stubbed zope.interface and Twisted

IPython/frontend/frontendbase.py

@@ -1,396 +1,407
 # encoding: utf-8
 # -*- test-case-name: IPython.frontend.tests.test_frontendbase -*-
 """
 frontendbase provides an interface and base class for GUI frontends for 
 IPython.kernel/IPython.kernel.core.
 
 Frontend implementations will likely want to subclass FrontEndBase. 
 
 Author: Barry Wark
 """
 __docformat__ = "restructuredtext en"
 
 #-------------------------------------------------------------------------------
 #  Copyright (C) 2008  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-------------------------------------------------------------------------------
 
 #-------------------------------------------------------------------------------
 # Imports
 #-------------------------------------------------------------------------------
 import string
 import uuid
 import _ast
 
-import zope.interface as zi
+try:
+    from zope.interface import Interface, Attribute, implements, classProvides
+except ImportError:
+    #zope.interface is not available
+    Interface = object
+    def Attribute(name, doc): pass
+    def implements(interface): pass
+    def classProvides(interface): pass
 
 from IPython.kernel.core.history import FrontEndHistory
 from IPython.kernel.core.util import Bunch
 from IPython.kernel.engineservice import IEngineCore
 
-from twisted.python.failure import Failure
+try:
+    from twisted.python.failure import Failure
+except ImportError:
+    #Twisted not available
+    Failure = Exception
 
 ##############################################################################
 # TEMPORARY!!! fake configuration, while we decide whether to use tconfig or
 # not
 
 rc = Bunch()
 rc.prompt_in1 = r'In [$number]:  '
 rc.prompt_in2 = r'...'
 rc.prompt_out = r'Out [$number]:  '
 
 ##############################################################################
 
-class IFrontEndFactory(zi.Interface):
+class IFrontEndFactory(Interface):
     """Factory interface for frontends."""
     
     def __call__(engine=None, history=None):
         """
         Parameters:
         interpreter : IPython.kernel.engineservice.IEngineCore
         """
         
         pass
 
 
 
-class IFrontEnd(zi.Interface):
+class IFrontEnd(Interface):
     """Interface for frontends. All methods return t.i.d.Deferred"""
     
-    zi.Attribute("input_prompt_template", "string.Template instance\
+    Attribute("input_prompt_template", "string.Template instance\
                 substituteable with execute result.")
-    zi.Attribute("output_prompt_template", "string.Template instance\
+    Attribute("output_prompt_template", "string.Template instance\
                 substituteable with execute result.")
-    zi.Attribute("continuation_prompt_template", "string.Template instance\
+    Attribute("continuation_prompt_template", "string.Template instance\
                 substituteable with execute result.")
     
     def update_cell_prompt(result, blockID=None):
         """Subclass may override to update the input prompt for a block. 
         Since this method will be called as a 
         twisted.internet.defer.Deferred's callback/errback,
         implementations should return result when finished.
         
         Result is a result dict in case of success, and a
         twisted.python.util.failure.Failure in case of an error
         """
         
         pass
     
     
     def render_result(result):
         """Render the result of an execute call. Implementors may choose the
          method of rendering.
         For example, a notebook-style frontend might render a Chaco plot 
         inline.
         
         Parameters:
             result : dict (result of IEngineBase.execute )
                 blockID = result['blockID']
         
         Result:
             Output of frontend rendering
         """
         
         pass
     
     def render_error(failure):
         """Subclasses must override to render the failure. Since this method 
         will be called as a twisted.internet.defer.Deferred's callback, 
         implementations should return result when finished.
         
         blockID = failure.blockID
         """
         
         pass
     
     
     def input_prompt(number=''):
         """Returns the input prompt by subsituting into 
         self.input_prompt_template
         """
         pass
     
     def output_prompt(number=''):
         """Returns the output prompt by subsituting into 
         self.output_prompt_template
         """
         
         pass
     
     def continuation_prompt():
         """Returns the continuation prompt by subsituting into 
         self.continuation_prompt_template
         """
         
         pass
     
     def is_complete(block):
         """Returns True if block is complete, False otherwise."""
         
         pass
     
     def compile_ast(block):
         """Compiles block to an _ast.AST"""
         
         pass
     
     
     def get_history_previous(currentBlock):
         """Returns the block previous in  the history. Saves currentBlock if
         the history_cursor is currently at the end of the input history"""
         pass
     
     def get_history_next():
         """Returns the next block in the history."""
         
         pass
     
 
 class FrontEndBase(object):
     """
     FrontEndBase manages the state tasks for a CLI frontend:
         - Input and output history management
         - Input/continuation and output prompt generation
         
     Some issues (due to possibly unavailable engine):
         - How do we get the current cell number for the engine?
         - How do we handle completions?
     """
     
     history_cursor = 0
     
     current_indent_level = 0
     
     
     input_prompt_template = string.Template(rc.prompt_in1)
     output_prompt_template = string.Template(rc.prompt_out)
     continuation_prompt_template = string.Template(rc.prompt_in2)
     
     def __init__(self, shell=None, history=None):
         self.shell = shell
         if history is None:
                 self.history = FrontEndHistory(input_cache=[''])
         else:
             self.history = history
         
     
     def input_prompt(self, number=''):
         """Returns the current input prompt
         
         It would be great to use ipython1.core.prompts.Prompt1 here
         """
         return self.input_prompt_template.safe_substitute({'number':number})
     
     
     def continuation_prompt(self):
         """Returns the current continuation prompt"""
         
         return self.continuation_prompt_template.safe_substitute()
     
     def output_prompt(self, number=''):
         """Returns the output prompt for result"""
         
         return self.output_prompt_template.safe_substitute({'number':number})
     
     
     def is_complete(self, block):
         """Determine if block is complete.
         
