Package net.sf.saxon.s9api

Class XPathCompiler

  • public class XPathCompiler
extends java.lang.Object
    An XPathCompiler object allows XPath queries to be compiled. The compiler holds information that represents the static context for an XPath expression.

    To construct an XPathCompiler, use the factory method Processor.newXPathCompiler().

    An XPathCompiler may be used repeatedly to compile multiple queries. Any changes made to the XPathCompiler (that is, to the static context) do not affect queries that have already been compiled. An XPathCompiler may be used concurrently in multiple threads, but it should not then be modified once initialized.

    Changes to an XPathCompiler are cumulative. There is no simple way to reset the XPathCompiler to its initial state; instead, simply create a new XPathCompiler.

    The XPathCompiler has the ability to maintain a cache of compiled expressions. This is active only if enabled by calling setCaching(boolean). If caching is enabled, then the compiler will recognize an attempt to compile the same expression twice, and will avoid the cost of recompiling it. The cache is emptied by any method that changes the static context for subsequent expressions, for example, setBaseURI(java.net.URI). Unless the cache is emptied, it grows indefinitely: compiled expressions are never discarded.

    Since:
    9.0

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      protected XPathCompiler​(Processor processor)
      Protected constructor

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void addXsltFunctionLibrary​(XsltPackage libraryPackage)
      Make available a set of functions defined in an XSLT 3.0 package.
      XPathExecutable compile​(java.lang.String source)
      Compile an XPath expression, supplied as a character string.
      XPathExecutable compilePattern​(java.lang.String source)
      Compile an XSLT 2.0 pattern, supplied as a character string.
      void declareDefaultCollation​(java.lang.String uri)
      Declare the default collation
      void declareNamespace​(java.lang.String prefix, java.lang.String uri)
      Declare a namespace binding as part of the static context for XPath expressions compiled using this XPathCompiler
      void declareVariable​(QName qname)
      Declare a variable as part of the static context for XPath expressions compiled using this XPathCompiler.
      void declareVariable​(QName qname, ItemType itemType, OccurrenceIndicator occurrences)
      Declare a variable as part of the static context for XPath expressions compiled using this XPathCompiler.
      XdmValue evaluate​(java.lang.String expression, XdmItem contextItem)
      Compile and evaluate an XPath expression, supplied as a character string, with a given context item.
      XdmItem evaluateSingle​(java.lang.String expression, XdmItem contextItem)
      Compile and evaluate an XPath expression whose result is expected to be a single item, with a given context item.
      java.net.URI getBaseURI()
      Get the static base URI for XPath expressions compiled using this XPathCompiler.
      java.lang.String getLanguageVersion()
      Ask whether an XPath 2.0, XPath 3.0, XPath 3.1 or XPath 4.0 processor is being used
      Processor getProcessor()
      Get the Processor from which this XPathCompiler was constructed
      ItemType getRequiredContextItemType()
      Get the required type of the context item.
      StaticContext getUnderlyingStaticContext()
      Escape-hatch method to get the underlying static context object used by the implementation.
      UnprefixedElementMatchingPolicy getUnprefixedElementMatchingPolicy()
      Get the policy for matching unprefixed element names in XPath expressions
      void importSchemaNamespace​(java.lang.String uri)
      Import a schema namespace: that is, add the element and attribute declarations and type definitions contained in a given namespace to the static context for the XPath expression.
      boolean isAllowUndeclaredVariables()
      Ask whether undeclared variables are allowed.
      boolean isBackwardsCompatible()
      Ask whether XPath 1.0 backwards compatibility mode is in force.
      boolean isCaching()
      Ask whether the compiler is maintaining a cache of compiled expressions
      boolean isFastCompilation()
      Ask if fast compilation has been enabled.
      boolean isSchemaAware()
      Ask whether XPath expressions compiled using this XPathCompiler are schema-aware.
      void setAllowUndeclaredVariables​(boolean allow)
      Say whether undeclared variables are allowed.
      void setBackwardsCompatible​(boolean option)
      Say whether XPath 1.0 backwards compatibility mode is to be used.
      void setBaseURI​(java.net.URI uri)
      Set the static base URI for XPath expressions compiled using this XPathCompiler.
      void setCaching​(boolean caching)
      Say whether the compiler should maintain a cache of compiled expressions.
      void setDecimalFormatProperty​(QName format, java.lang.String property, java.lang.String value)
      Registers the required decimal format properties, for use in calls to the fn:format-number() function.
      void setFastCompilation​(boolean fast)
      Request fast compilation.
      void setLanguageVersion​(java.lang.String value)
      Say whether an XPath 2.0, XPath 3.0, XPath 3.1 or XPath 4.0 processor is required.
      void setRequiredContextItemType​(ItemType type)
      Declare the static type of the context item.
      void setSchemaAware​(boolean schemaAware)
      Say whether XPath expressions compiled using this XPathCompiler are schema-aware.
      void setUnprefixedElementMatchingPolicy​(UnprefixedElementMatchingPolicy policy)
      Set the policy for matching unprefixed element names in XPath expressions
      void setWarningHandler​(ErrorReporter reporter)
      Set the error reporter to be used for reporting static warnings during compilation.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • XPathCompiler

        protected XPathCompiler​(Processor processor)
        Protected constructor
        Parameters:
        processor - the s9api Processor

