Make size of rewrite prompt flexible.

IPython/core/prompts.py

@@ -1,382 +1,394 b''
 # -*- coding: utf-8 -*-
 """Classes for handling input/output prompts.
 
 Authors:
 
 * Fernando Perez
 * Brian Granger
 * Thomas Kluyver
 """
 
 #-----------------------------------------------------------------------------
 #       Copyright (C) 2008-2011 The IPython Development Team
 #       Copyright (C) 2001-2007 Fernando Perez <[e-mail]>
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import os
 import re
 import socket
 import sys
 import time
 
 from IPython.config.configurable import Configurable
 from IPython.core import release
 from IPython.utils import coloransi
 from IPython.utils.traitlets import (Unicode, Instance, Dict, Bool, Int)
 
 #-----------------------------------------------------------------------------
 # Color schemes for prompts
 #-----------------------------------------------------------------------------
 
 InputColors = coloransi.InputTermColors  # just a shorthand
 Colors = coloransi.TermColors  # just a shorthand
 
 color_lists = dict(normal=Colors(), inp=InputColors(), nocolor=coloransi.NoColors())
 
 PColNoColors = coloransi.ColorScheme(
     'NoColor',
     in_prompt  = InputColors.NoColor,  # Input prompt
     in_number  = InputColors.NoColor,  # Input prompt number
     in_prompt2 = InputColors.NoColor, # Continuation prompt
     in_normal  = InputColors.NoColor,  # color off (usu. Colors.Normal)
 
     out_prompt = Colors.NoColor, # Output prompt
     out_number = Colors.NoColor, # Output prompt number
 
     normal = Colors.NoColor  # color off (usu. Colors.Normal)
     )
 
 # make some schemes as instances so we can copy them for modification easily:
 PColLinux =  coloransi.ColorScheme(
     'Linux',
     in_prompt  = InputColors.Green,
     in_number  = InputColors.LightGreen,
     in_prompt2 = InputColors.Green,
     in_normal  = InputColors.Normal,  # color off (usu. Colors.Normal)
 
     out_prompt = Colors.Red,
     out_number = Colors.LightRed,
 
     normal = Colors.Normal
     )
 
 # Slightly modified Linux for light backgrounds
 PColLightBG  = PColLinux.copy('LightBG')
 
 PColLightBG.colors.update(
     in_prompt  = InputColors.Blue,
     in_number  = InputColors.LightBlue,
     in_prompt2 = InputColors.Blue
 )
 
 #-----------------------------------------------------------------------------
 # Utilities
 #-----------------------------------------------------------------------------
 
 class LazyEvaluate(object):
     """This is used for formatting strings with values that need to be updated
     at that time, such as the current time or working directory."""
     def __init__(self, func, *args, **kwargs):
         self.func = func
         self.args = args
         self.kwargs = kwargs
     
     def __call__(self, **kwargs):
         self.kwargs.update(kwargs)
         return self.func(*self.args, **self.kwargs)
     
     def __str__(self):
         return str(self())
 
 def multiple_replace(dict, text):
     """ Replace in 'text' all occurences of any key in the given
     dictionary by its corresponding value.  Returns the new string."""
 
     # Function by Xavier Defrang, originally found at:
     # http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/81330
 
     # Create a regular expression  from the dictionary keys
     regex = re.compile("(%s)" % "|".join(map(re.escape, dict.keys())))
     # For each match, look-up corresponding value in dictionary
     return regex.sub(lambda mo: dict[mo.string[mo.start():mo.end()]], text)
 
 #-----------------------------------------------------------------------------
 # Special characters that can be used in prompt templates, mainly bash-like
 #-----------------------------------------------------------------------------
 
 # If $HOME isn't defined (Windows), make it an absurd string so that it can
 # never be expanded out into '~'.  Basically anything which can never be a
 # reasonable directory name will do, we just want the $HOME -> '~' operation
 # to become a no-op.  We pre-compute $HOME here so it's not done on every
 # prompt call.
 
