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saxutils.py

00001 """
A library of useful helper classes to the saxlib classes, for the
convenience of application and driver writers.

$Id: saxutils.py,v 1.35 2004/03/20 07:46:04 fdrake Exp $
"""

import os, urlparse, urllib2, types
import handler
import xmlreader
import sys, _exceptions, saxlib

try:
    _StringTypes = [types.StringType, types.UnicodeType]
except AttributeError: # 1.5 compatibility:UnicodeType not defined
    _StringTypes = [types.StringType]

00018 def __dict_replace(s, d):
    """Replace substrings of a string using a dictionary."""
    for key, value in d.items():
        s = s.replace(key, value)
    return s

00024 def escape(data, entities={}):
    """Escape &, <, and > in a string of data.

    You can escape other strings of data by passing a dictionary as
    the optional entities parameter.  The keys and values must all be
    strings; each key will be replaced with its corresponding value.
    """
    data = data.replace("&", "&amp;")
    data = data.replace("<", "&lt;")
    data = data.replace(">", "&gt;")
    if entities:
        data = __dict_replace(data, entities)
    return data

00038 def unescape(data, entities={}):
    """Unescape &amp;, &lt;, and &gt; in a string of data.

    You can unescape other strings of data by passing a dictionary as
    the optional entities parameter.  The keys and values must all be
    strings; each key will be replaced with its corresponding value.
    """
    data = data.replace("&lt;", "<")
    data = data.replace("&gt;", ">")
    if entities:
        data = __dict_replace(data, entities)
    # must do ampersand last
    return data.replace("&amp;", "&")

00052 def quoteattr(data, entities={}):
    """Escape and quote an attribute value.

    Escape &, <, and > in a string of data, then quote it for use as
    an attribute value.  The \" character will be escaped as well, if
    necessary.

    You can escape other strings of data by passing a dictionary as
    the optional entities parameter.  The keys and values must all be
    strings; each key will be replaced with its corresponding value.
    """
    data = escape(data, entities)
    if '"' in data:
        if "'" in data:
            data = '"%s"' % data.replace('"', "&quot;")
        else:
            data = "'%s'" % data
    else:
        data = '"%s"' % data
    return data

# --- DefaultHandler

00075 class DefaultHandler(handler.EntityResolver, handler.DTDHandler,
                     handler.ContentHandler, handler.ErrorHandler):
    """Default base class for SAX2 event handlers. Implements empty
    methods for all callback methods, which can be overridden by
    application implementors. Replaces the deprecated SAX1 HandlerBase
    class."""

# --- Location

00084 class Location:
    """Represents a location in an XML entity. Initialized by being passed
    a locator, from which it reads off the current location, which is then
    stored internally."""

    def __init__(self, locator):
        self.__col = locator.getColumnNumber()
        self.__line = locator.getLineNumber()
        self.__pubid = locator.getPublicId()
        self.__sysid = locator.getSystemId()

    def getColumnNumber(self):
        return self.__col

    def getLineNumber(self):
        return self.__line

    def getPublicId(self):
        return self.__pubid

    def getSystemId(self):
        return self.__sysid

    def __str__(self):
        if self.__line is None:
            line = "?"
        else:
            line = self.__line
        if self.__col is None:
            col = "?"
        else:
            col = self.__col
        return "%s:%s:%s" % (
            self.__sysid or self.__pubid or "<unknown>",
            line, col)

# --- ErrorPrinter

class ErrorPrinter:
    "A simple class that just prints error messages to standard out."

    def __init__(self, level=0, outfile=sys.stderr):
        self._level = level
        self._outfile = outfile

    def warning(self, exception):
        if self._level <= 0:
            self._outfile.write("WARNING in %s: %s\n" %
                               (self.__getpos(exception),
                                exception.getMessage()))

    def error(self, exception):
        if self._level <= 1:
            self._outfile.write("ERROR in %s: %s\n" %
                               (self.__getpos(exception),
                                exception.getMessage()))

    def fatalError(self, exception):
        if self._level <= 2:
            self._outfile.write("FATAL ERROR in %s: %s\n" %
                               (self.__getpos(exception),
                                exception.getMessage()))

    def __getpos(self, exception):
        if isinstance(exception, _exceptions.SAXParseException):
            return "%s:%s:%s" % (exception.getSystemId(),
                                 exception.getLineNumber(),
                                 exception.getColumnNumber())
        else:
            return "<unknown>"

# --- ErrorRaiser

class ErrorRaiser:
    "A simple class that just raises the exceptions it is passed."

