This file describes changes for versions 7.0 and later. For changes prior to version 7.0, see http://saxon.sf.net/saxon6.5.2/changes.html.
641793 -
<xsl:element name="{local-name()}"/> fails (with the message "namespace prefix has not been declared").
641940 - No diagnostics for Saxon internal errors when using the Crimson parser
641948 -
NullPointerException when two xsl:strip-space or xsl:preserve-space declarations
name the same element
645190 -
<xsl:namespace> rejects a zero-length string as the name, and fails to detect a conflict
with the namespace of the containing element
646844 -
The <saxon:query> extension element throws a NullPointerException if the columns
attribute is omitted
The code for <xsl:number level="any"> has been optimized. The conditions that must apply
for this optimization are
that the count and from patterns must not contain any variable references; either the count pattern must
be specified, or the name and type of the context node must be statically obtainable, typically from
the match pattern of the containing template rule. Under these circumstances, Saxon will remember the
result of evaluating the instruction, and the next time it is evaluated, if the first node encountered
in its reverse scan of the document is the one that was most recently numbered, it will simply add one
to the remembered number.
Note: a similar optimization for <xsl:number> with no attributes has been
in use for some time.
The numbering code also now passes down the required node name and kind to the axis iterator that is used to find the nodes being counted. This reduces the overhead of skipping non-matching nodes.
The code for navigating the parent and ancestor axes in the TinyTree implementation has been improved. The next pointer for the last sibling now points to the parent node; this is distinguished from a normal next pointer by virtue of the fact that it always points backwards in the node array. When a search is needed to find the parent, this is now done by reading the next-sibling pointer chain until the owner is found, which in general is faster than the previous technique, of scanning all preceding nodes until one is found whose depth is lower.
This was done after exploring a number of alternative approaches, none of which led to significant performance improvements. In particular, I tried various ways of remembering the parent node during a scan of the descendant axis, but in all cases the benefit achieved when the parent node was actually used was less than the extra cost of maintaining the information in the cases where it wasn't needed.
Note: I have not identified any circumstances in which the "standard" tree implementation out-performs the TinyTree. The "standard" implementation is retained, however, because it is used for stylesheets during compilation.
A small improvement has been made to the code for evaluating an attribute reference.
Various expression classes now contain their own implementations of the effectiveBooleanValue() method, avoiding the need to use the general-purpose logic in cases where the value is already known to be a singleton.
My main test case for these performance improvements was the stylesheet used to render the XSLT 2.0 specification. The execution time for this stylesheet improved from 16.4 seconds to 7.6 seconds. Improvements for other stylesheets are very unlikely to be as high as this. Another test case improved from 66.8 to 59.8 seconds, which is probably more typical.
References in curly braces identify the test cases used to test each new feature.
603928 - [position()!=last()] in a pattern fails.
607442 - unparsed-text() function fails.
608416 - command line processor calls System.exit().
616543 - xsl:param needn't come first in a template.
616548 - multithreading bug when using saxon:preview declaration.
617103 - ./EXPR doesn't sort results into document order.
620851 - precedence of conflicting xsl:namespace-alias declarations.
626277 - exlst:leading() and exslt:trailing with empty node-set arguments.
635433 - SQLInsert attempts commit() even when autocommit is set.
636661 - interaction of cdata-section-elements with disable-output-escaping.
637117 - creating two namespaces with same prefix and different URI.
637292 - xsl:for-each and xsl:for-each-group don't nullify the current template rule.
The xsl:principal-result-document element is withdrawn.
Note, however, that the ability to NOT have a principal result tree is not yet available.
A principal output file will be created even if it is empty.
Attributes of xsl:output can no longer be attribute value templates.
A new attribute has been added to xsl:output: saxon:byte-order-mark="yes"
causes a byte order mark (hex FEFF) to be inserted at the start of the output file. This is most
useful with UTF-8 and UTF-16 encoding, as some text editors recognize it, but it is available for
use with any output method and any encoding. {outp70}
The saxon:omit-meta-tag attribute in xsl:output has been replaced with the
new (standard) include-content-type attribute. Note that this works the other way around:
replace saxon:omit-meta-tag="yes" by include-content-type="no".
{saxon47, outp71}
The new (standard) escape-uri-attributes attribute in xsl:output has
been implemented for the HTML output method. (URI escaping is not yet implemented for method="xhtml").
{outp71}
The built-in template rules now pass parameters through unchanged to the templates for their child
elements. This applies whether the rule is called because of xsl:apply-templates
or xsl:apply-imports {cnfr21, cnfr22}.
The base URI of the root of a temporary tree is now taken from the base URI of the xsl:variable
element in the stylesheet. Previously it was taken from the system ID. There is a difference in the case
where xml:base is used. {not tested}
A variable that is never referenced will no longer be evaluated. This can cause problems if evaluation
of the variable has side-effects (e.g. by calling an extension function, or saxon:assign). You
can force evaluation of the variable by setting saxon:assignable="yes".
The terminate attribute of xsl:message may now be an attribute value
template. {ver14}
The copy-namespaces attribute of xsl:copy and xsl:copy-of is
now supported. {copy12-13}
The type attribute of xsl:variable, xsl:param,
and xsl:result is renamed as.
The as and collation attributes of xsl:key are now supported.
This allows indexing of nodes by numeric or date values, and matching using case-blind or accent-blind comparisons.
{idky25-29}.
The type-annotation attribute of xsl:attribute and xsl:element
and the xsl:type-annotation of literal result elements are supported. For example, you
can now annotate attributes of elements on a temporary tree as type-annotation="xs:ID", and
then use the id() function to find them, using an expression such as $tree/id('A001').
The actual value of the element or attribute must be valid according the the type given in the type annotation. Only built-in
schema-defined types are currently supported. Attribute types derived from a DTD will be recorded if they
are reported by the parser (but CDATA is treated as untyped, and the list types IDREFS, ENTITIES, and NMTOKENS
are not yet supported). Although the values must be valid according to their type, there are no checks on
uniqueness constraints (ID) or referential integrity constraints (IDREF). {schema001-4}
The type annotations are retained on the tree only if the attribute type-information="preserve"
is present. If the attribute is absent, or is set to none, the type-annotation on any
elements or attributes in the tree will still be used to validate the content, but will not result
in any annotation of the nodes on the tree. The values strict and lax
for this attribute are not yet implemented. {schema005-6}
The type-information attribute is also available on xsl:result-document.