 # FIXME:
 
 # - This should be turned into a class which does proper namespace management,
 # since the prompt specials need to be evaluated in a certain namespace.
 # Currently it's just globals, which need to be managed manually by code
 # below.
 
 # - I also need to split up the color schemes from the prompt specials
 # somehow.  I don't have a clean design for that quite yet.
 
 HOME = os.environ.get("HOME","//////:::::ZZZZZ,,,~~~")
 
 # We precompute a few more strings here for the prompt_specials, which are
 # fixed once ipython starts.  This reduces the runtime overhead of computing
 # prompt strings.
 USER           = os.environ.get("USER")
 HOSTNAME       = socket.gethostname()
 HOSTNAME_SHORT = HOSTNAME.split(".")[0]
 ROOT_SYMBOL    = "#" if (os.name=='nt' or os.getuid()==0) else "$"
 
 prompt_abbreviations = {
     # Prompt/history count
     '%n' : '{color.number}' '{count}' '{color.prompt}',
     r'\#': '{color.number}' '{count}' '{color.prompt}',
     # Just the prompt counter number, WITHOUT any coloring wrappers, so users
     # can get numbers displayed in whatever color they want.
     r'\N': '{count}',
 
     # Prompt/history count, with the actual digits replaced by dots.  Used
     # mainly in continuation prompts (prompt_in2)
     r'\D': '{dots}',
 
     # Current time
     r'\T' : '{time}',
     # Current working directory
     r'\w': '{cwd}',
     # Basename of current working directory.
     # (use os.sep to make this portable across OSes)
     r'\W' : '{cwd_last}',
     # These X<N> are an extension to the normal bash prompts.  They return
     # N terms of the path, after replacing $HOME with '~'
     r'\X0': '{cwd_x[0]}',
     r'\X1': '{cwd_x[1]}',
     r'\X2': '{cwd_x[2]}',
     r'\X3': '{cwd_x[3]}',
     r'\X4': '{cwd_x[4]}',
     r'\X5': '{cwd_x[5]}',
     # Y<N> are similar to X<N>, but they show '~' if it's the directory
     # N+1 in the list.  Somewhat like %cN in tcsh.
     r'\Y0': '{cwd_y[0]}',
     r'\Y1': '{cwd_y[1]}',
     r'\Y2': '{cwd_y[2]}',
     r'\Y3': '{cwd_y[3]}',
     r'\Y4': '{cwd_y[4]}',
     r'\Y5': '{cwd_y[5]}',
     # Hostname up to first .
     r'\h': HOSTNAME_SHORT,
     # Full hostname
     r'\H': HOSTNAME,
     # Username of current user
     r'\u': USER,
     # Escaped '\'
     '\\\\': '\\',
     # Newline
     r'\n': '\n',
     # Carriage return
     r'\r': '\r',
     # Release version
     r'\v': release.version,
     # Root symbol ($ or #)
     r'\$': ROOT_SYMBOL,
     }
 
 #-----------------------------------------------------------------------------
 # More utilities
 #-----------------------------------------------------------------------------
 
 def cwd_filt(depth):
     """Return the last depth elements of the current working directory.
 
     $HOME is always replaced with '~'.
     If depth==0, the full path is returned."""
 
     cwd = os.getcwd().replace(HOME,"~")
     out = os.sep.join(cwd.split(os.sep)[-depth:])
     return out or os.sep
 
 def cwd_filt2(depth):
     """Return the last depth elements of the current working directory.
 
