Lib/xml/sax/_exceptions.py

   1 """Different kinds of SAX Exceptions"""
   2 import sys
   3 if sys.platform[:4] == "java":
   4     from java.lang import Exception
   5 del sys
   6
   7 # ===== SAXEXCEPTION =====
   8
   9 class SAXException(Exception):
  10     """Encapsulate an XML error or warning. This class can contain
  11     basic error or warning information from either the XML parser or
  12     the application: you can subclass it to provide additional
  13     functionality, or to add localization. Note that although you will
  14     receive a SAXException as the argument to the handlers in the
  15     ErrorHandler interface, you are not actually required to throw
  16     the exception; instead, you can simply read the information in
  17     it."""
  18
  19     def __init__(self, msg, exception=None):
  20         """Creates an exception. The message is required, but the exception
  21         is optional."""
  22         self._msg = msg
  23         self._exception = exception
  24         Exception.__init__(self, msg)
  25
  26     def getMessage(self):
  27         "Return a message for this exception."
  28         return self._msg
  29
  30     def getException(self):
  31         "Return the embedded exception, or None if there was none."
  32         return self._exception
  33
  34     def __str__(self):
  35         "Create a string representation of the exception."
  36         return self._msg
  37
  38     def __getitem__(self, ix):
  39         """Avoids weird error messages if someone does exception[ix] by
  40         mistake, since Exception has __getitem__ defined."""
  41         raise AttributeError("__getitem__")
  42
  43
  44 # ===== SAXPARSEEXCEPTION =====
  45
  46 class SAXParseException(SAXException):
  47     """Encapsulate an XML parse error or warning.
  48
  49     This exception will include information for locating the error in
  50     the original XML document. Note that although the application will
  51     receive a SAXParseException as the argument to the handlers in the
  52     ErrorHandler interface, the application is not actually required
  53     to throw the exception; instead, it can simply read the
  54     information in it and take a different action.
  55
  56     Since this exception is a subclass of SAXException, it inherits
  57     the ability to wrap another exception."""
  58
  59     def __init__(self, msg, exception, locator):
  60         "Creates the exception. The exception parameter is allowed to be None."
  61         SAXException.__init__(self, msg, exception)
  62         self._locator = locator
  63
  64         # We need to cache this stuff at construction time.
  65         # If this exception is thrown, the objects through which we must
  66         # traverse to get this information may be deleted by the time
  67         # it gets caught.
  68         self._systemId = self._locator.getSystemId()
  69         self._colnum = self._locator.getColumnNumber()
  70         self._linenum = self._locator.getLineNumber()
  71
  72     def getColumnNumber(self):
  73         """The column number of the end of the text where the exception
  74         occurred."""
  75         return self._colnum
  76
  77     def getLineNumber(self):
  78         "The line number of the end of the text where the exception occurred."
  79         return self._linenum
  80
  81     def getPublicId(self):
  82         "Get the public identifier of the entity where the exception occurred."
  83         return self._locator.getPublicId()
  84
  85     def getSystemId(self):
  86         "Get the system identifier of the entity where the exception occurred."
  87         return self._systemId
  88
  89     def __str__(self):
  90         "Create a string representation of the exception."
  91         sysid = self.getSystemId()
  92         if sysid is None:
  93             sysid = "<unknown>"
  94         linenum = self.getLineNumber()
  95         if linenum is None:
  96            linenum = "?"
  97         colnum = self.getColumnNumber()
  98         if colnum is None:
  99            colnum = "?"
 100         return "%s:%s:%s: %s" % (sysid, linenum, colnum, self._msg)
 101
 102
 103 # ===== SAXNOTRECOGNIZEDEXCEPTION =====
 104
 105 class SAXNotRecognizedException(SAXException):
 106     """Exception class for an unrecognized identifier.
 107
 108     An XMLReader will raise this exception when it is confronted with an
 109     unrecognized feature or property. SAX applications and extensions may
 110     use this class for similar purposes."""
 111
 112
 113 # ===== SAXNOTSUPPORTEDEXCEPTION =====
 114
 115 class SAXNotSupportedException(SAXException):
 116     """Exception class for an unsupported operation.
 117
 118     An XMLReader will raise this exception when a service it cannot
 119     perform is requested (specifically setting a state or value). SAX
 120     applications and extensions may use this class for similar
 121     purposes."""
 122
 123 # ===== SAXNOTSUPPORTEDEXCEPTION =====
 124
 125 class SAXReaderNotAvailable(SAXNotSupportedException):
 126     """Exception class for a missing driver.
 127
 128     An XMLReader module (driver) should raise this exception when it
 129     is first imported, e.g. when a support module cannot be imported.
 130     It also may be raised during parsing, e.g. if executing an external
 131     program is not permitted."""