    • Method Detail

      • getProcessor

        public Processor getProcessor()
        Get the Processor from which this XPathCompiler was constructed
        Returns:
        the Processor to which this XPathCompiler belongs
        Since:
        9.3

      • setBackwardsCompatible

        public void setBackwardsCompatible​(boolean option)
        Say whether XPath 1.0 backwards compatibility mode is to be used. In backwards compatibility mode, more implicit type conversions are allowed in XPath expressions, for example it is possible to compare a number with a string. The default is false (backwards compatibility mode is off).
        Parameters:
        option - true if XPath 1.0 backwards compatibility is to be enabled, false if it is to be disabled.
        Since:
        9.1; changed in 9.8 to throw IllegalStateException if the feature is not available; change reverted by bug 3817.

      • isBackwardsCompatible

        public boolean isBackwardsCompatible()
        Ask whether XPath 1.0 backwards compatibility mode is in force.
        Returns:
        true if XPath 1.0 backwards compatibility is enabled, false if it is disabled.

      • setSchemaAware

        public void setSchemaAware​(boolean schemaAware)
        Say whether XPath expressions compiled using this XPathCompiler are schema-aware. They will automatically be schema-aware if the method importSchemaNamespace(String) is called. An XPath expression must be marked as schema-aware if it is to handle typed (validated) input documents.
        Parameters:
        schemaAware - true if expressions are to be schema-aware, false otherwise
        Throws:
        java.lang.UnsupportedOperationException - if schema-awareness is requested when this is not a licensed Saxon-EE configuration.
        Since:
        9.3. Changed in 9.9 to throw an exception if Saxon-EE is not available (previously, the option was either silently ignored, or caused a failure at some later time.)

      • isSchemaAware

        public boolean isSchemaAware()
        Ask whether XPath expressions compiled using this XPathCompiler are schema-aware. They will automatically be schema-aware if the method importSchemaNamespace(String) is called. An XPath expression must be marked as schema-aware if it is to handle typed (validated) input documents.
        Returns:
        true if expressions are to be schema-aware, false otherwise
        Since:
        9.3

      • setLanguageVersion

        public void setLanguageVersion​(java.lang.String value)
        Say whether an XPath 2.0, XPath 3.0, XPath 3.1 or XPath 4.0 processor is required.
        Parameters:
        value - One of the values 1.0, 2.0, 3.0, 3.05, 3.1, 4.0.

        Setting the option to 1.0 requests an XPath 2.0 processor running in 1.0 compatibility mode; this is equivalent to setting the language version to 2.0 and backwards compatibility mode to true. Requesting "3.05" gives XPath 3.0 plus the extensions defined in the XSLT 3.0 specification (map types and map constructors).

        Throws:
        java.lang.IllegalArgumentException - if the version is not numerically equal to 1.0, 2.0, 3.0, 3.05, 3.1, or 4.0.
        Since:
        9.3

      • getLanguageVersion

        public java.lang.String getLanguageVersion()
        Ask whether an XPath 2.0, XPath 3.0, XPath 3.1 or XPath 4.0 processor is being used
        Returns:
        version: "2.0", "3.0", "3.1" or "4.0"
        Since:
        9.3

      • setBaseURI

        public void setBaseURI​(java.net.URI uri)
        Set the static base URI for XPath expressions compiled using this XPathCompiler. The base URI is part of the static context, and is used to resolve any relative URIs appearing within an XPath expression, for example a relative URI passed as an argument to the doc() function. If no static base URI is supplied, then the current working directory is used.
        Parameters:
        uri - the base URI to be set in the static context. This must be an absolute URI, or null to indicate that no static base URI is available.

