4Suite API Documentation

Module Ft.Xml.XPath.BuiltInExtFunctions

4XPath-specific extension functions
Copyright 2006 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


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.
Returns the system-dependent path of Fourthought binaries
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(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.
EndsWith(context, outer, inner)
Returns true if the string given in the first argument ends with the substring given in the second argument.
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
is equivalent to
given a mapping from fs to http://xmlns.4suite.org/xslt/env-system-property
EscapeXml(context, text)
Returns the given string with XML markup characters "&", "<" and ">" escaped as "&amp;", "&lt;" and "&gt;", respectively.
Returns a random UUID string.
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.
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)
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.
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()
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
NormalizeEol(context, text)
Normalizes end-of-line characters in input string, returning the normalized string. Normalization involves replacing " ", " " or " " with " "
OsPath2Uri(context, path)
Returns the given OS path as a URI. The result varies depending on the underlying operating system.
ParseDate(context, date, format)
This function is similar to EXSLT's date:parse-date() except that it uses Python rather than Java conventions for the date formatting.
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:output method="text"/>
  <xsl:variable name="doc"

  <xsl:template match="/">
    <xsl:value-of select="f:parse-xml($doc)/spam/monty"/>

...run against any XML source should yield:


See also: XSLT (not XPath) extension function f:serialize-xml()
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
Random(context, max=None, forceInt=0)
Returns a random number between 0 (inclusive) and max (exclusive). 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 rounded to an integer. See also: EXSLT's math:random()
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.
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()
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.
ResolveUrl(context, base, rel)
Returns the relative URL ref given in the second argument resolved against the base given in the first argument. In case of URI processing error an empty string is returned
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.
Returns the system-dependent path to modifiable data
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()
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.
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()
Uri2OsPath(context, uri)
Returns the given URI as an OS path. The result varies depending on the underlying operating system.
Returns the 4Suite version number as a string.
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, '&#10;', ''). http://lists.fourthought.com/pipermail/4suite-dev/2002-December/000878.html


DEFAULT_RNG = <Ft.Lib.Random.FtSystemRandom object>
A PRNG that uses an OS-specific random number source, if available, falling back on an instance of FtRandom.
Calls to seed(), jumpahead(), getstate() and setstate() only affect
the fallback FtRandom instance.

Implements getrandbits() in all versions of Python.
Also adds getrandbytes(), which returns a str of bytes.
ExtFunctions = {('http://xmlns.4suite.org/ext', 'base-uri'): <function BaseUri>, ('http://xmlns.4suite.org/ext', 'bin-path'): <function BinPath>, ('http://xmlns.4suite.org/ext', 'cos'): <function Cos>, ('http://xmlns.4suite.org/ext', 'decode'): <function Decode>, ('http://xmlns.4suite.org/ext', 'degrees-to-rads'): <function DegreesToRads>, ('http://xmlns.4suite.org/ext', 'encode'): <function Encode>, ('http://xmlns.4suite.org/ext', 'ends-with'): <function EndsWith>, ('http://xmlns.4suite.org/ext', 'escape-xml'): <function EscapeXml>, ('http://xmlns.4suite.org/ext', 'fact'): <function Fact>, ('http://xmlns.4suite.org/ext', 'generate-uuid'): <function GenerateUuid>, ...}
ExtNamespaces = {'http://xmlns.4suite.org/ext': 'f'}
FT_EXT_NAMESPACE = 'http://xmlns.4suite.org/ext'
InsecureExtFunctions = {('http://xmlns.4suite.org/ext', 'env-var'): <function EnvVar>, ('http://xmlns.4suite.org/ext', 'spawnv'): <function Spawnv>, ('http://xmlns.4suite.org/ext', 'system'): <function System>}