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−#!/usr/bin/env python
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−#
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−# Mercurial hook to check for inappropriate whitespace.  Currently it
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−# only checks Python files.
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−#
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−# This script is based on the code in the Mercurial book
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−# <http://hgbook.red-bean.com/read/handling-repository-events-with-hooks.html#id403945>
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−
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−'''hook to refuse commits that introduce some bad inputs.
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−Inputs that are refused are conflict markers (rows of < or >
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−characters), and tabs and trailing white space in Python sources.
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−
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−Usage: in your ~/.hgrc file add:
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−[hooks]
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−pretxncommit.whitespace = python:/path/to/check_whitespace.py:hook
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−pretxnchangegroup.whitespace = python:/path/to/check_whitespace.py:hook
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−'''
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−
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−import re
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−
+
−def trailing_whitespace(difflines):
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−    linenum = 0
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−    header = False
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−    filename = ''
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−    fnre = re.compile(r'(?:---|\+\+\+) (?P<filename>[^\t\r\n]+)')
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−    lnre = re.compile(r'@@ -\d+,\d+ \+(?P<lineno>\d+),')
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−    wsre = re.compile(r'\+.*[ \t]$')
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−    tbre = re.compile(r'\+.*\t')
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−    resre = re.compile(r'\+(<<<<<<<|>>>>>>>)')
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−
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−    for chunk in difflines:
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−        for line in chunk.split('\n'):
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−            if header:
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−                # remember the name of the file that this diff affects
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−                m = fnre.match(line)
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−                if m is not None and m.group('filename') != '/dev/null':
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−                    filename = m.group('filename').split('/', 1)[-1]
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−                if line.startswith('+++ '):
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−                    header = False
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−                continue
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−            if line.startswith('diff '):
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−                header = True
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−                continue
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−            # hunk header - save the line number
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−            m = lnre.match(line)
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−            if m is not None:
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−                linenum = int(m.group('lineno'))
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−                continue
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−            if header or not filename:
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−                continue
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−            # hunk body - check for an added line with bad whitespace
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−            if filename[-3:] == '.py' or filename[-5:] == '.py.in':
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−                m = tbre.match(line)
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−                if m is not None:
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−                    yield filename, linenum, 'TABs'
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−            # trailing whitespace, for now only in Python source
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−            m = wsre.match(line)
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−            if m is not None:
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−                if filename[-3:] == '.py' or filename[-5:] == '.py.in':
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−                    yield filename, linenum, 'trailing whitespace'
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−            # conflict markers
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−            m = resre.match(line)
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−            if m is not None:
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−                yield filename, linenum, 'conflict marker'
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−            if line and line[0] in ' +':
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−                linenum += 1
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−
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−def hook(ui, repo, hooktype, node, **kwargs):
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−    import os, sys, subprocess
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−
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−    added = 0
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−    for filename, linenum, msg in trailing_whitespace(repo[node].diff()):
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−        print >> sys.stderr, ('%s, line %d: %s added' %
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−                              (filename, linenum, msg))
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−        added += 1
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−    if added:
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−        # save the commit message so we don't need to retype it
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−        cmtsv = os.path.join('.hg','commit.save')
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−        subprocess.call(['hg', 'tip', '--template', '{desc}'],
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−                        stdout=open(cmtsv, 'w'))
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−        print >> sys.stderr, 'commit message saved to %s' % cmtsv
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−        return True
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−
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−if __name__ == '__main__':
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−    if hook(None, None, None, None):
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−        sys.exit(1)