Source Code for Module flumotion.common.xmlwriter

  1  # -*- Mode: Python; -*- 
  2  # vi:si:et:sw=4:sts=4:ts=4 
  3  # 
  4  # Flumotion - a streaming media server 
  5  # Copyright (C) 2004,2005,2006,2007,2008 Fluendo, S.L. (www.fluendo.com). 
  6  # All rights reserved. 
  7   
  8  # This file may be distributed and/or modified under the terms of 
  9  # the GNU General Public License version 2 as published by 
 10  # the Free Software Foundation. 
 11  # This file is distributed without any warranty; without even the implied 
 12  # warranty of merchantability or fitness for a particular purpose. 
 13  # See "LICENSE.GPL" in the source distribution for more information. 
 14   
 15  # Licensees having purchased or holding a valid Flumotion Advanced 
 16  # Streaming Server license may use this file in accordance with the 
 17  # Flumotion Advanced Streaming Server Commercial License Agreement. 
 18  # See "LICENSE.Flumotion" in the source distribution for more information. 
 19   
 20  # Headers in this file shall remain intact. 
 21   
 22  """xml serializer and component comparison 
 23  """ 
 24   
 25  from cStringIO import StringIO 
 26  from xml.sax.saxutils import quoteattr 
 27   
 28  __version__ = "$Rev: 6964 $" 
 29   
 30   
 31 -class XMLWriter(object): 
 32 -    def __init__(self): 
 33          self._data = StringIO() 
 34          self._tagStack = [] 
 35          self._indent = 0 
 36          self._indentChar = ' ' 
 37          self._indentUnit = 2 
 38   
 39      # Private 
 40   
 41 -    def _calcAttrsLength(self, attributes, indent): 
 42          if indent == -1: 
 43              return -1 
 44          attrLength = 0 
 45          for attr, value in attributes: 
 46              if value is None: 
 47                  raise ValueError( 
 48                      "value for attribute %s cannot be None" % (attr,)) 
 49              attrLength += 1 + len(attr) + len(quoteattr(value)) 
 50          return attrLength + indent 
 51   
 52 -    def _collectAttributes(self, attributes, indent=-1): 
 53          if not attributes: 
 54              return '' 
 55   
 56          if self._calcAttrsLength(attributes, indent) > 79: 
 57              indentLen = self._indent + indent 
 58          else: 
 59              indentLen = 0 
 60          first = True 
 61          attrValue = '' 
 62          for attr, value in attributes: 
 63              if indentLen and not first: 
 64                  attrValue += '\n%s' % (self._indentChar * indentLen) 
 65              if value is None: 
 66                  raise ValueError( 
 67                      "value for attribute %s cannot be None" % (attr,)) 
 68              attrValue += ' %s=%s' % (attr, quoteattr(value)) 
 69              if first: 
 70                  first = False 
 71          return attrValue 
 72   
 73 -    def _openTag(self, tagName, attributes=None): 
 74          attrs = self._collectAttributes( 
 75              attributes, len(tagName) + 1) 
 76          self.writeLine('<%s%s>' % (tagName, attrs)) 
 77   
 78 -    def _closeTag(self, tagName): 
 79          self.writeLine('</%s>' % (tagName,)) 
 80   
 81      # Public API 
 82   
 83 -    def getXML(self): 
 84          """Fetches the xml written by the writer 
 85          @returns: the xml 
 86          @rtype: string 
 87          """ 
 88          return self._data.getvalue() 
 89   
 90 -    def writeLine(self, line=''): 
 91          """Write a line to the xml. 
 92          This method honors the current indentation. 
 93          """ 
 94          self._data.write('%s%s\n' % (self._indentChar * self._indent, line)) 
 95   
 96 -    def writeTag(self, tagName, attributes=None, data=None): 
 97          """Writes out and closes a tag. Optionally writes data as a child node. 
 98          @param tagName: name of the tag 
 99          @param attributes: attributes or None 
100          @param data: data or None 
101          """ 
102          if attributes is None: 
103              attributes = [] 
104          prefix = '<%s' % (tagName,) 
105          if data is not None: 
106              suffix = '>%s</%s>' % (data, tagName) 
107          else: 
108              suffix = '/>' 
109          attrs = self._collectAttributes( 
110              attributes, len(prefix) + len(suffix)) 
111          self.writeLine(prefix + attrs + suffix) 
112   
113 -    def pushTag(self, tagName, attributes=None): 
114          """Push a tag:: 
115            - writes the tag and the attributes 
116            - increase the indentation for subsequent calls 
117          @param tagName: name of the tag to write 
118          @type tagName: string 
119          @param attributes: attributes to write 
120          @type attributes: list of 2 sizes tuples; (name, value) 
121          """ 
122          self._openTag(tagName, attributes) 
123          self._tagStack.append(tagName) 
124          self._indent += self._indentUnit 
125   
126 -    def popTag(self): 
127          """Decreases the indentation and closes the previously opened tag. 
128          @returns: name of the closed tag 
129          """ 
130          self._indent -= self._indentUnit 
131          tagName = self._tagStack.pop() 
132          self._closeTag(tagName) 
133          return tagName 
134   
135   
136 -def cmpComponentType(aType, bType): 
137      """Compare two component types the way they should be written in an xml 
138      file. Suitable for using as cmp argument to list.sort() or sorted(). 
139      @param aType: first component type 
140      @type aType: 
141      @param bType: second component type 
142      @type bType: 
143      @returns: -1, 0 or 1, see L{__builtin__.cmp} 
144      """ 
145      for suffix in ['-producer', 
146                     '-converter', 
147                     '-encoder', 
148                     '-muxer', 
149                     '-streamer']: 
150          bHasSuffix = bType.endswith(suffix) 
151          if aType.endswith(suffix): 
152              if bHasSuffix: 
153                  return cmp(aType, bType) 
154              else: 
155                  return -1 
156          elif bHasSuffix: 
157              return 1 
158      return cmp(aType, bType) 
159