OsmApi.py

   1 #-*- coding: utf-8 -*-
   2
   3 ###########################################################################
   4 ##                                                                       ##
   5 ## Copyrights Etienne Chové <chove@crans.org> 2009                       ##
   6 ##                                                                       ##
   7 ## This program is free software: you can redistribute it and/or modify  ##
   8 ## it under the terms of the GNU General Public License as published by  ##
   9 ## the Free Software Foundation, either version 3 of the License, or     ##
  10 ## (at your option) any later version.                                   ##
  11 ##                                                                       ##
  12 ## This program is distributed in the hope that it will be useful,       ##
  13 ## but WITHOUT ANY WARRANTY; without even the implied warranty of        ##
  14 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         ##
  15 ## GNU General Public License for more details.                          ##
  16 ##                                                                       ##
  17 ## You should have received a copy of the GNU General Public License     ##
  18 ## along with this program.  If not, see <http://www.gnu.org/licenses/>. ##
  19 ##                                                                       ##
  20 ###########################################################################
  21
  22 ## HomePage : http://wiki.openstreetmap.org/wiki/PythonOsmApi
  23
  24 ###########################################################################
  25 ## History                                                               ##
  26 ###########################################################################
  27 ## 0.2.7   2009-10-09 implement all missing fonctions except             ##
  28 ##                    ChangesetsGet and GetCapabilities                  ##
  29 ## 0.2.6   2009-10-09 encoding clean-up                                  ##
  30 ## 0.2.5   2009-10-09 implements NodesGet, WaysGet, RelationsGet         ##
  31 ##                               ParseOsm, ParseOsc                      ##
  32 ## 0.2.4   2009-10-06 clean-up                                           ##
  33 ## 0.2.3   2009-09-09 keep http connection alive for multiple request    ##
  34 ##                    (Node|Way|Relation)Get return None when object     ##
  35 ##                    have been deleted (raising error before)           ##
  36 ## 0.2.2   2009-07-13 can identify applications built on top of the lib  ##
  37 ## 0.2.1   2009-05-05 some changes in constructor -- chove@crans.org     ##
  38 ## 0.2     2009-05-01 initial import                                     ##
  39 ###########################################################################
  40
  41 __version__ = '0.2.7'
  42
  43 import httplib, base64, xml.dom.minidom, time
  44
  45 ###########################################################################
  46 ## Main class                                                            ##
  47
  48 class OsmApi:
  49
  50     def __init__(self, username = None, password = None, passwordfile = None, appid = "", created_by = "PythonOsmApi/"+__version__, api = "www.openstreetmap.org"):
  51
  52         # Get username
  53         if username:
  54             self._username = username
  55         elif passwordfile:
  56             self._username =  open(passwordfile).readline().split(":")[0].strip()
  57
  58         # Get password
  59         if password:
  60             self._password   = password
  61         elif passwordfile:
  62             for l in open(passwordfile).readlines():
  63                 l = l.strip().split(":")
  64                 if l[0] == self._username:
  65                     self._password = l[1]
  66
  67         # Get API
  68         self._api = api
  69
  70         # Get created_by
  71         if appid == "":
  72                 self._created_by = created_by
  73         else:
  74                 self._created_by = appid + " (" + created_by + ")"
  75
  76         # Initialisation
  77         self._CurrentChangesetId = -1
  78
  79         # Http connection
  80         self._conn = httplib.HTTPConnection(self._api, 80)
  81
  82     #######################################################################
  83     # Capabilities                                                        #
