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"""
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Base front end class for all line-oriented frontends, rather than
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block-oriented.
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Currently this focuses on synchronous frontends.
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"""
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__docformat__ = "restructuredtext en"
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#-------------------------------------------------------------------------------
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# Copyright (C) 2008 The IPython Development Team
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#
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# Distributed under the terms of the BSD License. The full license is in
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# the file COPYING, distributed as part of this software.
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#-------------------------------------------------------------------------------
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#-------------------------------------------------------------------------------
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# Imports
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#-------------------------------------------------------------------------------
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import re
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import IPython
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import sys
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from frontendbase import FrontEndBase
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from IPython.kernel.core.interpreter import Interpreter
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def common_prefix(strings):
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""" Given a list of strings, return the common prefix between all
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these strings.
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"""
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ref = strings[0]
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prefix = ''
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for size in range(len(ref)):
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test_prefix = ref[:size+1]
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for string in strings[1:]:
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if not string.startswith(test_prefix):
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return prefix
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prefix = test_prefix
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return prefix
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#-------------------------------------------------------------------------------
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# Base class for the line-oriented front ends
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#-------------------------------------------------------------------------------
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class LineFrontEndBase(FrontEndBase):
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""" Concrete implementation of the FrontEndBase class. This is meant
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to be the base class behind all the frontend that are line-oriented,
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rather than block-oriented.
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"""
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# We need to keep the prompt number, to be able to increment
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# it when there is an exception.
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prompt_number = 1
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# We keep a reference to the last result: it helps testing and
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# programatic control of the frontend.
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last_result = dict(number=0)
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# The input buffer being edited
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input_buffer = ''
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# Set to true for debug output
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debug = False
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# A banner to print at startup
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banner = None
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#--------------------------------------------------------------------------
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# FrontEndBase interface
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#--------------------------------------------------------------------------
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def __init__(self, shell=None, history=None, banner=None, *args, **kwargs):
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if shell is None:
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shell = Interpreter()
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FrontEndBase.__init__(self, shell=shell, history=history)
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if banner is not None:
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self.banner = banner
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def start(self):
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""" Put the frontend in a state where it is ready for user
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interaction.
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"""
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if self.banner is not None:
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self.write(self.banner, refresh=False)
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self.new_prompt(self.input_prompt_template.substitute(number=1))
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def complete(self, line):
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"""Complete line in engine's user_ns
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Parameters
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----------
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line : string
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Result
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------
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The replacement for the line and the list of possible completions.
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"""
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completions = self.shell.complete(line)
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complete_sep = re.compile('[\s\{\}\[\]\(\)\=]')
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if completions:
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prefix = common_prefix(completions)
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residual = complete_sep.split(line)[:-1]
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line = line[:-len(residual)] + prefix
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return line, completions
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def render_result(self, result):
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""" Frontend-specific rendering of the result of a calculation
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that has been sent to an engine.
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"""
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if 'stdout' in result and result['stdout']:
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self.write('\n' + result['stdout'])
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if 'display' in result and result['display']:
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self.write("%s%s\n" % (
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self.output_prompt_template.substitute(
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number=result['number']),
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result['display']['pprint']
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) )
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def render_error(self, failure):
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""" Frontend-specific rendering of error.
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"""
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self.write('\n\n'+str(failure)+'\n\n')
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return failure
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def is_complete(self, string):
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""" Check if a string forms a complete, executable set of
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commands.
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For the line-oriented frontend, multi-line code is not executed
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as soon as it is complete: the users has to enter two line
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returns.
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"""
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if string in ('', '\n'):
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# Prefiltering, eg through ipython0, may return an empty
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# string although some operations have been accomplished. We
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# thus want to consider an empty string as a complete
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# statement.
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return True
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elif ( len(self.input_buffer.split('\n'))>2
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and not re.findall(r"\n[\t ]*\n[\t ]*$", string)):
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return False
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else:
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# Add line returns here, to make sure that the statement is
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# complete.
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return FrontEndBase.is_complete(self, string.rstrip() + '\n\n')
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def write(self, string, refresh=True):
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""" Write some characters to the display.
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Subclass should overide this method.