    def __init__(self, level = 0):
        self._level = level

    def error(self, exception):
        if self._level <= 1:
            raise exception

    def fatalError(self, exception):
        if self._level <= 2:
            raise exception

    def warning(self, exception):
        if self._level <= 0:
            raise exception

# --- AttributesImpl now lives in xmlreader
from xmlreader import AttributesImpl

# --- XMLGenerator is the SAX2 ContentHandler for writing back XML
import codecs

def _outputwrapper(stream,encoding):
    writerclass = codecs.lookup(encoding)[3]
    return writerclass(stream)

if hasattr(codecs, "register_error"):
    def writetext(stream, text, entities={}):
        stream.errors = "xmlcharrefreplace"
        stream.write(escape(text, entities))
        stream.errors = "strict"
else:
    def writetext(stream, text, entities={}):
        text = escape(text, entities)
        try:
            stream.write(text)
        except UnicodeError:
            for c in text:
                try:
                    stream.write(c)
                except UnicodeError:
                    stream.write(u"&#%d;" % ord(c))

def writeattr(stream, text):
    countdouble = text.count('"')
    if countdouble:
        countsingle = text.count("'")
        if countdouble <= countsingle:
            entities = {'"': "&quot;"}
            quote = '"'
        else:
            entities = {"'": "&apos;"}
            quote = "'"
    else:
        entities = {}
        quote = '"'
    stream.write(quote)
    writetext(stream, text, entities)
    stream.write(quote)


class XMLGenerator(handler.ContentHandler):
    GENERATED_PREFIX = "xml.sax.saxutils.prefix%s"

    def __init__(self, out=None, encoding="iso-8859-1"):
        if out is None:
            import sys
            out = sys.stdout
        handler.ContentHandler.__init__(self)
        self._out = _outputwrapper(out,encoding)
        self._ns_contexts = [{}] # contains uri -> prefix dicts
        self._current_context = self._ns_contexts[-1]
        self._undeclared_ns_maps = []
        self._encoding = encoding
        self._generated_prefix_ctr = 0
        return

    # ContentHandler methods

    def startDocument(self):
        self._out.write('<?xml version="1.0" encoding="%s"?>\n' %
                        self._encoding)

    def startPrefixMapping(self, prefix, uri):
        self._ns_contexts.append(self._current_context.copy())
        self._current_context[uri] = prefix
        self._undeclared_ns_maps.append((prefix, uri))

    def endPrefixMapping(self, prefix):
        self._current_context = self._ns_contexts[-1]
        del self._ns_contexts[-1]

    def startElement(self, name, attrs):
        self._out.write('<' + name)
        for (name, value) in attrs.items():
            self._out.write(' %s=' % name)
            writeattr(self._out, value)
        self._out.write('>')

    def endElement(self, name):
        self._out.write('</%s>' % name)

    def startElementNS(self, name, qname, attrs):
        if name[0] is None:
            name = name[1]
        elif self._current_context[name[0]] is None:
            # default namespace
            name = name[1]
        else:
            name = self._current_context[name[0]] + ":" + name[1]
        self._out.write('<' + name)

        for k,v in self._undeclared_ns_maps:
            if k is None:
                self._out.write(' xmlns="%s"' % (v or ''))
            else:
                self._out.write(' xmlns:%s="%s"' % (k,v))
        self._undeclared_ns_maps = []

        for (name, value) in attrs.items():
            if name[0] is None:
                name = name[1]
            elif self._current_context[name[0]] is None:
                # default namespace
                #If an attribute has a nsuri but not a prefix, we must
                #create a prefix and add a nsdecl
                prefix = self.GENERATED_PREFIX % self._generated_prefix_ctr
                self._generated_prefix_ctr = self._generated_prefix_ctr + 1
                name = prefix + ':' + name[1]
                self._out.write(' xmlns:%s=%s' % (prefix, quoteattr(name[0])))
                self._current_context[name[0]] = prefix
            else:
                name = self._current_context[name[0]] + ":" + name[1]
            self._out.write(' %s=' % name)
            writeattr(self._out, value)
        self._out.write('>')

    def endElementNS(self, name, qname):
        # XXX: if qname is not None, we better use it.
        # Python 2.0b2 requires us to use the recorded prefix for
        # name[0], though
        if name[0] is None:
            qname = name[1]
        elif self._current_context[name[0]] is None:
            qname = name[1]
        else:
            qname = self._current_context[name[0]] + ":" + name[1]
        self._out.write('</%s>' % qname)

    def characters(self, content):
        writetext(self._out, content)

    def ignorableWhitespace(self, content):
        self._out.write(content)

    def processingInstruction(self, target, data):
        self._out.write('<?%s %s?>' % (target, data))


