from xml.sax.handler import ContentHandler
from xml.sax.xmlreader import Locator
import sys
import xml.sax
import xml.sax.handler
class AimlParserError(Exception): pass
class AimlHandler(ContentHandler):
# The legal states of the AIML parser
_STATE_OutsideAiml = 0
_STATE_InsideAiml = 1
_STATE_InsideCategory = 2
_STATE_InsidePattern = 3
_STATE_AfterPattern = 4
_STATE_InsideThat = 5
_STATE_AfterThat = 6
_STATE_InsideTemplate = 7
_STATE_AfterTemplate = 8
def __init__(self, encoding = "UTF-8"):
self.categories = {}
self._encoding = encoding
self._state = self._STATE_OutsideAiml
self._version = ""
self._namespace = ""
self._forwardCompatibleMode = False
self._currentPattern = ""
self._currentThat = ""
self._currentTopic = ""
self._insideTopic = False
self._currentUnknown = "" # the name of the current unknown element
# This is set to true when a parse error occurs in a category.
self._skipCurrentCategory = False
# Counts the number of parse errors in a particular AIML document.
# query with getNumErrors(). If 0, the document is AIML-compliant.
self._numParseErrors = 0
# TODO: select the proper validInfo table based on the version number.
self._validInfo = self._validationInfo101
# This stack of bools is used when parsing <li> elements inside
# <condition> elements, to keep track of whether or not an
# attribute-less "default" <li> element has been found yet. Only
# one default <li> is allowed in each <condition> element. We need
# a stack in order to correctly handle nested <condition> tags.
self._foundDefaultLiStack = []
# This stack of strings indicates what the current whitespace-handling
# behavior should be. Each string in the stack is either "default" or
# "preserve". When a new AIML element is encountered, a new string is
# pushed onto the stack, based on the value of the element's "xml:space"
# attribute (if absent, the top of the stack is pushed again). When
# ending an element, pop an object off the stack.
self._whitespaceBehaviorStack = ["default"]
self._elemStack = []
self._locator = Locator()
self.setDocumentLocator(self._locator)
def getNumErrors(self):
"Return the number of errors found while parsing the current document."
return self._numParseErrors
def setEncoding(self, encoding):
"""Set the text encoding to use when encoding strings read from XML.
Defaults to 'UTF-8'.
"""
self._encoding = encoding
def _location(self):
"Return a string describing the current location in the source file."
line = self._locator.getLineNumber()
column = self._locator.getColumnNumber()
return "(line %d, column %d)" % (line, column)
def _pushWhitespaceBehavior(self, attr):
"""Push a new string onto the whitespaceBehaviorStack.
The string's value is taken from the "xml:space" attribute, if it exists
and has a legal value ("default" or "preserve"). Otherwise, the previous
stack element is duplicated.
"""
assert len(self._whitespaceBehaviorStack) > 0, "Whitespace behavior stack should never be empty!"
try:
if attr["xml:space"] == "default" or attr["xml:space"] == "preserve":
self._whitespaceBehaviorStack.append(attr["xml:space"])
else:
raise AimlParserError, "Invalid value for xml:space attribute "+self._location()
except KeyError:
self._whitespaceBehaviorStack.append(self._whitespaceBehaviorStack[-1])
def startElementNS(self, name, qname, attr):
print "QNAME:", qname
print "NAME:", name
uri,elem = name
if (elem == "bot"): print "name:", attr.getValueByQName("name"), "a'ite?"
self.startElement(elem, attr)
pass
def startElement(self, name, attr):
# Wrapper around _startElement, which catches errors in _startElement()
# and keeps going.
# If we're inside an unknown element, ignore everything until we're
# out again.
if self._currentUnknown != "":
return
# If we're skipping the current category, ignore everything until
# it's finished.
if self._skipCurrentCategory:
return
# process this start-element.
try: self._startElement(name, attr)
except AimlParserError, msg:
# Print the error message
sys.stderr.write("PARSE ERROR: %s\n" % msg)
self._numParseErrors += 1 # increment error count
# In case of a parse error, if we're inside a category, skip it.
if self._state >= self._STATE_InsideCategory:
self._skipCurrentCategory = True
def _startElement(self, name, attr):
if name == "aiml":
# <aiml> tags are only legal in the OutsideAiml state
if self._state != self._STATE_OutsideAiml:
raise AimlParserError, "Unexpected <aiml> tag "+self._location()
self._state = self._STATE_InsideAiml
self._insideTopic = False
self._currentTopic = u""
try: self._version = attr["version"]
except KeyError:
# This SHOULD be a syntax error, but so many AIML sets out there are missing
# "version" attributes that it just seems nicer to let it slide.
#raise AimlParserError, "Missing 'version' attribute in <aiml> tag "+self._location()
#print "WARNING: Missing 'version' attribute in <aiml> tag "+self._location()
#print " Defaulting to version 1.0"
self._version = "1.0"
self._forwardCompatibleMode = (self._version != "1.0.1")
self._pushWhitespaceBehavior(attr)
# Not sure about this namespace business yet...
#try:
# self._namespace = attr["xmlns"]
# if self._version == "1.0.1" and self._namespace != "http://alicebot.org/2001/AIML-1.0.1":
# raise AimlParserError, "Incorrect namespace for AIML v1.0.1 "+self._location()
#except KeyError:
# if self._version != "1.0":
# raise AimlParserError, "Missing 'version' attribute(s) in <aiml> tag "+self._location()
elif self._state == self._STATE_OutsideAiml:
# If we're outside of an AIML element, we ignore all tags.
return
elif name == "topic":
# <topic> tags are only legal in the InsideAiml state, and only
# if we're not already inside a topic.
if (self._state != self._STATE_InsideAiml) or self._insideTopic:
raise AimlParserError, "Unexpected <topic> tag", self._location()
try: self._currentTopic = unicode(attr['name'])
except KeyError:
raise AimlParserError, "Required \"name\" attribute missing in <topic> element "+self._location()
self._insideTopic = True
elif name == "category":
# <category> tags are only legal in the InsideAiml state
if self._state != self._STATE_InsideAiml:
raise AimlParserError, "Unexpected <category> tag "+self._location()
self._state = self._STATE_InsideCategory
self._currentPattern = u""
self._currentThat = u""
# If we're not inside a topic, the topic is implicitly set to *
if not self._insideTopic: self._currentTopic = u"*"
self._elemStack = []
self._pushWhitespaceBehavior(attr)
elif name == "pattern":
# <pattern> tags are only legal in the InsideCategory state
if self._state != self._STATE_InsideCategory:
raise AimlParserError, "Unexpected <pattern> tag "+self._location()
self._state = self._STATE_InsidePattern
elif name == "that" and self._state == self._STATE_AfterPattern:
# <that> are legal either inside a <template> element, or
# inside a <category> element, between the <pattern> and the
# <template> elements. This clause handles the latter case.
self._state = self._STATE_InsideThat
elif name == "template":
# <template> tags are only legal in the AfterPattern and AfterThat
# states
if self._state not in [self._STATE_AfterPattern, self._STATE_AfterThat]:
raise AimlParserError, "Unexpected <template> tag "+self._location()
# if no <that> element was specified, it is implicitly set to *
if self._state == self._STATE_AfterPattern:
self._currentThat = u"*"
self._state = self._STATE_InsideTemplate
self._elemStack.append(['template',{}])
self._pushWhitespaceBehavior(attr)
elif self._state == self._STATE_InsidePattern:
# Certain tags are allowed inside <pattern> elements.
if name == "bot" and attr.has_key("name") and attr["name"] == u"name":
# Insert a special character string that the PatternMgr will
# replace with the bot's name.
self._currentPattern += u" BOT_NAME "
else:
raise AimlParserError, ("Unexpected <%s> tag " % name)+self._location()
elif self._state == self._STATE_InsideThat:
# Certain tags are allowed inside <that> elements.
if name == "bot" and attr.has_key("name") and attr["name"] == u"name":
# Insert a special character string that the PatternMgr will
# replace with the bot's name.
self._currentThat += u" BOT_NAME "
else:
raise AimlParserError, ("Unexpected <%s> tag " % name)+self._location()
elif self._state == self._STATE_InsideTemplate and self._validInfo.has_key(name):
# Starting a new element inside the current pattern. First
# we need to convert 'attr' into a native Python dictionary,
# so it can later be marshaled.
attrDict = {}
for k,v in attr.items():
#attrDict[k[1].encode(self._encoding)] = v.encode(self._encoding)
attrDict[k.encode(self._encoding)] = unicode(v)
self._validateElemStart(name, attrDict, self._version)
