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// Copyright (c) 2018-2023 Saxonica Limited
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
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/**
* This package provides classes associated with XSLT pattern handling.
* The principal classes are:
* Pattern:
* This represents an XSLT Pattern. There is a static method Pattern.make() which is
* used to construct a Pattern from a String (it is a factory method rather than a
* constructor, because it typically returns some subclass of Pattern according
* to the syntax supplied). Subclasses of Pattern represent different kinds of pattern
* such as LocationPathPattern and IDKeyPattern. What they all have in common is a match()
* method, which determines whether a given node matches the pattern. A pattern is
* not in itself an Expression, but the class PatternSponsor is used
* to wrap a pattern making it look like an expression for the benefit of the static analysis
* (allowing the same mechanisms to be used for example to find all the references to a variable).
* NodeTest:
* This represents a NodeTest within a step of an XPath expression. A NodeTest performs several
* roles: as well as its use in conjuction with an axis to form a step of a path expression,
* it acts as an ItemType used in handling type checking of nodes, and (wrapped in a NodeTestPattern)
* it acts as an XSLT pattern for use in constructs such as the match attribute of
* xsl:template and xsl:key.
* A NodeTest is used directly to implement simple patterns such as match="item"
* or match="*". There are several subclasses of NodeTest, depending on the conditions
* to be matched: node type, node name, namespace URI, and so on. The class AnyNodeTest matches any node,
* while NoNodeTest matches nothing. NodeTests can also be combined using the operators of intersection,
* difference, and union, to describe the more complex types that are sometimes computed by the type
* checking machinery.
*/
package net.sf.saxon.pattern;