Status of this Document
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
This is a Public Working Draft for review by W3C Members and other interested parties. Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
This document was produced through the efforts of the W3C XML Query Working Group (part of the W3C XML Activity). It is designed to be read in conjunction with the following documents: [XQuery 1.0: An XML Query Language] and [XQuery 1.0 Formal Semantics].
This document specifies an XML syntax for XQuery. The XML Query WG anticipates that XQueryX will be an optional conformance feature for XQuery 1.0. Feedback is invited regarding security considerations with respect to exchanging queries represented in XQueryX syntax on the Web or Internet.
This draft includes many corrections and changes based on member-only and public comments on the Last Call Working Draft (http://www.w3.org/TR/2005/WD-xqueryx-20050404/). These changes include realigning the XQueryX schema with the current XQuery grammar, incorporation of a new schema model that uses substitution groups instead of an inheritance hierarchy, use of named types for various kinds of expressions, adoption of a "paired naming"
approach to QName references, and a number of minor corrections. A list of changes introduced by this draft can be found in D Change log. These decisions are recorded in the Bugzilla database (http://www.w3.org/Bugs/Public/).
This draft is being provided to permit public review of the changes that have been made as a result of the Last Call comments. Comments on the changes should be made against the pertinent Last Call comment (instructions can be found at http://www.w3.org/XML/2005/04/qt-bugzilla). If access to that system is not feasible, you may send your comments to the W3C mailing list, public-qt-comments@w3.org
(archived at http://lists.w3.org/Archives/Public/public-qt-comments/). Please start the subject line with “[XQueryX]” so comments can be classified correctly.
The XML Query and XSL Working Groups expect to progress this document to Candidate Recommendation status in the very near future.
The patent policy for this document is specified in 5 February 2004 W3C Patent Policy. Patent disclosures relevant to this specification may be found on the XML Query Working Group's patent disclosure page. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) with respect to this specification should disclose the
information in accordance with section 6 of the W3C Patent Policy.
1 Introduction
The [XML Query 1.0 Requirements] states that "The XML Query Language MAY have more than one syntax binding. One query language syntax MUST be convenient for humans to read and write. One query language syntax MUST be expressed in XML in a way that reflects the underlying structure of the query."
XQueryX is an XML representation of an XQuery. It was created by mapping the productions of the XQuery grammar into XML productions. The result is not particularly convenient for humans to read and write, but it is easy for programs to parse, and because XQueryX is represented in XML, standard XML tools can be used to create, interpret, or modify queries.
There are several environments in which XQueryX may be useful:
-
Parser Reuse. In heterogeneous environments, a variety of systems may be used to execute a query. One parser can generate XQueryX for all of these systems.
-
Queries on Queries. Because XQueryX is represented in XML, queries can be queried and can be transformed into new queries. For instance, a query can be performed against a set of XQueryX queries to determine which queries use FLWOR expressions to range over a set of invoices.
-
Generating Queries. In some XML-oriented programming environments, it may be more convenient to build a query in its XQueryX representation than in the corresponding XQuery representation, since ordinary XML tools can be used.
-
Embedding Queries in XML. XQueryX can be embedded directly in an XML document.
2 Mapping the XQuery Syntax
XQueryX is an XML representation of the abstract syntax found in Appendix A of the [XQuery 1.0: An XML Query Language]. The XQueryX syntax is defined by the XQueryX Schema, which is specified in 4 An XML Schema for the XQuery XML Syntax. The XQueryX semantics are defined by a stylesheet that maps an instance of XQueryX to an instance of XQuery; see B Transforming XQueryX to XQuery.
The main data structure in the XQueryX Schema is the set of types that describe expressions. We have chosen to model expressions using substitution groups, with an "expr" abstract base class and a number of intermediate abstract classes.
Consider the following productions from the abstract syntax:
FLWORExpr ::= (ForClause | LetClause)+ WhereClause? OrderByClause? "return" ExprSingle
ForClause ::= <"for" "$"> VarName TypeDeclaration? PositionalVar? "in"
ExprSingle ("," "$" VarName TypeDeclaration? PositionalVar?
"in" ExprSingle)*
LetClause ::= <"let" "$"> VarName TypeDeclaration? ":="
ExprSingle ("," "$" VarName TypeDeclaration? ":=" ExprSingle)*
WhereClause ::= "where" ExprSingle
The following XQueryX Schema definitions reflect the structure of those productions from that abstract syntax:
<!-- The base class -->
<xsd:complexType name="expr"/>
<xsd:element name="expr" type="expr" abstract="true"/>
<!-- Simple wrapper class -->
<xsd:complexType name="exprWrapper">
<xsd:sequence>
<xsd:element ref="expr"/>
</xsd:sequence>
</xsd:complexType>
<xsd:complexType name="flworExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:choice maxOccurs="unbounded">
<xsd:element ref="forClause"/>
<xsd:element ref="letClause"/>
</xsd:choice>
<xsd:element name="whereClause" minOccurs="0"/>
<xsd:element name="orderByClause" minOccurs="0"/>
<xsd:element name="returnClause"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="flworExpr" type="flworExpr" substitutionGroup="expr"/>
<xsd:element name="forClause">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="forClauseItem" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="forClauseItem">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="typedVariableBinding"/>
<xsd:element ref="positionalVariableBinding" minOccurs="0"/>
<xsd:element name="forExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="letClause">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="letClauseItem" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="letClauseItem">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="typedVariableBinding"/>
<xsd:element name="letExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="whereClause" type="exprWrapper"/>
<xsd:element name="returnClause" type="exprWrapper"/>
Since XQuery uses the expression production liberally to allow expressions to be flexibly combined, XQueryX uses the exprWrapper type in embedded contexts to allow all expression types to occur.
3 Examples from the XML Query Use Cases in XML Syntax
Three of following examples are based on the data and queries in the XMP (Experiences and Exemplars) use case in [XML Query Use Cases], while a fourth example is based on the data and queries in the NS (Queries Using Namespaces) use case. For each example we show the English description of the query, the XQuery solution given in [XML Query Use Cases], an XQueryX solution, and the XQuery that results from applying the XQueryX-to-XQuery
transformation defined by the stylesheet in B Transforming XQueryX to XQuery to the XQueryX solution. That produced XQuery is presented only as a sanity-check — the intent of the stylesheet is not to create the identical XQuery expression given in [XML Query Use Cases], but to produce a valid XQuery expression with the same semantics. The semantics of the XQueryX solution are determined by the semantics of the XQuery expression that
results from that transformation. The "correctness" of that transformation is determined by asking the following the question: Can some XQueryX processor QX process some XQueryX document D1 to produce results R1, after which the stylesheet is used to translate D1 into an XQuery expression E1 that, when processed by some XQuery processor Q, produces results R2 that are equivalent (under some meaningful definition of "equivalent") to results R1?
Comparison of the results of the XQueryX-to-XQuery transformation given in this document with the XQuery solutions in the [XML Query Use Cases] may be helpful in evaluating the correctness of the XQueryX solution in each example.
The XQuery Use Cases solution given for each example is provided only to assist readers of this document in understanding the XQueryX solution. There is no intent to imply that this document specifies a "compilation" or "transformation" of XQuery syntax into XQueryX syntax.
In the following examples, note that path expressions are expanded to show their structure. Also, note that the prefix syntax for binary operators like "and" makes the precedence explicit. In general, humans find it easier to read an XML representation that does not expand path expressions, but it is less convenient for programmatic representation and manipulation. XQueryX is designed as a language that is convenient for production and modification by software, and not as a convenient syntax for humans
to read and write.
Finally, please note that white space, including new lines, have been added to some of the XQueryX documents and XQuery expressions for readability. That additional white space is not produced by the XQueryX-to-XQuery transformation.
3.1 Example 1
Here is Q1 from the [XML Query Use Cases], use case XMP (Experiences and Exemplars): "List books published by Addison-Wesley after 1991, including their year and title."