# Push the current element onto the element stack.
self._elemStack.append([name.encode(self._encoding),attrDict])
self._pushWhitespaceBehavior(attr)
# If this is a condition element, push a new entry onto the
# foundDefaultLiStack
if name == "condition":
self._foundDefaultLiStack.append(False)
else:
# we're now inside an unknown element.
if self._forwardCompatibleMode:
# In Forward Compatibility Mode, we ignore the element and its
# contents.
self._currentUnknown = name
else:
# Otherwise, unknown elements are grounds for error!
raise AimlParserError, ("Unexpected <%s> tag " % name)+self._location()
def characters(self, ch):
# Wrapper around _characters which catches errors in _characters()
# and keeps going.
if self._state == self._STATE_OutsideAiml:
# If we're outside of an AIML element, we ignore all text
return
if self._currentUnknown != "":
# If we're inside an unknown element, ignore all text
return
if self._skipCurrentCategory:
# If we're skipping the current category, ignore all text.
return
try: self._characters(ch)
except AimlParserError, msg:
# Print the message
sys.stderr.write("PARSE ERROR: %s\n" % msg)
self._numParseErrors += 1 # increment error count
# In case of a parse error, if we're inside a category, skip it.
if self._state >= self._STATE_InsideCategory:
self._skipCurrentCategory = True
def _characters(self, ch):
text = unicode(ch)
if self._state == self._STATE_InsidePattern:
self._currentPattern += text
elif self._state == self._STATE_InsideThat:
self._currentThat += text
elif self._state == self._STATE_InsideTemplate:
# First, see whether the element at the top of the element stack
# is permitted to contain text.
try:
parent = self._elemStack[-1][0]
parentAttr = self._elemStack[-1][1]
required, optional, canBeParent = self._validInfo[parent]
nonBlockStyleCondition = (parent == "condition" and not (parentAttr.has_key("name") and parentAttr.has_key("value")))
if not canBeParent:
raise AimlParserError, ("Unexpected text inside <%s> element "%parent)+self._location()
elif parent == "random" or nonBlockStyleCondition:
# <random> elements can only contain <li> subelements. However,
# there's invariably some whitespace around the <li> that we need
# to ignore. Same for non-block-style <condition> elements (i.e.
# those which don't have both a "name" and a "value" attribute).
if len(text.strip()) == 0:
# ignore whitespace inside these elements.
return
else:
# non-whitespace text inside these elements is a syntax error.
raise AimlParserError, ("Unexpected text inside <%s> element "%parent)+self._location()
except IndexError:
# the element stack is empty. This should never happen.
raise AimlParserError, "Element stack is empty while validating text "+self._location()
# Add a new text element to the element at the top of the element
# stack. If there's already a text element there, simply append the
# new characters to its contents.
try: textElemOnStack = (self._elemStack[-1][-1][0] == "text")
except IndexError: textElemOnStack = False
except KeyError: textElemOnStack = False
if textElemOnStack:
self._elemStack[-1][-1][2] += text
else:
self._elemStack[-1].append(["text", {"xml:space": self._whitespaceBehaviorStack[-1]}, text])
else:
# all other text is ignored
pass
def endElementNS(self, name, qname):
uri, elem = name
self.endElement(elem)
def endElement(self, name):
"""Wrapper around _endElement which catches errors in _characters()
and keeps going.
"""
if self._state == self._STATE_OutsideAiml:
# If we're outside of an AIML element, ignore all tags
return
if self._currentUnknown != "":
# see if we're at the end of an unknown element. If so, we can
# stop ignoring everything.
if name == self._currentUnknown:
self._currentUnknown = ""
return
if self._skipCurrentCategory:
# If we're skipping the current category, see if it's ending. We
# stop on ANY </category> tag, since we're not keeping track of
# state in ignore-mode.
if name == "category":
self._skipCurrentCategory = False
self._state = self._STATE_InsideAiml
return
try: self._endElement(name)
except AimlParserError, msg:
# Print the message
sys.stderr.write("PARSE ERROR: %s\n" % msg)
self._numParseErrors += 1 # increment error count
# In case of a parse error, if we're inside a category, skip it.
if self._state >= self._STATE_InsideCategory:
self._skipCurrentCategory = True
def _endElement(self, name):
"""Verify that an AIML end element is valid in the current
context.
