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# $Header: /var/local/cvsroot/4Suite/Ft/Xml/XPath/BuiltInExtFunctions.py,v 1.65 2005/02/27 04:17:36 jkloth Exp $
"""
4XPath-specific extension functions
Copyright 2005 Fourthought, Inc. (USA).
Detailed license and copyright information: http://4suite.org/COPYRIGHT
Project home, documentation, distributions: http://4suite.org/
Extension functions are implemented by a module, such as this one,
that defines an ExtFunctions global dictionary that maps (namespace,
local-name) string tuples to a corresponding Python function. The
function must take a Context object as the first argument, and any
additional arguments accepted will correspond to the arguments passed
in. See other API docs to see how to make use of modules that contain
ExtFunctions.
"""
import os, re, codecs, time
from xml.dom import Node
import Ft
from Ft.Lib import boolean, Uri, Wrap as LineWrap
from Ft.Lib.Random import Random as Random_
from Ft.Xml.XPath import Conversions
from Ft.Xml.XPath import FT_EXT_NAMESPACE
def _toUnicode(s):
"""
Supports BaseUri(). Given a string (str or unicode),
returns the string as unicode.
"""
if isinstance(s, unicode):
return s
else:
return unicode(s, 'us-ascii', errors='replace')
def BaseUri(context, arg=None):
"""
Returns the base URI of the first node in the given node-set, or
of the context node if no argument is given. If the given node-set
is empty, an empty string is returned.
"""
if arg is None:
arg = [context.node]
elif not arg:
return u''
if hasattr(arg[0],'baseURI'):
return _toUnicode(arg[0].baseURI)
elif hasattr(arg[0],'refUri'):
return _toUnicode(arg[0].refUri)
elif hasattr(arg[0].ownerDocument,'baseURI'):
return _toUnicode(arg[0].ownerDocument.baseURI)
elif hasattr(arg[0].ownerDocument,'refUri'):
return _toUnicode(arg[0].ownerDocument.refUri)
return u''
def Decode(context, object, encoding):
"""
f:decode mirrors the Python decode function/method. It takes a
foreign object that is a Python byte string, and an encoding,
and returns another foreign object which is a Unicode object.
"""
encode, decode, reader, writer = codecs.lookup(encoding)
return decode(object)[0]
def Encode(context, object, encoding):
"""
f:encode mirrors the Python encode function/method. It takes a
foreign object that is a Unicode object, and an encoding,
and returns another foreign object which is a Python byte string.
"""
encode, decode, reader, writer = codecs.lookup(encoding)
return encode(object)[0]
def EndsWith(context, outer, inner):
"""
Returns true if the string given in the first argument ends with
the substring given in the second argument.
"""
outer = Conversions.StringValue(outer)
inner = Conversions.StringValue(inner)
return outer.endswith(inner) and boolean.true or boolean.false
def EscapeXml(context, text):
"""
Returns the given string with XML markup characters "&", "<" and
">" escaped as "&", "<" and ">", respectively.
"""
from xml.sax.saxutils import escape
return escape(Conversions.StringValue(text))
def GenerateUuid(context):
"""
Returns a random UUID string.
"""
from Ft.Lib import Uuid
rt = Uuid.UuidAsString(Uuid.GenerateUuid())
rt = unicode(rt, 'us-ascii', errors='replace')
return rt
def If(context, cond, v1, v2=None):
"""
If the first argument, when converted to a boolean, is true,
returns the second argument. Otherwise, returns the third
argument, or if the third argument is not given, returns an
empty node-set.
"""
# contributed by Lars Marius Garshol;
# originally using namespace URI 'http://garshol.priv.no/symbolic/'
if Conversions.BooleanValue(cond):
return v1
elif v2 is None:
return []
else:
return v2
# why does this exist?
def ImportString(context, object):
"""
f:import-string takes a Unicode FO and returns an XPath string. It is
an error if the FO contains illegal XML chars. (although eventually
this function might be extended to recover from this error)
"""
#FIXME: Add validation of object as valid XPath string,
#and possibly mapping ops to PUA for illegal characters.
#We probably need an Export string if we add PUA shifting
return object
def Indent(context, text, levels, indentstring=None):
"""
f:indent() returns a string with each line of the text indented the
given number of levels. For each level, the indent string, normally
2 spaces by default, is prepended to each line.
