Extensions/wms/parser.py

# Copyright (c) 2004 by Intevation GmbH
# Authors:
# Martin Schulze <[email protected]>
#
# 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 2 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, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

"""
Inspect WMS Capabilities for later processing.

Information should only be retrieved with the proper get*() methods.

class WMSCapabilitiesParser:
    __init__()

    grok(string)

    getTitle()
    getAbstract()
    getFees()
    getAccessConstraints()
    getFormats()
    getLayers()
    getSRS()

    getLayerTitle(layer)
    getLayerSRS(layer)
    getLayerLatLonBBox(layer)
    getLayerBBox(layer, srs)

    isQueryable(layer)

    get_srs_discrepancies()
"""

__version__ = "$Revision$"
# $Source$
# $Id$

import xml.dom.minidom

from domutils import getElementsByName, getElementByName

from Thuban import _

class WMSCapabilitiesParser:
    """
    Thuban class to parse capabilities supplied as large string.

    This class provides methods to parse and retrieve particular
    information from the WMS capabilities XML.  Information should
    only be extracted by the respective get*() methods.
    """

    layers = None
    title = None
    abstract = None
    fees = None
    access = None
    formats = None
    srs_discrepancies = None
    error = None


    def __init__(self):
        """
        Initialises an instance in this class.
        """

        # Note that we must not initialise internal variables of the
        # class in a mutable way or it will be shared among all
        # instances.  None is immutable, [] is not.
        self.error = []


    def grok(self, data):
        """
        Parses the XML response to a WMS GetCapabilities request.

        Internal datastructure of the class will be filled.
        Information should only be retrieved with the respective
        get*() methods.
        """
        xml_dom = xml.dom.minidom.parseString(data)
        root = xml_dom.documentElement

        # Extract the title
        foo = getElementByName(getElementByName(root, 'Service'), 'Title')
        if foo:
            self.title = foo.childNodes[0].data
        
        # Extract the abstract
        foo = getElementByName(getElementByName(root, 'Service'), 'Abstract')
        if foo and len(foo.childNodes[0].data):
            self.abstract = foo.childNodes[0].data
        
        # Extract fees information
        foo = getElementByName(getElementByName(root, 'Service'), 'Fees')
        if foo and len(foo.childNodes[0].data) \
               and foo.childNodes[0].data.lower() != 'none':
            self.fees = foo.childNodes[0].data
        
        # Extract access information
        foo = getElementByName(getElementByName(root, 'Service'),
                               'AccessConstraints')
        if foo and len(foo.childNodes[0].data) \
               and foo.childNodes[0].data.lower() != 'none':
            self.access = foo.childNodes[0].data
        
        # Extract output format information
        foo = getElementsByName(
            getElementByName(getElementByName(getElementByName(
            root, 'Capability'), 'Request'), 'GetMap'), 'Format')
        self.formats = map((lambda i: i.childNodes[0].data), foo)

        # Extract layer names
        self.layers = []
        self.peekLayers(getElementByName(getElementByName(
            root, 'Capability'), 'Layer'), -1)

        xml_dom.unlink()


    def peekLayers(self, top, parent):
        """
        Inspect the provided DOM fragment referenced as top.

        This method will inspect all included layers and traverse the
        tree recursively in order to fill the internal datastructure.

        Note that SRS other than EPSG:* are not yet supported,
        especially there is no support for AUTO and NONE.
        """

        index = len (self.layers)
        self.layers.append({})
        self.layers[index]['parent'] = parent

        for foo in top.attributes.keys():
            if foo == 'queryable':
                self.layers[index]['queryable'] \
                    = int(top.attributes.get(foo).nodeValue)

        foo = getElementByName(top, 'Title')
        if foo and len(foo.childNodes[0].data):
            self.layers[index]['title'] = foo.childNodes[0].data
        else:
            # A <Title> is required for each layer, <name> is optional
            # See OGC 01-068r3, 7.1.4.5.1 and 7.1.4.5.2
            self.error.append(_("No title found for layer #%d") % index)

        foo = getElementByName(top, 'Name')
        if foo and len(foo.childNodes[0].data):
            self.layers[index]['name'] = foo.childNodes[0].data