3.1.1 XQuery solution in XQuery Use Cases:
<bib>
{
for $b in doc("http://bstore1.example.com/bib.xml")/bib/book
where $b/publisher = "Addison-Wesley" and $b/@year > 1991
return
<book year="{ $b/@year }">
{ $b/title }
</book>
}
</bib>
3.1.2 A Solution in XQueryX:
<?xml version="1.0"?>
<xqx:module xmlns:xqx="http://www.w3.org/2005/XQueryX"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.w3.org/2005/XQueryX/xqueryx.xsd">
<xqx:mainModule>
<xqx:queryBody>
<xqx:elementConstructor>
<xqx:tagName>bib</xqx:tagName>
<xqx:elementContent>
<xqx:flworExpr>
<xqx:forClause>
<xqx:forClauseItem>
<xqx:typedVariableBinding>
<xqx:varName>b</xqx:varName>
</xqx:typedVariableBinding>
<xqx:forExpr>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:functionCallExpr>
<xqx:functionName>doc</xqx:functionName>
<xqx:arguments>
<xqx:stringConstantExpr>
<xqx:value>http://bstore1.example.com/bib.xml</xqx:value>
</xqx:stringConstantExpr>
</xqx:arguments>
</xqx:functionCallExpr>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>bib</xqx:nameTest>
</xqx:stepExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>book</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:forExpr>
</xqx:forClauseItem>
</xqx:forClause>
<xqx:whereClause>
<xqx:andOp>
<xqx:firstOperand>
<xqx:equalOp>
<xqx:firstOperand>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>b</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>publisher</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:firstOperand>
<xqx:secondOperand>
<xqx:stringConstantExpr>
<xqx:value>Addison-Wesley</xqx:value>
</xqx:stringConstantExpr>
</xqx:secondOperand>
</xqx:equalOp>
</xqx:firstOperand>
<xqx:secondOperand>
<xqx:greaterThanOp>
<xqx:firstOperand>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>b</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>attribute</xqx:xpathAxis>
<xqx:nameTest>year</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:firstOperand>
<xqx:secondOperand>
<xqx:integerConstantExpr>
<xqx:value>1991</xqx:value>
</xqx:integerConstantExpr>
</xqx:secondOperand>
</xqx:greaterThanOp>
</xqx:secondOperand>
</xqx:andOp>
</xqx:whereClause>
<xqx:returnClause>
<xqx:elementConstructor>
<xqx:tagName>book</xqx:tagName>
<xqx:attributeList>
<xqx:attributeConstructor>
<xqx:attributeName>year</xqx:attributeName>
<xqx:attributeValueExpr>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>b</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>attribute</xqx:xpathAxis>
<xqx:nameTest>year</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:attributeValueExpr>
</xqx:attributeConstructor>
</xqx:attributeList>
<xqx:elementContent>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>b</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>title</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:elementContent>
</xqx:elementConstructor>
</xqx:returnClause>
</xqx:flworExpr>
</xqx:elementContent>
</xqx:elementConstructor>
</xqx:queryBody>
</xqx:mainModule>
</xqx:module>
3.1.3 Transformation of XQueryX Solution into XQuery
Applying the stylesheet in B Transforming XQueryX to XQuery to the XQueryX solution, we get:
<bib>{
for $b in doc("http://bstore1.example.com/bib.xml")/child::bib/child::book
where (($b/child::publisher = "Addison-Wesley") and ($b/attribute::year > 1991))
return <book year="{$b/attribute::year}">{$b/child::title}</book>
}</bib>
3.1.4 Corresponding Grammar Abstract Parse Tree
For comparison, here is the abstract parse tree corresponding to the XQuery for Example 1, as produced by the XQuery grammar applets found at http://www.w3.org/2005/qt-applets/xqueryApplet.html.
XPath2
QueryList
Module
MainModule
Prolog
QueryBody
Expr
PathExpr
Constructor
DirectConstructor
DirElemConstructor
StartTagOpenRoot <
TagQName bib
DirAttributeList
StartTagClose >
DirElemContent
ElementContentChar
DirElemContent
ElementContentChar
DirElemContent
CommonContent
EnclosedExpr
Lbrace {
Expr
FLWORExpr
VarName b
In in
PathExpr
FunctionCall
QNameLpar doc(
PathExpr
StringLiteral "http://bstore1.example.com/bib.xml"
StepExpr
NodeTest
NameTest
QName bib
StepExpr
NodeTest
NameTest
QName book
WhereClause
Where where
AndExpr and
ComparisonExpr =
PathExpr
VarName b
StepExpr
NodeTest
NameTest
QName publisher
PathExpr
StringLiteral "Addison-Wesley"
ComparisonExpr >
PathExpr
VarName b
StepExpr
At @
NodeTest
NameTest
QName year
PathExpr
IntegerLiteral 1991
PathExpr
Constructor
DirectConstructor
DirElemConstructor
StartTagOpenRoot <
TagQName book
DirAttributeList
S
TagQName year
ValueIndicator =
DirAttributeValue
OpenQuot "
QuotAttrValueContent
CommonContent
EnclosedExpr
Lbrace {
Expr
PathExpr
VarName b
StepExpr
At @
NodeTest
NameTest
QName year
Rbrace }
CloseQuot "
StartTagClose >
DirElemContent
ElementContentChar
DirElemContent
ElementContentChar
DirElemContent
ElementContentChar
DirElemContent
ElementContentChar
DirElemContent
ElementContentChar
DirElemContent
ElementContentChar
DirElemContent
CommonContent
EnclosedExpr
Lbrace {
Expr
PathExpr
VarName b
StepExpr
NodeTest
NameTest
QName title
Rbrace }
DirElemContent
ElementContentChar
DirElemContent
ElementContentChar
DirElemContent
ElementContentChar
DirElemContent
ElementContentChar
DirElemContent
ElementContentChar
EndTagOpen </
TagQName book
EndTagClose >
Rbrace }
DirElemContent
ElementContentChar
EndTagOpen </
TagQName bib
EndTagClose >
3.2 Example 2
Here is Q4 from the [XML Query Use Cases], use case XMP (Experiences and Exemplars): "For each author in the bibliography, list the author's name and the titles of all books by that author, grouped inside a "result" element."
