color: make a test for curse availability explicite

We won't use terminfo when curse failed to load. Before this change, we were
doing an indirect test, relying on the fact some variable ('_terminfo_params')
would be empty if curses failed to load. We update the code to be more explicit
and directly checks if we managed to load the curse module.

hgext/color.py

@@ -1,434 +1,434
 # color.py color output for Mercurial commands
 #
 # Copyright (C) 2007 Kevin Christen <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 '''colorize output from some commands
 
 The color extension colorizes output from several Mercurial commands.
 For example, the diff command shows additions in green and deletions
 in red, while the status command shows modified files in magenta. Many
 other commands have analogous colors. It is possible to customize
 these colors.
 
 Effects
 -------
 
 Other effects in addition to color, like bold and underlined text, are
 also available. By default, the terminfo database is used to find the
 terminal codes used to change color and effect.  If terminfo is not
 available, then effects are rendered with the ECMA-48 SGR control
 function (aka ANSI escape codes).
 
 The available effects in terminfo mode are 'blink', 'bold', 'dim',
 'inverse', 'invisible', 'italic', 'standout', and 'underline'; in
 ECMA-48 mode, the options are 'bold', 'inverse', 'italic', and
 'underline'.  How each is rendered depends on the terminal emulator.
 Some may not be available for a given terminal type, and will be
 silently ignored.
 
 If the terminfo entry for your terminal is missing codes for an effect
 or has the wrong codes, you can add or override those codes in your
 configuration::
 
   [color]
   terminfo.dim = \E[2m
 
 where '\E' is substituted with an escape character.
 
 Labels
 ------
 
 Text receives color effects depending on the labels that it has. Many
 default Mercurial commands emit labelled text. You can also define
 your own labels in templates using the label function, see :hg:`help
 templates`. A single portion of text may have more than one label. In
 that case, effects given to the last label will override any other
 effects. This includes the special "none" effect, which nullifies
 other effects.
 
 Labels are normally invisible. In order to see these labels and their
 position in the text, use the global --color=debug option. The same
 anchor text may be associated to multiple labels, e.g.
 
   [log.changeset changeset.secret|changeset:   22611:6f0a53c8f587]
 
 The following are the default effects for some default labels. Default
 effects may be overridden from your configuration file::
 
   [color]
   status.modified = blue bold underline red_background
   status.added = green bold
   status.removed = red bold blue_background
   status.deleted = cyan bold underline
   status.unknown = magenta bold underline
   status.ignored = black bold
 
   # 'none' turns off all effects
   status.clean = none
   status.copied = none
 
   qseries.applied = blue bold underline
   qseries.unapplied = black bold
   qseries.missing = red bold
 
   diff.diffline = bold
   diff.extended = cyan bold
   diff.file_a = red bold
   diff.file_b = green bold
   diff.hunk = magenta
   diff.deleted = red
   diff.inserted = green
   diff.changed = white
   diff.tab =
   diff.trailingwhitespace = bold red_background
 
   # Blank so it inherits the style of the surrounding label
   changeset.public =
   changeset.draft =
   changeset.secret =
 
   resolve.unresolved = red bold
   resolve.resolved = green bold
 
   bookmarks.active = green
 
   branches.active = none
   branches.closed = black bold
   branches.current = green
   branches.inactive = none
 
   tags.normal = green
   tags.local = black bold
 
   rebase.rebased = blue
   rebase.remaining = red bold
 
   shelve.age = cyan
   shelve.newest = green bold
   shelve.name = blue bold
 
   histedit.remaining = red bold
 
 Custom colors
 -------------
 
 Because there are only eight standard colors, this module allows you
 to define color names for other color slots which might be available
 for your terminal type, assuming terminfo mode.  For instance::
 
   color.brightblue = 12
   color.pink = 207
   color.orange = 202
 
 to set 'brightblue' to color slot 12 (useful for 16 color terminals
 that have brighter colors defined in the upper eight) and, 'pink' and
 'orange' to colors in 256-color xterm's default color cube.  These
 defined colors may then be used as any of the pre-defined eight,
 including appending '_background' to set the background to that color.
 
 Modes
 -----
 
 By default, the color extension will use ANSI mode (or win32 mode on
 Windows) if it detects a terminal. To override auto mode (to enable
 terminfo mode, for example), set the following configuration option::
 
   [color]
   mode = terminfo
 
 Any value other than 'ansi', 'win32', 'terminfo', or 'auto' will
 disable color.
 
 Note that on some systems, terminfo mode may cause problems when using
 color with the pager extension and less -R. less with the -R option
 will only display ECMA-48 color codes, and terminfo mode may sometimes
 emit codes that less doesn't understand. You can work around this by
 either using ansi mode (or auto mode), or by using less -r (which will
 pass through all terminal control codes, not just color control
 codes).
 