        # These values are only used for an integrity check
        for foo in getElementsByName(top, 'SRS'):
            for srs in foo.childNodes[0].data.split(" "):
                if srs[0:5] == 'EPSG:':
                    srs = srs[5:]
                try:
                    int(srs)
                    try:
                        self.layers[index]['srs'].append(srs)
                    except KeyError:
                        self.layers[index]['srs'] = [srs]
                except ValueError:
                    if srs[0:4].upper() == 'AUTO' \
                           or srs[0:4].upper() == 'NONE':
                        try:
                            self.layers[index]['_srs_'].append(srs)
                        except KeyError:
                            self.layers[index]['_srs_'] = [srs]
                    else:
                        self.error.append(_("SRS '%s' is not numerical and not"
                                            " AUTO/NONE in layer '%s'") \
                                          % (srs, self.layers[index]['title']))

        foo = getElementByName(top, 'LatLonBoundingBox')
        if foo is not None:
            self.layers[index]['llbbox'] = {}
            for corner in ['minx', 'miny', 'maxx', 'maxy']:
                self.layers[index]['llbbox'][corner] \
                    = foo.attributes.get(corner).nodeValue

        boxes = getElementsByName(top, 'BoundingBox')
        if boxes != []:
            self.layers[index]['bbox'] = {}
        for foo in boxes:
            srs = foo.attributes.get('SRS').nodeValue
            if srs[0:5] == 'EPSG:':
                srs = srs[5:]
            self.layers[index]['bbox'][srs] = {}
            for corner in ['minx', 'miny', 'maxx', 'maxy']:
                self.layers[index]['bbox'][srs][corner] \
                    = foo.attributes.get(corner).nodeValue
            
        # Traverse subsidiary layers
        sublayer = getElementsByName(top, 'Layer')
        for l in sublayer:
            self.peekLayers(l, index)


    def getTitle(self):
        """
        Returns the main title of the WMS object.

        If no title is provided in the capabilities, an empty string
        is returned.
        """
        if self.title is None:
            return ''
        else:
            return self.title


    def getAbstract(self):
        """
        Returns the abstract of the WMS object.

        If no abstract is provided in the capabilities, an empty
        string is returned.
        """
        if self.abstract is None:
            return ''
        else:
            return self.abstract


    def getFees(self):
        """
        Returns the fees information of the WMS object.

        If no information is provided in the capabilities or if it is
        set to 'none', an empty string is returned.
        """
        if self.fees is None:
            return ''
        else:
            return self.fees


    def getAccessConstraints(self):
        """
        Returns information about access constraints for the WMS object.

        If no information is provided in the capabilities or if it is
        set to 'none', an empty string is returned.
        """
        if self.access is None:
            return ''
        else:
            return self.access


    def getFormats(self):
        """
        Returns a list of supported output formats.

        These are used in the GetMap request.  This method will
        default to 'image/jpeg' if no format is recognised in XML
        Capabilities, assuming that JPEG will always be supported on
        the server side.
        """
        if self.formats is None:
            return ['image/jpeg']
        else:
            return self.formats

    def getLayers(self):
        """
        Returns a list of layer names.

        Only named layers will be returned, since a layer may have a
        title but doesn't have to have a name associated to it as
        well.  If no layers were found, an empty list is returned.
        """
        result = []
        for layer in self.layers:
            if 'name' in layer:
                result.append(layer['name'])

        return result


    def getSRS(self):
        """
        Returns the root list of spatial reference systems (SRS).

        This list is taken from the root layer.  Those SRS are common
        to all subsidiary layers.  If no SRS are common to all layers,
        an empty list is returned.  If no layers were detected, an
        empty list is returned as well.
        """
        if len(self.layers) == 0:
            return []

        # index 0 denotes the root layer by design
        if 'srs' in self.layers[0].keys():
            return self.layers[0]['srs']


    def getLayerTitle(self, name):
        """
        Returns the title of the named layer.

        If no such title or no such layer exists, an empty string is
        returned.
        """
        for layer in self.layers:
            if 'name' in layer:
                if layer['name'] == name:
                    if 'title' in layer:
                        return layer['title']

        return ''


    def getLayerSRS(self, name):
        """
        Returns a list of spacial reference systems (SRS).

        The SRS are specified by the European Petroleum Survey Group
        (EPSG).  There should be at least one SRS per layer, though.
        The prefix 'EPSG:' will be stripped.  If none exists, an empty
        list is returned.