It only affects the outcome if the result tree is captured using a user-written Receiver in which
the annotations will be available. At present the type annotations are NOT retained if
the result is fed into another stylesheet using
saxon:next-in-chain: this is because the chaining goes via a SAX2 ContentHandler
which cannot pass the type information through. {schema007, schema013}
The attribute copy-type-annotations is available on xsl:copy-of. The default
is "no", which means that type annotations are NOT copied from the source tree to the result tree.
{schema011-012}
The effect of xsl:namespace-alias has been changed. Elements and attributes whose namespace
is changed by an xsl:namespace-alias declaration will now take the prefix given in
the result-prefix attribute, where possible. Previously they took the new namespace URI
but retained their original prefix. This was technically conformant with the specification, but untidy,
and it often led to the result document containing multiple declarations
of the same namespace URI. {nspc36-38}
Conflicting xsl:namespace-alias declarations are now reported as a static error.
{error007}
The precedence of different expressions in the XPath grammar has been aligned with the August 2002
working draft. This meant making a few changes: range expressions (such as 1 to 10) now bind more
tightly than conditional expressions; all comparison operators now have the same precedence, and consecutive
operators (as in a = b = c) are not allowed; unary minus binds more tightly than union;
cast and treat expressions are no longer allowed as steps in a path expression. Saxon implements
the full XPath 2.0 grammar with the exceptions of the validate expression and schema-related
aspects of the SequenceType production.
Removed the ability to do a "mapping cast", that is, to cast a sequence as a sequence. This functionality went beyond the semantics of cast as defined in the XPath 2.0 specification. The argument and result of a cast must now be a singleton, and if the input is an empty sequence, the output is an empty sequence. The actual conversion rules still need some work to align them fully with the evolving XPath specification.
Implemented the escape-uri() function. The '#' character is treated as a reserved character, in addition
to those listed in the specification. {expr85}
Implemented the item-at() function, but with restrictions: if the subscript is out of range, it should
raise an error, but it currently returns the empty sequence. {pos65}
Implemented the data() function. {schema008, 009, 010, 012}
The concept of "effective boolean value" has been implemented. This algorithm
is now used when converting any value to a boolean
in contexts such as conditional expressions, filter predicates, and the boolean() function. It is
fully backwards compatible with XPath 1.0.
A different,
more restricted algorithm is used when casting values to booleans using a cast expression or the xs:boolean()
constructor: for strings in particular, the effective boolean value gives false for a zero-length string
and true for any other string, while xs:boolean() (in line with W3C Schema) gives true for "1" or "true",
false for "0" or "false", and an error for any other string. {type034}
xs:boolean() changes are not yet complete for supplied values other than string.
The algorithm for "atomize" is also available for all expressions, though at present it is used only for the argument of a cast. It is also simpler than the algorithm described in the specification because at present the typed value of a node is always the same as the string value.
Changed the EXSLT set:leading() and set:trailing() functions (as required by the spec) so that if the second
argument is empty, the first argument is returned. Changed saxon:before() and saxon:after() so they work the
same way. Previously, the empty node-set was returned. This change will be retrofitted to 6.5.x. There is a further
deviation from the spec: If no node in the second node-set is present in the first node-set, Saxon
returns all nodes before/after the first/last in the second node-set, whereas the spec requires it to return
an empty sequence. This would require a redesign, and it prevents a pipelined implementation, so I don't intend
to implement this change.
Implemented the string-to-codepoints() and codepoints-to-string() functions,
replacing saxon:string-to-unicode()
and saxon:unicode-to-string(). {saxon68-69}
Implemented the string-join() function. {str125}
Implemented the castable as operator. {type030}
Implemented the types xs:anyURI and xs:QName, and the functions expanded-QName(),
get-local-name-from-QName(), get-namespace-from-QName() {type031-33}
Implemented the SequenceType grammar for "attribute of type T" and "element of type T". T must be a built-in simple type. {schema002-004, 014; error009, 012}.
The second argument of saxon:serialize() must now be known at compile-time. This is because details
of xsl:output declarations are not available at run-time unless they are actually referenced.
The results of the function-available() and element-available() functions may be inaccurate
if the argument is not known at compile-time. Specifically, only system-defined functions and
instructions are known at run-time. In practice, these functions are designed to perform compile-time
tests so this is very unlikely to be a problem. There is also some justification in that the only
functions that can be called dynamically (using saxon:evaluate()) are system-defined functions.
As a result of the changes affecting stylesheet compilation, there are some new restrictions on
the extension function saxon:evaluate() (and also saxon:expression()). In particular, the dynamically
constructed expression can no longer reference any XSLT variables, and it cannot access any stylesheet
functions, Saxon extension functions, or XSLT-specific functions such as key() and generate-id().
There has been a substantial change to the way stylesheets are "compiled". In previous releases, the compiled stylesheet was actually a standard tree representation of the source XML stylesheet, with annotations on the nodes to assist efficient execution. In this release, the tree representation of the stylesheet is discarded once compilation is complete, and a custom data structure is used to represent the executable stylesheet.
The compiled stylesheet may now be serialized (using Java serialization), enabling it to be saved on
disk, or transferred between machines - this is especially useful in an Enterprise Java Beans environment.
A new command java net.sf.saxon.Compile stylesheet output is available to
compile a stylesheet, and the java net.sf.saxon.Transform command has a new option -c
which causes the stylesheet parameter to be taken as a compiled stylesheet rather than a source
stylesheet. In fact, using compiled stylesheets from the command line does not give a great performance
advantage over recompiling them each time they are used, because the compilation time is dominated by
Java initialization; the benefits are more likely to be realized in
a high-throughput server-based environment, where it is now possible to use disk caching of stylesheets as
an alternative to in-memory caching.
These changes bring (or promise) a number of benefits:
xsl:fallback is made entirely
at compile-time.The main drawback is that less of the static context is available during execution. This makes a number of things more difficult, or in some cases impossible:
saxon:evaluate and
the saxon:allow-avt attribute which allows dyanamic selection of a template in xsl:call-templateIn general I expect that stylesheets will need to be recompiled whenever a new Saxon version is issued, though this may be avoidable the case of a bug-clearance release.