00318 class LexicalXMLGenerator(XMLGenerator, saxlib.LexicalHandler):
    """A XMLGenerator that also supports the LexicalHandler interface"""

    def __init__(self, out=None, encoding="iso-8859-1"):
        XMLGenerator.__init__(self, out, encoding)
        self._in_cdata = 0

00325     def characters(self, content):
        if self._in_cdata:
            self._out.write(content.replace(']]>', ']]>]]&gt;<![CDATA['))
        else:
            self._out.write(escape(content))

    # LexicalHandler methods
    # (we only support the most important ones and inherit the rest)

00334     def startDTD(self, name, public_id, system_id):
        self._out.write('<!DOCTYPE %s' % name)
        if public_id:
            self._out.write(' PUBLIC %s %s' % (
                quoteattr(public_id or ""), quoteattr(system_id or "")
            ))
        elif system_id:
            self._out.write(' SYSTEM %s' % quoteattr(system_id or ""))

    def endDTD(self):
        self._out.write('>')

00346     def comment(self, content):
        self._out.write('<!--')
        self._out.write(content)
        self._out.write('-->')

00351     def startCDATA(self):
        self._in_cdata = 1
        self._out.write('<![CDATA[')

    def endCDATA(self):
        self._in_cdata = 0
        self._out.write(']]>')


# --- ContentGenerator is the SAX1 DocumentHandler for writing back XML
class ContentGenerator(XMLGenerator):

    def characters(self, str, start, end):
        # In SAX1, characters receives start and end; in SAX2, it receives
        # a string. For plain strings, we may want to use a buffer object.
        return XMLGenerator.characters(self, str[start:start+end])

# --- XMLFilterImpl
00369 class XMLFilterBase(saxlib.XMLFilter):
    """This class is designed to sit between an XMLReader and the
    client application's event handlers.  By default, it does nothing
    but pass requests up to the reader and events on to the handlers
    unmodified, but subclasses can override specific methods to modify
    the event stream or the configuration requests as they pass
    through."""

    # ErrorHandler methods

    def error(self, exception):
        self._err_handler.error(exception)

    def fatalError(self, exception):
        self._err_handler.fatalError(exception)

    def warning(self, exception):
        self._err_handler.warning(exception)

    # ContentHandler methods

    def setDocumentLocator(self, locator):
        self._cont_handler.setDocumentLocator(locator)

    def startDocument(self):
        self._cont_handler.startDocument()

    def endDocument(self):
        self._cont_handler.endDocument()

    def startPrefixMapping(self, prefix, uri):
        self._cont_handler.startPrefixMapping(prefix, uri)

    def endPrefixMapping(self, prefix):
        self._cont_handler.endPrefixMapping(prefix)

    def startElement(self, name, attrs):
        self._cont_handler.startElement(name, attrs)

    def endElement(self, name):
        self._cont_handler.endElement(name)

    def startElementNS(self, name, qname, attrs):
        self._cont_handler.startElementNS(name, qname, attrs)

    def endElementNS(self, name, qname):
        self._cont_handler.endElementNS(name, qname)

    def characters(self, content):
        self._cont_handler.characters(content)

    def ignorableWhitespace(self, chars):
        self._cont_handler.ignorableWhitespace(chars)

    def processingInstruction(self, target, data):
        self._cont_handler.processingInstruction(target, data)

    def skippedEntity(self, name):
        self._cont_handler.skippedEntity(name)

    # DTDHandler methods

    def notationDecl(self, name, publicId, systemId):
        self._dtd_handler.notationDecl(name, publicId, systemId)

    def unparsedEntityDecl(self, name, publicId, systemId, ndata):
        self._dtd_handler.unparsedEntityDecl(name, publicId, systemId, ndata)

    # EntityResolver methods

    def resolveEntity(self, publicId, systemId):
        self._ent_handler.resolveEntity(publicId, systemId)

    # XMLReader methods

    def parse(self, source):
        self._parent.setContentHandler(self)
        self._parent.setErrorHandler(self)
        self._parent.setEntityResolver(self)
        self._parent.setDTDHandler(self)
        self._parent.parse(source)

    def setLocale(self, locale):
        self._parent.setLocale(locale)

    def getFeature(self, name):
        return self._parent.getFeature(name)

    def setFeature(self, name, state):
        self._parent.setFeature(name, state)

    def getProperty(self, name):
        return self._parent.getProperty(name)

    def setProperty(self, name, value):
        self._parent.setProperty(name, value)