        The specification [OGC 01-068r3] says about inheritance of
        SRS:

        - Every layer is available in one or more SRS (or in an
          undefined SRS)

        - Geographic information whose SRS is undefined
          (e.g. digitised historical maps) shall use 'NONE'
          (case-sensitive).  This implementation does not support
          this.

        - Every layer shall have at least one SRS element that is
          either stated explicitly or inherited from a parent layer.

        - The root layer element shall include a sequence of zero or
          more SRS elements listing all SRS which are common for to
          all subsidiary layers.

        - Layers may optionally add to the global SRS list, or to the
          list inherited from a parent layer.

        - A server which has the ability to transform data to
          different SRSes may choose not to provide an explicit
          BoundingBox for every possible SRS available for each Layer.
          Thus the list of <SRS> elements are authoritative.

        This implementation returns the list of SRS for the given
        layer, calculated by looking at BoundingBoxes defined in the
        named layer and all layers higher in the hierarchy up to the
        root layer which weren't overwritten.
        """
        for i in range(len(self.layers)):
            if 'name' in self.layers[i]:
                if self.layers[i]['name'] == name:
                    pivot = i
                    break
        else:
            return []

        result = []
        while pivot != -1:
            if 'srs' in self.layers[pivot]:
                for srs in self.layers[pivot]['srs']:
                    if srs not in result:
                        result.append(srs)
            pivot = self.layers[pivot]['parent']

        return result


    def getLayerLatLonBBox(self, name):
        """
        Returns a dictionary of the LatLonBoundingBox.

        ... for the named layer if it exists.  The SRS is always
        EPSG:4326 per convention.  There should be at least one,
        though, inherited from the root layer at least.  If none
        exists, the value None is returned.
        """
        for layer in self.layers:
            if 'name' in layer:
                if layer['name'] == name:
                    if 'llbbox' in layer:
                        return layer['llbbox']
                    else:
                        # No LatLonBoundingBox found in current layer,
                        # so traverse the hierarchy upwards and check
                        # again until there is one.
                        pivot = layer
                        while pivot['parent'] != -1:
                            pivot = self.layers[pivot['parent']]
                            if 'llbbox' in pivot:
                                return pivot['llbbox']

        return None


    def getLayerBBox(self, name, srs):
        """
        Returns a dictionary of the BoundingBox.

        If no such BoundingBox exists, None is returned.

        The specification [OGC 01-068r3] says about BoundingBoxes:

        - Layers may have zero or more BoundingBox elements what are
          either stated explicitly or inherited from a parent layer.

        - A layer may have multiple BoundingBox elements, but each one
          shall state a different SRS.

        - A layer inherits any BoundingBoxes defined by its
          parents.

        - A BoundingBox inherited from the parent layer for a
          particular SRS is replaced by any declaration for the same
          SRS in the current layer.

        - A BoundingBox in the child layer for a new SRS which is not
          already declared by the parent, is added to the list of
          BoundingBoxes for the child layer.

        - A single layer shall not contain more than one BoundingBox
          element for the same SRS.
        """
        for layer in self.layers:
            if 'name' in layer:
                if layer['name'] == name:
                    if 'bbox' in layer:
                        if srs in layer['bbox']:
                            return layer['bbox'][srs]
                    
                    # No BoundingBox for the given SRS found in
                    # current layer, so traverse the hierarchy upwards
                    # and check again until there is one.
                    pivot = layer
                    while pivot['parent'] != -1:
                        pivot = self.layers[pivot['parent']]
                        if 'bbox' in pivot:
                            if srs in pivot['bbox']:
                                return pivot['bbox'][srs]

        # No matching BBox found, let's see if it was EPSG:4326
        if srs == '4326':
            return self.getLayerLatLonBBox(name)

        return None


    def isQueryable(self, name):
        """
        Returns the value of the queryable attribute of a layer.

        This attribute denotes whether this layer can be queried
        through the GetFeatureInfo request.  The default value is 0.