"""
text = Conversions.StringValue(text)
levels = int(Conversions.NumberValue(levels))
if indentstring is None:
indentstring = u' '
else:
indentstring = Conversions.StringValue(indentstring)
if indentstring and levels > 0:
indent = indentstring * levels
return indent + ('\n' + indent).join(text.split('\n'))
else:
return text
def NormalizeEol(context, text):
"""
Normalizes end-of-line characters in input string, returning the
normalized string. Normalization involves replacing "\n\r", "\r\n"
or "\r" with "\n"
"""
text = text.replace("\n\r", "\n")
text = text.replace("\r\n", "\n")
text = text.replace("\r", "\n")
return text
def OsPath2Uri(context, path):
"""
Returns the given OS path as a URI.
The result varies depending on the underlying operating system.
"""
return Uri.OsPathToUri(Conversions.StringValue(path))
def ParseXml(context, src, parameters=None):
"""
f:parse-xml() parses the string-value of the given object as XML
and returns a node-set whose sole item is the resulting parsed
document's root node. The XML must be a well-formed document.
src - the string or object to be parsed as XML.
parameters - the name of a parameter set for the operation.
The parameters argument is ignored for now. In the future, it
will provide a way to specify a base URI for the resolution of
relative URIs in entity declarations and XIncludes.
Also for now, if the XML contains an encoding declaration, the
declaration must specify UTF-8.
An example:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:f="http://xmlns.4suite.org/ext"
version="1.0"
>
<xsl:output method="text"/>
<xsl:variable name="doc"
select="'<spam>eggs<monty>python</monty></spam>'"/>
<xsl:template match="/">
<xsl:value-of select="f:parse-xml($doc)/spam/monty"/>
</xsl:template>
</xsl:stylesheet>
...run against any XML source should yield:
python
See also: XSLT (not XPath) extension function f:serialize-xml()
"""
from Ft.Xml import Domlette
src = Conversions.StringValue(src).encode("utf-8")
# prepare a base URI for the XML
instruction = getattr(context, 'currentInstruction', None)
if instruction:
uri = instruction.baseUri
else:
uri = context.node.baseUri
if not uri:
uri = OsPathToUri('__parse-xml-extension-function__',
attemptAbsolute=1)
# append "XML-string-(something_unique)" as a fragment
uri += '%sXML-string-%s' % ((uri.find('#') + 1 and ';' or '#'),
str(time.time()))
doc = Domlette.NonvalidatingReader.parseString(src, uri)
return [doc]
def Range(context, lo, hi):
"""
Returns a node-set consisting of text nodes encapsulating integers
in the numeric range bounded by the given low and high values.
"""
# contributed by Lars Marius Garshol;
# originally using namespace URI 'http://garshol.priv.no/symbolic/'
doc = context.node.rootNode
lo = Conversions.NumberValue(lo)
hi = Conversions.NumberValue(hi)
nodeset = []
for number in xrange(lo, hi):
nodeset.append(doc.createTextNode(str(number)))
return nodeset
def ResolvePath(context, base, rel):
"""
Resolves a Posix-style path, such as the path portion of a URL,
against a base. Similar to f:resolve-url, but allows the base to be
just a path, not necessarily a full URL.
"""
base = Conversions.StringValue(base)
rel = Conversions.StringValue(rel)
return Uri.BaseJoin(base, rel)
def ResolveUrl(context, base, rel):
"""
Returns the relative URL ref given in the second argument
resolved against the base given in the first argument.
"""
base = Conversions.StringValue(base)
rel = Conversions.StringValue(rel)
return Uri.BASIC_RESOLVER.normalize(rel, base)
def ShaHash(context, text):
"""
Returns a SHA message digest of the given string, as a string of
several groups of hex digits separated by '-'. See
http://www.itl.nist.gov/fipspubs/fip180-1.htm for info on SHA.
"""
text = Conversions.StringValue(text)
import sha
rv = sha.sha(text).hexdigest()
rv = unicode(rv, 'us-ascii', errors='replace')
return rv
def SharePath(context):
"""
Returns the system-dependent path to modifiable data
"""
return unicode(Ft.GetConfigVar('LOCALSTATEDIR'), 'us-ascii',
errors='replace')
def BinPath(context):
"""
Returns the system-dependent path of Fourthought binaries
"""
return unicode(Ft.GetConfigVar('BINDIR'), 'us-ascii', errors='replace')
def Uri2OsPath(context, uri):
"""
Returns the given URI as an OS path.