      • getBaseURI

        public java.net.URI getBaseURI()
        Get the static base URI for XPath expressions compiled using this XPathCompiler. The base URI is part of the static context, and is used to resolve any relative URIs appearing within an XPath expression, for example a relative URI passed as an argument to the doc() function. If no static base URI has been explicitly set, this method returns null.
        Returns:
        the base URI from the static context

      • setUnprefixedElementMatchingPolicy

        public void setUnprefixedElementMatchingPolicy​(UnprefixedElementMatchingPolicy policy)
        Set the policy for matching unprefixed element names in XPath expressions
        Parameters:
        policy - the policy to be used

      • getUnprefixedElementMatchingPolicy

        public UnprefixedElementMatchingPolicy getUnprefixedElementMatchingPolicy()
        Get the policy for matching unprefixed element names in XPath expressions
        Returns:
        the policy being used

      • setWarningHandler

        public void setWarningHandler​(ErrorReporter reporter)
        Set the error reporter to be used for reporting static warnings during compilation. By default, the ErrorReporter associated with the Saxon Configuration is used.

        Note that fatal static errors are always reported in the form of an exception thrown by the compile(String) method, so this method only controls the handling of warnings

        Parameters:
        reporter - the ErrorReporter to which warnings will be notified
        Since:
        10.0

      • declareNamespace

        public void declareNamespace​(java.lang.String prefix,
                             java.lang.String uri)
        Declare a namespace binding as part of the static context for XPath expressions compiled using this XPathCompiler
        Parameters:
        prefix - The namespace prefix. If the value is a zero-length string, this method sets the default namespace for elements and types.
        uri - The namespace URI. It is possible to specify a zero-length string to "undeclare" a namespace; in this case the prefix will not be available for use, except in the case where the prefix is also a zero length string, in which case the absence of a prefix implies that the name is in no namespace.
        Throws:
        java.lang.NullPointerException - if either the prefix or uri is null.

      • importSchemaNamespace

        public void importSchemaNamespace​(java.lang.String uri)
        Import a schema namespace: that is, add the element and attribute declarations and type definitions contained in a given namespace to the static context for the XPath expression.

        This method will not cause the schema to be loaded. That must be done separately, using the SchemaManager. This method will not fail if the schema has not been loaded (but in that case the set of declarations and definitions made available to the XPath expression is empty). The schema document for the specified namespace may be loaded before or after this method is called.

        This method does not bind a prefix to the namespace. That must be done separately, using the declareNamespace(String, String) method.

        Parameters:
        uri - The schema namespace to be imported. To import declarations in a no-namespace schema, supply a zero-length string.
        Since:
        9.1

      • setAllowUndeclaredVariables

        public void setAllowUndeclaredVariables​(boolean allow)
        Say whether undeclared variables are allowed. By default, they are not allowed. When undeclared variables are allowed, it is not necessary to predeclare the variables that may be used in the XPath expression; instead, a variable is automatically declared when a reference to the variable is encountered within the expression.
        Parameters:
        allow - true if undeclared variables are allowed, false if they are not allowed.
        Since:
        9.2

      • isAllowUndeclaredVariables

        public boolean isAllowUndeclaredVariables()
        Ask whether undeclared variables are allowed. By default, they are not allowed. When undeclared variables are allowed, it is not necessary to predeclare the variables that may be used in the XPath expression; instead, a variable is automatically declared when a reference to the variable is encountered within the expression.
        Returns:
        true if undeclared variables are allowed, false if they are not allowed.
        Since:
        9.2

      • declareVariable

        public void declareVariable​(QName qname)
        Declare a variable as part of the static context for XPath expressions compiled using this XPathCompiler. It is an error for the XPath expression to refer to a variable unless it has been declared, unless the method setAllowUndeclaredVariables(boolean) has been called to permit undeclared variables. This method declares the existence of the variable, but it does not bind any value to the variable; that is done later, when the XPath expression is evaluated. The variable is allowed to have any type (that is, the required type is item()*).
        Parameters:
        qname - The name of the variable, expressions as a QName

      • declareVariable

        public void declareVariable​(QName qname,
                            ItemType itemType,
                            OccurrenceIndicator occurrences)
        Declare a variable as part of the static context for XPath expressions compiled using this XPathCompiler. It is an error for the XPath expression to refer to a variable unless it has been declared, unless the method setAllowUndeclaredVariables(boolean) has been called to permit undeclared variables. This method declares the existence of the variable, and defines the required type of the variable, but it does not bind any value to the variable; that is done later, when the XPath expression is evaluated.
        Parameters:
        qname - The name of the variable, expressed as a QName
        itemType - The required item type of the value of the variable, for example ItemType.BOOLEAN
        occurrences - The allowed number of items in the sequence forming the value of the variable

      • addXsltFunctionLibrary

        public void addXsltFunctionLibrary​(XsltPackage libraryPackage)
        Make available a set of functions defined in an XSLT 3.0 package. All functions defined with visibility="public" (or exposed as public using xsl:expose become part of the static context for an XPath expression created using this XPathCompiler. The functions are added to the search path after all existing functions, including functions added using a previous call on this method.