        The specification [OGC 01-068r3] this attribute can be
        inherited.
        """

        for layer in self.layers:
            if 'name' in layer:
                if layer['name'] == name:
                    try:
                        return layer['queryable']
                    except KeyError:
                        # No attribute in this layer, so traverse the
                        # hierarchy upwards
                        pivot = layer
                        while pivot['parent'] != -1:
                            pivot = self.layers[pivot['parent']]
                            if 'queryable' in pivot:
                                return pivot['queryable']
        return 0


    def get_srs_discrepancies(self):
        """
        Returns a list of layer identifications where the denoted SRS
        values differ from the calculated ones through BoundingBox
        elements.
        """
        return self.srs_discrepancies


if __name__ == "__main__":
    print "This module cannot be executed standalone."

    import os

    sample = "test/sample.xml"
    try:
        f = open(sample, "r")
    except IOError:
        try:
            f = open(os.path.dirname(__file__) + "/" + sample, "r")
        except IOError:
            print "Cannot open %s for reading" % sample

    if f is not None:
        sample = f.read();
        f.close()
        
        ina = WMSCapabilitiesParser()
        ina.grok(sample)
1	joey	2133	# Copyright (c) 2004 by Intevation GmbH
2			# Authors:
3			# Martin Schulze <[email protected]>
4			#
5			# This program is free software; you can redistribute it and/or modify
6			# it under the terms of the GNU General Public License as published by
7			# the Free Software Foundation; either version 2 of the License, or
8			# (at your option) any later version.
9			#
10			# This program is distributed in the hope that it will be useful,
11			# but WITHOUT ANY WARRANTY; without even the implied warranty of
12			# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13			# GNU General Public License for more details.
14			#
15			# You should have received a copy of the GNU General Public License
16			# along with this program; if not, write to the Free Software
17			# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18
19			"""
20			Inspect WMS Capabilities for later processing.
21
22			Information should only be retrieved with the proper get*() methods.
23
24			class WMSCapabilitiesParser:
25			__init__()
26
27			grok(string)
28
29			getTitle()
30			getAbstract()
31			getFees()
32			getAccessConstraints()
33			getFormats()
34			getLayers()
35			getSRS()
36
37			getLayerTitle(layer)
38			getLayerSRS(layer)
39			getLayerLatLonBBox(layer)
40			getLayerBBox(layer, srs)
41
42			isQueryable(layer)
43
44			get_srs_discrepancies()
45			"""
46
47			__version__ = "$Revision$"
48			# $Source$
49			# $Id$
50
51			import xml.dom.minidom
52
53			from domutils import getElementsByName, getElementByName
54
55	joey	2165	from Thuban import _
56
57	joey	2133	class WMSCapabilitiesParser:
58			"""
59			Thuban class to parse capabilities supplied as large string.
60
61			This class provides methods to parse and retrieve particular
62			information from the WMS capabilities XML. Information should
63			only be extracted by the respective get*() methods.
64			"""
65
66			layers = None
67			title = None
68			abstract = None
69			fees = None
70			access = None
71			formats = None
72			srs_discrepancies = None
73	joey	2165	error = None
74	joey	2133
75
76			def __init__(self):
77			"""
78			Initialises an instance in this class.
79			"""
80
81			# Note that we must not initialise internal variables of the
82			# class in a mutable way or it will be shared among all
83			# instances. None is immutable, [] is not.
84	joey	2165	self.error = []
85	joey	2133
86
87			def grok(self, data):
88			"""
89			Parses the XML response to a WMS GetCapabilities request.
90
91			Internal datastructure of the class will be filled.
92			Information should only be retrieved with the respective
93			get*() methods.
94			"""
95	joey	2153	xml_dom = xml.dom.minidom.parseString(data)
96			root = xml_dom.documentElement
97	joey	2133
98			# Extract the title
99			foo = getElementByName(getElementByName(root, 'Service'), 'Title')
100			if foo:
101			self.title = foo.childNodes[0].data
102
103			# Extract the abstract