Stylesheet compilation is a little fragile at this release. It has proved difficult to test it
comprehensively. One known restriction is that stylesheets containing saxon:collation declarations
cannot be compiled (because it uses Java classes that are not serializable). There may be other restrictions:
please let me know if you find any.
As part of this change, the stylesheet tree now uses a different NamePool from the source tree. This
NamePool is discarded as soon as compilation is complete. Names
used in XPath expressions, names of literal result elements and attributes, and names of keys, variables,
templates, and functions, are still registered in the NamePool for the source document, but the names
of XSLT elements and attributes (e.g. xsl:template, select) no longer appear.
This significantly reduces the size of the compiled version of a small stylesheet, and makes loading
of the compiled stylesheet correspondingly faster. It also means that names used in the source document
are less likely to encounter hashing conflicts in the NamePool, giving a small run-time speed-up.
There have been a number of changes to APIs that may affect users.
XSLTContext object has been merged into net.sf.saxon.Controller. This
class was exposed in the traditional Saxon Java event-handling API, and was also available for use
by extension functions, extension elements, and trace listeners. Extension functions that require
context information must now declare a first argument of class XPathContext.net.sf.saxon.instruct.Instruction. The SQL extension library has been
updated to show how the new scheme works.I have introduced a new interface, net.sf.saxon.event.Receiver, which is intended to
replace the old Emitter interface. This supports setting type
annotations on element and attribute nodes: it allows the type information to be carried with the
element and attribute events, and also allows various properties to be associated with each event, used
for disable-output-escaping and to indicate when validation has already been done so it does not get
done twice.
The classes that implement this interface are largely in package net.sf.saxon.event, which
replaces the old net.sf.saxon.output package.
The new interface largely replaces the Outputter interface, ending the artificial distinction between the Outputter and the Emitter, which was there historically because events were handled in a different order at the two interfaces.
The "sticky d-o-e" facility is not working in this release: that is, an error is reported when output is written to a temporary tree with disable-output-escaping="yes". The same happens if the final output of the stylesheet is written to a Saxon tree, for example when using a Saxon-created DOMResult, or when using stylesheet chaining. It is possible that "sticky d-o-e" will not be allowed in the final XSLT 2.0 specification, though at present there are open issues concerning this. {outp09, bug17}
The class hierarchy for XPath expressions (net.sf.saxon.expr.Expression) has been simplified. The two abstract classes SingleValueExpression and SequenceExpression have disappeared; their functionality has moved into the parent class, Expression, driven by the static cardinality of the expression as determined by the getCardinality() method. This allows greater re-use of classes such as BinaryExpression. There is potential for many expressions to be implemented as functions, allowing more use of generic code and table-driven static analysis.
The implementation of SequenceExpressions of the form (1,2,3) has changed completely,
and is much simpler.
They are now handled by breaking them up into a tree of binary expressions, treating "," as a list
concatenation operator. {expr53, 54, 55, 86}
The implementation of FilterExpressions has been rewritten and simplified. Two different iterators are now used, a FilterIterator where every value needs to be tested, and a PositionIterator where the value is known statically to be numeric. This greatly simplifies the code. The way in which reverse axes are handled has also been simplified.
I want to move away from run-time expression reduction on filters to doing a static rewrite that pulls non-dependent subexpressions out of the predicate, but this has not yet been done.
The class XPathException is now abstract. There are two concrete subclasses,
XPathException.Static and XPathException.Dynamic, used to distinguish static
from dynamic errors. (Other subtypes, for example XPathException.TypeError may be
introduced in future. A dynamic error that occurs when an XPath expression is evaluated early (at
compile time) is now not reported until run-time, and is only reported if the expression is actually
evaluated.
I have decided to drop the integration with Apache's FOP processor. The API has changed yet again between FOP 0.20.3 and FOP 0.20.4. It is simply too much hassle to keep chasing a moving target, especially as the changes are not well documented and impossible to make without studying the FOP source code.
It is now possible to control the use of NamePools via the TransformerFactory. The call
factory.setAttribute(FeatureKeys.NAME_POOL, pool) causes the specified namepool
to be used by all stylesheets that are compiled (using newTemplates()) following
this call. Note: unless you really know what you are doing, it is safest to let Saxon manage
the namePools automatically.
The HTML output method now uses its own internal method for URI escaping, rather than relying on the utf8 encoding available in the Java IO library. {outp52, 57}
Support for SAX1 XML parsers is withdrawn. All mainstream parsers support SAX2, with the possible exception of James Clark's xp. Similarly, output will no longer be directed to a SAX1 DocumentHandler: you must supply a SAX2 ContentHandler instead. Saxon now compiles without any deprecation warnings.
Saxon 7.2 requires Java JDK 1.4
Saxon 7.2 requires JDK 1.4. This is primarily to support the use of regular expressions: Saxon now uses
the JDK 1.4 regular expression library to support xsl:analyze-string and the functions
matches(), replace(), and tokenize().
Since JDK 1.4 includes an XML parser, there is no longer any good reason for Saxon to supply its own XML parser. Therefore AElfred is no longer included in the Saxon package, and the default will be to use the Crimson parser (or whatever is included in the JDK 1.4 distribution).
Note: JDK 1.4 appears to require more [or allocate less] stack space than JDK 1.3, some transformations that ran successfully in JDK 1.3 run out of stack space with JDK 1.4. This equally affects earlier Saxon releases when running with JDK 1.4
542981: Saxon fails with JDOM beta 0.8.
553347: The context node is not reset correctly after a stylesheet function is called from within an XPath predicate.
558696: Cannot include a simplified stylesheet.
561695: Error message "more than one method matches" when calling a Java method that accepts argument of class Object.
573314: The expression
string-length($x)=0 gives wrong result for "0" and "false".
576632: Match on parent node in a pattern fails.
580989: NullPointerException when tracing using -T option.
581515: Duplicate DOCTYPE declaration when using an identity transformer and HTML serialization.
583939: Memory leak when using keys.
584944: Attribute value templates on <xsl:sort> cannot depend on the context node.
Implemented the xsl:analyze-string instruction, which supports regular expression
matching.