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The refresh keyword argument is used in frontends with an
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event loop, to choose whether the write should trigget an UI
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refresh, and thus be syncrhonous, or not.
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"""
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print >>sys.__stderr__, string
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def execute(self, python_string, raw_string=None):
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""" Stores the raw_string in the history, and sends the
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python string to the interpreter.
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"""
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if raw_string is None:
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raw_string = python_string
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# Create a false result, in case there is an exception
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self.last_result = dict(number=self.prompt_number)
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try:
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self.history.input_cache[-1] = raw_string.rstrip()
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result = self.shell.execute(python_string)
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self.last_result = result
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self.render_result(result)
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except:
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self.show_traceback()
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finally:
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self.after_execute()
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#--------------------------------------------------------------------------
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# LineFrontEndBase interface
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#--------------------------------------------------------------------------
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def prefilter_input(self, string):
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""" Prefilter the input to turn it in valid python.
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"""
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string = string.replace('\r\n', '\n')
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string = string.replace('\t', 4*' ')
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# Clean the trailing whitespace
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string = '\n'.join(l.rstrip() for l in string.split('\n'))
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return string
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def after_execute(self):
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""" All the operations required after an execution to put the
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terminal back in a shape where it is usable.
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"""
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self.prompt_number += 1
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self.new_prompt(self.input_prompt_template.substitute(
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number=(self.last_result['number'] + 1)))
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# Start a new empty history entry
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self._add_history(None, '')
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self.history_cursor = len(self.history.input_cache) - 1
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def complete_current_input(self):
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""" Do code completion on current line.
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"""
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if self.debug:
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print >>sys.__stdout__, "complete_current_input",
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line = self.input_buffer
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new_line, completions = self.complete(line)
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if len(completions)>1:
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self.write_completion(completions, new_line=new_line)
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elif not line == new_line:
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|
self.input_buffer = new_line
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if self.debug:
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print >>sys.__stdout__, 'line', line
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print >>sys.__stdout__, 'new_line', new_line
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print >>sys.__stdout__, completions
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def get_line_width(self):
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|
""" Return the width of the line in characters.
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"""
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return 80
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def write_completion(self, possibilities, new_line=None):
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|
""" Write the list of possible completions.
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|
new_line is the completed input line that should be displayed
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|
after the completion are writen. If None, the input_buffer
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|
before the completion is used.
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"""
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if new_line is None:
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|
new_line = self.input_buffer
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self.write('\n')
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|
max_len = len(max(possibilities, key=len)) + 1
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|
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|
# Now we check how much symbol we can put on a line...
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|
chars_per_line = self.get_line_width()
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|
symbols_per_line = max(1, chars_per_line/max_len)
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|
pos = 1
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|
buf = []
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|
for symbol in possibilities:
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|
if pos < symbols_per_line:
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|
buf.append(symbol.ljust(max_len))
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|
pos += 1
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|
else:
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|
buf.append(symbol.rstrip() + '\n')
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pos = 1
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|
self.write(''.join(buf))
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|
self.new_prompt(self.input_prompt_template.substitute(
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|
|
number=self.last_result['number'] + 1))
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|
self.input_buffer = new_line
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|
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|
|
|
|
|
|
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 = ''
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|
self.write(prompt)
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|
|
|
|
|
|
#--------------------------------------------------------------------------
|
|
|
# Private API
|
|
|
#--------------------------------------------------------------------------
|
|
|
|
|
|
def _on_enter(self):
|
|
|
""" Called when the return key is pressed in a line editing
|
|
|
buffer.
|
|
|
"""
|
|
|
current_buffer = self.input_buffer
|
|
|
cleaned_buffer = self.prefilter_input(current_buffer)
|
|
|
if self.is_complete(cleaned_buffer):
|
|
|
self.execute(cleaned_buffer, raw_string=current_buffer)
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|
|
else:
|
|
|
self.input_buffer += self._get_indent_string(
|
|
|
current_buffer[:-1])
|
|
|
if current_buffer[:-1].split('\n')[-1].rstrip().endswith(':'):
|
|
|
self.input_buffer += '\t'
|
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|
|
|
|
|
|
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) + \
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|
|
' '*(indent_chars % 4)
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|
|
|
return indent_string
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|
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|