  84     #######################################################################
  85
  86     def Capabilities(self):
  87         raise NotImplemented
  88
  89     #######################################################################
  90     # Node                                                                #
  91     #######################################################################
  92
  93     def NodeGet(self, NodeId, NodeVersion = -1):
  94         """ Returns NodeData for node #NodeId. """
  95         uri = "/api/0.6/node/"+str(NodeId)
  96         if NodeVersion <> -1: uri += "/"+str(NodeVersion)
  97         data = self._get(uri)
  98         if not data: return data
  99         data = xml.dom.minidom.parseString(data)
 100         data = data.getElementsByTagName("osm")[0].getElementsByTagName("node")[0]
 101         return self._DomParseNode(data)
 102
 103     def NodeUpdate(self, NodeData):
 104         """ Updates node with NodeData. Returns updated NodeData (without timestamp). """
 105         if self._CurrentChangesetId == -1:
 106             raise Exception, "No changeset currently opened"
 107         NodeData[u"changeset"] = self._CurrentChangesetId
 108         result = self._put("/api/0.6/node/"+str(NodeData[u"id"]), self._XmlBuild("node", NodeData))
 109         NodeData[u"version"] = int(result.strip())
 110         if u"timestamp" in NodeData: NodeData.pop(u"timestamp")
 111         return NodeData
 112
 113     def NodeDelete(self, NodeData):
 114         """ Delete node with NodeData. Returns updated NodeData (without timestamp). """
 115         if self._CurrentChangesetId == -1:
 116             raise Exception, "No changeset currently opened"
 117         NodeData[u"changeset"] = self._CurrentChangesetId
 118         result = self._delete("/api/0.6/node/"+str(NodeData[u"id"]), self._XmlBuild("node", NodeData))
 119         NodeData[u"version"] = int(result.strip())
 120         NodeData[u"visible"] = False
 121         if u"timestamp" in NodeData: NodeData.pop(u"timestamp")
 122         return NodeData
 123
 124     def NodeCreate(self, NodeData):
 125         """ Creates a node. Returns updated NodeData (without timestamp). """
 126         if self._CurrentChangesetId == -1:
 127             raise Exception, "No changeset currently opened"
 128         if NodeData.get(u"id", -1) > 0:
 129             raise Exception, "This node already exists"
 130         NodeData[u"changeset"] = self._CurrentChangesetId
 131         result = self._put("/api/0.6/node/create", self._XmlBuild("node", NodeData))
 132         NodeData[u"id"]      = int(result.strip())
 133         NodeData[u"version"] = 1
 134         if u"timestamp" in NodeData: NodeData.pop(u"timestamp")
 135         return NodeData
 136
 137     def NodeHistory(self, NodeId):
 138         """ Returns dict(NodeVerrsion: NodeData). """
 139         uri = "/api/0.6/node/"+str(NodeId)+"/history"
 140         data = self._get(uri)
 141         data = xml.dom.minidom.parseString(data)
 142         result = {}
 143         for data in data.getElementsByTagName("osm")[0].getElementsByTagName("node"):
 144             data = self._DomParseNode(data)
 145             result[data[u"version"]] = data
 146         return result
 147
 148     def NodeWays(self, NodeId):
 149         """ Returns [WayData, ... ] containing node #NodeId. """
 150         uri = "/api/0.6/node/%d/ways"%NodeId
 151         data = self._get(uri)
 152         data = xml.dom.minidom.parseString(data)
 153         result = []
 154         for data in data.getElementsByTagName("osm")[0].getElementsByTagName("way"):
 155             data = self._DomParseRelation(data)
 156             result.append(data)
 157         return result
 158
 159     def NodeRelations(self, NodeId):
 160         """ Returns [RelationData, ... ] containing node #NodeId. """
 161         uri = "/api/0.6/node/%d/relations"%NodeId
 162         data = self._get(uri)
 163         data = xml.dom.minidom.parseString(data)
 164         result = []
 165         for data in data.getElementsByTagName("osm")[0].getElementsByTagName("relation"):
 166             data = self._DomParseRelation(data)
 167             result.append(data)
 168         return result
 169
 170     def NodesGet(self, NodeIdList):
 171         """ Returns dict(NodeId: NodeData) for each node in NodeIdList """
 172         uri  = "/api/0.6/nodes?nodes=" + ",".join([str(x) for x in NodeIdList])