Where an embedded expression within an attribute value template yields a sequence of more than one
item, the string values of all the items are now output, separated by spaces. This is incompatible
with XSLT 1.0, which ignored all but the first node in a node-set. If this causes compatibility
problems (a) you can fix it by using the filter [1] after the expression, (b) please
let me know: the XSL WG wants to know whether this incompatible change is likely to cause problems
in practice.
The elements xsl:variable, xsl:param, and xsl:result may
now take a type attribute indicating the required type of the value. The supplied value
will be converted to this type if necessary. The value of the attribute is the same subset of the
XPath SequenceType production as is implemented for "cast as" and "instance of" expressions: basically,
the fixed types such as "item" and "element" and the built-in types such as xs:string and xs:date, followed
by an optional occurrence indicator.
Parameters to xsl:function may no longer specify a default value: all arguments
must be supplied in the function call.
An xsl:message instruction may now appear inside an xsl:function.
The xsl:text instruction may now contain other instructions, such as xsl:value-of.
Pending resolution of issue 132 in the spec, avoid using disable-output-escaping with nested xsl:text
elements. The effect is unlikely to be what you expected..
It is now an error to specify the mode or priority attributes on an
xsl:template element with no match attribute.
Match patterns using the id() and key() functions can now reference global
variables or parameters for the value of the id or key.
The attributes version, exclude-result-prefixes, and extension-element-prefixes
may now appear on any element in the XSLT namespace. Note that these attributes are prefixed xsl:
when used on a literal result element, but have no prefix when used on an XSLT element.
The attribute [xsl:]default-xpath-namespace is now available on all elements. It defines the defualt
namespace to be used for unprefixed element names in path expressions and patterns.
The xsl:apply-templates element now allows mode="#current" and
mode="#default". The xsl:template allows the mode attribute
to be a list of mode names, optionally including #default to match the default mode.
The disable-output-escaping attribute of xsl:attribute is implemented, replacing
the saxon:disable-output-escaping extension, which is no longer available.
The xsl:destination element is renamed xsl:principal-result-document. (This was
misdocumented in version 7.1).
Implemented the unparsed-text() function (with the second argument being mandatory).
Added a -v option to the command line to request XML validation. This applies to the principal source document and other files read using the document() function. It requires an XML parser that supports validation.
The same feature is available in the API using setFeature(FeatureKeys.VALIDATION, Boolean.TRUE)
on the TransformerFactory.
Added a getTransformer() method to the net.sf.saxon.Filter class that is
created in response to SAXTransformerFactory#newXMLFilter(). This allows setting of stylesheet
parameters, a URIResolver, etc, when using this interface. Not tested.
The standard TraceListener now outputs an abbreviated version of the file name of the stylesheet module containing an instruction, as well as the line number.
The indentation algorithm for method="xml" has been changed so no extra whitespace is output if there is already enough whitespace in the result tree: specifically, if a start tag is preceded by a newline and as many spaces as the indentation would output, then no extra indentation takes place. The effect is to avoid adding blank lines when copying XML that is already indented. This change does not affect method="html", because the HTML indentation rules are more complex and can easily affect the appearance of text in the browser if applied wrongly.
Implemented the regular expression functions matches(), replace() and tokenize() as defined in the Functions and Operators specification; also the regex-group() function defined in the XSLT 2.0 WD.
The only option in the construct A instance of [only] B has been
removed, as it is no longer defined in the XPath WD.
Changed the rules for the context document: this is now always the document containing the context node. If the context item is not a node, there is no context document, and any absolute path expression (or calls on id(), key(), or unparsed-entity-uri()) will cause a dynamic error.
Implemented the time data type, the constructor xs:time(),
and the functions current-date() and current-time(). Time values can be compared for equality or
ordering, and can be sorted.
Implemented the component extraction functions, get-x-from-y, for date, dateTime, and time.
Changed DateTime and time classes so that the timezone is retained as part of the value. Equality and ordering is done by normalizing the time to UTC, but conversion to a string, and extraction of components, reflects the timezone as originally specified.
Constructor functions such as dateTime() have been moved to the schema namespace (you can use either "http://www.w3.org/2001/XMLSchema" (conventional prefix xs) or "http://www.w3.org/2001/XMLSchema-datatypes" (conventional prefix xsd). Stylesheets that use these constructor functions must be changed. The semantics of these constructor are identical to the cast expression.
Added the duration data-type, including conversion to and from strings, comparison for equality and
ordering, sorting, and component extraction. (This goes beyond the XPath 2.0 drafts, which do not allow
ordering on durations.) Ordering is based on the average length of a month (one
year = 365.25... days): so P365D < P1Y and P366D > P1Y.
Component extraction works on any kind of duration, and the functions are currently
named get-X-from-duration(), not get-X-from-yearMonthDuration() or get-X-from-dayTimeDuration().
Arithmetic involving durations or dates is not yet implemented.
Added the two XPath-defined subtypes of duration: xs:dayTimeDuration and xs:yearMonthDuration. Implemented the functions to construct these from a number of months or seconds. The "+" and "-" operators can be used to add two durations of the same type, and the "*" and "div" operators to multiply or divide a duration by a number.
Added the subtypes of xs:integer (xs:long, xs:int, xs:short and the rest). The type promotion rules for comparison and arithmetic on numeric types have been brought into line with the specification, though there are probably still a few minor discrepancies (especially where fallback conversions from strings are involved).
Added the idiv operator for integer division. For example, 10 idiv 3 is 3.
The div operator always returns a double result.
Added the subtypes of xs:string (token, language, Name, NCName, ID, IDREF, ENTITY, NMTOKEN); but not the list types IDREF, ENTITIES, NMTOKENS. These have no useful functionality beyond the ability to validate the lexical rules for each type.
Implemented the distinct-nodes() function (at the same time fixing a bug in union, intersect and except when supplied with arguments that are not in document order).
Implemented the deep-equal() function. Because nodes are still untyped, it compares string values of text nodes rather than typed values. Not yet tested with an explicit collation.
Renamed the sublist() function as subsequence().
Implemented the sequence-node-equal() and sequence-deep-equal() functions. Not yet tested with an explicit collation.
Implemented the functions node-kind(), root(), context-item().