Raises an AimlParserError if an illegal end element is encountered.
"""
if name == "aiml":
# </aiml> tags are only legal in the InsideAiml state
if self._state != self._STATE_InsideAiml:
raise AimlParserError, "Unexpected </aiml> tag "+self._location()
self._state = self._STATE_OutsideAiml
self._whitespaceBehaviorStack.pop()
elif name == "topic":
# </topic> tags are only legal in the InsideAiml state, and
# only if _insideTopic is true.
if self._state != self._STATE_InsideAiml or not self._insideTopic:
raise AimlParserError, "Unexpected </topic> tag "+self._location()
self._insideTopic = False
self._currentTopic = u""
elif name == "category":
# </category> tags are only legal in the AfterTemplate state
if self._state != self._STATE_AfterTemplate:
raise AimlParserError, "Unexpected </category> tag "+self._location()
self._state = self._STATE_InsideAiml
# End the current category. Store the current pattern/that/topic and
# element in the categories dictionary.
key = (self._currentPattern.strip(), self._currentThat.strip(),self._currentTopic.strip())
self.categories[key] = self._elemStack[-1]
self._whitespaceBehaviorStack.pop()
elif name == "pattern":
# </pattern> tags are only legal in the InsidePattern state
if self._state != self._STATE_InsidePattern:
raise AimlParserError, "Unexpected </pattern> tag "+self._location()
self._state = self._STATE_AfterPattern
elif name == "that" and self._state == self._STATE_InsideThat:
# </that> tags are only allowed inside <template> elements or in
# the InsideThat state. This clause handles the latter case.
self._state = self._STATE_AfterThat
elif name == "template":
# </template> tags are only allowed in the InsideTemplate state.
if self._state != self._STATE_InsideTemplate:
raise AimlParserError, "Unexpected </template> tag "+self._location()
self._state = self._STATE_AfterTemplate
self._whitespaceBehaviorStack.pop()
elif self._state == self._STATE_InsidePattern:
# Certain tags are allowed inside <pattern> elements.
if name not in ["bot"]:
raise AimlParserError, ("Unexpected </%s> tag " % name)+self._location()
elif self._state == self._STATE_InsideThat:
# Certain tags are allowed inside <that> elements.
if name not in ["bot"]:
raise AimlParserError, ("Unexpected </%s> tag " % name)+self._location()
elif self._state == self._STATE_InsideTemplate:
# End of an element inside the current template. Append the
# element at the top of the stack onto the one beneath it.
elem = self._elemStack.pop()
self._elemStack[-1].append(elem)
self._whitespaceBehaviorStack.pop()
# If the element was a condition, pop an item off the
# foundDefaultLiStack as well.
if elem[0] == "condition": self._foundDefaultLiStack.pop()
else:
# Unexpected closing tag
raise AimlParserError, ("Unexpected </%s> tag " % name)+self._location()
# A dictionary containing a validation information for each AIML
# element. The keys are the names of the elements. The values are a
# tuple of three items. The first is a list containing the names of
# REQUIRED attributes, the second is a list of OPTIONAL attributes,
# and the third is a boolean value indicating whether or not the
# element can contain other elements and/or text (if False, the
# element can only appear in an atomic context, such as <date/>).
_validationInfo101 = {
"bot": ( ["name"], [], False ),
"condition": ( [], ["name", "value"], True ), # can only contain <li> elements
"date": ( [], [], False ),
"formal": ( [], [], True ),
"gender": ( [], [], True ),
"get": ( ["name"], [], False ),
"gossip": ( [], [], True ),
"id": ( [], [], False ),
"input": ( [], ["index"], False ),
"javascript": ( [], [], True ),
"learn": ( [], [], True ),
"li": ( [], ["name", "value"], True ),
"lowercase": ( [], [], True ),
"person": ( [], [], True ),
"person2": ( [], [], True ),
"random": ( [], [], True ), # can only contain <li> elements
"sentence": ( [], [], True ),
"set": ( ["name"], [], True),
"size": ( [], [], False ),
"sr": ( [], [], False ),
"srai": ( [], [], True ),
"star": ( [], ["index"], False ),
"system": ( [], [], True ),
"template": ( [], [], True ), # needs to be in the list because it can be a parent.