# FIXME: remove this backward compatibility hack when not needed anymore
XMLFilterImpl = XMLFilterBase

# --- BaseIncrementalParser

00471 class BaseIncrementalParser(xmlreader.IncrementalParser):
    """This class implements the parse method of the XMLReader
    interface using the feed, close and reset methods of the
    IncrementalParser interface as a convenience to SAX 2.0 driver
    writers."""

    def parse(self, source):
        source = prepare_input_source(source)
        self.prepareParser(source)

        self._cont_handler.startDocument()

        # FIXME: what about char-stream?
        inf = source.getByteStream()
        buffer = inf.read(16384)
        while buffer != "":
            self.feed(buffer)
            buffer = inf.read(16384)

        self.close()
        self.reset()

        self._cont_handler.endDocument()

00495     def prepareParser(self, source):
        """This method is called by the parse implementation to allow
        the SAX 2.0 driver to prepare itself for parsing."""
        raise NotImplementedError("prepareParser must be overridden!")

# --- Utility functions

00502 def prepare_input_source(source, base = ""):
    """This function takes an InputSource and an optional base URL and
    returns a fully resolved InputSource object ready for reading."""

    if type(source) in _StringTypes:
        source = xmlreader.InputSource(source)
    elif hasattr(source, "read"):
        f = source
        source = xmlreader.InputSource()
        source.setByteStream(f)
        if hasattr(f, "name"):
            source.setSystemId(f.name)

    if source.getByteStream() is None:
        sysid = source.getSystemId()
        if os.path.isfile(sysid):
            basehead = os.path.split(os.path.normpath(base))[0]
            source.setSystemId(os.path.join(basehead, sysid))
            f = open(sysid, "rb")
        else:
            source.setSystemId(urlparse.urljoin(base, sysid))
            f = urllib2.urlopen(source.getSystemId())

        source.setByteStream(f)

    return source

# ===========================================================================
#
# DEPRECATED SAX 1.0 CLASSES
#
# ===========================================================================

# --- AttributeMap

00537 class AttributeMap:
    """An implementation of AttributeList that takes an (attr,val) hash
    and uses it to implement the AttributeList interface."""

    def __init__(self, map):
        self.map=map

    def getLength(self):
        return len(self.map.keys())

    def getName(self, i):
        try:
            return self.map.keys()[i]
        except IndexError,e:
            return None

    def getType(self, i):
        return "CDATA"

    def getValue(self, i):
        try:
            if type(i)==types.IntType:
                return self.map[self.getName(i)]
            else:
                return self.map[i]
        except KeyError,e:
            return None

    def __len__(self):
        return len(self.map)

    def __getitem__(self, key):
        if type(key)==types.IntType:
            return self.map.keys()[key]
        else:
            return self.map[key]

    def items(self):
        return self.map.items()

    def keys(self):
        return self.map.keys()

    def has_key(self,key):
        return self.map.has_key(key)

    def get(self, key, alternative=None):
        return self.map.get(key, alternative)

    def copy(self):
        return AttributeMap(self.map.copy())

    def values(self):
        return self.map.values()

# --- Event broadcasting object

00594 class EventBroadcaster:
    """Takes a list of objects and forwards any method calls received
    to all objects in the list. The attribute list holds the list and
    can freely be modified by clients."""

    class Event:
        "Helper objects that represent event methods."

        def __init__(self,list,name):
            self.list=list
            self.name=name

        def __call__(self,*rest):
            for obj in self.list:
                apply(getattr(obj,self.name), rest)

    def __init__(self,list):
        self.list=list

    def __getattr__(self,name):
        return self.Event(self.list,name)

    def __repr__(self):
        return "<EventBroadcaster instance at %d>" % id(self)

# --- ESIS document handler
import saxlib
class ESISDocHandler(saxlib.HandlerBase):
    "A SAX document handler that produces naive ESIS output."