 173         data = self._get(uri)
 174         data = xml.dom.minidom.parseString(data)
 175         result = {}
 176         for data in data.getElementsByTagName("osm")[0].getElementsByTagName("node"):
 177             data = self._DomParseNode(data)
 178             result[data[u"id"]] = data
 179         return result
 180
 181     #######################################################################
 182     # Way                                                                 #
 183     #######################################################################
 184
 185     def WayGet(self, WayId, WayVersion = -1):
 186         """ Returns WayData for way #WayId. """
 187         uri = "/api/0.6/way/"+str(WayId)
 188         if WayVersion <> -1: uri += "/"+str(WayVersion)
 189         data = self._get(uri)
 190         if not data: return data
 191         data = xml.dom.minidom.parseString(data)
 192         data = data.getElementsByTagName("osm")[0].getElementsByTagName("way")[0]
 193         return self._DomParseWay(data)
 194
 195     def WayUpdate(self, WayData):
 196         """ Updates way with WayData. Returns updated WayData (without timestamp). """
 197         if self._CurrentChangesetId == -1:
 198             raise Exception, "No changeset currently opened"
 199         WayData[u"changeset"] = self._CurrentChangesetId
 200         result = self._put("/api/0.6/way/"+str(WayData[u"id"]), self._XmlBuild("way", WayData))
 201         WayData[u"version"] = int(result.strip())
 202         if u"timestamp" in WayData: WayData.pop(u"timestamp")
 203         return WayData
 204
 205     def WayDelete(self, WayData):
 206         """ Delete way with WayData. Returns updated WayData (without timestamp). """
 207         if self._CurrentChangesetId == -1:
 208             raise Exception, "No changeset currently opened"
 209         WayData[u"changeset"] = self._CurrentChangesetId
 210         result = self._delete("/api/0.6/way/"+str(WayData[u"id"]), self._XmlBuild("way", WayData))
 211         WayData[u"version"] = int(result.strip())
 212         WayData[u"visible"] = False
 213         if u"timestamp" in WayData: WayData.pop(u"timestamp")
 214         return WayData
 215
 216     def WayCreate(self, WayData):
 217         """ Creates a way. Returns updated WayData (without timestamp). """
 218         if self._CurrentChangesetId == -1:
 219             raise Exception, "No changeset currently opened"
 220         if NodeData.get(u"id", -1) > 0:
 221             raise Exception, "This way already exists"
 222         WayData[u"changeset"] = self._CurrentChangesetId
 223         result = self._put("/api/0.6/way/create", self._XmlBuild("way", WayData))
 224         WayData[u"id"]      = int(result.strip())
 225         WayData[u"version"] = 1
 226         if u"timestamp" in WayData: WayData.pop(u"timestamp")
 227         return WayData
 228
 229     def WayHistory(self, WayId):
 230         """ Returns dict(WayVerrsion: WayData). """
 231         uri = "/api/0.6/way/"+str(WayId)+"/history"
 232         data = self._get(uri)
 233         data = xml.dom.minidom.parseString(data)
 234         result = {}
 235         for data in data.getElementsByTagName("osm")[0].getElementsByTagName("way"):
 236             data = self._DomParseWay(data)
 237             result[data[u"version"]] = data
 238         return result
 239
 240     def WayRelations(self, WayId):
 241         """ Returns [RelationData, ...] containing way #WayId. """
 242         uri = "/api/0.6/way/%d/relations"%WayId
 243         data = self._get(uri)
 244         data = xml.dom.minidom.parseString(data)
 245         result = []
 246         for data in data.getElementsByTagName("osm")[0].getElementsByTagName("relation"):
 247             data = self._DomParseRelation(data)
 248             result.append(data)
 249         return result
 250
 251     def WayFull(self, WayId):
 252         """ Return full data for way WayId as list of {type: node|way|relation, data: {}}. """
 253         uri = "/api/0.6/way/"+str(WayId)+"/full"
 254         data = self._get(uri)
 255         return self.ParseOsm(data)
 256
 257     def WaysGet(self, WayIdList):
 258         """ Returns dict(WayId: WayData) for each way in WayIdList """
 259         uri = "/api/0.6/ways?ways=" + ",".join([str(x) for x in WayIdList])
 260         data = self._get(uri)
 261         data = xml.dom.minidom.parseString(data)