Added the EXSLT functions in package math: abs, acos, asin, atan, atan2, constant, cos, exp, log, power, random, sin, sqrt, tan. Thanks to Simon St. Laurent for these. Only partially tested.
The saxon:intersection and saxon:difference extension functions have been dropped; instead use either the XPath 2.0 operators (intersect, except) or the EXSLT functions.
Many internal iterators work with a one-item lookahead. This is wasteful if the iteration is not
continued to completion, which happens for example with a numeric predicate such as expr[1], or
with an existential comparison such as sequenceA = sequenceB, or when converting a
sequence to a string or a boolean. This lookahead has been removed for some commonly used iterations,
notably the FilterIterator, the MappingIterator, and the TinyTree SiblingIterator.
A consequence is that the hasNext() method of SequenceIterator can now throw an XPathException.
Deferred evaluation of variables happened in the past when the expression was a SequenceExpression. It now happens only if the compile-time cardinality of the expression allows more than one item. This means that deferred evaluation will not be used for an expression of the form expr[1]. And when deferred evaluation is used, the iterator is not primed by calling hasNext(): this means that (for an iterator that doesn't do lookahead), the search for the first item is now deferred until the variable is first used, and doesn't have to be repeated unnecessarily. In addition, if the variable is referenced in a context where only the first item in the sequence is required (e.g. to get the value as a boolean or as a string), the value is now saved without evaluating the full sequence.
I have added an optimization for constructs of the form <xsl:if test="a | b">.
Where a union expression is evaluated in a boolean context it is now treated as if the operator were "or".
This potentially avoids the need to sort the two node-sets into document order.
There are some changes in the way global variables are handled. At compile time, a hash table is used in place of linear searching to search for duplicates: this should improve compilation performance for stylesheets with many global variables, especially when many of the variables are overridden by an importing stylesheet. At run-time, evaluation of global variables is now deferred until the first reference to the variable, which will improve execution performance when there are global variables that are never referenced. Note that this change will be visible if <xsl:message> is used to trace execution.
A filter expression of the form f[a and b] is now rewritten as f[a][b] when
appropriate, to enable an early exit in the case where a is positional: for example
item[position() = 1 and child::desc]. This is only done if a is positional and
b is not.
A union (or intersection or difference) of two path expressions is now rewritten to do the combination
as late as possible: for example ( /a/b/c | /a/b/d ) is rewritten as ( /a/b/(c|d) ).
Note, this is a first small step in the identification of common subexpressions. The cases where two
subexpressions are detected as being identical are fairly limited, for example there is no knowledge
of which operators are commutative or associative.
The organization of the net.sf.saxon.functions package has changed. Much of the fixed information associated with individual functions is now contained in a static table in the StandardFunction.java module, rather than being returned by methods associated with each function. Most of the optimization methods (simplify, getDependencies, and reduce) now have a generic default implementation in the Function.java class, which most of the individual functions now use. This has reduced the overhead associated with implementing each function, which is important as the number of functions in XPath 2.0 has grown so much. It also creates further opportunities for combining the implementation of several related functions in one module, with better ability to share common code.
Unique document numbers are now allocated in the NamePool rather than the DocumentPool. This is visible in the results of generate-id(), because it means document numbers are not reset at the beginning of each transformation. This change has been made so that functions that rely on unique document numbers (for example, comparison of nodes into document order, or the union operation) can be done safely in a free-standing XPath environment. Eventually this will also allow document() to be executed outside an XSLT context - but not yet.
I have tested Saxon with the Resin XML parser, but found it very buggy (version 2.1.1)
I have tested Saxon with the Piccolo XML parser (version 1.03), and found it worked very well except for a few stress tests, particularly in the area of namespace handling. I have reported four bugs.
The tables for converting XPath data types to Java types (when calling extension functions) have been revamped. The design has changed so that where there are two methods that appear to match the function call, one of them will generally be chosen even if the choice is arbitrary: this is because in many cases where Java classes define polymorphic methods, the results will be the same whichever method is chosen.
This version of Saxon has been modified and tested to work with JDOM beta 0.8 and with FOP 0.20.3. In both cases, code changes were needed to work with these versions, and I have not tested whether the code still works with earlier versions; the chances are that it doesn't.
In general, bugs that have been cleared in Saxon 6.5.1 or Saxon 6.5.2 have also been cleared in this release. For details of the clearance of specific bugs, see the bug tracker at Sourceforge. Remember that closed bugs are not listed unless you ask for them.
The href attribute of xsl:result-document is now interpreted as a relative
URI, relative to the system ID of the principal result document. This works only where the system ID of the
principal output is known, and uses the "file://" protocol. The result document is no longer created
relative to the current working directory, for security reasons (it causes problems when executing
an untrusted stylesheet in a servlet environment).
Note that when Saxon is invoked from the command line, the -o option should be used to specify the
principal output destination. This will ensure that a suitable system ID is available. If the result document
is sent to the standard output stream (even if this is redirected to a file), Saxon will not know the
system identifier and will therefore be unable to create a secondary output destination using a relative
URI. It is still possible, of course, to specify an absolute URI as the value of the href
attribute - note that this must be a URL, not a filename, so it will typically start with file://.
It is now possible to specify an OutputURIResolver to be used to resolve the URI specified in the href
attribute of the xsl:result-document element. This will be used in place of the standard output URI
resolver. The OutputURIResolver is called when writing of the output document starts, at which point it must
return a JAXP Result object to act as the output destination. It is called again when writing of an output document
is complete. You can nominate an OutputURIResolver by calling
((Controller)transformer).setOutputURIResolver(new UserOutputResolver()),
or by calling factory.setAttribute("http://saxon.sf.net/feature/outputURIResolver",
new UserOutputResolver()).
If the -t option is used, a message is written to the standard error output identifying the
files written using using xsl:result-document.
It is now an error to use xsl:result-document when the current output destination
is a temporary tree.
The meaning of the ALLOW_EXTENSION_FUNCTIONS attribute in the TransformerFactory has been
extended so that setting the value to false also disables extension elements and
the creation of multiple output files. This is because all these operations carry similar risks
when a servlet is allowed to execute untrusted stylesheets.
Added support for the separator attribute of <xsl:copy-of>.
The current() function may now be used in a pattern (specifically, within a predicate).
Its value is the node being tested against the pattern. For example, match="*[*[name()=name(current())]"
matches any element that contains another element with the same name.
