222 

   223 def build_field (value):

   224     """

   225         Build a single field as part of a dhcp.conf line.

   226 

   227         >>> print build_field('foo')

   228         foo

   229         >>> print build_field('foo bar')

   230         "foo bar"

   231     """

   232 

   233     value = str(value)

   234 

   235     if any(c.isspace() for c in value):

   236         # quoted

   237         return '"{value}"'.format(value=value)

   238     else:

   239         return value

   240 

   241 def build_line (item, end, indent=0):

   242     """

   243         Build a structured line.

   244 

   245         >>> print build_line(['foo'], ';')

   246         foo;

   247         >>> print build_line(['host', 'foo'], ' {')

   248         host foo {

   249         >>> print build_line(['foo', 'bar quux'], ';', indent=1)

   250             foo "bar quux";

   251     """

   252 

   253     return '    '*indent + ' '.join(build_field(field) for field in item) + end

   254 

   255 def build_item (item, **opts):

   256     """

   257         Build a single parameter line.

   258 

   259         >>> print build_item(['foo'])

   260         foo;

   261     """

   262 

   263     return build_line(item, end=';', **opts)

   264 

   265 def build_block (block, items, blocks=(), indent=0, comment=None):

   266     """

   267         Build a complete block.

   268 

   269         >>> for line in build_block(('host', 'foo'), [('hardware', 'ethernet', '00:11:22:33:44:55')], comment="Testing"): print line

   270         # Testing

   271         host foo {

   272             hardware ethernet 00:11:22:33:44:55;

   273         }

   274         >>> for line in build_block(('group', ), [('next-server', 'booter')], [ \

   275                     (('host', 'foo'), [('hardware', 'ethernet', '00:11:22:33:44:55')], ()) \

   276                 ]): print line

   277         group {

   278             next-server booter;

   279         <BLANKLINE>

   280             host foo {

   281                 hardware ethernet 00:11:22:33:44:55;

   282             }

   283         }

   284     """

   285 

   286     if comment:

   287         yield build_line((), end="# {comment}".format(comment=comment), indent=indent)

   288 

   289     yield build_line(block, end=' {', indent=indent)

   290     

   291     for item in items:

   292         yield build_item(item, indent=indent+1)

   293 

   294     for subblock, subitems, subblocks in blocks:

   295         yield ''

   296 

   297         for line in build_block(subblock, subitems, subblocks, indent=indent+1):

   298             yield line

   299 

   300     yield build_line((), end='}', indent=indent)

   301