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Other Built in Functions

document(), json-to-xml(), xml-to-json()

document() is equivalent to doc():
<xsl:value-of select="document('zoo.xml')"/>
<xsl:value-of select="doc('zoo.xml')"/>

Both instructions are equivalent.

json-to-xml() converts a JSON string into an XML representation using the http://www.w3.org/2013/XSL/json namespace:
json-to-xml('{"x": 1, "y": [3,4,5]}')
<map xmlns="http://www.w3.org/2013/XSL/json">
<number key="x">1</number>
<array key="y">
<number>3</number>
<number>4</number>
<number>5</number>
</array>
</map>

Result of the call above.

xml-to-json() performs the reverse conversion, and has two signatures:

element-available(), function-available(), type-available()

These functions test, at run time, whether a given instruction, function or type is supported by the processor. The example below tests <xsl:for-each>, substring() and xs:string. 

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="3.0"
            xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
            xmlns:xs="http://www.w3.org/2001/XMLSchema" >
   <xsl:template match="/">
      <xsl:value-of select="element-available('xsl:for-each')"/>
      <xsl:value-of select="function-available('substring')"/>
      <xsl:value-of select="type-available('xs:string')"/>
   </xsl:template>
</xsl:stylesheet>

truetruetrue

current(), system-property(), unparsed-entity-public-id(), unparsed-entity-uri(), snapshot()

current() refers to the context item that was current when the containing expression began evaluating, which is not necessarily the same as a bare, optional leading dot ('.'):
<xsl:apply-templates select="//glossary/entry[@name=current()/@ref]"/>
<xsl:apply-templates select="//glossary/entry[@name=./@ref]"/>

In the first line, current() refers to the outer context item. In the second line, the dot is simply optional, and @ref belongs to the entry elements being tested — the two expressions are not equivalent.

system-property($property) returns the value of a system property; $property can be one of: 'xsl:version', 'xsl:vendor', 'xsl:vendor-url', 'xsl:product-name', 'xsl:product-version', 'xsl:is-schema-aware', 'xsl:supports-serialization', 'xsl:supports-backwards-compatibility', 'xsl:supports-namespace-axis', 'xsl:supports-streaming', 'xsl:supports-dynamic-evaluation'.
unparsed-entity-public-id($entity) returns the public identifier of the unparsed entity named by the string $entity.
unparsed-entity-uri($entity) returns the URI (system identifier) of the unparsed entity named by the string $entity.
snapshot($nodes) returns a copy of a node together with its ancestors and descendants, and their attributes and namespaces.