104			foo = getElementByName(getElementByName(root, 'Service'), 'Abstract')
105			if foo and len(foo.childNodes[0].data):
106			self.abstract = foo.childNodes[0].data
107
108			# Extract fees information
109			foo = getElementByName(getElementByName(root, 'Service'), 'Fees')
110			if foo and len(foo.childNodes[0].data) \
111	joey	2155	and foo.childNodes[0].data.lower() != 'none':
112	joey	2133	self.fees = foo.childNodes[0].data
113
114			# Extract access information
115			foo = getElementByName(getElementByName(root, 'Service'),
116			'AccessConstraints')
117			if foo and len(foo.childNodes[0].data) \
118	joey	2155	and foo.childNodes[0].data.lower() != 'none':
119	joey	2133	self.access = foo.childNodes[0].data
120
121			# Extract output format information
122			foo = getElementsByName(
123			getElementByName(getElementByName(getElementByName(
124			root, 'Capability'), 'Request'), 'GetMap'), 'Format')
125			self.formats = map((lambda i: i.childNodes[0].data), foo)
126
127			# Extract layer names
128			self.layers = []
129			self.peekLayers(getElementByName(getElementByName(
130			root, 'Capability'), 'Layer'), -1)
131
132	joey	2153	xml_dom.unlink()
133	joey	2133
134	joey	2153
135	joey	2133	def peekLayers(self, top, parent):
136			"""
137			Inspect the provided DOM fragment referenced as top.
138
139			This method will inspect all included layers and traverse the
140			tree recursively in order to fill the internal datastructure.
141
142			Note that SRS other than EPSG:* are not yet supported,
143			especially there is no support for AUTO and NONE.
144			"""
145
146			index = len (self.layers)
147			self.layers.append({})
148			self.layers[index]['parent'] = parent
149
150			for foo in top.attributes.keys():
151			if foo == 'queryable':
152			self.layers[index]['queryable'] \
153			= int(top.attributes.get(foo).nodeValue)
154
155			foo = getElementByName(top, 'Title')
156			if foo and len(foo.childNodes[0].data):
157			self.layers[index]['title'] = foo.childNodes[0].data
158	joey	2165	else:
159			# A <Title> is required for each layer, <name> is optional
160			# See OGC 01-068r3, 7.1.4.5.1 and 7.1.4.5.2
161			self.error.append(_("No title found for layer #%d") % index)
162	joey	2133
163			foo = getElementByName(top, 'Name')
164			if foo and len(foo.childNodes[0].data):
165			self.layers[index]['name'] = foo.childNodes[0].data
166
167			# These values are only used for an integrity check
168			for foo in getElementsByName(top, 'SRS'):
169			for srs in foo.childNodes[0].data.split(" "):
170			if srs[0:5] == 'EPSG:':
171			srs = srs[5:]
172			try:
173	joey	2167	int(srs)
174			try:
175			self.layers[index]['srs'].append(srs)
176			except KeyError:
177			self.layers[index]['srs'] = [srs]
178			except ValueError:
179			if srs[0:4].upper() == 'AUTO' \
180			or srs[0:4].upper() == 'NONE':
181			try:
182			self.layers[index]['_srs_'].append(srs)
183			except KeyError:
184			self.layers[index]['_srs_'] = [srs]
185			else:
186			self.error.append(_("SRS '%s' is not numerical and not"
187			" AUTO/NONE in layer '%s'") \
188			% (srs, self.layers[index]['title']))
189	joey	2133
190			foo = getElementByName(top, 'LatLonBoundingBox')
191			if foo is not None:
192			self.layers[index]['llbbox'] = {}
193			for corner in ['minx', 'miny', 'maxx', 'maxy']:
194			self.layers[index]['llbbox'][corner] \
195			= foo.attributes.get(corner).nodeValue
196
197			boxes = getElementsByName(top, 'BoundingBox')
198			if boxes != []:
199			self.layers[index]['bbox'] = {}
200			for foo in boxes:
201			srs = foo.attributes.get('SRS').nodeValue
202			if srs[0:5] == 'EPSG:':
203			srs = srs[5:]
204			self.layers[index]['bbox'][srs] = {}
205			for corner in ['minx', 'miny', 'maxx', 'maxy']:
206			self.layers[index]['bbox'][srs][corner] \
207			= foo.attributes.get(corner).nodeValue
208
209			# Traverse subsidiary layers
210			sublayer = getElementsByName(top, 'Layer')
211			for l in sublayer:
212			self.peekLayers(l, index)
213
214
215			def getTitle(self):
216			"""
217			Returns the main title of the WMS object.
218
219			If no title is provided in the capabilities, an empty string
220			is returned.
221			"""
222			if self.title is None:
223			return ''
224			else:
225			return self.title
226
227
228			def getAbstract(self):
229			"""
230			Returns the abstract of the WMS object.
231