3.2.1 XQuery solution in XQuery Use Cases:
<results>
{
let $a := doc("http://bstore1.example.com/bib/bib.xml")//author
for $last in distinct-values($a/last),
$first in distinct-values($a[last=$last]/first)
order by $last, $first
return
<result>
<author>
<last>{ $last }</last>
<first>{ $first }</first>
</author>
{
for $b in doc("http://bstore1.example.com/bib.xml")/bib/book
where some $ba in $b/author
satisfies ($ba/last = $last and $ba/first=$first)
return $b/title
}
</result>
}
</results>
3.2.2 A solution in XQueryX:
<?xml version="1.0"?>
<xqx:module xmlns:xqx="http://www.w3.org/2005/XQueryX"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.w3.org/2005/XQueryX/xqueryx.xsd">
<xqx:mainModule>
<xqx:queryBody>
<xqx:elementConstructor>
<xqx:tagName>results</xqx:tagName>
<xqx:elementContent>
<xqx:flworExpr>
<xqx:letClause>
<xqx:letClauseItem>
<xqx:typedVariableBinding>
<xqx:varName>a</xqx:varName>
</xqx:typedVariableBinding>
<xqx:letExpr>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:functionCallExpr>
<xqx:functionName>doc</xqx:functionName>
<xqx:arguments>
<xqx:stringConstantExpr>
<xqx:value>http://bstore1.example.com/bib.xml</xqx:value>
</xqx:stringConstantExpr>
</xqx:arguments>
</xqx:functionCallExpr>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>descendant-or-self</xqx:xpathAxis>
<xqx:anyKindTest/>
</xqx:stepExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>author</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:letExpr>
</xqx:letClauseItem>
</xqx:letClause>
<xqx:forClause>
<xqx:forClauseItem>
<xqx:typedVariableBinding>
<xqx:varName>last</xqx:varName>
</xqx:typedVariableBinding>
<xqx:forExpr>
<xqx:functionCallExpr>
<xqx:functionName>distinct-values</xqx:functionName>
<xqx:arguments>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>a</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>last</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:arguments>
</xqx:functionCallExpr>
</xqx:forExpr>
</xqx:forClauseItem>
<xqx:forClauseItem>
<xqx:typedVariableBinding>
<xqx:varName>first</xqx:varName>
</xqx:typedVariableBinding>
<xqx:forExpr>
<xqx:functionCallExpr>
<xqx:functionName>distinct-values</xqx:functionName>
<xqx:arguments>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>a</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:predicates>
<xqx:equalOp>
<xqx:firstOperand>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:contextItemExpr/>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>last</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:firstOperand>
<xqx:secondOperand>
<xqx:varRef>
<xqx:name>last</xqx:name>
</xqx:varRef>
</xqx:secondOperand>
</xqx:equalOp>
</xqx:predicates>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>first</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:arguments>
</xqx:functionCallExpr>
</xqx:forExpr>
</xqx:forClauseItem>
</xqx:forClause>
<xqx:orderByClause>
<xqx:orderBySpec>
<xqx:orderByExpr>
<xqx:varRef>
<xqx:name>last</xqx:name>
</xqx:varRef>
</xqx:orderByExpr>
</xqx:orderBySpec>
<xqx:orderBySpec>
<xqx:orderByExpr>
<xqx:varRef>
<xqx:name>first</xqx:name>
</xqx:varRef>
</xqx:orderByExpr>
</xqx:orderBySpec>
</xqx:orderByClause>
<xqx:returnClause>
<xqx:elementConstructor>
<xqx:tagName>result</xqx:tagName>
<xqx:elementContent>
<xqx:elementConstructor>
<xqx:tagName>author</xqx:tagName>
<xqx:elementContent>
<xqx:elementConstructor>
<xqx:tagName>last</xqx:tagName>
<xqx:elementContent>
<xqx:varRef>
<xqx:name>last</xqx:name>
</xqx:varRef>
</xqx:elementContent>
</xqx:elementConstructor>
<xqx:elementConstructor>
<xqx:tagName>first</xqx:tagName>
<xqx:elementContent>
<xqx:varRef>
<xqx:name>first</xqx:name>
</xqx:varRef>
</xqx:elementContent>
</xqx:elementConstructor>
</xqx:elementContent>
</xqx:elementConstructor>
<xqx:flworExpr>
<xqx:forClause>
<xqx:forClauseItem>
<xqx:typedVariableBinding>
<xqx:varName>b</xqx:varName>
</xqx:typedVariableBinding>
<xqx:forExpr>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:functionCallExpr>
<xqx:functionName>doc</xqx:functionName>
<xqx:arguments>
<xqx:stringConstantExpr>
<xqx:value>http://bstore1.example.com/bib.xml</xqx:value>
</xqx:stringConstantExpr>
</xqx:arguments>
</xqx:functionCallExpr>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>bib</xqx:nameTest>
</xqx:stepExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>book</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:forExpr>
</xqx:forClauseItem>
</xqx:forClause>
<xqx:whereClause>
<xqx:quantifiedExpr>
<xqx:quantifier>some</xqx:quantifier>
<xqx:quantifiedExprInClause>
<xqx:typedVariableBinding>
<xqx:varName>ba</xqx:varName>
</xqx:typedVariableBinding>
<xqx:sourceExpr>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>b</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>author</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:sourceExpr>
</xqx:quantifiedExprInClause>
<xqx:predicateExpr>
<xqx:andOp>
<xqx:firstOperand>
<xqx:equalOp>
<xqx:firstOperand>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>ba</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>last</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:firstOperand>
<xqx:secondOperand>
<xqx:varRef>
<xqx:name>last</xqx:name>
</xqx:varRef>
</xqx:secondOperand>
</xqx:equalOp>
</xqx:firstOperand>
<xqx:secondOperand>
<xqx:equalOp>
<xqx:firstOperand>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>ba</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>first</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:firstOperand>
<xqx:secondOperand>
<xqx:varRef>
<xqx:name>first</xqx:name>
</xqx:varRef>
</xqx:secondOperand>
</xqx:equalOp>
</xqx:secondOperand>
</xqx:andOp>
</xqx:predicateExpr>
</xqx:quantifiedExpr>
</xqx:whereClause>
<xqx:returnClause>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>b</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>title</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:returnClause>
</xqx:flworExpr>
</xqx:elementContent>
</xqx:elementConstructor>
</xqx:returnClause>
</xqx:flworExpr>
</xqx:elementContent>
</xqx:elementConstructor>
</xqx:queryBody>
</xqx:mainModule>
</xqx:module>
3.2.3 Transformation of XQueryX Solution into XQuery
Applying the stylesheet in B Transforming XQueryX to XQuery to the XQueryX solution, we get:
<results>{
let $a:=doc("http://bstore1.example.com/bib.xml")/
descendant-or-self::node()/child::author
for $last in distinct-values($a/child::last),
$first in distinct-values($a[(./child::last = $last)]/child::first)
order by $last , $first
return <result>{<author>{<last>{$last}</last>}{<first>{$first}</first>}</author>}{
for $b in doc("http://bstore1.example.com/bib.xml")/child::bib/child::book
where (some $ba in $b/child::author satisfies
(($ba/child::last = $last) and ($ba/child::first = $first)))
return $b/child::title
}</result>
}</results>
3.3 Example 3
Here is Q7 from the [XML Query Use Cases], use case XMP (Experiences and Exemplars): "List the titles and years of all books published by Addison-Wesley after 1991, in alphabetic order."
3.3.1 XQuery solution in XQuery Use Cases:
<bib>
{
for $b in doc("http://bstore1.example.com/bib.xml")//book
where $b/publisher = "Addison-Wesley" and $b/@year > 1991
order by $b/title
return
<book>
{ $b/@year }
{ $b/title }
</book>
}
</bib>
3.3.2 A solution in XQueryX:
<?xml version="1.0"?>
<xqx:module xmlns:xqx="http://www.w3.org/2005/XQueryX"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.w3.org/2005/XQueryX/xqueryx.xsd">
<xqx:mainModule>
<xqx:queryBody>
<xqx:elementConstructor>
<xqx:tagName>bib</xqx:tagName>
<xqx:elementContent>
<xqx:flworExpr>
<xqx:forClause>
<xqx:forClauseItem>
<xqx:typedVariableBinding>
<xqx:varName>b</xqx:varName>
</xqx:typedVariableBinding>
<xqx:forExpr>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:functionCallExpr>
<xqx:functionName>doc</xqx:functionName>
<xqx:arguments>
<xqx:stringConstantExpr>
<xqx:value>http://bstore1.example.com/bib.xml</xqx:value>
</xqx:stringConstantExpr>
</xqx:arguments>
</xqx:functionCallExpr>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>descendant-or-self</xqx:xpathAxis>
<xqx:anyKindTest/>
</xqx:stepExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>book</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:forExpr>
</xqx:forClauseItem>
</xqx:forClause>
<xqx:whereClause>
<xqx:andOp>
<xqx:firstOperand>
<xqx:equalOp>
<xqx:firstOperand>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>b</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>publisher</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:firstOperand>
<xqx:secondOperand>
<xqx:stringConstantExpr>
<xqx:value>Addison-Wesley</xqx:value>
</xqx:stringConstantExpr>
</xqx:secondOperand>
</xqx:equalOp>
</xqx:firstOperand>
<xqx:secondOperand>
<xqx:greaterThanOp>
<xqx:firstOperand>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>b</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>attribute</xqx:xpathAxis>
<xqx:nameTest>year</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:firstOperand>
<xqx:secondOperand>
<xqx:integerConstantExpr>
<xqx:value>1991</xqx:value>
</xqx:integerConstantExpr>
</xqx:secondOperand>
</xqx:greaterThanOp>
</xqx:secondOperand>
</xqx:andOp>
</xqx:whereClause>
<xqx:orderByClause>
<xqx:orderBySpec>
<xqx:orderByExpr>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>b</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>title</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:orderByExpr>
</xqx:orderBySpec>
</xqx:orderByClause>
<xqx:returnClause>
<xqx:elementConstructor>
<xqx:tagName>book</xqx:tagName>
<xqx:elementContent>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>b</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>attribute</xqx:xpathAxis>
<xqx:nameTest>year</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>b</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest>title</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:elementContent>
</xqx:elementConstructor>
</xqx:returnClause>
</xqx:flworExpr>
</xqx:elementContent>
</xqx:elementConstructor>
</xqx:queryBody>
</xqx:mainModule>
</xqx:module>
3.3.3 Transformation of XQueryX Solution into XQuery
Applying the stylesheet in B Transforming XQueryX to XQuery to the XQueryX solution, we get:
<bib>{
for $b in doc("http://bstore1.example.com/bib.xml")/descendant-or-self::node()/child::book
where (($b/child::publisher = "Addison-Wesley") and ($b/attribute::year > 1991))
order by $b/child::title
return <book>{$b/attribute::year}{$b/child::title}</book>
}</bib>
3.4 Example 4
Here is Q8 from the [XML Query Use Cases], use case NS (Queries Using Namespaces): "Select all traders (either seller or high bidder) without negative comments."