The result varies depending on the underlying operating system.
"""
return Uri.UriToOsPath(Conversions.StringValue(uri))
def Version(context):
"""
Returns the 4Suite version number as a string.
"""
return unicode(Ft.VERSION, 'us-ascii', errors='replace')
def Wrap(context, text, width):
"""
f:wrap() returns a string with the text reflowed so that each line
fits within the given width. Existing linefeeds are preserved, but
spaces are considered inter-word separators that can be collapsed.
To reflow without preserving existing linefeeds, strip them first,
e.g. with translate(text, ' ', '').
http://lists.fourthought.com/pipermail/4suite-dev/2002-December/000878.html
"""
s = Conversions.StringValue(text)
width = Conversions.NumberValue(width)
return LineWrap(s, width)
def PytimeToExslt(context, t=None):
"""
Takes a Python time value as a number and returns a date/time as if
from EXSLT date-time()
t - a time stamp number, as from Python's time.time()
if omitted, use the current time
"""
from Ft.Lib import Time as FtTime
if t is not None:
t = Conversions.NumberValue(t)
return unicode(str(FtTime.FromPythonTime(t)), errors='replace')
else:
return unicode(str(FtTime.FromPythonTime()), errors='replace')
#---EXSLT-like functions------------------------------------------------
# (perhaps soon to be deprecated)
def Join(context, nodeset, delim=' '):
"""
Concatenates the string-values of the nodes in the given node-set,
inserting the delimiter given in the optional second argument in
between each string-value. The delimiter defaults to a space.
See also: EXSLT's str:concat()
"""
delim = Conversions.StringValue(delim)
comps = map(Conversions.StringValue, nodeset)
if delim:
return delim.join(comps)
else:
return ''.join(comps)
def Match(context, pattern, arg=None):
"""
Returns true if the string given in the optional second argument
(or the string-value of the context node if no second argument is
given) matches the regular expression given in the first argument.
See also: EXSLT's regexp:test()
This function does differ from XSLT 2.0 match() function
"""
if not arg:
arg = context.node
arg = Conversions.StringValue(arg)
return re.match(pattern, arg) and boolean.true or boolean.false
def ParseDate(context, date, format=None):
"""
This function is similar to EXSLT's date:parse-date()
except that it uses Python rather than Java conventions
for the date formatting.
"""
import time
date = Conversions.StringValue(date)
format = Conversions.StringValue(format)
time_tuple = time.strptime(format)
#perhaps add some variants for missing time tuple values?
str_time = time.strftime("%Y-%m-%dT%H:%M:%S", time_tuple)
return unicode(str_time, 'us-ascii', errors='replace')
def Random(context, max=None, forceInt=0):
"""
Returns a random number between 0 and max (max defaults to 1).
The first optional argument is a different value for max, and
the second argument is a flag that, if set, causes the random
number to be an integer.
See also: EXSLT's math:random()
"""
if max:
max = Conversions.NumberValue(max)
else:
max = 1.0
rt = Random_() * max
if forceInt:
#rt = int(rt)
rt = round(rt)
return rt
def Replace(context, old, new, arg=None):
"""
Returns the third argument string, which defaults to the
string-value of the context node, with occurrences of the substring
given in the first argument replaced by the string given in the
second argument.
See also: EXSLT's str:replace()
"""
if not arg:
arg = context.node
arg = Conversions.StringValue(arg)
old = Conversions.StringValue(old)
new = Conversions.StringValue(new)
return arg.replace(old, new)
def StrFTime(context, format, date=None):
"""
Returns the given ISO 8601 UTC date-time formatted according to
the given format string as would be used by Python's
time.strftime(). If no date-time string is given, the current
time is used.
"""
format = Conversions.StringValue(format)
if date is not None:
date = Conversions.StringValue(date)
time_str = time.strftime(format, time.strptime(date, '%Y-%m-%dT%H:%M:%SZ'))
else:
time_str = time.strftime(format)
return unicode(time_str, 'us-ascii', errors='replace')
#---OS System-aware functions------------------------------------------------
# (Not loaded by default for security reasons)
def EnvVar(context, var):
"""
Looks up a variable in the OS environment. Returns a string, either
the environment variable value or an empty string if there is no
such variable. The system default encoding is assumed.