232			If no abstract is provided in the capabilities, an empty
233			string is returned.
234			"""
235			if self.abstract is None:
236			return ''
237			else:
238			return self.abstract
239
240
241			def getFees(self):
242			"""
243			Returns the fees information of the WMS object.
244
245			If no information is provided in the capabilities or if it is
246			set to 'none', an empty string is returned.
247			"""
248			if self.fees is None:
249			return ''
250			else:
251			return self.fees
252
253
254			def getAccessConstraints(self):
255			"""
256			Returns information about access constraints for the WMS object.
257
258			If no information is provided in the capabilities or if it is
259			set to 'none', an empty string is returned.
260			"""
261			if self.access is None:
262			return ''
263			else:
264			return self.access
265
266
267			def getFormats(self):
268			"""
269			Returns a list of supported output formats.
270
271			These are used in the GetMap request. This method will
272			default to 'image/jpeg' if no format is recognised in XML
273			Capabilities, assuming that JPEG will always be supported on
274			the server side.
275			"""
276			if self.formats is None:
277			return ['image/jpeg']
278			else:
279			return self.formats
280
281			def getLayers(self):
282			"""
283			Returns a list of layer names.
284
285			Only named layers will be returned, since a layer may have a
286			title but doesn't have to have a name associated to it as
287			well. If no layers were found, an empty list is returned.
288			"""
289			result = []
290			for layer in self.layers:
291			if 'name' in layer:
292			result.append(layer['name'])
293
294			return result
295
296
297			def getSRS(self):
298			"""
299			Returns the root list of spatial reference systems (SRS).
300
301			This list is taken from the root layer. Those SRS are common
302			to all subsidiary layers. If no SRS are common to all layers,
303			an empty list is returned. If no layers were detected, an
304			empty list is returned as well.
305			"""
306			if len(self.layers) == 0:
307			return []
308
309			# index 0 denotes the root layer by design
310			if 'srs' in self.layers[0].keys():
311			return self.layers[0]['srs']
312
313
314			def getLayerTitle(self, name):
315			"""
316			Returns the title of the named layer.
317
318			If no such title or no such layer exists, an empty string is
319			returned.
320			"""
321			for layer in self.layers:
322			if 'name' in layer:
323			if layer['name'] == name:
324			if 'title' in layer:
325			return layer['title']
326
327			return ''
328
329
330			def getLayerSRS(self, name):
331			"""
332			Returns a list of spacial reference systems (SRS).
333
334			The SRS are specified by the European Petroleum Survey Group
335			(EPSG). There should be at least one SRS per layer, though.
336			The prefix 'EPSG:' will be stripped. If none exists, an empty
337			list is returned.
338
339			The specification [OGC 01-068r3] says about inheritance of
340			SRS:
341
342			- Every layer is available in one or more SRS (or in an
343			undefined SRS)
344
345			- Geographic information whose SRS is undefined
346			(e.g. digitised historical maps) shall use 'NONE'
347			(case-sensitive). This implementation does not support
348			this.
349
350			- Every layer shall have at least one SRS element that is
351			either stated explicitly or inherited from a parent layer.
352
353			- The root layer element shall include a sequence of zero or
354			more SRS elements listing all SRS which are common for to
355			all subsidiary layers.
356
357			- Layers may optionally add to the global SRS list, or to the
358			list inherited from a parent layer.
359
360	joey	2144	- A server which has the ability to transform data to
361			different SRSes may choose not to provide an explicit
362			BoundingBox for every possible SRS available for each Layer.
363			Thus the list of <SRS> elements are authoritative.
364
365	joey	2133	This implementation returns the list of SRS for the given
366			layer, calculated by looking at BoundingBoxes defined in the
367			named layer and all layers higher in the hierarchy up to the
368			root layer which weren't overwritten.
369			"""
370			for i in range(len(self.layers)):
371			if 'name' in self.layers[i]:
372			if self.layers[i]['name'] == name:
373			pivot = i
374			break
375			else:
376			return []
377
378			result = []
379			while pivot != -1:
380	joey	2144	if 'srs' in self.layers[pivot]:
381			for srs in self.layers[pivot]['srs']:
382	joey	2133	if srs not in result:
383			result.append(srs)
384			pivot = self.layers[pivot]['parent']
385
386			return result
387
388
389			def getLayerLatLonBBox(self, name):
390			"""
391			Returns a dictionary of the LatLonBoundingBox.
392
393			... for the named layer if it exists. The SRS is always
394			EPSG:4326 per convention. There should be at least one,
395			though, inherited from the root layer at least. If none
396			exists, the value None is returned.
397			"""
398			for layer in self.layers:
399			if 'name' in layer:
400			if layer['name'] == name:
401			if 'llbbox' in layer:
402			return layer['llbbox']
403			else:
404			# No LatLonBoundingBox found in current layer,
405			# so traverse the hierarchy upwards and check
406			# again until there is one.
407			pivot = layer
408			while pivot['parent'] != -1:
409			pivot = self.layers[pivot['parent']]
410			if 'llbbox' in pivot:
411			return pivot['llbbox']
412
413			return None
414
415
416			def getLayerBBox(self, name, srs):
417			"""
418			Returns a dictionary of the BoundingBox.
419
420			If no such BoundingBox exists, None is returned.
421
422			The specification [OGC 01-068r3] says about BoundingBoxes:
423
424			- Layers may have zero or more BoundingBox elements what are
425			either stated explicitly or inherited from a parent layer.
426
427			- A layer may have multiple BoundingBox elements, but each one
428			shall state a different SRS.
429
430			- A layer inherits any BoundingBoxes defined by its
431			parents.
432
433			- A BoundingBox inherited from the parent layer for a
434			particular SRS is replaced by any declaration for the same
435			SRS in the current layer.
436
437			- A BoundingBox in the child layer for a new SRS which is not
438			already declared by the parent, is added to the list of
439			BoundingBoxes for the child layer.
440
441			- A single layer shall not contain more than one BoundingBox
442			element for the same SRS.
443			"""
444			for layer in self.layers:
445			if 'name' in layer:
446			if layer['name'] == name:
447			if 'bbox' in layer:
448			if srs in layer['bbox']:
449			return layer['bbox'][srs]
450
451			# No BoundingBox for the given SRS found in
452			# current layer, so traverse the hierarchy upwards
453			# and check again until there is one.
454			pivot = layer
455			while pivot['parent'] != -1:
456			pivot = self.layers[pivot['parent']]
457			if 'bbox' in pivot:
458			if srs in pivot['bbox']:
459			return pivot['bbox'][srs]
460
461	joey	2170	# No matching BBox found, let's see if it was EPSG:4326
462			if srs == '4326':
463			return self.getLayerLatLonBBox(name)
464
465	joey	2133	return None
466
467
468			def isQueryable(self, name):
469			"""
470			Returns the value of the queryable attribute of a layer.
471
472			This attribute denotes whether this layer can be queried
473			through the GetFeatureInfo request. The default value is 0.
474
475			The specification [OGC 01-068r3] this attribute can be
476			inherited.
477			"""
478
479			for layer in self.layers:
480			if 'name' in layer:
481			if layer['name'] == name:
482			try:
483			return layer['queryable']
484			except KeyError:
485			# No attribute in this layer, so traverse the
486			# hierarchy upwards
487			pivot = layer
488			while pivot['parent'] != -1:
489			pivot = self.layers[pivot['parent']]
490			if 'queryable' in pivot:
491			return pivot['queryable']
492			return 0
493
494
495			def get_srs_discrepancies(self):
496			"""
497			Returns a list of layer identifications where the denoted SRS
498			values differ from the calculated ones through BoundingBox
499			elements.
500			"""
501			return self.srs_discrepancies
502
503
504			if __name__ == "__main__":
505			print "This module cannot be executed standalone."
506
507			import os
508
509	joey	2164	sample = "test/sample.xml"
510	joey	2133	try:
511	joey	2164	f = open(sample, "r")
512	joey	2133	except IOError:
513			try:
514	joey	2164	f = open(os.path.dirname(__file__) + "/" + sample, "r")
515	joey	2133	except IOError:
516	joey	2164	print "Cannot open %s for reading" % sample
517	joey	2133
518			if f is not None:
519			sample = f.read();
520			f.close()
521
522			ina = WMSCapabilitiesParser()
523			ina.grok(sample)
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