A global variable or parameter may now be used in the match pattern of xsl:template, provided that it does
not cause a circularity (that is, it must be possible to evaluate the variable without calling
xsl:apply-templates)
A global variable or parameter may now be used in the match pattern or the use expression
of xsl:key, provided that it does
not cause a circularity (that is, it must be possible to evaluate the variable without using the key()
function against the key being defined)
The key() function may now be used in the use or match attributes of
xsl:key, provided the key definitions are not circular. (For example, key k1 can be defined
in terms of key k2, provided that k2 is not defined in terms of k1.)
The group-ending-with attribute of xsl:for-each-group is implemented. It is especially
useful where the last node in each group carries some kind of marker, for example continued="no".
Added attribute default="yes"|"no" to saxon:collation, to specify whether this collation
should be used as the default collation. If more than one collation is specified as the default, the last one wins.
If no default collation is specified, Unicode codepoint collation is used. The default collation is used by
the compare() function if no third argument is supplied, by xsl:sort if no collation is specified (for data type text
or string), and also by the comparison operators =, !=, <, >, etc.
The collation name is now a URI, not a QName.
Sorting and comparison according to Unicode codepoints can be achieved by setting up a collator as
<saxon:collation name="unicode" class="net.sf.saxon.sort.CodepointCollator"/>
The implementation of the "and" and "or" operators has reverted to two-valued logic, since three-valued logic didn't make it into the published XPath 2.0 working draft. (Actually, it seems 3-valued logic wasn't working in Saxon 7.0 anyway).
Changed the "==" and "!==" operators to "is" and "isnot".
Changed string literals to allow the delimiting quote marks to be doubled. For example,
<xsl:value-of select="'[He isn''t]'"/> displays the string [He isn't]
Changed the some and every expressions to allow multiple range variables,
for example some $i in //I, $j in //J satisfies $i = $j
Implemented the singleton value-comparison operators (eq, ne, gt, lt, ge, le). These return an error if applied to a sequence containing more than one item, and return the empty sequence if either operand is an empty sequence; when applied to singletons, they return the same result as the XPath 1.0 operators (=, !=, etc).
Less-than and greater-than comparisons between nodes and/or strings now do a lexicographic comparison using the default collating sequence; at XPath 1.0 they did a numeric comparison. A warning is output in this situation (and one or two other situations, but not all) to advise of the backwards incompatibility.
The rules for deciding when path expressions need to be sorted have been revised. As a result many cases now require no sort where previously a sort was done. Examples of such expressions include a/b/c, .//a, $x[1]/a, //@a. In addition, most path expressions that return results in reverse document order are now sorted by a simple reversal, which is much faster than a full sort.
There's a temporary bug in that path expressions returning namespace nodes don't always return them in document order. I'm awaiting resolution of the XPath 2.0 data model rules before fixing this.
Suppress lazy evaluation of assignable variables. (This was designed to prevent a stack overflow, it didn't succeed, but it seems a good idea anyway).
Added the ability for a Source object to be supplied as the value of a stylesheet parameter or as the value returned by an extension function.
Added dateTime and date data types. Initially the only operations supported are the currentDateTime function, the dateTime and date constructors, and conversion between strings, dates, and dateTimes in both directions. Conversion to string uses the timezone of the current locale.
Implemented comparisons (equals, less-than, etc) between dates and dateTimes.
Also implemented sorting. The data-type of xsl:sort may take the two values "text" or "number"
(which are treated as synonyms of xs:string and xs:double) or any XML Schema built-in data type
for which sorting is supported. The values in the sequence to be sorted are converted to this
data type (using the same rules as for cast as) and the rules for this data type
determine the sort order.
Note that (as required by the XML Schema specification) dateTime values are normalized to UTC. The original timezone specified when the dateTime was constructed is not retained. If no timezone is present, this fact is remembered. Such a dateTime is compared with other dateTimes as if it were a UTC dateTime.
Implemented the instance of operator (including the instance of only variant):
for example if ($x instance of xs:integer *) then x else y. The types that are currently
supported are the 19 primitive schema types (the namespace may be either of the two namespaces
permitted in XML Schema Part 2), the derived type xs:integer, the node types document, element,
attribute, text, comment, processing-instruction, or namespace, and the abstract types node, and item.
(There is no syntax currently for the general numeric type or for the general atomic type). The
type name may be followed by one of the qualifiers "*", "+", or "?" to indicate the number of
occurrences; if there is no qualifier, there must be exactly one occurrence. The more sophisticated
forms of type-checking, using schema-defined complex types, are not yet supported.
Implemented the cast as data-type expression, for example cast as xs:boolean($x).
The conversion rules are the same as those which apply implicitly when a value is supplied
in a context where a different type is expected.
Implemented the treat as data-type expression. This doesn't actually have much use in an XSLT context, where type conversion is performed implicitly when required, and the semantics of the expression are probably not correctly implemented at this stage: the specification is still evolving.
A new API has been introduced for executing XPath expressions. This is simpler and safer than the API provided in previous releases, which was essentially improvised from implementation classes rather than being designed top-down as an interface suitable for application use. The API is loosely modelled on the proposed DOM Level 3 API for XPath.
The new API uses the class net.sf.saxon.xpath.XPathEvaluator. This class provides a few
simple configuration interfaces to set the source document, the static context, and the context node,
plus a number of methods for evaluating XPath expressions. The static context can be omitted if the
expression does not use namespaces, external variables, or extension functions. If the expression uses
namespaces, an instance of StandaloneContext can be supplied, allowing the required namespaces to be
declared either explicitly, or by reference to the in-scope namespaces of some Node.
There are two methods for direct evaluation, evaluate() which returns a List containing the result of the expression (which in general is a sequence), and evaluateSingle() which returns the first item in the result (this is appropriate where it is known that the result will be single-valued). The results are returned as NodeInfo objects in the case of nodes, or as objects of the most appropriate Java class in the case of atomic values: for example, Boolean, Double, or String in the case of the traditional XPath 1.0 data types.
It is also possible to prepare an XPath expression for subsequent execution, using the createExpression() method on the XPathEvaluator class. This is worthwhile where the same expression is to be executed repeatedly. The compiled expression is represented by an instance of the class net.sf.saxon.xpath.XPathExpression, and it can be executed repeatedly, with different context nodes. However, the compiled expression is bound to one particular source document (this is to ensure that the same NamePool is used).
