Given a list of declarations, return a list of output.Rule objects.
        
        Optionally provide an output directory for local copies of image files.

def get_line_pattern_rules(declarations, dirs):
    """ Given a list of declarations, return a list of output.Rule objects.
        
        Optionally provide an output directory for local copies of image files.
    """
    property_map = {'line-pattern-file': 'file', 'line-pattern-width': 'width',
                    'line-pattern-height': 'height', 'line-pattern-type': 'type',
                    'line-pattern-meta-output': 'meta-output', 'line-pattern-meta-writer': 'meta-writer'}

    
    property_names = property_map.keys()
    
    # a place to put rules
    rules = []
    
    for (filter, values) in filtered_property_declarations(declarations, property_names):
    
        line_pattern_file, line_pattern_type, line_pattern_width, line_pattern_height \
            = values.has_key('line-pattern-file') \
            and post_process_symbolizer_image_file(str(values['line-pattern-file'].value), dirs) \
            or (None, None, None, None)
        
        line_pattern_width = values.has_key('line-pattern-width') and values['line-pattern-width'].value or line_pattern_width
        line_pattern_height = values.has_key('line-pattern-height') and values['line-pattern-height'].value or line_pattern_height
        symbolizer = line_pattern_file and output.LinePatternSymbolizer(line_pattern_file, line_pattern_type, line_pattern_width, line_pattern_height)
        
        if symbolizer:
            rules.append(make_rule(filter, symbolizer))
    
    return rules