 262         result = {}
 263         for data in data.getElementsByTagName("osm")[0].getElementsByTagName("way"):
 264             data = self._DomParseWay(data)
 265             result[data[u"id"]] = data
 266         return result
 267
 268     #######################################################################
 269     # Relation                                                            #
 270     #######################################################################
 271
 272     def RelationGet(self, RelationId, RelationVersion = -1):
 273         """ Returns RelationData for relation #RelationId. """
 274         uri = "/api/0.6/relation/"+str(RelationId)
 275         if RelationVersion <> -1: uri += "/"+str(RelationVersion)
 276         data = self._get(uri)
 277         if not data: return data
 278         data = xml.dom.minidom.parseString(data)
 279         data = data.getElementsByTagName("osm")[0].getElementsByTagName("relation")[0]
 280         return self._DomParseRelation(data)
 281
 282     def RelationUpdate(self, RelationData):
 283         """ Updates relation with RelationData. Returns updated RelationData (without timestamp). """
 284         if self._CurrentChangesetId == -1:
 285             raise Exception, "No changeset currently opened"
 286         RelationData[u"changeset"] = self._CurrentChangesetId
 287         result = self._put("/api/0.6/relation/"+str(RelationData[u"id"]), self._XmlBuild("relation", RelationData))
 288         RelationData[u"version"] = int(result.strip())
 289         if u"timestamp" in RelationData: RelationData.pop(u"timestamp")
 290         return RelationData
 291
 292     def RelationDelete(self, RelationData):
 293         """ Delete relation with RelationData. Returns updated RelationData (without timestamp). """
 294         if self._CurrentChangesetId == -1:
 295             raise Exception, "No changeset currently opened"
 296         RelationData[u"changeset"] = self._CurrentChangesetId
 297         result = self._delete("/api/0.6/relation/"+str(RelationData[u"id"]), self._XmlBuild("relation", RelationData))
 298         RelationData[u"version"] = int(result.strip())
 299         RelationData[u"visible"] = False
 300         if u"timestamp" in RelationData: RelationData.pop(u"timestamp")
 301         return RelationData
 302
 303     def RelationCreate(self, RelationData):
 304         """ Creates a relation. Returns updated RelationData (without timestamp). """
 305         if self._CurrentChangesetId == -1:
 306             raise Exception, "No changeset currently opened"
 307         if NodeData.get(u"id", -1) > 0:
 308             raise Exception, "This relation already exists"
 309         RelationData[u"changeset"] = self._CurrentChangesetId
 310         result = self._put("/api/0.6/relation/create", self._XmlBuild("relation", RelationData))
 311         RelationData[u"id"]      = int(result.strip())
 312         RelationData[u"version"] = 1
 313         if u"timestamp" in RelationData: RelationData.pop(u"timestamp")
 314         return RelationData
 315
 316     def RelationHistory(self, RelationId):
 317         """ Returns dict(RelationVerrsion: RelationData). """
 318         uri = "/api/0.6/relation/"+str(RelationId)+"/history"
 319         data = self._get(uri)
 320         data = xml.dom.minidom.parseString(data)
 321         result = {}
 322         for data in data.getElementsByTagName("osm")[0].getElementsByTagName("relation"):
 323             data = self._DomParseRelation(data)
 324             result[data[u"version"]] = data
 325         return result
 326
 327     def RelationRelations(self, RelationId):
 328         """ Returns list of RelationData containing relation #RelationId. """
 329         uri = "/api/0.6/relation/%d/relations"%RelationId
 330         data = self._get(uri)
 331         data = xml.dom.minidom.parseString(data)
 332         result = []
 333         for data in data.getElementsByTagName("osm")[0].getElementsByTagName("relation"):
 334             data = self._DomParseRelation(data)
 335             result.append(data)
 336         return result
 337
 338     def RelationFull(self, RelationId):
 339         """ Return full data for way WayId as list of {type: node|way|relation, data: {}}. """
 340         uri = "/api/0.6/relation/"+str(RelationId)+"/full"
 341         data = self._get(uri)
 342         return self.ParseOsm(data)
 343
 344     def RelationsGet(self, RelationIdList):