The design principle of this API is to minimize the number of Saxon classes that need to be used. Apart from the NodeInfo interface, which is needed when manipulating Saxon trees, only the four classes XPathProcessor, XPathExpression, StandaloneContext, and XPathException are needed. For convenience, XPathException and StandaloneContext have been moved to the net.sf.saxon.xpath package.
If you want to use extension functions or variables you will need to create your own implementation of StaticContext. Although this interface has been greatly simplified, this is still not to be attempted lightly.
The old APIs for executing expressions still exist for the time being, but they are likely to be less stable.
Changed ContentEmitter to check in startElement() that qname and local-name are both supplied; this checks against parser configuration errors. This change could (should?) be retrofitted to the 6.5 branch. The change also uses a stack of namecodes so that endElement() doesn't need to look up the names in the name pool. In implementing this change, I discovered that Saxon depends on the XML parser passing the QName argument to the startElement() call, something which according to the SAX2 specification is optional. However, all known parsers supply this argument, and the code changes to cope with its absence would damage performance, so I have simply documented this as a dependency on the parser.
Implemented infrastructure for data type support:
I have changed the implementation of temporary trees (result tree fragments). The FragmentValue class has disapeared. This delayed the construction of an actual tree until it the tree was actually used as a node-set: the effect was to optimize simple uses of temporary trees but at considerable cost to the more general usage which is now permitted in XSLT 2.0. Also, the introduction of tinytrees has reduced the value of this optimization. Therefore, a temporary tree is now constructed immediately as a real tree.
A side-effect of this change is that when disable-output-escaping is used while writing nodes to a tree, the instructions to switch escaping on and off are recorded in the tree in the form of the processing instructions defined by JAXP 1.1. Previously, these instructions were recorded in a form that kept the information through an xsl:copy-of instruction, but lost the information if the tree was processed in any other way. Note that the behavior of "sticky d-o-e" (that is, the effect of disabling output escaping when writing to a temporary tree) is currently an open issue in XSLT 2.0.
The indexes associated with keys are no longer referenced from each document instance, they are handled externally. This makes it easier to share the same index implementation across all the different document implementations. The indexes are now held by the KeyManager. It uses a WeakHashMap to ensure that when a document is removed from memory by the garbage collector, its indexes are removed too.
The mechanism for keeping stylesheet signatures in the namepool has been removed. It caused a creeping "memory leak" in continuously running services, and is not really needed. It was invented to allow namepools to be copied, but this facility has never been properly documented or tested. Instead, there is now a simple check that the source document and stylesheet are using the same namepool. (This change, or a simplified version of it, has also been made to 6.5.2).
The StaticContext interface has been greatly simplified, reducing duplication and making it easier to create a new implementation of this interface. This has been achieved partly by doing some work in the XPath ExpressionParser that was previously done in the StaticContext, and partly by changing those functions such as format-number() and sort() that only work in an XSLT context to check that the context is indeed XSLT before accessing the context information.
At the suggestion of Claudio Thomas [claudio.thomas@web.de], I have extended the sql:query instruction
to allow the attribute disable-output-escaping="yes|no". This is useful where the database
content being retrieved contains XML or HTML markup that is to be preserved in the output. Use this
with care; it disables escaping for all the rows and columns retrieved, some of which may contain
special characters such as "<" and "&" that do need to be escaped.
This change has not been tested.
Added extension functions: saxon:parse() and saxon:serialize(). These allow conversion of a string containing well-formed XML to a tree structure, and vice-versa.
Added extension functions: saxon:string-to-unicode() and saxon:unicode-to-string(). These allow conversion between a string and a sequence of integers representing the Unicode values of the characters in the string.
Added extension functions saxon:pause-tracing() and saxon:resume-tracing().
The return value from an extension function may now be an implementation of java.util.List,
representing a sequence. The members of the List must all implement net.sf.saxon.om.Item
An argument to an extension function may now be the class net.sf.saxon.om.NodeInfo, or
a subclass. If the supplied value is a sequence, the first node in the sequence is passed to the function;
it is an error if there is no node in the supplied sequence, or if the node is of the wrong type.
The rules for calling extension functions with a sequence-valued argument have been clarified, and
some new options are permitted, e.g. declaring the argument as java.util.List. The possibilities
have not been extensively tested.
Implemented memo functions (thanks to Robert Brotherus for the suggestion).
If you specify the attribute saxon:memo-function="yes" on xsl:function,
Saxon will keep a cache that maps the supplied argument values to the result of the
function, and if the function is called twice with the same arguments, the original
result will be returned without re-evaluating the function. Don't use this option on a function
that depends on the context, or on a function that creates a new temporary tree and
is required to create a new instance each time. Also note that there are cases where it
may be faster to re-evaluate the function than to do the lookup; this is especially true
if the argument is a large node-set.
This version introduces initial support of features defined in working drafts of XSLT 2.0 and XPath 2.0.
Version 7.0 should be regarded as an experimental alpha release. For production use, please continue to use Saxon 6.5
The Saxon package name has changed from com.icl.saxon to net.sf.saxon.
Any applications that use Saxon java classes directly (rather than relying on the JAXP
interface) will need to be modified. Note that this also affects the settings of the system
properties javax.xml.parsers.SAXParserFactory and
javax.xml.transform.TransformerFactory.
The entry point from the command line has changed from com.icl.saxon.StyleSheet to net.sf.saxon.Transform.
The namespace URI for saxon extensions has changed from http://icl.com/saxon to http://saxon.sf.net/. Note that many extensions have been withdrawn, as they are superseded by facilities in XPath 2.0 and/or XSLT 2.0.
To allow coexistence, the name of the JAR file for this release has changed to
saxon7.jar. The SQL extensions are now in a separate JAR file, saxon7-sql.jar.
A transformation can now be executed directly from the JAR file using the command
java -jar saxon7.jar in place of java net.sf.saxon.Transform.
Saxon now requires JDK 1.2 or later to run. In consequence, Saxon will no longer work with the Microsoft Java VM, and the Instant Saxon version of the product is therefore no longer available.