3.4.1 XQuery solution in XQuery Use Cases:
declare namespace ma = "http://www.example.com/AuctionWatch";
<Q8 xmlns:ma="http://www.example.com/AuctionWatch"
xmlns:eachbay="http://www.example.com/auctioneers#eachbay"
xmlns:xlink="http://www.w3.org/1999/xlink">
{
for $s in doc("auction.xml")//ma:Trading_Partners/(ma:Seller | ma:High_Bidder)
where $s/*:NegativeComments = 0
return $s
}
</Q8>
3.4.2 A solution in XQueryX:
<?xml version="1.0"?>
<xqx:module xmlns:xqx="http://www.w3.org/2005/XQueryX"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.w3.org/2005/XQueryX/xqueryx.xsd">
<xqx:mainModule>
<xqx:prolog>
<xqx:namespaceDecl>
<xqx:prefix>ma</xqx:prefix>
<xqx:uri>http://www.example.com/AuctionWatch</xqx:uri>
</xqx:namespaceDecl>
</xqx:prolog>
<xqx:queryBody>
<xqx:elementConstructor>
<xqx:tagName>Q8</xqx:tagName>
<xqx:attributeList>
<xqx:attributeConstructor>
<xqx:attributeName>xmlns:ma</xqx:attributeName>
<xqx:attributeValue>http://www.example.com/AuctionWatch</xqx:attributeValue>
</xqx:attributeConstructor>
<xqx:attributeConstructor>
<xqx:attributeName>xmlns:eachbay</xqx:attributeName>
<xqx:attributeValue>http://www.example.com/auctioneers#eachbay</xqx:attributeValue>
</xqx:attributeConstructor>
<xqx:attributeConstructor>
<xqx:attributeName>xmlns:xlink</xqx:attributeName>
<xqx:attributeValue>http://www.w3.org/1999/xlink</xqx:attributeValue>
</xqx:attributeConstructor>
</xqx:attributeList>
<xqx:elementContent>
<xqx:flworExpr>
<xqx:forClause>
<xqx:forClauseItem>
<xqx:typedVariableBinding>
<xqx:varName>s</xqx:varName>
</xqx:typedVariableBinding>
<xqx:forExpr>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:functionCallExpr>
<xqx:functionName xqx:prefix="fn">doc</xqx:functionName>
<xqx:arguments>
<xqx:stringConstantExpr>
<xqx:value>auction.xml</xqx:value>
</xqx:stringConstantExpr>
</xqx:arguments>
</xqx:functionCallExpr>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>descendant-or-self</xqx:xpathAxis>
<xqx:anyKindTest/>
</xqx:stepExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:nameTest xqx:prefix="ma">Trading_Partners</xqx:nameTest>
</xqx:stepExpr>
<xqx:stepExpr>
<xqx:filterExpr>
<xqx:parenthesizedExpr>
<xqx:unionOp>
<xqx:firstOperand>
<xqx:pathExpr>
<xqx:stepExpr>
<xqx:nameTest xqx:prefix="ma">Seller</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:firstOperand>
<xqx:secondOperand>
<xqx:pathExpr>
<xqx:stepExpr>
<xqx:nameTest xqx:prefix="ma">High_Bidder</xqx:nameTest>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:secondOperand>
</xqx:unionOp>
</xqx:parenthesizedExpr>
</xqx:filterExpr>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:forExpr>
</xqx:forClauseItem>
</xqx:forClause>
<xqx:whereClause>
<xqx:equalOp>
<xqx:firstOperand>
<xqx:pathExpr>
<xqx:argExpr>
<xqx:varRef>
<xqx:name>s</xqx:name>
</xqx:varRef>
</xqx:argExpr>
<xqx:stepExpr>
<xqx:xpathAxis>child</xqx:xpathAxis>
<xqx:Wildcard>
<xqx:star/>
<xqx:NCName>NegativeComments</xqx:NCName>
</xqx:Wildcard>
</xqx:stepExpr>
</xqx:pathExpr>
</xqx:firstOperand>
<xqx:secondOperand>
<xqx:integerConstantExpr>
<xqx:value>0</xqx:value>
</xqx:integerConstantExpr>
</xqx:secondOperand>
</xqx:equalOp>
</xqx:whereClause>
<xqx:returnClause>
<xqx:varRef>
<xqx:name>s</xqx:name>
</xqx:varRef>
</xqx:returnClause>
</xqx:flworExpr>
</xqx:elementContent>
</xqx:elementConstructor>
</xqx:queryBody>
</xqx:mainModule>
</xqx:module>
3.4.3 Transformation of XQueryX Solution into XQuery
Applying the stylesheet in B Transforming XQueryX to XQuery to the XQueryX solution, we get:
declare namespace ma="http://www.example.com/AuctionWatch";
<Q8 xmlns:ma="http://www.example.com/AuctionWatch"
xmlns:eachbay="http://www.example.com/auctioneers#eachbay"
xmlns:xlink="http://www.w3.org/1999/xlink">{
for $s in fn:doc("auction.xml")/descendant-or-self::node()/
child::ma:Trading_Partners/(ma:Seller union ma:High_Bidder)
where ($s/child::*:NegativeComments = 0)
return $s
}</Q8>
4 An XML Schema for the XQuery XML Syntax
Here is the XML Schema for the proposed syntax.
<?xml version="1.0"?>
<!-- Changes from LC document:
Includes various Last Call comment resolutions:
* paired name for QName references
* parallel substitution groups resolution for expressions
* removal of infixOp
* fix typo in generalComparisonOpTypes (moot, in this schema)
* removed unnecessary alternative in piTest
* replace use of named group in itemType stuff with substitution group
Additional fix: multiplication was missing for some reason
Tightens grammar rules for operators by creating an element for each
operator type, analogous to the way we have a different element for
integer literal expressions versus string literal expressions etc.
using essentially the same technique.
Readers of this schema are reminded that the default value for both
minOccurs and maxOccurs is 1.