         Parameters
         block : string
         
         Result 
         True if block can be sent to the engine without compile errors.
         False otherwise.
         """
         
         try:
             ast = self.compile_ast(block)
         except:
             return False
         
         lines = block.split('\n')
         return (len(lines)==1 or str(lines[-1])=='')
     
     
     def compile_ast(self, block):
         """Compile block to an AST
         
         Parameters:
             block : str
         
         Result:
             AST
         
         Throws:
             Exception if block cannot be compiled
         """
         
         return compile(block, "<string>", "exec", _ast.PyCF_ONLY_AST)
     
     
     def execute(self, block, blockID=None):
         """Execute the block and return the result.
         
         Parameters:
             block : {str, AST}
             blockID : any
                 Caller may provide an ID to identify this block. 
                 result['blockID'] := blockID
         
         Result:
             Deferred result of self.interpreter.execute
         """
         
         if(not self.is_complete(block)):
             raise Exception("Block is not compilable")
         
         if(blockID == None):
             blockID = uuid.uuid4() #random UUID
         
         try:
             result = self.shell.execute(block)
         except Exception,e:
             e = self._add_block_id_for_failure(e, blockID=blockID)
             e = self.update_cell_prompt(e, blockID=blockID)
             e = self.render_error(e)
         else:
             result = self._add_block_id_for_result(result, blockID=blockID)
             result = self.update_cell_prompt(result, blockID=blockID)
             result = self.render_result(result)
         
         return result
     
     
     def _add_block_id_for_result(self, result, blockID):
         """Add the blockID to result or failure. Unfortunatley, we have to 
         treat failures differently than result dicts.
         """
         
         result['blockID'] = blockID
         
         return result
     
     def _add_block_id_for_failure(self, failure, blockID):
         """_add_block_id_for_failure"""
         
         failure.blockID = blockID
         return failure
     
     
     def _add_history(self, result, block=None):
         """Add block to the history"""
         
         assert(block != None)
         self.history.add_items([block])
         self.history_cursor += 1
         
         return result
     
     
     def get_history_previous(self, currentBlock):
         """ Returns previous history string and decrement history cursor.
         """
         command = self.history.get_history_item(self.history_cursor - 1)
         
         if command is not None:
             if(self.history_cursor == len(self.history.input_cache)):
                 self.history.input_cache[self.history_cursor] = currentBlock
             self.history_cursor -= 1
         return command
     
     
     def get_history_next(self):
         """ Returns next history string and increment history cursor.
         """
         command = self.history.get_history_item(self.history_cursor+1)
         
         if command is not None:
             self.history_cursor += 1
         return command
     
     ###
     # Subclasses probably want to override these methods...
     ###
     
     def update_cell_prompt(self, result, blockID=None):
         """Subclass may override to update the input prompt for a block. 
         Since this method will be called as a 
         twisted.internet.defer.Deferred's callback, implementations should 
         return result when finished.
         """
         
         return result
     
     
     def render_result(self, result):
         """Subclasses must override to render result. Since this method will
         be called as a twisted.internet.defer.Deferred's callback, 
         implementations should return result when finished.
         """
         
         return result
     
     
     def render_error(self, failure):
         """Subclasses must override to render the failure. Since this method 
         will be called as a twisted.internet.defer.Deferred's callback, 
         implementations should return result when finished.
         """
         
         return failure
     
 
 
 class AsynchronousFrontEndBase(FrontEndBase):
     """
     Overrides FrontEndBase to wrap execute in a deferred result.
     All callbacks are made as callbacks on the deferred result.
     """
     
-    zi.implements(IFrontEnd)
-    zi.classProvides(IFrontEndFactory)
+    implements(IFrontEnd)
+    classProvides(IFrontEndFactory)
     
     def __init__(self, engine=None, history=None):
         assert(engine==None or IEngineCore.providedBy(engine))
         self.engine = IEngineCore(engine)
         if history is None:
                 self.history = FrontEndHistory(input_cache=[''])
         else:
             self.history = history
     
     
     def execute(self, block, blockID=None):
         """Execute the block and return the deferred result.
         
         Parameters:
             block : {str, AST}
             blockID : any
                 Caller may provide an ID to identify this block. 
                 result['blockID'] := blockID
         
         Result:
             Deferred result of self.interpreter.execute
         """
         
         if(not self.is_complete(block)):
             return Failure(Exception("Block is not compilable"))
         
         if(blockID == None):
             blockID = uuid.uuid4() #random UUID
         
         d = self.engine.execute(block)
         d.addCallback(self._add_history, block=block)
         d.addCallbacks(self._add_block_id_for_result,
                 errback=self._add_block_id_for_failure,
                 callbackArgs=(blockID,),
                 errbackArgs=(blockID,))
         d.addBoth(self.update_cell_prompt, blockID=blockID)
         d.addCallbacks(self.render_result, 
             errback=self.render_error)
         
         return d