 On some systems (such as MSYS in Windows), the terminal may support
 a different color mode than the pager (activated via the "pager"
 extension). It is possible to define separate modes depending on whether
 the pager is active::
 
   [color]
   mode = auto
   pagermode = ansi
 
 If ``pagermode`` is not defined, the ``mode`` will be used.
 '''
 
 from __future__ import absolute_import
 
 try:
     import curses
     curses.COLOR_BLACK # force import
 except ImportError:
     curses = None
 
 from mercurial.i18n import _
 from mercurial import (
     cmdutil,
     color,
     commands,
     dispatch,
     encoding,
     extensions,
     pycompat,
     subrepo,
     ui as uimod,
     util,
 )
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
 # Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
 # extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
 # be specifying the version(s) of Mercurial they are tested with, or
 # leave the attribute unspecified.
 testedwith = 'ships-with-hg-core'
 
 def _terminfosetup(ui, mode):
     '''Initialize terminfo data and the terminal if we're in terminfo mode.'''
 
     # If we failed to load curses, we go ahead and return.
-    if not color._terminfo_params:
+    if curses is None:
         return
     # Otherwise, see what the config file says.
     if mode not in ('auto', 'terminfo'):
         return
 
     color._terminfo_params.update((key[6:], (False, int(val), ''))
         for key, val in ui.configitems('color')
         if key.startswith('color.'))
     color._terminfo_params.update((key[9:],
                                    (True, '', val.replace('\\E', '\x1b')))
         for key, val in ui.configitems('color')
         if key.startswith('terminfo.'))
 
     try:
         curses.setupterm()
     except curses.error as e:
         color._terminfo_params.clear()
         return
 
     for key, (b, e, c) in color._terminfo_params.items():
         if not b:
             continue
         if not c and not curses.tigetstr(e):
             # Most terminals don't support dim, invis, etc, so don't be
             # noisy and use ui.debug().
             ui.debug("no terminfo entry for %s\n" % e)
             del color._terminfo_params[key]
     if not curses.tigetstr('setaf') or not curses.tigetstr('setab'):
         # Only warn about missing terminfo entries if we explicitly asked for
         # terminfo mode.
         if mode == "terminfo":
             ui.warn(_("no terminfo entry for setab/setaf: reverting to "
               "ECMA-48 color\n"))
         color._terminfo_params.clear()
 
 def _modesetup(ui, coloropt):
     if coloropt == 'debug':
         return 'debug'
 
     auto = (coloropt == 'auto')
     always = not auto and util.parsebool(coloropt)
     if not always and not auto:
         return None
 
     formatted = (always or (encoding.environ.get('TERM') != 'dumb'
                  and ui.formatted()))
 
     mode = ui.config('color', 'mode', 'auto')
 
     # If pager is active, color.pagermode overrides color.mode.
     if getattr(ui, 'pageractive', False):
         mode = ui.config('color', 'pagermode', mode)
 
     realmode = mode
     if mode == 'auto':
         if pycompat.osname == 'nt':
             term = encoding.environ.get('TERM')
             # TERM won't be defined in a vanilla cmd.exe environment.
 
             # UNIX-like environments on Windows such as Cygwin and MSYS will
             # set TERM. They appear to make a best effort attempt at setting it
             # to something appropriate. However, not all environments with TERM
             # defined support ANSI. Since "ansi" could result in terminal
             # gibberish, we error on the side of selecting "win32". However, if
             # w32effects is not defined, we almost certainly don't support
             # "win32", so don't even try.
             if (term and 'xterm' in term) or not color.w32effects:
                 realmode = 'ansi'
             else:
                 realmode = 'win32'
         else:
             realmode = 'ansi'
 
     def modewarn():
         # only warn if color.mode was explicitly set and we're in
         # a formatted terminal
         if mode == realmode and ui.formatted():
             ui.warn(_('warning: failed to set color mode to %s\n') % mode)
 
     if realmode == 'win32':
         color._terminfo_params.clear()
         if not color.w32effects:
             modewarn()
             return None
         color._effects.update(color.w32effects)
     elif realmode == 'ansi':
         color._terminfo_params.clear()
     elif realmode == 'terminfo':
         _terminfosetup(ui, mode)
         if not color._terminfo_params:
             ## FIXME Shouldn't we return None in this case too?
             modewarn()
             realmode = 'ansi'
     else:
         return None
 
     if always or (auto and formatted):
         return realmode
     return None
 
 class colorui(uimod.ui):
     _colormode = 'ansi'
     def write(self, *args, **opts):
         if self._colormode is None:
             return super(colorui, self).write(*args, **opts)
 