 345         """ Returns dict(RelationId: RelationData) for each relation in RelationIdList """
 346         uri = "/api/0.6/relations?relations=" + ",".join([str(x) for x in RelationIdList])
 347         data = self._get(uri)
 348         data = xml.dom.minidom.parseString(data)
 349         result = {}
 350         for data in data.getElementsByTagName("osm")[0].getElementsByTagName("relation"):
 351             data = self._DomParseRelation(data)
 352             result[data[u"id"]] = data
 353         return result
 354
 355     #######################################################################
 356     # Changeset                                                           #
 357     #######################################################################
 358
 359     def ChangesetGet(self, ChangesetId):
 360         """ Returns ChangesetData for changeset #ChangesetId. """
 361         data = self._get("/api/0.6/changeset/"+str(ChangesetId))
 362         data = xml.dom.minidom.parseString(data)
 363         data = data.getElementsByTagName("osm")[0].getElementsByTagName("changeset")[0]
 364         return self._DomParseChangeset(data)
 365
 366     def ChangesetUpdate(self, ChangesetTags = {}):
 367         """ Updates current changeset with ChangesetTags. """
 368         if self._CurrentChangesetId == -1:
 369             raise Exception, "No changeset currently opened"
 370         if u"created_by" not in ChangesetTags:
 371             ChangesetTags[u"created_by"] = self._created_by
 372         result = self._put("/api/0.6/changeset/"+str(self._CurrentChangesetId), self._XmlBuild("changeset", {u"tag": ChangesetTags}))
 373         return self._CurrentChangesetId
 374
 375     def ChangesetCreate(self, ChangesetTags = {}):
 376         """ Opens a changeset. Returns #ChangesetId. """
 377         if self._CurrentChangesetId <> -1:
 378             raise Exception, "Changeset alreadey opened"
 379         if u"created_by" not in ChangesetTags:
 380             ChangesetTags[u"created_by"] = self._created_by
 381         result = self._put("/api/0.6/changeset/create", self._XmlBuild("changeset", {u"tag": ChangesetTags}))
 382         self._CurrentChangesetId   = int(result)
 383         self._CurrentChangesetTags = ChangesetTags
 384         self._CurrentChangesetCpt  = 0
 385         return self._CurrentChangesetId
 386
 387     def ChangesetClose(self):
 388         """ Closes current changeset. Returns #ChangesetId. """
 389         if self._CurrentChangesetId == -1:
 390             raise Exception, "No changeset currently opened"
 391         result = self._put("/api/0.6/changeset/"+str(self._CurrentChangesetId)+"/close", u"")
 392         CurrentChangesetId = self._CurrentChangesetId
 393         self._CurrentChangesetId = -1
 394         return CurrentChangesetId
 395
 396     def ChangesetUpload(self):
 397         raise NotImplemented
 398
 399     def ChangesetDownload(self, ChangesetId):
 400         """ Download data from a changeset. Returns list of dict {type: node|way|relation, action: create|delete|modify, data: {}}. """
 401         uri = "/api/0.6/changeset/"+str(ChangesetId)+"/download"
 402         data = self._get(uri)
 403         return self.ParseOsc(data)
 404
 405     def ChangesetsGet(self, min_lon=None, min_lat=None, max_lon=None, max_lat=None, userid=None, closed_after=None, created_before=None, only_open=False, only_closed=False):
 406         """ Returns dict(ChangsetId: ChangesetData) matching all criteria. """
 407         raise NotImplemented
 408
 409     #######################################################################
 410     # Other                                                               #
 411     #######################################################################
 412
 413     def Map(self, min_lon, min_lat, max_lon, max_lat):
 414         """ Download data in bounding box. Returns list of dict {type: node|way|relation, data: {}}. """
 415         uri = "/api/0.6/map?bbox=%f,%f,%f,%f"%(min_lon, min_lat, max_lon, max_lat)
 416         data = self._get(uri)
 417         return self.ParseOsm(data)
 418
 419     #######################################################################
 420     # Data parser                                                         #
 421     #######################################################################
 422
 423     def ParseOsm(self, data):
