options # To start with there are no repeats vars['repeat'] = self.repeatMap vars['attrs'] = None # Add all of these to the global context for name in list(vars.keys()): self.addGlobal (name,vars[name]) # Add also under CONTEXTS self.addGlobal ('CONTEXTS', vars)