Add utility to detect duplicate anchors in documentation files

#! /usr/bin/env python3

# LAMMPS Documentation Utilities

#

# Scan for duplicate anchor labels in documentation files

#

# Copyright (C) 2017 Richard Berger

#

# This program is free software: you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation, either version 3 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import re

import sys

import argparse

def main():

    parser = argparse.ArgumentParser(description='scan for duplicate anchor labels in documentation files')

    parser.add_argument('files',  metavar='file', nargs='+', help='one or more files to scan')

    parsed_args = parser.parse_args()

    anchor_pattern = re.compile(r'^:link\(([^,\)]*)\)')

    anchors = {}

    for filename in parsed_args.files:

        with open(filename, 'rt') as f:

            for line_number, line in enumerate(f):

                m = anchor_pattern.match(line)

                if m:

                    label = m.group(1)

                    if label in anchors:

                        anchors[label].append((filename, line_number))

                    else:

                        anchors[label] = [(filename, line_number)]

    count = 0

    for label in sorted(anchors.keys()):

        if len(anchors[label]) > 1:

            print(label)

            count += 1

            for filename, line_number in anchors[label]:

                print(" - %s:%d" % (filename, line_number))

    if count > 0:

        print("Found %d anchor label errors." % count)

        sys.exit(1)

    else:

        print("No anchor label errors.")

if __name__ == "__main__":

    main()

      tests_require=['nose'],

      entry_points = {

          "console_scripts": ['txt2html = lammpsdoc.txt2html:main',

                              'txt2rst  = lammpsdoc.txt2rst:main']

                              'txt2rst  = lammpsdoc.txt2rst:main',

                              'doc_anchor_check = lammpsdoc.doc_anchor_check:main ']

      },

)