pager: set an attribute on ui indicating that a pager is active

A subsequent patch will teach the color extension to do different things
depending on whether a pager is active. This patch leaves a breadcrumb
on the ui instance to allow it do that that.

hgext/pager.py

@@ -1,168 +1,170 b''
 # pager.py - display output using a pager
 #
 # Copyright 2008 David Soria Parra <[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.
 #
 # To load the extension, add it to your configuration file:
 #
 #   [extension]
 #   pager =
 #
 # Run "hg help pager" to get info on configuration.
 
 '''browse command output with an external pager
 
 To set the pager that should be used, set the application variable::
 
   [pager]
   pager = less -FRX
 
 If no pager is set, the pager extensions uses the environment variable
 $PAGER. If neither pager.pager, nor $PAGER is set, no pager is used.
 
 You can disable the pager for certain commands by adding them to the
 pager.ignore list::
 
   [pager]
   ignore = version, help, update
 
 You can also enable the pager only for certain commands using
 pager.attend. Below is the default list of commands to be paged::
 
   [pager]
   attend = annotate, cat, diff, export, glog, log, qdiff
 
 Setting pager.attend to an empty value will cause all commands to be
 paged.
 
 If pager.attend is present, pager.ignore will be ignored.
 
 Lastly, you can enable and disable paging for individual commands with
 the attend-<command> option. This setting takes precedence over
 existing attend and ignore options and defaults::
 
   [pager]
   attend-cat = false
 
 To ignore global commands like :hg:`version` or :hg:`help`, you have
 to specify them in your user configuration file.
 
 The --pager=... option can also be used to control when the pager is
 used. Use a boolean value like yes, no, on, off, or use auto for
 normal behavior.
 
 '''
 
 import atexit, sys, os, signal, subprocess, errno, shlex
 from mercurial import commands, dispatch, util, extensions, cmdutil
 from mercurial.i18n import _
 
 testedwith = 'internal'
 
 def _pagerfork(ui, p):
     if not util.safehasattr(os, 'fork'):
         sys.stdout = util.popen(p, 'wb')
         if ui._isatty(sys.stderr):
             sys.stderr = sys.stdout
         return
     fdin, fdout = os.pipe()
     pid = os.fork()
     if pid == 0:
         os.close(fdin)
         os.dup2(fdout, sys.stdout.fileno())
         if ui._isatty(sys.stderr):
             os.dup2(fdout, sys.stderr.fileno())
         os.close(fdout)
         return
     os.dup2(fdin, sys.stdin.fileno())
     os.close(fdin)
     os.close(fdout)
     try:
         os.execvp('/bin/sh', ['/bin/sh', '-c', p])
     except OSError, e:
         if e.errno == errno.ENOENT:
             # no /bin/sh, try executing the pager directly
             args = shlex.split(p)
             os.execvp(args[0], args)
         else:
             raise
 
 def _pagersubprocess(ui, p):
     pager = subprocess.Popen(p, shell=True, bufsize=-1,
                              close_fds=util.closefds, stdin=subprocess.PIPE,
                              stdout=sys.stdout, stderr=sys.stderr)
 
     stdout = os.dup(sys.stdout.fileno())
     stderr = os.dup(sys.stderr.fileno())
     os.dup2(pager.stdin.fileno(), sys.stdout.fileno())
     if ui._isatty(sys.stderr):
         os.dup2(pager.stdin.fileno(), sys.stderr.fileno())
 
     @atexit.register
     def killpager():
         if util.safehasattr(signal, "SIGINT"):
             signal.signal(signal.SIGINT, signal.SIG_IGN)
         pager.stdin.close()
         os.dup2(stdout, sys.stdout.fileno())
         os.dup2(stderr, sys.stderr.fileno())
         pager.wait()
 
 def _runpager(ui, p):
     # The subprocess module shipped with Python <= 2.4 is buggy (issue3533).
     # The compat version is buggy on Windows (issue3225), but has been shipping
     # with hg for a long time.  Preserve existing functionality.
     if sys.version_info >= (2, 5):
         _pagersubprocess(ui, p)
     else:
         _pagerfork(ui, p)
 
 def uisetup(ui):
     if '--debugger' in sys.argv or not ui.formatted():
         return
 
     def pagecmd(orig, ui, options, cmd, cmdfunc):
         p = ui.config("pager", "pager", os.environ.get("PAGER"))
         usepager = False
         always = util.parsebool(options['pager'])
         auto = options['pager'] == 'auto'
 
         if not p:
             pass
         elif always:
             usepager = True
         elif not auto:
             usepager = False
         else:
             attend = ui.configlist('pager', 'attend', attended)
             ignore = ui.configlist('pager', 'ignore')
             cmds, _ = cmdutil.findcmd(cmd, commands.table)
 
             for cmd in cmds:
                 var = 'attend-%s' % cmd
                 if ui.config('pager', var):
                     usepager = ui.configbool('pager', var)
                     break
                 if (cmd in attend or
                      (cmd not in ignore and not attend)):
                     usepager = True
                     break
 
+        setattr(ui, 'pageractive', usepager)
+
         if usepager:
             ui.setconfig('ui', 'formatted', ui.formatted(), 'pager')
             ui.setconfig('ui', 'interactive', False, 'pager')
             if util.safehasattr(signal, "SIGPIPE"):
                 signal.signal(signal.SIGPIPE, signal.SIG_DFL)
             _runpager(ui, p)
         return orig(ui, options, cmd, cmdfunc)
 
     extensions.wrapfunction(dispatch, '_runcommand', pagecmd)
 
 def extsetup(ui):
     commands.globalopts.append(
         ('', 'pager', 'auto',
          _("when to paginate (boolean, always, auto, or never)"),
          _('TYPE')))
 
 attended = ['annotate', 'cat', 'diff', 'export', 'glog', 'log', 'qdiff']