     $HOME is always replaced with '~'.
     If depth==0, the full path is returned."""
 
     full_cwd = os.getcwd()
     cwd = full_cwd.replace(HOME,"~").split(os.sep)
     if '~' in cwd and len(cwd) == depth+1:
         depth += 1
     drivepart = ''
     if sys.platform == 'win32' and len(cwd) > depth:
         drivepart = os.path.splitdrive(full_cwd)[0]
     out = drivepart + '/'.join(cwd[-depth:])
 
     return out or os.sep
 
 #-----------------------------------------------------------------------------
 # Prompt classes
 #-----------------------------------------------------------------------------
 
 lazily_evaluate = {'time': LazyEvaluate(time.strftime, "%H:%M:%S"),
                    'cwd': LazyEvaluate(os.getcwd),
                    'cwd_last': LazyEvaluate(lambda: os.getcwd().split(os.sep)[-1]),
                    'cwd_x': [LazyEvaluate(lambda: os.getcwd().replace("%s","~"))] +\
                             [LazyEvaluate(cwd_filt, x) for x in range(1,6)],
                    'cwd_y': [LazyEvaluate(cwd_filt2, x) for x in range(6)]
                    }
+
+misc_fields = {'rarrow': "-> "
+              }
         
 
 class PromptManager(Configurable):
     """This is the primary interface for producing IPython's prompts."""
     shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
     
     color_scheme_table = Instance(coloransi.ColorSchemeTable)
     color_scheme = Unicode('Linux', config=True)
     def _color_scheme_changed(self, name, new_value):
         self.color_scheme_table.set_active_scheme(new_value)
         for pname in ['in', 'in2', 'out', 'rewrite']:
             # We need to recalculate the number of invisible characters
             self.update_prompt(pname)
     
     lazy_evaluate_fields = Dict(help="""
         This maps field names used in the prompt templates to functions which
         will be called when the prompt is rendered. This allows us to include
         things like the current time in the prompts. Functions are only called
         if they are used in the prompt.
         """)
     def _lazy_evaluate_fields_default(self): return lazily_evaluate.copy()
     
     in_template = Unicode('In [\\#]: ', config=True,
         help="Input prompt.  '\\#' will be transformed to the prompt number")
     in2_template = Unicode('   .\\D.: ', config=True,
         help="Continuation prompt.")
     out_template = Unicode('Out[\\#]: ', config=True,
         help="Output prompt. '\\#' will be transformed to the prompt number")
-    rewrite_template = Unicode("------> ", config=True,
+    rewrite_template = Unicode("{rarrow:->{txtwidth}}", config=True,
         help="Rewrite prompt. When inputs are transformed, the rewritten input will follow this.")
     
     justify = Bool(True, config=True, help="""
         If True (default), each prompt will be right-aligned with the
         preceding one.
         """)
     
     # We actually store the expanded templates here:
     templates = Dict()
     
     # The number of characters in the last prompt rendered, not including
     # colour characters.
     width = Int()
+    txtwidth = Int()   # Not including right-justification
     
     # The number of characters in each prompt which don't contribute to width
     invisible_chars = Dict()
     def _invisible_chars_default(self):
         return {'in': 0, 'in2': 0, 'out': 0, 'rewrite': 0}
     
     def __init__(self, shell, config=None):
         super(PromptManager, self).__init__(shell=shell, config=config)
         
         # Prepare colour scheme table
         self.color_scheme_table = coloransi.ColorSchemeTable([PColNoColors,
                                     PColLinux, PColLightBG], self.color_scheme)
         
         # Prepare templates
         self.update_prompt('in', self.in_template)
         self.update_prompt('in2', self.in2_template)
         self.update_prompt('out', self.out_template)
         self.update_prompt('rewrite', self.rewrite_template)
         self.on_trait_change(self._update_prompt_trait, ['in_template',
                             'in2_template', 'out_template', 'rewrite_template'])
     
     def update_prompt(self, name, new_template=None):
         """This is called when a prompt template is updated. It processes
         abbreviations used in the prompt template (like \#) and calculates how
         many invisible characters (ANSI colour escapes) the resulting prompt
         contains.
         