-->
<xsd:schema xmlns="http://www.w3.org/2005/XQueryX"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.w3.org/2005/XQueryX"
elementFormDefault="qualified" attributeFormDefault="qualified">
<!-- A few helper declarations -->
<xsd:complexType name="emptyContent"/>
<!-- 2005-09-05 JM: The QName element definition is not needed; delete it -->
<xsd:element name="NCName" type="xsd:NCName"/>
<xsd:complexType name="QName">
<xsd:simpleContent>
<xsd:extension base="xsd:NCName">
<xsd:attribute name="prefix" type="xsd:NCName" use="optional"/>
</xsd:extension>
</xsd:simpleContent>
</xsd:complexType>
<!-- The base class -->
<xsd:complexType name="expr"/>
<xsd:element name="expr" type="expr" abstract="true"/>
<!-- A list of expressions -->
<xsd:complexType name="exprList">
<xsd:sequence>
<xsd:element ref="expr" minOccurs="0" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:complexType>
<!-- JM 2005-06-29: Added simple wrapper class with optional contents -->
<xsd:complexType name="exprWrapperOptional">
<xsd:sequence>
<xsd:element ref="expr" minOccurs="0"/>
</xsd:sequence>
</xsd:complexType>
<!-- Simple wrapper class -->
<xsd:complexType name="exprWrapper">
<xsd:sequence>
<xsd:element ref="expr"/>
</xsd:sequence>
</xsd:complexType>
<!-- constant expressions. We have 4 different subclasses for this -->
<xsd:complexType name="constantExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="value" type="xsd:anyType"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="constantExpr" type="constantExpr" abstract="true" substitutionGroup="expr"/>
<xsd:complexType name="integerConstantExpr">
<xsd:complexContent>
<xsd:restriction base="constantExpr">
<xsd:sequence>
<xsd:element name="value" type="xsd:integer"/>
</xsd:sequence>
</xsd:restriction>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="integerConstantExpr" type="integerConstantExpr" substitutionGroup="constantExpr"/>
<xsd:complexType name="decimalConstantExpr">
<xsd:complexContent>
<xsd:restriction base="constantExpr">
<xsd:sequence>
<xsd:element name="value" type="xsd:decimal"/>
</xsd:sequence>
</xsd:restriction>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="decimalConstantExpr" type="decimalConstantExpr" substitutionGroup="constantExpr"/>
<xsd:complexType name="doubleConstantExpr">
<xsd:complexContent>
<xsd:restriction base="constantExpr">
<xsd:sequence>
<xsd:element name="value" type="xsd:double"/>
</xsd:sequence>
</xsd:restriction>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="doubleConstantExpr" type="doubleConstantExpr" substitutionGroup="constantExpr"/>
<xsd:complexType name="stringConstantExpr">
<xsd:complexContent>
<xsd:restriction base="constantExpr">
<xsd:sequence>
<xsd:element name="value" type="xsd:string"/>
</xsd:sequence>
</xsd:restriction>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="stringConstantExpr" type="stringConstantExpr" substitutionGroup="constantExpr"/>
<!-- Variables -->
<xsd:complexType name="varRef">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="name" type="QName"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="varRef" type="varRef" substitutionGroup="expr"/>
<!-- root and context-item expressions -->
<xsd:complexType name="rootExpr">
<xsd:complexContent>
<xsd:extension base="expr"/>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="rootExpr" type="rootExpr" substitutionGroup="expr"/>
<xsd:complexType name="contextItemExpr">
<xsd:complexContent>
<xsd:extension base="expr"/>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="contextItemExpr" type="contextItemExpr" substitutionGroup="expr"/>
<!-- Pragmas and extension expressions -->
<xsd:element name="pragma">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="pragmaName" type="QName"/>
<xsd:element name="pragmaContents" type="xsd:string"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:complexType name="extensionExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element ref="pragma" maxOccurs="unbounded"/>
<xsd:element name="argExpr" type="exprWrapper" minOccurs="0"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="extensionExpr" type="extensionExpr" substitutionGroup="expr"/>
<xsd:complexType name="functionCallExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="functionName" type="QName"/>
<xsd:element name="arguments" type="exprList" minOccurs="0"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="functionCallExpr" type="functionCallExpr" substitutionGroup="expr"/>
<!-- Constructor functions -->
<xsd:complexType name="constructorFunctionExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="typeName" type="QName"/>
<xsd:element name="argExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="constructorFunctionExpr" type="constructorFunctionExpr" substitutionGroup="expr"/>
<xsd:complexType name="sequenceExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element ref="expr" minOccurs="0" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="sequenceExpr" type="sequenceExpr" substitutionGroup="expr"/>
<xsd:complexType name="rangeSequenceExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="startExpr" type="exprWrapper"/>
<xsd:element name="endExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="rangeSequenceExpr" type="rangeSequenceExpr" substitutionGroup="expr"/>
<!-- Builtin operator expressions -->
<xsd:complexType name="operatorExpr">
<xsd:complexContent>
<xsd:extension base="expr"/>
</xsd:complexContent>
</xsd:complexType>
<xsd:complexType name="unaryOperatorExpr">
<xsd:complexContent>
<xsd:extension base="operatorExpr">
<xsd:sequence>
<xsd:element name="operand" type="exprWrapper"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:complexType name="binaryOperatorExpr">
<xsd:complexContent>
<xsd:extension base="operatorExpr">
<xsd:sequence>
<xsd:element name="firstOperand" type="exprWrapper"/>
<xsd:element name="secondOperand" type="exprWrapper"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="operatorExpr" type="operatorExpr" abstract="true" substitutionGroup="expr"/>
<xsd:element name="arithmeticOp" type="operatorExpr" abstract="true" substitutionGroup="operatorExpr"/>
<xsd:element name="addOp" type="binaryOperatorExpr" substitutionGroup="arithmeticOp"/>
<xsd:element name="subtractOp" type="binaryOperatorExpr" substitutionGroup="arithmeticOp"/>
<xsd:element name="multiplyOp" type="binaryOperatorExpr" substitutionGroup="arithmeticOp"/>
<xsd:element name="divOp" type="binaryOperatorExpr" substitutionGroup="arithmeticOp"/>
<xsd:element name="idivOp" type="binaryOperatorExpr" substitutionGroup="arithmeticOp"/>
<xsd:element name="modOp" type="binaryOperatorExpr" substitutionGroup="arithmeticOp"/>
<xsd:element name="unaryMinusOp" type="unaryOperatorExpr" substitutionGroup="arithmeticOp"/>
<xsd:element name="unaryPlusOp" type="unaryOperatorExpr" substitutionGroup="arithmeticOp"/>
<xsd:element name="comparisonOp" type="binaryOperatorExpr" abstract="true"
substitutionGroup="operatorExpr"/>
<xsd:element name="valueComparisonOp" type="binaryOperatorExpr" abstract="true"
substitutionGroup="operatorExpr"/>
<xsd:element name="eqOp" type="binaryOperatorExpr" substitutionGroup="valueComparisonOp"/>
<xsd:element name="neOp" type="binaryOperatorExpr" substitutionGroup="valueComparisonOp"/>
<xsd:element name="gtOp" type="binaryOperatorExpr" substitutionGroup="valueComparisonOp"/>
<xsd:element name="geOp" type="binaryOperatorExpr" substitutionGroup="valueComparisonOp"/>
<xsd:element name="ltOp" type="binaryOperatorExpr" substitutionGroup="valueComparisonOp"/>
<xsd:element name="leOp" type="binaryOperatorExpr" substitutionGroup="valueComparisonOp"/>
<xsd:element name="generalComparisonOp" type="binaryOperatorExpr" abstract="true"
substitutionGroup="operatorExpr"/>
<xsd:element name="equalOp" type="binaryOperatorExpr" substitutionGroup="generalComparisonOp"/>
<xsd:element name="notEqualOp" type="binaryOperatorExpr" substitutionGroup="generalComparisonOp"/>
<xsd:element name="lessThanOp" type="binaryOperatorExpr" substitutionGroup="generalComparisonOp"/>
<xsd:element name="lessThanOrEqualOp" type="binaryOperatorExpr"
substitutionGroup="generalComparisonOp"/>
<xsd:element name="greaterThanOp" type="binaryOperatorExpr" substitutionGroup="generalComparisonOp"/>
<xsd:element name="greaterThanOrEqualOp" type="binaryOperatorExpr"
substitutionGroup="generalComparisonOp"/>
<xsd:element name="nodeComparisonOp" type="binaryOperatorExpr" abstract="true"
substitutionGroup="operatorExpr"/>
<xsd:element name="isOp" type="binaryOperatorExpr" substitutionGroup="nodeComparisonOp"/>
<xsd:element name="orderComparisonOp" type="binaryOperatorExpr" abstract="true"
substitutionGroup="operatorExpr"/>
<xsd:element name="nodeBeforeOp" type="binaryOperatorExpr" substitutionGroup="orderComparisonOp"/>
<xsd:element name="nodeAfterOp" type="binaryOperatorExpr" substitutionGroup="orderComparisonOp"/>
<xsd:element name="logicalOp" type="binaryOperatorExpr" abstract="true"
substitutionGroup="operatorExpr"/>
<xsd:element name="andOp" type="binaryOperatorExpr" substitutionGroup="logicalOp"/>
<xsd:element name="orOp" type="binaryOperatorExpr" substitutionGroup="logicalOp"/>
