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# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
# Functions to help represent data as lists of elements and attributes
from util import *
element = "'element"
attribute = "'attribute"
atsign = "'@"
# Return true if a value is an element
def isElement(v):
if not isList(v) or isNil(v) or v == None or car(v) != element:
return False
return True
# Return true if a value is an attribute
def isAttribute(v):
if not isList(v) or isNil(v) or v == None or car(v) != attribute:
return False
return True
# Return the name of attribute
def attributeName(l):
return cadr(l)
# Return the value of attribute
def attributeValue(l):
return caddr(l)
# Return the name of an element
def elementName(l):
return cadr(l)
# Return true if an element has children
def elementHasChildren(l):
return not isNil(cddr(l))
# Return the children of an element
def elementChildren(l):
return cddr(l)
# Return true if an element has a value
def elementHasValue(l):
r = reverse(l)
if isSymbol(car(r)):
return False
if isList(car(r)) and not isNil(car(r)) and isSymbol(car(car(r))):
return False
return True
# Return the value of an element
def elementValue(l):
return car(reverse(l))
# Convert an element to a value
def elementToValueIsList(v):
if not isList(v):
return False
return isNil(v) or not isSymbol(car(v))
def elementToValue(t):
if isTaggedList(t, attribute):
return (atsign + attributeName(t)[1:], attributeValue(t))
if isTaggedList(t, element):
if elementHasValue(t):
if not elementToValueIsList(elementValue(t)):
return (elementName(t), elementValue(t))
return cons(elementName(t), (elementsToValues(elementValue(t)),))
return cons(elementName(t), elementsToValues(elementChildren(t)))
if not isList(t):
return t
return elementsToValues(t)
# Convert a list of elements to a list of values
def elementToValueIsSymbol(v):
if not isList(v):
return False
if (isNil(v)):
return False
if not isSymbol(car(v)):
return False
return True
def elementToValueGroupValues(v, l):
if isNil(l) or not elementToValueIsSymbol(v) or not elementToValueIsSymbol(car(l)):
return cons(v, l)
if car(car(l)) != car(v):
return cons(v, l)
if not elementToValueIsList(cadr(car(l))):
g = (car(v), (cdr(v), cdr(car(l))))
return elementToValueGroupValues(g, cdr(l))
g = (car(v), cons(cdr(v), cadr(car(l))))
return elementToValueGroupValues(g, cdr(l))
def elementsToValues(e):
if isNil(e):
return e
return elementToValueGroupValues(elementToValue(car(e)), elementsToValues(cdr(e)))
# Convert a value to an element
def valueToElement(t):
if isList(t) and not isNil(t) and isSymbol(car(t)):
n = car(t)
v = cadr(t)
if not isList(v):
if n[0:2] == atsign:
return (attribute, n[1:], v)
return (element, n, v)
if isNil(v) or not isSymbol(car(v)):
return cons(element, cons(n, (valuesToElements(v),)))
return cons(element, cons(n, valuesToElements(cdr(t))))
if not isList(t):
return t
return valuesToElements(t)
# Convert a list of values to a list of elements
def valuesToElements(l):
if isNil(l):
return l
return cons(valueToElement(car(l)), valuesToElements(cdr(l)))
# Return a selector lambda function which can be used to filter elements
def evalSelect(s, v):
if isNil(s):
return True
if isNil(v):
return False
if car(s) != car(v):
return False
return evalSelect(cdr(s), cdr(v))
def selector(s):
return lambda v: evalSelect(s, v)
# Return the value of the attribute with the given name
def namedAttributeValue(name, l):
f = filter(lambda v: isAttribute(v) and attributeName(v) == name, l)
if isNil(f):
return None
return caddr(car(f))
# Return child elements with the given name
def namedElementChildren(name, l):
return filter(lambda v: isElement(v) and elementName(v) == name, l)
# Return the child element with the given name
def namedElementChild(name, l):
f = namedElementChildren(name, l)
if isNil(f):
return None
return car(f)
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