         It is also called for each prompt on changing the colour scheme. In both
         cases, traitlets should take care of calling this automatically.
         """
         if new_template is not None:
             self.templates[name] = multiple_replace(prompt_abbreviations, new_template)
-        invis_chars = len(self.render(name, color=True, just=False)) - \
-                            len(self.render(name, color=False, just=False))
+        invis_chars = len(self._render(name, color=True)) - \
+                            len(self._render(name, color=False))
         self.invisible_chars[name] = invis_chars
     
     def _update_prompt_trait(self, traitname, new_template):
         name = traitname[:-9]   # Cut off '_template'
         self.update_prompt(name, new_template)
     
-    def render(self, name, color=True, just=None, **kwargs):
-        """
-        Render the selected prompt.
-        
-        Parameters
-        ----------
-        name : str
-          Which prompt to render. One of 'in', 'in2', 'out', 'rewrite'
-        color : bool
-          If True (default), include ANSI escape sequences for a coloured prompt.
-        just : bool
-          If True, justify the prompt to the width of the last prompt. The
-          default is stored in self.justify.
-        **kwargs :
-          Additional arguments will be passed to the string formatting operation,
-          so they can override the values that would otherwise fill in the
-          template.
-        
-        Returns
-        -------
-        A string containing the rendered prompt.
+    def _render(self, name, color=True, **kwargs):
+        """Render but don't justify, or update the width or txtwidth attributes.
         """
         if color:
             scheme = self.color_scheme_table.active_colors
             if name=='out':
                 colors = color_lists['normal']
                 colors.number, colors.prompt, colors.normal = \
                         scheme.out_number, scheme.out_prompt, scheme.normal
             elif name=='rewrite':
                 colors = color_lists['normal']
                 # We need a non-input version of these escapes
                 colors.number = scheme.in_number.replace("\001","").replace("\002","")
                 colors.prompt = scheme.in_prompt.replace("\001","").replace("\002","")
                 colors.normal = scheme.normal
             else:
                 colors = color_lists['inp']
                 colors.number, colors.prompt, colors.normal = \
                         scheme.in_number, scheme.in_prompt, scheme.in_normal
                 if name=='in2':
                     colors.prompt = scheme.in_prompt2
         else:
             # No color
             colors = color_lists['nocolor']
             colors.number, colors.prompt, colors.normal = '', '', ''
         
         count = self.shell.execution_count    # Shorthand
         # Build the dictionary to be passed to string formatting
         fmtargs = dict(color=colors, count=count,
-                        dots="."*len(str(count)) )
+                        dots="."*len(str(count)),
+                        width=self.width, txtwidth=self.txtwidth )
         fmtargs.update(self.lazy_evaluate_fields)
+        fmtargs.update(misc_fields)
         fmtargs.update(kwargs)
         
         # Prepare the prompt
         prompt = colors.prompt + self.templates[name] + colors.normal
         
         # Fill in required fields
-        res = prompt.format(**fmtargs)
+        return prompt.format(**fmtargs)
+    
+    def render(self, name, color=True, just=None, **kwargs):
+        """
+        Render the selected prompt.
+        
+        Parameters
+        ----------
+        name : str
+          Which prompt to render. One of 'in', 'in2', 'out', 'rewrite'
+        color : bool
+          If True (default), include ANSI escape sequences for a coloured prompt.
+        just : bool
+          If True, justify the prompt to the width of the last prompt. The
+          default is stored in self.justify.
+        **kwargs :
+          Additional arguments will be passed to the string formatting operation,
+          so they can override the values that would otherwise fill in the
+          template.
+        
+        Returns
+        -------
+        A string containing the rendered prompt.
+        """
+        res = self._render(name, color=color, **kwargs)
         
         # Handle justification of prompt
         invis_chars = self.invisible_chars[name] if color else 0
+        self.txtwidth = len(res) - invis_chars
         just = self.justify if (just is None) else just
         if just:
             res = res.rjust(self.width + invis_chars)
         self.width = len(res) - invis_chars
         return res