""" Base front end class for all line-oriented frontends, rather than block-oriented. Currently this focuses on synchronous frontends. """ __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 re import sys import codeop from frontendbase import FrontEndBase from IPython.kernel.core.interpreter import Interpreter def common_prefix(strings): """ Given a list of strings, return the common prefix between all these strings. """ ref = strings[0] prefix = '' for size in range(len(ref)): test_prefix = ref[:size+1] for string in strings[1:]: if not string.startswith(test_prefix): return prefix prefix = test_prefix return prefix #----------------------------------------------------------------------------- # Base class for the line-oriented front ends #----------------------------------------------------------------------------- class LineFrontEndBase(FrontEndBase): """ Concrete implementation of the FrontEndBase class. This is meant to be the base class behind all the frontend that are line-oriented, rather than block-oriented. """ # We need to keep the prompt number, to be able to increment # it when there is an exception. prompt_number = 1 # We keep a reference to the last result: it helps testing and # programatic control of the frontend. last_result = dict(number=0) # The last prompt displayed. Useful for continuation prompts. last_prompt = '' # The input buffer being edited input_buffer = '' # Set to true for debug output debug = False # A banner to print at startup banner = None #-------------------------------------------------------------------------- # FrontEndBase interface #-------------------------------------------------------------------------- def __init__(self, shell=None, history=None, banner=None, *args, **kwargs): if shell is None: shell = Interpreter() FrontEndBase.__init__(self, shell=shell, history=history) if banner is not None: self.banner = banner def start(self): """ Put the frontend in a state where it is ready for user interaction. """ if self.banner is not None: self.write(self.banner, refresh=False) self.new_prompt(self.input_prompt_template.substitute(number=1)) def complete(self, line): """Complete line in engine's user_ns Parameters ---------- line : string Returns ------- The replacement for the line and the list of possible completions. """ completions = self.shell.complete(line) complete_sep = re.compile('[\s\{\}\[\]\(\)\=]') if completions: prefix = common_prefix(completions) residual = complete_sep.split(line)[:-1] line = line[:-len(residual)] + prefix return line, completions def render_result(self, result): """ Frontend-specific rendering of the result of a calculation that has been sent to an engine. """ if 'stdout' in result and result['stdout']: self.write('\n' + result['stdout']) if 'display' in result and result['display']: self.write("%s%s\n" % ( self.output_prompt_template.substitute( number=result['number']), result['display']['pprint'] ) ) def render_error(self, failure): """ Frontend-specific rendering of error. """ self.write('\n\n'+str(failure)+'\n\n') return failure def is_complete(self, string): """ Check if a string forms a complete, executable set of commands. For the line-oriented frontend, multi-line code is not executed as soon as it is complete: the users has to enter two line returns. """ if string in ('', '\n'): # Prefiltering, eg through ipython0, may return an empty # string although some operations have been accomplished. We # thus want to consider an empty string as a complete # statement. return True elif ( len(self.input_buffer.split('\n'))>2 and not re.findall(r"\n[\t ]*\n[\t ]*$", string)): return False else: self.capture_output() try: # Add line returns here, to make sure that the statement is # complete (except if '\' was used). # This should probably be done in a different place (like # maybe 'prefilter_input' method? For now, this works. clean_string = string.rstrip('\n') if not clean_string.endswith('\\'): clean_string +='\n\n' is_complete = codeop.compile_command(clean_string, "", "exec") self.release_output() except Exception, e: # XXX: Hack: return True so that the # code gets executed and the error captured. is_complete = True return is_complete def write(self, string, refresh=True): """ Write some characters to the display. Subclass should overide this method. The refresh keyword argument is used in frontends with an event loop, to choose whether the write should trigget an UI refresh, and thus be syncrhonous, or not. """ print >>sys.