<!-- JM 2005-06-22: Changed name from miscOp to setOp -->
<xsd:element name="setOp" type="binaryOperatorExpr" abstract="true" substitutionGroup="operatorExpr"/>
<!-- JM 2005-06-22: Changed name from miscOp to setOp -->
<xsd:element name="unionOp" type="binaryOperatorExpr" substitutionGroup="setOp"/>
<!-- JM 2005-06-22: Changed name from miscOp to setOp -->
<xsd:element name="intersectOp" type="binaryOperatorExpr" substitutionGroup="setOp"/>
<!-- JM 2005-06-22: Changed name from miscOp to setOp -->
<xsd:element name="exceptOp" type="binaryOperatorExpr" substitutionGroup="setOp"/>
<!-- Basic typenames -->
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<xsd:element name="atomicType" type="QName" substitutionGroup="itemType"/>
<!-- Used in castable expression -->
<xsd:element name="singleType">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="atomicType"/>
<xsd:element name="optional" type="emptyContent" minOccurs="0"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<!-- Specifically, itemType was the name of a choice group; now, it's an abstract element -->
<!-- JM 2005-08-22: It doesn't make sense for this to have a type, so get rid of it -->
<xsd:element name="itemType" abstract="true"/>
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<!-- JM 2005-08-22: It makes no sense for this to be based on QName, so get rid of that -->
<xsd:complexType name="emptyItemTypeContent"/>
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<xsd:element name="anyItemType" type="emptyItemTypeContent" substitutionGroup="itemType"/>
<xsd:simpleType name="occurrenceIndicator">
<xsd:restriction base="xsd:string">
<xsd:enumeration value="?"/>
<xsd:enumeration value="*"/>
<xsd:enumeration value="+"/>
</xsd:restriction>
</xsd:simpleType>
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<xsd:complexType name="sequenceType">
<xsd:choice>
<xsd:element name="voidSequenceType" type="emptyContent"/>
<xsd:sequence>
<xsd:element ref="itemType"/>
<xsd:element name="occurrenceIndicator" type="occurrenceIndicator" minOccurs="0"/>
</xsd:sequence>
</xsd:choice>
</xsd:complexType>
<xsd:element name="sequenceType" type="sequenceType"/>
<xsd:element name="typeDeclaration" type="sequenceType"/>
<!-- Represents a "typed" variable (for clause, let clause etc) -->
<xsd:element name="typedVariableBinding">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="varName" type="QName"/>
<xsd:element ref="typeDeclaration" minOccurs="0"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="positionalVariableBinding" type="QName"/>
<xsd:element name="variableBinding" type="QName"/>
<xsd:element name="forClauseItem">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="typedVariableBinding"/>
<xsd:element ref="positionalVariableBinding" minOccurs="0"/>
<xsd:element name="forExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="forClause">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="forClauseItem" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="letClauseItem">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="typedVariableBinding"/>
<xsd:element name="letExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="letClause">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="letClauseItem" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="whereClause" type="exprWrapper"/>
<xsd:element name="returnClause" type="exprWrapper"/>
<xsd:simpleType name="emptyOrderingMode">
<xsd:restriction base="xsd:string">
<xsd:enumeration value="empty greatest"/>
<xsd:enumeration value="empty least"/>
</xsd:restriction>
</xsd:simpleType>
<xsd:simpleType name="orderingKind">
<xsd:restriction base="xsd:string">
<xsd:enumeration value="ascending"/>
<xsd:enumeration value="descending"/>
</xsd:restriction>
</xsd:simpleType>
<!-- JM 2005-06-20: Changed maxOccurs of child elements from unbounded to 1 -->
<xsd:element name="orderModifier">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="orderingKind" type="orderingKind" minOccurs="0"/>
<xsd:element name="emptyOrderingMode" type="emptyOrderingMode" minOccurs="0"/>
<xsd:element name="collation" type="xsd:string" minOccurs="0"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="orderBySpec">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="orderByExpr" type="exprWrapper"/>
<xsd:element ref="orderModifier" minOccurs="0"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="orderByClause">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="stable" type="emptyContent" minOccurs="0"/>
<xsd:element ref="orderBySpec" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<!-- This is the flwor expression -->
<xsd:complexType name="flworExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:choice maxOccurs="unbounded">
<xsd:element ref="forClause"/>
<xsd:element ref="letClause"/>
</xsd:choice>
<xsd:element ref="whereClause" minOccurs="0"/>
<xsd:element ref="orderByClause" minOccurs="0"/>
<xsd:element ref="returnClause"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="flworExpr" type="flworExpr" substitutionGroup="expr"/>
<!-- conditional expressions -->
<xsd:complexType name="ifThenElseExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="ifClause" type="exprWrapper"/>
<xsd:element name="thenClause" type="exprWrapper"/>
<xsd:element name="elseClause" type="exprWrapper"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="ifThenElseExpr" type="ifThenElseExpr" substitutionGroup="expr"/>
<!-- The following clauses describe quantified expressions -->
<xsd:simpleType name="quantifier">
<xsd:restriction base="xsd:NMTOKEN">
<xsd:enumeration value="some"/>
<xsd:enumeration value="every"/>
</xsd:restriction>
</xsd:simpleType>
<xsd:element name="quantifiedExprInClause">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="typedVariableBinding"/>
<xsd:element name="sourceExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:complexType name="quantifiedExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="quantifier" type="quantifier"/>
<xsd:element ref="quantifiedExprInClause" maxOccurs="unbounded"/>
<xsd:element name="predicateExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="quantifiedExpr" type="quantifiedExpr" substitutionGroup="expr"/>
<!-- handle the typeswitch construct -->
<!-- Note: no substitutionGroup as we cannot use this anywhere -->
<xsd:element name="typeswitchExprCaseClause">
<xsd:complexType>
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element ref="variableBinding" minOccurs="0"/>
<xsd:element ref="typeDeclaration"/>
<xsd:element name="resultExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
</xsd:element>
<!-- Note: no substitutionGroup as we cannot use this anywhere -->
<xsd:element name="typeswitchExprDefaultClause">
<xsd:complexType>
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element ref="variableBinding" minOccurs="0"/>
<xsd:element name="resultExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
</xsd:element>
<xsd:complexType name="typeswitchExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="argExpr" type="exprWrapper"/>
<xsd:element ref="typeswitchExprCaseClause" maxOccurs="unbounded"/>
<xsd:element ref="typeswitchExprDefaultClause"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="typeswitchExpr" type="typeswitchExpr" substitutionGroup="expr"/>
<!-- instance-of expressions -->
<xsd:complexType name="instanceOfExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="argExpr" type="exprWrapper"/>
<xsd:element ref="sequenceType"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="instanceOfExpr" type="instanceOfExpr" substitutionGroup="expr"/>
<!-- treat-as expressions -->
<xsd:complexType name="treatExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="argExpr" type="exprWrapper"/>
<xsd:element ref="sequenceType"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="treatExpr" type="treatExpr" substitutionGroup="expr"/>
<!-- castable and cast expressions -->
<xsd:complexType name="castableExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="argExpr" type="exprWrapper"/>
<xsd:element ref="singleType"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="castableExpr" type="castableExpr" substitutionGroup="expr"/>
<xsd:complexType name="castExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="argExpr" type="exprWrapper"/>
<xsd:element ref="singleType"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="castExpr" type="castExpr" substitutionGroup="expr"/>
<!-- Validate expressions -->
<xsd:simpleType name="validationMode">
<xsd:restriction base="xsd:NMTOKEN">
<xsd:enumeration value="lax"/>
<xsd:enumeration value="strict"/>
</xsd:restriction>
</xsd:simpleType>
<xsd:complexType name="validateExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="validationMode" type="validationMode" minOccurs="0"/>
<xsd:element name="argExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="validateExpr" type="validateExpr" substitutionGroup="expr"/>
<!-- Direct constructors. Only elementConstructor for now -->
<!-- Note the absence of constructors corresponding to
the directCommentConstructor and the directPIConstructor
productions in the XQuery grammar. This is because they are