"that": ( [], ["index"], False ),
"thatstar": ( [], ["index"], False ),
"think": ( [], [], True ),
"topicstar": ( [], ["index"], False ),
"uppercase": ( [], [], True ),
"version": ( [], [], False ),
}
def _validateElemStart(self, name, attr, version):
"""Test the validity of an element starting inside a <template>
element.
This function raises an AimlParserError exception if it the tag is
invalid. Otherwise, no news is good news.
"""
# Check the element's attributes. Make sure that all required
# attributes are present, and that any remaining attributes are
# valid options.
required, optional, canBeParent = self._validInfo[name]
for a in required:
if a not in attr and not self._forwardCompatibleMode:
raise AimlParserError, ("Required \"%s\" attribute missing in <%s> element " % (a,name))+self._location()
for a in attr:
if a in required: continue
if a[0:4] == "xml:": continue # attributes in the "xml" namespace can appear anywhere
if a not in optional and not self._forwardCompatibleMode:
raise AimlParserError, ("Unexpected \"%s\" attribute in <%s> element " % (a,name))+self._location()
# special-case: several tags contain an optional "index" attribute.
# This attribute's value must be a positive integer.
if name in ["star", "thatstar", "topicstar"]:
for k,v in attr.items():
if k == "index":
temp = 0
try: temp = int(v)
except:
raise AimlParserError, ("Bad type for \"%s\" attribute (expected integer, found \"%s\") " % (k,v))+self._location()
if temp < 1:
raise AimlParserError, ("\"%s\" attribute must have non-negative value " % (k))+self._location()
# See whether the containing element is permitted to contain
# subelements. If not, this element is invalid no matter what it is.
try:
parent = self._elemStack[-1][0]
parentAttr = self._elemStack[-1][1]
except IndexError:
# If the stack is empty, no parent is present. This should never
# happen.
raise AimlParserError, ("Element stack is empty while validating <%s> " % name)+self._location()
required, optional, canBeParent = self._validInfo[parent]
nonBlockStyleCondition = (parent == "condition" and not (parentAttr.has_key("name") and parentAttr.has_key("value")))
if not canBeParent:
raise AimlParserError, ("<%s> elements cannot have any contents "%parent)+self._location()
# Special-case test if the parent element is <condition> (the
# non-block-style variant) or <random>: these elements can only
# contain <li> subelements.
elif (parent == "random" or nonBlockStyleCondition) and name!="li":
raise AimlParserError, ("<%s> elements can only contain <li> subelements "%parent)+self._location()
# Special-case test for <li> elements, which can only be contained
# by non-block-style <condition> and <random> elements, and whose
# required attributes are dependent upon which attributes are
# present in the <condition> parent.
elif name=="li":
if not (parent=="random" or nonBlockStyleCondition):
raise AimlParserError, ("Unexpected <li> element contained by <%s> element "%parent)+self._location()
if nonBlockStyleCondition:
if parentAttr.has_key("name"):
# Single-predicate condition. Each <li> element except the
# last must have a "value" attribute.
if len(attr) == 0:
# This could be the default <li> element for this <condition>,
# unless we've already found one.
if self._foundDefaultLiStack[-1]:
raise AimlParserError, "Unexpected default <li> element inside <condition> "+self._location()
else:
self._foundDefaultLiStack[-1] = True
elif len(attr) == 1 and attr.has_key("value"):
pass # this is the valid case
else:
raise AimlParserError, "Invalid <li> inside single-predicate <condition> "+self._location()
elif len(parentAttr) == 0:
# Multi-predicate condition. Each <li> element except the
# last must have a "name" and a "value" attribute.
if len(attr) == 0:
# This could be the default <li> element for this <condition>,
# unless we've already found one.
if self._foundDefaultLiStack[-1]:
raise AimlParserError, "Unexpected default <li> element inside <condition> "+self._location()
else:
self._foundDefaultLiStack[-1] = True
elif len(attr) == 2 and attr.has_key("value") and attr.has_key("name"):
pass # this is the valid case
else:
raise AimlParserError, "Invalid <li> inside multi-predicate <condition> "+self._location()
# All is well!
return True
def create_parser():
"""Create and return an AIML parser object."""
parser = xml.sax.make_parser()
handler = AimlHandler("UTF-8")
parser.setContentHandler(handler)
#parser.setFeature(xml.sax.handler.feature_namespaces, True)
return parser
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