__stderr__, string def execute(self, python_string, raw_string=None): """ Stores the raw_string in the history, and sends the python string to the interpreter. """ if raw_string is None: raw_string = python_string # Create a false result, in case there is an exception self.last_result = dict(number=self.prompt_number) try: try: self.history.input_cache[-1] = raw_string.rstrip() result = self.shell.execute(python_string) self.last_result = result self.render_result(result) except: self.show_traceback() finally: self.after_execute() #-------------------------------------------------------------------------- # LineFrontEndBase interface #-------------------------------------------------------------------------- def prefilter_input(self, string): """ Prefilter the input to turn it in valid python. """ string = string.replace('\r\n', '\n') string = string.replace('\t', 4*' ') # Clean the trailing whitespace string = '\n'.join(l.rstrip() for l in string.split('\n')) return string def after_execute(self): """ All the operations required after an execution to put the terminal back in a shape where it is usable. """ self.prompt_number += 1 self.new_prompt(self.input_prompt_template.substitute( number=(self.last_result['number'] + 1))) # Start a new empty history entry self._add_history(None, '') self.history_cursor = len(self.history.input_cache) - 1 def complete_current_input(self): """ Do code completion on current line. """ if self.debug: print >>sys.__stdout__, "complete_current_input", line = self.input_buffer new_line, completions = self.complete(line) if len(completions)>1: self.write_completion(completions, new_line=new_line) elif not line == new_line: self.input_buffer = new_line if self.debug: print >>sys.__stdout__, 'line', line print >>sys.__stdout__, 'new_line', new_line print >>sys.__stdout__, completions def get_line_width(self): """ Return the width of the line in characters. """ return 80 def write_completion(self, possibilities, new_line=None): """ Write the list of possible completions. new_line is the completed input line that should be displayed after the completion are writen. If None, the input_buffer before the completion is used. """ if new_line is None: new_line = self.input_buffer self.write('\n') max_len = len(max(possibilities, key=len)) + 1 # Now we check how much symbol we can put on a line... chars_per_line = self.get_line_width() symbols_per_line = max(1, chars_per_line/max_len) pos = 1 completion_string = [] for symbol in possibilities: if pos < symbols_per_line: completion_string.append(symbol.ljust(max_len)) pos += 1 else: completion_string.append(symbol.rstrip() + '\n') pos = 1 self.write(''.join(completion_string)) self.new_prompt(self.input_prompt_template.substitute( number=self.last_result['number'] + 1)) self.input_buffer = new_line def new_prompt(self, prompt): """ Prints a prompt and starts a new editing buffer. Subclasses should use this method to make sure that the terminal is put in a state favorable for a new line input. """ self.input_buffer = '' self.write(prompt) def continuation_prompt(self): """Returns the current continuation prompt. """ return ("."*(len(self.last_prompt)-2) + ': ') def execute_command(self, command, hidden=False): """ Execute a command, not only in the model, but also in the view, if any. """ return self.shell.execute(command) #-------------------------------------------------------------------------- # Private API #-------------------------------------------------------------------------- def _on_enter(self, new_line_pos=0): """ Called when the return key is pressed in a line editing buffer. Parameters ---------- new_line_pos : integer, optional Position of the new line to add, starting from the end (0 adds a new line after the last line, -1 before the last line...) Returns ------- True if execution is triggered """ current_buffer = self.input_buffer # XXX: This string replace is ugly, but there should be no way it # fails. prompt_less_buffer = re.sub('^' + self.continuation_prompt(), '', current_buffer).replace('\n' + self.continuation_prompt(), '\n') cleaned_buffer = self.prefilter_input(prompt_less_buffer) if self.is_complete(cleaned_buffer): self.execute(cleaned_buffer, raw_string=current_buffer) return True else: # Start a new line. new_line_pos = -new_line_pos lines = current_buffer.split('\n')[:-1] prompt_less_lines = prompt_less_buffer.split('\n') # Create the new line, with the continuation prompt, and the # same amount of indent than the line above it. new_line = self.continuation_prompt() + \ self._get_indent_string('\n'.join( prompt_less_lines[:new_line_pos-1])) if len(lines) == 1: # We are starting a first continuation line. Indent it. new_line += '\t' elif current_buffer[:-1].split('\n')[-1].rstrip().endswith(':'): # The last line ends with ":", autoindent the new line. new_line += '\t' if new_line_pos == 0: lines.append(new_line) else: lines.insert(new_line_pos, new_line) self.input_buffer = '\n'.join(lines) def _get_indent_string(self, string): """ Return the string of whitespace that prefixes a line. Used to add the right amount of indendation when creating a new line. """ string = string.replace('\t', ' '*4) string = string.split('\n')[-1] indent_chars = len(string) - len(string.lstrip()) indent_string = '\t'*(indent_chars // 4) + \ ' '*(indent_chars % 4) return indent_string