Source Code for Module qubx.xmlt

  1  """ XML tools; so far just conversion between object attributes and xml. 
  2   
  3  Copyright 2007-2011 Research Foundation State University of New York  
  4  This file is part of QUB Express.                                           
  5   
  6  QUB Express is free software; you can redistribute it and/or modify           
  7  it under the terms of the GNU General Public License as published by  
  8  the Free Software Foundation, either version 3 of the License, or     
  9  (at your option) any later version.                                   
 10   
 11  QUB Express is distributed in the hope that it will be useful,                
 12  but WITHOUT ANY WARRANTY; without even the implied warranty of        
 13  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         
 14  GNU General Public License for more details.                          
 15   
 16  You should have received a copy of the GNU General Public License,    
 17  named LICENSE.txt, in the QUB Express program directory.  If not, see         
 18  <http://www.gnu.org/licenses/>.                                       
 19   
 20  """ 
 21   
 22  import xml.dom.minidom 
 23  from qubx.util_types import * 
 24  import sys 
 25   
 26  try: 
 27      import xml.dom.ext 
 28      XMLPrettyPrint = xml.dom.ext.PrettyPrint 
 29  except: 
 30 -    def XMLPrettyPrint(doc, f=None): 
 31          fi = f or sys.stdout 
 32          fi.write(doc.toxml()) 
 33   
 34 -class Field(Anon): 
 35      """ 
 36  Field(name, default, accept=str, format=str): an attribute for <properties>. 
 37   
 38      - name: the object attribute of interest, e.g. name="foo" selects obj.foo 
 39      - default: default value, of whatever type 
 40      - accept: function which parses a string and returns the appropriate type, or raises an exception 
 41        in this case the exception means to fall back to the default 
 42      - format: function which converts your type to string; or a %-style format string, e.g. "%.8g" 
 43  """ 
 44   
 45 -def PropertiesToXML(obj, doc, ns, fields): 
 46      """ 
 47  Returns a DOM element representing specified fields of obj. 
 48       
 49      - obj: any python object 
 50      - doc: the destination xml.dom Document 
 51      - ns:  doc's xml.dom namespace 
 52      - fields: a list of qubx.xmlt.Field(name, default, accept=str, format=str) 
 53   
 54  example: 
 55        >>> obj = object() 
 56        >>> obj.name = 'x' 
 57        >>> obj.length = obj.volume = 0.0 
 58         
 59        >>> fields = [Field(name='name', accept=str, default='untitled'), 
 60        ...           Field(name='length', accept=float, format=str, default=2.3), 
 61        ...           Field(name='volume', accept=float, format='%9g', default=2.3)] 
 62   
 63        >>> print PropertiesToXML(obj, doc, ns, fields) 
 64        <properties> 
 65          <property name='name'>x</property> 
 66          <property name='length'>0.0</property> 
 67          <property name='volume'>0.0</property> 
 68        </properties> 
 69  """ 
 70   
 71      properties = doc.createElementNS(ns, 'properties') 
 72      for field in fields: 
 73          prop = properties.appendChild( doc.createElementNS(ns, 'property') ) 
 74          prop.setAttribute('name', field.name) 
 75          val = obj.__getattr__(field.name) 
 76          data = None 
 77          if field.format: 
 78              try: 
 79                  if callable(field.format): 
 80                      data = field.format(val) 
 81                  else: 
 82                      data = field.format % val 
 83              except: 
 84                  traceback.print_exc() 
 85          if data is None: 
 86              data = str(val) 
 87          prop.appendChild( doc.createTextNode(data) ) 
 88      return properties 
 89   
 90 -def XMLToProperties(properties, obj, fields=None): 
 91      """ 
 92  Sets attributes of obj from xml.dom element <properties>. 
 93   
 94      @param properties: an xml.dom element with children <property name=''>value</property> 
 95      @param obj: the receiver of obj.name = value 
 96      @param fields: optional list of qubx.xmlt.Field(name, default, accept=str, format=str):: 
 97        if fields is None: 
 98            obj.name = string value for all <property> elements 
 99        else: 
100            only <property>s listed in fields are copied; 
101            obj.name = default if no <property> or failed "accept" conversion 
102   
103        example: 
104   
105        >>> obj = object() 
106        >>> fields = [Field(name='name', accept=str, default='untitled'), 
107        ...           Field(name='length', accept=float, format=str, default=2.3), 
108        ...           Field(name='volume', accept=float, format='%9g', default=2.3)] 
109        >>> XMLToProperties(properties_element, obj, fields) 
110        >>> print obj.name, obj.length, obj.volume 
111        x, 0.0, 0.0 
112  """ 
113   
114      if fields is None: 
115          strs = obj 
116      else: 
117          strs = Anon() 
118      for node in properties.childNodes: 
119          try: 
120              if node.nodeName == 'property': 
121                  name = node.getAttribute('name') 
122                  data = node.childNodes[0] 
123                  strs.__setattr__(name, data.nodeValue) 
124          except: 
125              traceback.print_exc() 
126      if not (fields is None): 
127          for field in fields: 
128              accept = field.accept or str 
129              sval = strs.__getattr__(field.name) 
130              if not (sval is None): 
131                  try: 
132                      obj.__setattr__(field.name, accept(sval)) 
133                  except: 
134                      traceback.print_exc() 
135              if obj.__getattr__(field.name) is None: 
136                  obj.__setattr__(field.name, field.default) 
137