def parse_symbol_attribute(self, symbol_attribute):
        """ Extract attributes from a symbol. """
        x = int(symbol_attribute.get('x'))
        y = int(symbol_attribute.get('y'))
        rotation = float(symbol_attribute.get('rotation'))

        # Make SymbolAttribute
        symbol_attr = SymbolAttribute(x, y, rotation)

        # Add Annotations
        for annotation in symbol_attribute.get('annotations'):
            anno = self.parse_annotation(annotation)
            symbol_attr.add_annotation(anno)

        # Return SymbolAttribute to be added to it's ComponentInstance
        return symbol_attr
    def parse_component_instance(self, f):
        """ Parse a component instance from a $Comp block """
        # pylint: disable=R0914

        # name & reference
        prefix, name, reference = f.readline().split()
        assert prefix == 'L'

        # unit & convert
        prefix, unit, convert, _ = f.readline().split(None, 3)
        unit, convert = int(unit), int(convert)
        assert prefix == 'U'

        # position
        prefix, compx, compy = f.readline().split()
        assert prefix == 'P'
        compx, compy = int(compx), int(compy)

        line = f.readline()
        rotation = 0
        annotations = []

        while line.strip() not in ("$EndComp", ''):
            if line.startswith('F '):
                parts = line.split('"', 2)
                value = parts[1].decode('utf-8', errors='replace')
                parts = parts[2].strip().split()
                annotations.append(
                    Annotation(value,
                               make_length(int(parts[1]) - compx),
                               -make_length(int(parts[2]) - compy),
                               0 if parts[0] == 'H' else 1, 'true'))
            elif line.startswith('\t'):
                parts = line.strip().split()
                if len(parts) == 4:
                    rotation = MATRIX2ROTATION.get(
                        tuple(int(i) for i in parts), 0)
            line = f.readline()

        inst = ComponentInstance(reference, name, convert - 1)
        symbattr = SymbolAttribute(make_length(compx), -make_length(compy),
                                   rotation)
        for ann in annotations:
            symbattr.add_annotation(ann)
        inst.add_symbol_attribute(symbattr)

        return inst
    def parse_component(self, stream, params):
        """ Creates a component instance according to the component *params*.
            If the component is not known in the library, a the component 
            will be created according to its description in the embedded
            environment ``[]`` or a symbol file. The component is added
            to the library automatically if necessary. 
            An instance of this component will be created and added to 
            the design. 
            A GEDAError is raised when either the component file
            is invalid or the referenced symbol file cannot be found 
            in the known directories.

            Returns a tuple of Component and ComponentInstance objects.
        """
        basename, dummy = os.path.splitext(params['basename'])

        component_name = basename
        if params['mirror']:
            component_name += '_MIRRORED'

        if component_name in self.design.components.components:
            component = self.design.components.components[component_name]

            ## skipping embedded data might be required
            self.skip_embedded_section(stream)

        else:
            ##check if sym file is embedded or referenced 
            if basename.startswith('EMBEDDED'):
                ## embedded only has to be processed when NOT in symbol lookup
                if basename not in self.known_symbols:
                    component = self.parse_component_data(stream, params)
            else:
                if basename not in self.known_symbols:
                    log.warn("referenced symbol file '%s' unknown" % basename)
                    ## parse optional attached environment before continuing
                    self._parse_environment(stream)
                    return None, None

                ## requires parsing of referenced symbol file
                f_in = open(self.known_symbols[basename], "rU")
                self._check_version(f_in)

                component = self.parse_component_data(f_in, params) 

                f_in.close()
                        
            self.design.add_component(component_name, component)

        ## get all attributes assigned to component instance
        attributes = self._parse_environment(stream)

        ## refdes attribute is name of component (mandatory as of gEDA doc)
        ## examples if gaf repo have components without refdes, use part of
        ## basename
        if attributes is not None:
            instance = ComponentInstance(
                attributes.get('_refdes', component.name),
                component.name, 
                0
            )
            for key, value in attributes.items():
                instance.add_attribute(key, value)

        else:
            instance = ComponentInstance(
                component.name, 
                component.name, 
                0
            )

        ## generate a component instance using attributes
        self.design.add_component_instance(instance)

        symbol = SymbolAttribute(
            self.x_to_px(params['x']), 
            self.y_to_px(params['y']), 
            self.conv_angle(params['angle'])
        )
        instance.add_symbol_attribute(symbol)

        ## add annotation for special attributes 
        for idx, attribute_key in enumerate(['_refdes', 'device']):
            if attribute_key in component.attributes \
               or attribute_key in instance.attributes:

                symbol.add_annotation(
                    Annotation(
                        '{{%s}}' % attribute_key, 
                        0, 0+idx*10, 0.0, 'true'
                    )
                )

        return component, instance
    def parse(self, filename, library_filename=None):
        """ Parse a kicad file into a design """

        # Rough'n'dirty parsing, assume nothing useful comes before
        # the description
        circuit = Design()
        segments = set()  # each wire segment
        junctions = set()  # wire junction point (connects all wires under it)

        if library_filename is None:
            library_filename = splitext(filename)[0] + '-cache.lib'
            if exists(library_filename):
                self.parse_library(library_filename, circuit)

        f = open(filename)

        # Read until the end of the description
        while f.readline().strip() != "$EndDescr":
            pass

        # Now parse wires and components, ignore connections, we get
        # connectivity from wire segments

        line = f.readline()
        while line:
            element = line.split()[0]  # whats next on the list
            if element == "Wire":  # Wire Segment, coords on 2nd line
                x1, y1, x2, y2 = [int(i) for i in f.readline().split()]
                if not (x1 == x2 and y1 == y2):  # ignore zero-length segments
                    segments.add(((x1, y1), (x2, y2)))
            elif element == "Connection":  # Store these to apply later
                x, y = [int(i) for i in line.split()[2:4]]
                junctions.add((x, y))
            elif element == "$Comp":  # Component Instance
                # name & reference
                prefix, name, reference = f.readline().split()
                assert prefix == 'L'

                # timestamp
                prefix, _ = f.readline().split(None, 1)
                assert prefix == 'U'

                # position
                prefix, compx, compy = f.readline().split()
                assert prefix == 'P'
                compx, compy = int(compx), int(compy)

                # TODO(ajray): ignore all the fields for now, probably
                # could make these annotations

                while f.readline().strip() not in ("$EndComp", ''):
                    pass

                # TODO: calculate rotation
                inst = ComponentInstance(reference, name, 0)
                inst.add_symbol_attribute(SymbolAttribute(compx, compy, 0))

                circuit.add_component_instance(inst)

            line = f.readline()

        f.close()

        segments = self.divide(segments, junctions)
        circuit.nets = self.calc_nets(segments)

        return circuit