CAUTION: Using this function could be a security hazard.
You can also use system-property() for the same purpose
f:env-var('foo')
is equivalent to
system-property('fs:foo')
given a mapping from fs to http://xmlns.4suite.org/xslt/env-system-property
"""
var = Conversions.StringValue(var)
result = os.environ.get(var, '')
result = unicode(result, errors='replace')
return result
def Spawnv(context, command, *args):
"""
Executes a command in the operating system's shell, passing in the
command line arguments separately. Returns the result of the command
(a numeric exit code, typically).
CAUTION: Using this function could be a security hazard.
See also: f:system()
"""
command = Conversions.StringValue(command)
result = os.spawnv(os.P_WAIT, command, args)
return result
def System(context, command):
"""
Executes a command in the operating system's shell and returns the
command's result (a numeric exit code, typically).
CAUTION: Using this function could be a security hazard.
See also: f:spawnv()
"""
command = Conversions.StringValue(command)
result = os.system(command)
return result
ExtNamespaces = {
FT_EXT_NAMESPACE : 'f',
}
ExtFunctions = {
(FT_EXT_NAMESPACE, 'base-uri'): BaseUri,
(FT_EXT_NAMESPACE, 'decode') : Decode,
(FT_EXT_NAMESPACE, 'encode') : Encode,
(FT_EXT_NAMESPACE, 'ends-with'): EndsWith,
(FT_EXT_NAMESPACE, 'escape-xml'): EscapeXml,
(FT_EXT_NAMESPACE, 'generate-uuid'): GenerateUuid,
(FT_EXT_NAMESPACE, 'if'): If,
(FT_EXT_NAMESPACE, 'import-string') : ImportString,
(FT_EXT_NAMESPACE, 'indent') : Indent,
(FT_EXT_NAMESPACE, 'join'): Join,
(FT_EXT_NAMESPACE, 'match'): Match,
(FT_EXT_NAMESPACE, 'normalize-eol') : NormalizeEol,
(FT_EXT_NAMESPACE, 'ospath2uri'): OsPath2Uri,
(FT_EXT_NAMESPACE, 'parse-date'): ParseDate,
(FT_EXT_NAMESPACE, 'pytime-to-exslt'): PytimeToExslt,
(FT_EXT_NAMESPACE, 'parse-xml') : ParseXml,
(FT_EXT_NAMESPACE, 'random'): Random,
(FT_EXT_NAMESPACE, 'range'): Range,
(FT_EXT_NAMESPACE, 'replace'): Replace,
(FT_EXT_NAMESPACE, 'resolve-url'): ResolveUrl,
(FT_EXT_NAMESPACE, 'resolve-path'): ResolvePath,
(FT_EXT_NAMESPACE, 'sha-hash') : ShaHash,
(FT_EXT_NAMESPACE, 'share-path'): SharePath,
(FT_EXT_NAMESPACE, 'bin-path'): BinPath,
(FT_EXT_NAMESPACE, 'uri2ospath'): Uri2OsPath,
(FT_EXT_NAMESPACE, 'version'): Version,
(FT_EXT_NAMESPACE, 'wrap') : Wrap,
(FT_EXT_NAMESPACE, 'strftime') : StrFTime,
}
InsecureExtFunctions = {
(FT_EXT_NAMESPACE, 'spawnv'): Spawnv,
(FT_EXT_NAMESPACE, 'system'): System,
(FT_EXT_NAMESPACE, 'env-var'): EnvVar,
}
import MathFunctions
ExtFunctions.update(MathFunctions.ExtFunctions)
# Deprecated functions removed for 4Suite 1.0a4:
#
# (FT_EXT_NAMESPACE, 'escape-url'): EscapeUrl,
# (FT_EXT_NAMESPACE, 'evaluate'): Evaluate,
# (FT_EXT_NAMESPACE, 'iso-time'): IsoTime,
# (FT_EXT_NAMESPACE, 'distinct'): Distinct,
# (FT_EXT_NAMESPACE, 'find'): Find,
# (FT_EXT_NAMESPACE, 'node-set'): NodeSet,
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