Because Saxon no longer runs with the Java VM, it can now be run as an applet within Internet Explorer only if the Sun Java plug-in is installed. You can get this from http://java.sun.com/getjava. This may require some configuration changes because of the differences in security policy.
The following sections summarize the main new features. These assume familiarity with the XPath 2.0 and XSLT 2.0 specifications; however, summaries of the new syntax for expressions and XSLT elements are included in this package.
($a, $b, $c).
Path expressions now return a sequence of nodes containing no duplicates, in document
order.a/(b|c)/d,
or document('x')/key('a','b')1 to 10 evaluates to the
sequence ( 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 )*:localname (like prefix:*) is allowed in path expressions, and also
in patterns and in xsl:strip-space and xsl:preserve-space. It matches
any node with the given local name, regardless of namespace.xsl:value-of element has a new separator attribute, so it can
be used to output a sequence.xsl:for-each element supports arbitrary sequences.saxon:group and saxon:item are
withdrawn.xsl:for-each-group instruction, and the associated current-group()
function, are implemented.xsl:function and xsl:result elements are implemented;
these replace saxon:function and exslt:function.
Note that the XSLT 2.0 specification is more restrictive as to what can appear in a function
body: it has to be zero or more xsl:param elements, followed by zero or more
xsl:variable elements, followed by an xsl:result element.
However, this is not a serious restriction in practice, because most computations can now
be carried out within a single XPath expression.xsl:namespace instruction is implemented (it writes a
namespace node to the result tree)xsl:copy-of can now handle sequences containing simple-values
(the simple value is converted to a string and written to the result tree).
However, the separator attribute is not yet implemented.
xsl:document element (and its synonym saxon:output)
are replaced by xsl:result-document. This no longer includes the serialization
attributes directly, instead it refers by name to an xsl:output declaration,
or can use the unnamed xsl:output declaration by default.xsl:output element now supports method="xhtml",
replacing method="saxon:xhtml". The precise details of the output may not be fully
conformant with the specification.xsl:destination element is provided, however, since the href
attribute is currently ignored, it is not very useful at this stage.saxon:handler element is no longer supported.xsl:script element is no longer supported - however,
the synonym saxon:script remains availablecollation attribute has been added to xsl:sort,
and the implementation of sorting now uses JDK 1.2 collators. The collation
attribute must match the name attribute of a saxon:collation element.
If none is specified, the lang attribute is now used to select a collator, or if the
lang attribute is omitted, a collator is obtained for the default locale. xsl:sort-key element. A named
sort key may be used to perform a sort from within an XPath expression, using the new
XSLT-defined sort() function.I have made the following changes to the function library:
saxon:distinct() extension function now works on any sequence.count() and sum() functions now ork on any sequence,
and new functions avg(), min(), and max() are provided.ends-with()upper-case() and lower-case().
These use the rules defined by the Java default localesystem-property()saxon:range() extension function
(it can now be done using the syntax "a to b")saxon:tokenize() to return a sequence of strings instead of a node-setkey() so that the second argument can be any sequence;
each member of the
sequence is converted to a string and treated as a potential key valuedocument() so that the first argument can be any sequence; each member of
the sequence can be a URI of a document to be loaded.saxon:node-set() extension function, which is now obsolete.saxon:if() extension function, which is superseded by XPath 2.0
conditional expressions.saxon:closure() function is temporarily withdrawn, because it relies on non-standard
use of the current() function.node-set() function in the EXSLT common module is now a no-op; the object-type()
function returns one of "sequence", "boolean", "number", "string", or "external".highest() and lowest() in the EXSLT math
module to work on arbitrary sequences.exists() and empty(),
insert() and remove(),
index-of() and sublist().not3() (three-valued not() function)string-pad() functionsaxon:exists() and saxon:for-all():
these are superseded by the some and every
constructs in XPath 2.0compare() function: the third argument (collation) is initially mandatory, and must
be a QName matching a saxon:collation elementbase-uri() function replacing the undocumented
saxon:base-uri() extension functionfloat() is the only way of creating a single-precision
floating point number.In general, features of XSLT 2.0 and XPath 2.0 not listed above have not been implemented. In particular, these include:
type attribute of xsl:variable, etc.instance of and
cast as.As might be expected, the Saxon code has undergone major change internally, which will affect any application making significant use of internal interfaces. Here are some of the highlights:
for
expressions. It is also used in various other contexts, e.g. in the implementation of
the document(), key() and id() functions.getStringValue,
this allows both SimpleValues and Nodes to implement the new Item interface, which
represents a member of a sequence.net.sf.saxon.value, now contains all the data-type related classes. I have removed documentation of the saxon:trace extension attribute; it seems this hasn't been working for some time.
Context class no longer implements the XSLT 1.1 WD interface
org.w3c.xsl.XSLTContext.com.icl.saxon.handlers (ElementHandler etc). It is still
possible for a Java application to register a NodeHandler to receive events; this
must now be written as an implementation of the net.sf.saxon.NodeHandler interface.
See the ShowBooks.java sample application to see how.data-type
or lang attribute of xsl:sort; instead, it must be specified using the
collation attribute,
with a saxon:collation element that maps the named collation to a Java
class that implements the JDK java.util.Comparator interface.A new sql:query instruction has been added, to accompany the
existing sql:connect, sql:insert, etc.
Attributes:
| table | The table to be queried (the contents of the FROM clause of the select statement). This is mandatory, the value is an attribute value template. |
| column | The columns to be retrieved (the contents of the SELECT clause of the select statement). May be "*" to retrieve all columns. This is mandatory, the value is an attribute value template. |
| where | The conditions to be applied (the contents of the WHERE clause of the select statement). This is optional, if present the value is an attribute value template. |
| row-tag | The element name to be used to contain each row. Must be a simple name (no colon allowed). Default is "row". |
| column-tag | The element name to be used to contain each column. Must be a simple name (no colon allowed). Default is "col". |
The xsl:query instruction writes zero or more row elements to the current
result tree, each containing zero or more column elements, which contain the data values.
Thanks to Claudio Thomas [claudio.thomas@web.de] who supplied the original version of this code.
The SQL extensions are now contained in a separate JAR file, saxon7-sql.jar,
which must be on the class path if these extensions are used.
Michael H. Kay
10 December 2002