trivially identical to the computed variants
-->
<!-- attributeConstructor is no longer a subclass of expr -->
<!-- 2005-08-16 JM: Allowed attributeValueExpr to be an exprList -->
<xsd:complexType name="attributeConstructor">
<xsd:sequence>
<xsd:element name="attributeName" type="QName"/>
<xsd:choice>
<xsd:element name="attributeValueExpr" type="exprList"/>
<xsd:element name="attributeValue" type="xsd:string"/>
</xsd:choice>
</xsd:sequence>
</xsd:complexType>
<xsd:element name="attributeList">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="attributeConstructor" type="attributeConstructor" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="elementContent" type="exprList"/>
<xsd:complexType name="elementConstructor">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="tagName" type="QName"/>
<xsd:element ref="attributeList" minOccurs="0"/>
<xsd:element ref="elementContent" minOccurs="0"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="elementConstructor" type="elementConstructor" substitutionGroup="expr"/>
<!-- computed constructors -->
<xsd:complexType name="computedElementConstructor">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:choice>
<xsd:element name="tagName" type="QName"/>
<xsd:element name="tagNameExpr" type="exprWrapper"/>
</xsd:choice>
<xsd:element name="contentExpr" type="exprWrapper" minOccurs="0"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="computedElementConstructor" type="computedElementConstructor"
substitutionGroup="expr"/>
<xsd:complexType name="computedAttributeConstructor">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:choice>
<xsd:element name="tagName" type="QName"/>
<xsd:element name="tagNameExpr" type="exprWrapper"/>
</xsd:choice>
<xsd:element name="valueExpr" type="exprWrapper" minOccurs="0"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="computedAttributeConstructor" type="computedAttributeConstructor"
substitutionGroup="expr"/>
<xsd:complexType name="computedDocumentConstructor">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="argExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="computedDocumentConstructor" type="computedDocumentConstructor"
substitutionGroup="expr"/>
<xsd:complexType name="computedTextConstructor">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="argExpr" type="exprWrapper" minOccurs="0"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="computedTextConstructor" type="computedTextConstructor" substitutionGroup="expr"/>
<xsd:complexType name="computedCommentConstructor">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="argExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="computedCommentConstructor" type="computedCommentConstructor"
substitutionGroup="expr"/>
<xsd:complexType name="computedPIConstructor">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:choice>
<xsd:element name="piTarget" type="xsd:NCName"/>
<xsd:element name="piTargetExpr" type="exprWrapper"/>
</xsd:choice>
<xsd:element name="piValueExpr" type="exprWrapper" minOccurs="0"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="computedPIConstructor" type="computedPIConstructor" substitutionGroup="expr"/>
<!-- ordered and unordered expressions -->
<xsd:complexType name="unorderedExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="argExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="unorderedExpr" type="unorderedExpr" substitutionGroup="expr"/>
<xsd:complexType name="orderedExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:element name="argExpr" type="exprWrapper"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="orderedExpr" type="orderedExpr" substitutionGroup="expr"/>
<xsd:complexType name="simpleWildcard">
<xsd:choice>
<xsd:element name="QName" type="QName"/>
<xsd:element name="star" type="emptyContent"/>
</xsd:choice>
</xsd:complexType>
<xsd:element name="Wildcard">
<xsd:complexType>
<xsd:all>
<xsd:element name="star" type="emptyContent" minOccurs="0"/>
<xsd:element ref="NCName" minOccurs="0"/>
</xsd:all>
</xsd:complexType>
</xsd:element>
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<xsd:element name="schemaAttributeTest" type="QName" substitutionGroup="kindTest"/>
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<xsd:element name="attributeTest" substitutionGroup="kindTest">
<xsd:complexType>
<xsd:complexContent>
<xsd:extension base="emptyItemTypeContent">
<xsd:sequence minOccurs="0">
<xsd:element name="attributeName" type="simpleWildcard"/>
<xsd:element name="typeName" type="QName" minOccurs="0"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
</xsd:element>
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<!-- JM 2005-08-22: It doesn't make sense for this to have a type, so get rid of it -->
<xsd:element name="anyElementTest" abstract="true" substitutionGroup="kindTest"/>
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<xsd:element name="schemaElementTest" type="QName" substitutionGroup="anyElementTest"/>
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<xsd:element name="elementTest" substitutionGroup="anyElementTest">
<xsd:complexType>
<xsd:complexContent>
<xsd:extension base="emptyItemTypeContent">
<xsd:sequence minOccurs="0">
<xsd:element name="elementName" type="simpleWildcard"/>
<xsd:sequence minOccurs="0">
<xsd:element name="typeName" type="QName"/>
<xsd:element name="nillable" type="emptyContent" minOccurs="0"/>
</xsd:sequence>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
</xsd:element>
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<xsd:element name="documentTest" substitutionGroup="kindTest">
<xsd:complexType>
<xsd:complexContent>
<xsd:extension base="emptyItemTypeContent">
<xsd:sequence>
<xsd:element ref="anyElementTest" minOccurs="0"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
</xsd:element>
<!-- 2005-08-12 JM: Removed string literal variant of PI target; not needed
in XQueryX because backward compatibility with XPath 1.0 is irrelevant -->
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<xsd:element name="piTest" substitutionGroup="kindTest">
<xsd:complexType>
<xsd:complexContent>
<xsd:extension base="emptyItemTypeContent">
<xsd:sequence>
<xsd:element name="piTarget" type="xsd:NCName" minOccurs="0"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
</xsd:element>
<!-- JM 2005-06-26: Redefined element nameTest to have type QName -->
<xsd:element name="nameTest" type="QName"/>
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<!-- JM 2005-08-22: It doesn't make sense for this to have a type, so get rid of it -->
<xsd:element name="kindTest" substitutionGroup="itemType"/>
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<xsd:element name="textTest" type="emptyItemTypeContent" substitutionGroup="kindTest"/>
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<xsd:element name="commentTest" type="emptyItemTypeContent" substitutionGroup="kindTest"/>
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<xsd:element name="anyKindTest" type="emptyItemTypeContent" substitutionGroup="kindTest"/>
<xsd:element name="xpathAxis">
<xsd:simpleType>
<xsd:restriction base="xsd:NMTOKEN">
<xsd:enumeration value="child"/>
<xsd:enumeration value="attribute"/>
<xsd:enumeration value="self"/>
<xsd:enumeration value="parent"/>
<xsd:enumeration value="descendant-or-self"/>
<xsd:enumeration value="descendant"/>
<xsd:enumeration value="following"/>
<xsd:enumeration value="following-sibling"/>
<xsd:enumeration value="ancestor"/>
<xsd:enumeration value="ancestor-or-self"/>
<xsd:enumeration value="preceding"/>
<xsd:enumeration value="preceding-sibling"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:element>
<!-- JM 2005-06-29: Define global element for parenthesized expressions -->
<xsd:element name="parenthesizedExpr" type="exprWrapperOptional"/>
<!-- JM 2005-06-26: The group filterExpr is any of several possibilities -->
<!-- JM 2005-08-12: Added computedAttributeConstructor to correct oversight -->
<xsd:group name="filterExpr">
<xsd:choice>
<xsd:element ref="constantExpr"/>
<xsd:element ref="varRef"/>
<xsd:element ref="contextItemExpr"/>
<xsd:element ref="functionCallExpr"/>
<xsd:element ref="parenthesizedExpr"/>
<xsd:element ref="elementConstructor"/>
<xsd:element ref="computedElementConstructor"/>
<xsd:element ref="computedAttributeConstructor"/>
<xsd:element ref="computedDocumentConstructor"/>
<xsd:element ref="computedTextConstructor"/>
<xsd:element ref="computedCommentConstructor"/>
<xsd:element ref="computedPIConstructor"/>
<xsd:element ref="orderedExpr"/>
<xsd:element ref="unorderedExpr"/>
</xsd:choice>
</xsd:group>
<!-- JM 2005-06-26: Added new choice: the group filterExpr -->
<!-- JM 2005-06-27: Added new choices: nameTest and Wildcard -->
<!-- JM 2005-08-12: Changes related to replacement of named choice group with substitution group -->
<xsd:element name="stepExpr">
<xsd:complexType>
<xsd:sequence>
<xsd:choice>
<xsd:sequence>
<xsd:element ref="xpathAxis"/>
<xsd:choice>
<xsd:element ref="kindTest"/>
<xsd:element ref="nameTest"/>
<xsd:element ref="Wildcard"/>
</xsd:choice>
</xsd:sequence>
<xsd:element ref="nameTest"/>
<xsd:element ref="Wildcard"/>