 424         """ Parse osm data. Returns list of dict {type: node|way|relation, data: {}}. """
 425         data = xml.dom.minidom.parseString(data)
 426         data = data.getElementsByTagName("osm")[0]
 427         result = []
 428         for elem in data.childNodes:
 429             if elem.nodeName == u"node":
 430                 result.append({u"type": elem.nodeName, u"data": self._DomParseNode(elem)})
 431             elif elem.nodeName == u"way":
 432                 result.append({u"type": elem.nodeName, u"data": self._DomParseWay(elem)})
 433             elif elem.nodeName == u"relation":
 434                 result.append({u"type": elem.nodeName, u"data": self._DomParseRelation(elem)})
 435         return result
 436
 437     def ParseOsc(self, data):
 438         """ Parse osc data. Returns list of dict {type: node|way|relation, action: create|delete|modify, data: {}}. """
 439         data = xml.dom.minidom.parseString(data)
 440         data = data.getElementsByTagName("osmChange")[0]
 441         result = []
 442         for action in data.childNodes:
 443             if action.nodeName == u"#text": continue
 444             for elem in action.childNodes:
 445                 if elem.nodeName == u"node":
 446                     result.append({u"action":action.nodeName, u"type": elem.nodeName, u"data": self._DomParseNode(elem)})
 447                 elif elem.nodeName == u"way":
 448                     result.append({u"action":action.nodeName, u"type": elem.nodeName, u"data": self._DomParseWay(elem)})
 449                 elif elem.nodeName == u"relation":
 450                     result.append({u"action":action.nodeName, u"type": elem.nodeName, u"data": self._DomParseRelation(elem)})
 451         return result
 452
 453     #######################################################################
 454     # Internal http function                                              #
 455     #######################################################################
 456
 457     def _http_request(self, cmd, path, auth, send):
 458         self._conn.putrequest(cmd, path)
 459         self._conn.putheader('User-Agent', self._created_by)
 460         if auth:
 461             self._conn.putheader('Authorization', 'Basic ' + base64.encodestring(self._username + ':' + self._password).strip())
 462         if send:
 463             self._conn.putheader('Content-Length', len(send))
 464         self._conn.endheaders()
 465         if send:
 466             self._conn.send(send)
 467         response = self._conn.getresponse()
 468         if response.status <> 200:
 469             response.read()
 470             if response.status == 410:
 471                 return None
 472             raise Exception, "API returns unexpected status code "+str(response.status)+" ("+response.reason+")"
 473         return response.read()
 474
 475     def _http(self, cmd, path, auth, send):
 476         i = 0
 477         while True:
 478             i += 1
 479             try:
 480                 return self._http_request(cmd, path, auth, send)
 481             except:
 482                 if i == 5: raise
 483                 if i <> 1: time.sleep(2)
 484                 self._conn = httplib.HTTPConnection(self._api, 80)
 485
 486     def _get(self, path):
 487         return self._http('GET', path, False, None)
 488
 489     def _put(self, path, data):
 490         return self._http('PUT', path, True, data)
 491
 492     def _delete(self, path, data):
 493         return self._http('DELETE', path, True, data)
 494
 495     #######################################################################
 496     # Internal dom function                                               #
 497     #######################################################################
 498
 499     def _DomGetAttributes(self, DomElement):
 500         """ Returns a formated dictionnary of attributes of a DomElement. """
 501         result = {}
 502         for k, v in DomElement.attributes.items():
 503             if k == u"uid"         : v = int(v)
 504             elif k == u"changeset" : v = int(v)
 505             elif k == u"version"   : v = int(v)
 506             elif k == u"id"        : v = int(v)
 507             elif k == u"lat"       : v = float(v)
 508             elif k == u"lon"       : v = float(v)
 509             elif k == u"open"      : v = v=="true"
 510             elif k == u"visible"   : v = v=="true"