         label = opts.get('label', '')
         if self._buffers and not opts.get('prompt', False):
             if self._bufferapplylabels:
                 self._buffers[-1].extend(self.label(a, label) for a in args)
             else:
                 self._buffers[-1].extend(args)
         elif self._colormode == 'win32':
             for a in args:
                 color.win32print(a, super(colorui, self).write, **opts)
         else:
             return super(colorui, self).write(
                 *[self.label(a, label) for a in args], **opts)
 
     def write_err(self, *args, **opts):
         if self._colormode is None:
             return super(colorui, self).write_err(*args, **opts)
 
         label = opts.get('label', '')
         if self._bufferstates and self._bufferstates[-1][0]:
             return self.write(*args, **opts)
         if self._colormode == 'win32':
             for a in args:
                 color.win32print(a, super(colorui, self).write_err, **opts)
         else:
             return super(colorui, self).write_err(
                 *[self.label(a, label) for a in args], **opts)
 
     def showlabel(self, msg, label):
         if label and msg:
             if msg[-1] == '\n':
                 return "[%s|%s]\n" % (label, msg[:-1])
             else:
                 return "[%s|%s]" % (label, msg)
         else:
             return msg
 
     def label(self, msg, label):
         if self._colormode is None:
             return super(colorui, self).label(msg, label)
 
         if self._colormode == 'debug':
             return self.showlabel(msg, label)
 
         effects = []
         for l in label.split():
             s = color._styles.get(l, '')
             if s:
                 effects.append(s)
             elif color.valideffect(l):
                 effects.append(l)
         effects = ' '.join(effects)
         if effects:
             return '\n'.join([color._render_effects(line, effects)
                               for line in msg.split('\n')])
         return msg
 
 def uisetup(ui):
     if ui.plain():
         return
     if not isinstance(ui, colorui):
         colorui.__bases__ = (ui.__class__,)
         ui.__class__ = colorui
     def colorcmd(orig, ui_, opts, cmd, cmdfunc):
         mode = _modesetup(ui_, opts['color'])
         colorui._colormode = mode
         if mode and mode != 'debug':
             color.configstyles(ui_)
         return orig(ui_, opts, cmd, cmdfunc)
     def colorgit(orig, gitsub, commands, env=None, stream=False, cwd=None):
         if gitsub.ui._colormode and len(commands) and commands[0] == "diff":
                 # insert the argument in the front,
                 # the end of git diff arguments is used for paths
                 commands.insert(1, '--color')
         return orig(gitsub, commands, env, stream, cwd)
     extensions.wrapfunction(dispatch, '_runcommand', colorcmd)
     extensions.wrapfunction(subrepo.gitsubrepo, '_gitnodir', colorgit)
 
 def extsetup(ui):
     commands.globalopts.append(
         ('', 'color', 'auto',
          # i18n: 'always', 'auto', 'never', and 'debug' are keywords
          # and should not be translated
          _("when to colorize (boolean, always, auto, never, or debug)"),
          _('TYPE')))
 
 @command('debugcolor',
         [('', 'style', None, _('show all configured styles'))],
         'hg debugcolor')
 def debugcolor(ui, repo, **opts):
     """show available color, effects or style"""
     ui.write(('color mode: %s\n') % ui._colormode)
     if opts.get('style'):
         return _debugdisplaystyle(ui)
     else:
         return _debugdisplaycolor(ui)
 
 def _debugdisplaycolor(ui):
     oldstyle = color._styles.copy()
     try:
         color._styles.clear()
         for effect in color._effects.keys():
             color._styles[effect] = effect
         if color._terminfo_params:
             for k, v in ui.configitems('color'):
                 if k.startswith('color.'):
                     color._styles[k] = k[6:]
                 elif k.startswith('terminfo.'):
                     color._styles[k] = k[9:]
         ui.write(_('available colors:\n'))
         # sort label with a '_' after the other to group '_background' entry.
         items = sorted(color._styles.items(),
                        key=lambda i: ('_' in i[0], i[0], i[1]))
         for colorname, label in items:
             ui.write(('%s\n') % colorname, label=label)
     finally:
         color._styles.clear()
         color._styles.update(oldstyle)
 
 def _debugdisplaystyle(ui):
     ui.write(_('available style:\n'))
     width = max(len(s) for s in color._styles)
     for label, effects in sorted(color._styles.items()):
         ui.write('%s' % label, label=label)
         if effects:
             # 50
             ui.write(': ')
             ui.write(' ' * (max(0, width - len(label))))
             ui.write(', '.join(ui.label(e, e) for e in effects.split()))
         ui.write('\n')