<xsd:element name="filterExpr">
<xsd:complexType>
<xsd:sequence>
<xsd:group ref="filterExpr"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
</xsd:choice>
<xsd:element name="predicates" type="exprList" minOccurs="0"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<!-- JM 2005-05-24: Modified to permit the a pathExpr to start with a stepExpr -->
<!-- per suggestion from Mary Holstege, email 2005-05-24. -->
<xsd:complexType name="pathExpr">
<xsd:complexContent>
<xsd:extension base="expr">
<xsd:sequence>
<xsd:sequence minOccurs="0">
<xsd:element name="argExpr" type="exprWrapper"/>
<xsd:element name="predicates" type="exprList" minOccurs="0"/>
</xsd:sequence>
<xsd:element ref="stepExpr" minOccurs="0" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="pathExpr" type="pathExpr" substitutionGroup="expr"/>
<!-- The following constructs deal with the query prolog -->
<xsd:element name="module">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="versionDecl" minOccurs="0"/>
<xsd:choice>
<xsd:element ref="mainModule"/>
<xsd:element ref="libraryModule"/>
</xsd:choice>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="mainModule">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="prolog" minOccurs="0"/>
<xsd:element name="queryBody" type="exprWrapper"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:complexType name="namespaceDeclType">
<xsd:sequence>
<xsd:element name="prefix" type="xsd:NCName"/>
<xsd:element name="uri" type="xsd:string"/>
</xsd:sequence>
</xsd:complexType>
<xsd:element name="namespaceDecl" type="namespaceDeclType"/>
<xsd:element name="moduleDecl" type="namespaceDeclType"/>
<xsd:element name="libraryModule">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="moduleDecl"/>
<xsd:element ref="prolog" minOccurs="0"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="versionDecl">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="version" type="xsd:string"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="prolog">
<xsd:complexType>
<xsd:sequence>
<xsd:choice minOccurs="0" maxOccurs="unbounded">
<xsd:element ref="boundarySpaceDecl"/>
<xsd:element ref="defaultCollationDecl"/>
<xsd:element ref="baseUriDecl"/>
<xsd:element ref="constructionDecl"/>
<xsd:element ref="orderingModeDecl"/>
<xsd:element ref="emptyOrderingDecl"/>
<xsd:element ref="copyNamespacesDecl"/>
</xsd:choice>
<xsd:choice minOccurs="0" maxOccurs="unbounded">
<xsd:element ref="defaultNamespaceDecl"/>
<xsd:element ref="namespaceDecl"/>
<xsd:element ref="schemaImport"/>
<xsd:element ref="moduleImport"/>
</xsd:choice>
<xsd:choice minOccurs="0" maxOccurs="unbounded">
<xsd:element ref="varDecl"/>
<xsd:element ref="functionDecl"/>
<xsd:element ref="optionDecl"/>
</xsd:choice>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="boundarySpaceDecl">
<xsd:simpleType>
<xsd:restriction base="xsd:NMTOKEN">
<xsd:enumeration value="strip"/>
<xsd:enumeration value="preserve"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:element>
<xsd:element name="defaultCollationDecl" type="xsd:string"/>
<xsd:element name="baseUriDecl" type="xsd:string"/>
<xsd:element name="orderingModeDecl">
<xsd:simpleType>
<xsd:restriction base="xsd:NMTOKEN">
<xsd:enumeration value="ordered"/>
<xsd:enumeration value="unordered"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:element>
<xsd:element name="emptyOrderingDecl" type="emptyOrderingMode"/>
<xsd:element name="constructionDecl">
<xsd:simpleType>
<xsd:restriction base="xsd:NMTOKEN">
<xsd:enumeration value="strip"/>
<xsd:enumeration value="preserve"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:element>
<xsd:element name="copyNamespacesDecl">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="preserveMode">
<xsd:simpleType>
<xsd:restriction base="xsd:NMTOKEN">
<xsd:enumeration value="preserve"/>
<xsd:enumeration value="no-preserve"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:element>
<xsd:element name="inheritMode">
<xsd:simpleType>
<xsd:restriction base="xsd:NMTOKEN">
<xsd:enumeration value="inherit"/>
<xsd:enumeration value="no-inherit"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:element>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:simpleType name="defaultNamespaceCategory">
<xsd:restriction base="xsd:NMTOKEN">
<xsd:enumeration value="function"/>
<xsd:enumeration value="element"/>
</xsd:restriction>
</xsd:simpleType>
<xsd:element name="defaultNamespaceDecl">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="defaultNamespaceCategory" type="defaultNamespaceCategory"/>
<xsd:element name="uri" type="xsd:string"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="varDecl">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="varName" type="QName"/>
<xsd:element ref="typeDeclaration" minOccurs="0"/>
<xsd:choice>
<xsd:element name="varValue" type="exprWrapper"/>
<xsd:element name="external" type="emptyContent"/>
</xsd:choice>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="optionDecl">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="optionName" type="QName"/>
<xsd:element name="optionContents" type="xsd:string"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="param">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="varName" type="QName"/>
<xsd:element ref="typeDeclaration" minOccurs="0"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="paramList">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="param" minOccurs="0" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="functionDecl">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="functionName" type="QName"/>
<xsd:element ref="paramList"/>
<xsd:element ref="typeDeclaration" minOccurs="0"/>
<xsd:choice>
<xsd:element name="functionBody" type="exprWrapper"/>
<xsd:element name="externalDefinition" type="emptyContent"/>
</xsd:choice>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="moduleImport">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="namespacePrefix" type="xsd:NCName" minOccurs="0"/>
<xsd:element name="targetNamespace" type="xsd:string"/>
<xsd:element name="targetLocation" type="xsd:string" minOccurs="0" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="schemaImport">
<xsd:complexType>
<xsd:sequence>
<xsd:choice minOccurs="0">
<xsd:element name="namespacePrefix" type="xsd:NCName"/>
<xsd:element name="defaultElementNamespace" type="emptyContent"/>
</xsd:choice>
<xsd:element name="targetNamespace" type="xsd:string"/>
<xsd:element name="targetLocation" type="xsd:string" minOccurs="0" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<!-- The element below handles the trivial XQuery embedding -->
<xsd:element name="xquery" type="xsd:string"/>
</xsd:schema>
5 A Trivial Embedding of XQuery
1 Introduction observed that the [XML Query 1.0 Requirements] says "The XML Query Language MAY have more than one syntax binding. One query language syntax MUST be convenient for humans to read and write. One query language syntax MUST be expressed in XML in a way that reflects the underlying structure of the query." There are many possible ways to define an XML syntax for XQuery. This document specifies two XML Syntaxes for XQuery: the one
in 4 An XML Schema for the XQuery XML Syntax and the "trivial embedding" defined in this section. Of course, XQueries could be expressed in XML Syntax in other ways.
The trivial embedding specified here can be used when an XQuery is exchanged with other entities as XML or embedded in an XML document, and when it is not necessary to communicate the underying structure of the query. When this alternative is chosen, the XQuery expression is treated as though it were ordinary text. One consequence of this fact is that there is no interaction between any namespaces declared in the containing XML document and namespaces declared or used in the embedded XQuery
expression.
The trivial embedding defined in this specification requires that the entire query be enclosed within an element named "xquery" in the XQueryX namespace (the "xqx:" namespace prefix is used here only for the purposes of this example), as illustrated here:
<xqx:xquery>for $i... let $j...where $x = $y...return...</xqx:xquery>
If the XQuery contains characters that are prohibited in XML text (specifically < and &), except when they occur within a CDATA section within the XQuery, they must be "escaped" as either character entity references (< and &, respectively) or numeric character references (< and &, respectively).
<xqx:xquery>for $i... let $j...where $x < $y...return...</xqx:xquery>
or
<xqx:xquery>for $i... let $j...where $x &x003C; $y...return...</xqx:xquery>
This limitation may require that user agents scan the XQuery text, escaping such prohibited characters, before transmitting or embedding the XQuery as XML.
The following two more complete examples also illustrate the use of the XQueryX trivial embedding. In particular, CDATA sections are embedded in the same form in which they appear in any XML document.
<xqx:xquery>for $i in (1 to 5) let $j := 4 where $i < $j return
<x/><i>{$i}</i></x></xqx:xquery>
<xqx:xquery><![CDATA[for $i in (1 to 5) let $j := 4 where $i < $j
return <x/><i>{$i}</i></x>]]></xqx:xquery>