# pager.py - display output using a pager

#

# Copyright 2008 David Soria Parra <dsp@php.net>

#

# This software may be used and distributed according to the terms

# of the GNU General Public License, incorporated herein by reference.

#

# To load the extension add it to your .hgrc file

#

#   [extension]

#   hgext.pager =

#

# To set the pager that should be used, set the application variable

#

#   [pager]

#   application = less

#

# You can also set environment variables there

#

#   [pager]

#   application = LESS='FSRX' less

#

# If no application is set, the pager extensions use the environment

# variable $PAGER. If neither pager.application, nor

# $PAGER is set, no pager is used.

#

# If you notice "BROKEN PIPE" error messages, you can disable them

# by setting

#

#  [pager]

#  quiet = True

#

import sys, os, signal

def getpager(ui):

    '''return a pager

    We separate this method from the pager class as we don't want to

    instantiate a pager if it is not used at all

    '''

    if sys.stdout.isatty():

        return (ui.config("pager", "application")

                or os.environ.get("PAGER"))

def uisetup(ui):

    # disable broken pipe error messages

    if ui.configbool('pager', 'quiet', False):

        signal.signal(signal.SIGPIPE, signal.SIG_DFL)

    if getpager(ui):

        pager = os.popen(getpager(ui), 'wb')

        sys.stderr = pager

        sys.stdout = pager