 511             elif k == u"ref"       : v = int(v)
 512             result[k] = v
 513         return result
 514
 515     def _DomGetTag(self, DomElement):
 516         """ Returns the dictionnary of tags of a DomElement. """
 517         result = {}
 518         for t in DomElement.getElementsByTagName("tag"):
 519             k = t.attributes["k"].value
 520             v = t.attributes["v"].value
 521             result[k] = v
 522         return result
 523
 524     def _DomGetNd(self, DomElement):
 525         """ Returns the list of nodes of a DomElement. """
 526         result = []
 527         for t in DomElement.getElementsByTagName("nd"):
 528             result.append(int(int(t.attributes["ref"].value)))
 529         return result
 530
 531     def _DomGetMember(self, DomElement):
 532         """ Returns a list of relation members. """
 533         result = []
 534         for m in DomElement.getElementsByTagName("member"):
 535             result.append(self._DomGetAttributes(m))
 536         return result
 537
 538     def _DomParseNode(self, DomElement):
 539         """ Returns NodeData for the node. """
 540         result = self._DomGetAttributes(DomElement)
 541         result[u"tag"] = self._DomGetTag(DomElement)
 542         return result
 543
 544     def _DomParseWay(self, DomElement):
 545         """ Returns WayData for the way. """
 546         result = self._DomGetAttributes(DomElement)
 547         result[u"tag"] = self._DomGetTag(DomElement)
 548         result[u"nd"]  = self._DomGetNd(DomElement)
 549         return result
 550
 551     def _DomParseRelation(self, DomElement):
 552         """ Returns RelationData for the relation. """
 553         result = self._DomGetAttributes(DomElement)
 554         result[u"tag"]    = self._DomGetTag(DomElement)
 555         result[u"member"] = self._DomGetMember(DomElement)
 556         return result
 557
 558     def _DomParseChangeset(self, DomElement):
 559         """ Returns ChangesetData for the changeset. """
 560         result = self._DomGetAttributes(DomElement)
 561         result[u"tag"] = self._DomGetTag(DomElement)
 562         return result
 563
 564     #######################################################################
 565     # Internal xml builder                                                #
 566     #######################################################################
 567
 568     def _XmlBuild(self, ElementType, ElementData):
 569
 570         xml  = u""
 571         xml += u"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
 572         xml += u"<osm version=\"0.6\" generator=\"" + self._created_by + "\">\n"
 573
 574         # <element attr="val">
 575         xml += u"  <" + ElementType
 576         if u"id" in ElementData:
 577             xml += u" id=\"" + str(ElementData[u"id"]) + u"\""
 578         if u"lat" in ElementData:
 579             xml += u" lat=\"" + str(ElementData[u"lat"]) + u"\""
 580         if u"lon" in ElementData:
 581             xml += u" lon=\"" + str(ElementData[u"lon"]) + u"\""
 582         if u"version" in ElementData:
 583             xml += u" version=\"" + str(ElementData[u"version"]) + u"\""
 584         xml += u" visible=\"" + str(ElementData.get(u"visible", True)).lower() + u"\""
 585         if ElementType in [u"node", u"way", u"relation"]:
 586             xml += u" changeset=\"" + str(self._CurrentChangesetId) + u"\""
 587         xml += u">\n"
 588
 589         # <tag... />
 590         for k, v in ElementData.get(u"tag", {}).items():
 591             xml += u"    <tag k=\""+self._XmlEncode(k)+u"\" v=\""+self._XmlEncode(v)+u"\"/>\n"
 592
 593         # <member... />
 594         for member in ElementData.get(u"member", []):
 595             xml += u"    <member type=\""+member[u"type"]+"\" ref=\""+str(member[u"ref"])+u"\" role=\""+self._XmlEncode(member[u"role"])+"\"/>\n"
 596
 597         # <nd... />
 598         for ref in ElementData.get(u"nd", []):
 599             xml += u"    <nd ref=\""+str(ref)+u"\"/>\n"
 600
 601         # </element>
 602         xml += u"  </" + ElementType + u">\n"
 603
 604         xml += u"</osm>\n"
 605
 606         return xml.encode("utf8")
 607
 608     def _XmlEncode(self, text):
 609         return text.replace("&", "&amp;").replace("\"", "&quot;")
 610
 611 ## End of main class                                                     ##
 612 ###########################################################################