    def __init__(self,writer=sys.stdout):
        self.writer=writer

    def processingInstruction (self,target, remainder):
        """Receive an event signalling that a processing instruction
        has been found."""
        self.writer.write("?"+target+" "+remainder+"\n")

    def startElement(self,name,amap):
        "Receive an event signalling the start of an element."
        self.writer.write("("+name+"\n")
        for a_name in amap.keys():
            self.writer.write("A"+a_name+" "+amap[a_name]+"\n")

    def endElement(self,name):
        "Receive an event signalling the end of an element."
        self.writer.write(")"+name+"\n")

    def characters(self,data,start_ix,length):
        "Receive an event signalling that character data has been found."
        self.writer.write("-"+data[start_ix:start_ix+length]+"\n")

# --- XML canonizer

class Canonizer(saxlib.HandlerBase):
    "A SAX document handler that produces canonized XML output."

    def __init__(self,writer=sys.stdout):
        self.elem_level=0
        self.writer=writer

    def processingInstruction (self,target, remainder):
        if not target=="xml":
            self.writer.write("<?"+target+" "+remainder+"?>")

    def startElement(self,name,amap):
        self.writer.write("<"+name)

        a_names=amap.keys()
        a_names.sort()

        for a_name in a_names:
            self.writer.write(" "+a_name+"=\"")
            self.write_data(amap[a_name])
            self.writer.write("\"")
        self.writer.write(">")
        self.elem_level=self.elem_level+1

    def endElement(self,name):
        self.writer.write("</"+name+">")
        self.elem_level=self.elem_level-1

    def ignorableWhitespace(self,data,start_ix,length):
        self.characters(data,start_ix,length)

    def characters(self,data,start_ix,length):
        if self.elem_level>0:
            self.write_data(data[start_ix:start_ix+length])

    def write_data(self,data):
        "Writes datachars to writer."
        data=data.replace("&","&amp;")
        data=data.replace("<","&lt;")
        data=data.replace("\"","&quot;")
        data=data.replace(">","&gt;")
        data=data.replace(chr(9),"&#9;")
        data=data.replace(chr(10),"&#10;")
        data=data.replace(chr(13),"&#13;")
        self.writer.write(data)

# --- mllib

00696 class mllib:
    """A re-implementation of the htmllib, sgmllib and xmllib interfaces as a
    SAX DocumentHandler."""

# Unsupported:
# - setnomoretags
# - setliteral
# - translate_references
# - handle_xml
# - handle_doctype
# - handle_charref
# - handle_entityref
# - handle_comment
# - handle_cdata
# - tag_attributes

    def __init__(self):
        self.reset()

    def reset(self):
        import saxexts # only used here
        self.parser=saxexts.XMLParserFactory.make_parser()
        self.handler=mllib.Handler(self.parser,self)
        self.handler.reset()

    def feed(self,data):
        self.parser.feed(data)

    def close(self):
        self.parser.close()

    def get_stack(self):
        return self.handler.get_stack()

    # --- Handler methods (to be overridden)

    def handle_starttag(self,name,method,atts):
        method(atts)

    def handle_endtag(self,name,method):
        method()

    def handle_data(self,data):
        pass

    def handle_proc(self,target,data):
        pass

    def unknown_starttag(self,name,atts):
        pass

    def unknown_endtag(self,name):
        pass

    def syntax_error(self,message):
        pass

    # --- The internal handler class

00755     class Handler(saxlib.DocumentHandler,saxlib.ErrorHandler):
        """An internal class to handle SAX events and translate them to mllib
        events."""

        def __init__(self,driver,handler):
            self.driver=driver
            self.driver.setDocumentHandler(self)
            self.driver.setErrorHandler(self)
            self.handler=handler
            self.reset()

        def get_stack(self):
            return self.stack

        def reset(self):
            self.stack=[]

        # --- DocumentHandler methods

        def characters(self, ch, start, length):
            self.handler.handle_data(ch[start:start+length])

        def endElement(self, name):
            if hasattr(self.handler,"end_"+name):
                self.handler.handle_endtag(name,
                                          getattr(self.handler,"end_"+name))
            else:
                self.handler.unknown_endtag(name)

            del self.stack[-1]

        def ignorableWhitespace(self, ch, start, length):
            self.handler.handle_data(ch[start:start+length])

        def processingInstruction(self, target, data):
            self.handler.handle_proc(target,data)

        def startElement(self, name, atts):
            self.stack.append(name)

            if hasattr(self.handler,"start_"+name):
                self.handler.handle_starttag(name,
                                            getattr(self.handler,
                                                    "start_"+name),
                                             atts)
            else:
                self.handler.unknown_starttag(name,atts)

        # --- ErrorHandler methods

        def error(self, exception):
            self.handler.syntax_error(str(exception))

        def fatalError(self, exception):
            raise RuntimeError(str(exception))

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