        Note that if the library package includes functions that reference stylesheet parameters (or global variables that depend on the context item), then there is no way of supplying values for such parameters; calling such functions will cause a run-time error.

        Parameters:
        libraryPackage - the XSLT compiled library package whose functions are to be made available
        Since:
        10.0

      • setRequiredContextItemType

        public void setRequiredContextItemType​(ItemType type)
        Declare the static type of the context item. If this type is declared, and if a context item is supplied when the query is invoked, then the context item must conform to this type (no type conversion will take place to force it into this type).
        Parameters:
        type - the required type of the context item, for example, ItemType.ANY_NODE.
        Since:
        9.3

      • getRequiredContextItemType

        public ItemType getRequiredContextItemType()
        Get the required type of the context item. If no type has been explicitly declared for the context item, an instance of ItemType.ANY_ITEM (representing the type item()) is returned.
        Returns:
        the required type of the context item
        Since:
        9.3

      • declareDefaultCollation

        public void declareDefaultCollation​(java.lang.String uri)
        Declare the default collation
        Parameters:
        uri - the absolute URI of the default collation. This URI must identify a known collation; either one that has been explicitly declared, or one that is recognized implicitly, such as a UCA collation
        Throws:
        java.lang.IllegalStateException - if the collation URI is not recognized as a known collation
        Since:
        9.4

      • setCaching

        public void setCaching​(boolean caching)
        Say whether the compiler should maintain a cache of compiled expressions. The initial default value is false.
        Parameters:
        caching - if set to true, caching of compiled expressions is enabled. If set to false, any existing cache is cleared, and future compiled expressions will not be cached until caching is re-enabled. The cache is also cleared (but without disabling future caching) if any method is called that changes the static context for compiling expressions, for example declareVariable(QName) or declareNamespace(String, String).
        Since:
        9.3

      • isCaching

        public boolean isCaching()
        Ask whether the compiler is maintaining a cache of compiled expressions
        Returns:
        true if a cache is being maintained
        Since:
        9.3

      • setFastCompilation

        public void setFastCompilation​(boolean fast)
        Request fast compilation. Fast compilation will generally be achieved at the expense of run-time performance and quality of diagnostics. Fast compilation is a good trade-off if (a) the expression is known to be correct, and (b) once compiled, it is only executed once against a document of modest size.
        Parameters:
        fast - set to true to request fast compilation; set to false to revert to the optimization options defined in the Configuration.
        Since:
        9.9

      • isFastCompilation

        public boolean isFastCompilation()
        Ask if fast compilation has been enabled.
        Returns:
        true if fast compilation has been enabled
        Since:
        9.9

      • compile

        public XPathExecutable compile​(java.lang.String source)
                        throws SaxonApiException
        Compile an XPath expression, supplied as a character string.
        Parameters:
        source - A non-null string containing the source text of the XPath expression
        Returns:
        An XPathExecutable which represents the compiled xpath expression object. The XPathExecutable may be run as many times as required, in the same or a different thread. The XPathExecutable is not affected by any changes made to the XPathCompiler once it has been compiled.
        Throws:
        SaxonApiException - if any static error is detected while analyzing the expression.

        Note: prior to Saxon 9.7, static errors were also notified to the ErrorListener associated with the containing Processor/Configuration. This is no longer the case.

      • evaluate

        public XdmValue evaluate​(java.lang.String expression,
                         XdmItem contextItem)
                  throws SaxonApiException
        Compile and evaluate an XPath expression, supplied as a character string, with a given context item.
        Parameters:
        expression - A non-null string containing the source text of the XPath expression
        contextItem - The context item to be used for evaluating the expression. This may be null if the expression is to be evaluated with no context item.
        Returns:
        the result of evaluating the XPath expression with this context item. Note that the result is an Iterable, so that it can be used in a "for-each" loop such as for (XdmItem item : xpath.evaluate("//x", doc) {...}
        Throws:
        SaxonApiException - if any static error is detected while analyzing the expression, or if any dynamic error is detected while evaluating it.
        Since:
        9.3. Changed in 11.0 to use FastCompilation (i.e., to suppress most optimizations)

      • evaluateSingle

        public XdmItem evaluateSingle​(java.lang.String expression,
                              XdmItem contextItem)
                       throws SaxonApiException
        Compile and evaluate an XPath expression whose result is expected to be a single item, with a given context item. The expression is supplied as a character string.
        Parameters:
        expression - A non-null string containing the source text of the XPath expression
        contextItem - The context item to be used for evaluating the expression. This may be null if the expression is to be evaluated with no context item.
        Returns:
        the result of evaluating the XPath expression with this context item. If the result is a singleton it is returned as an XdmItem; if it is an empty sequence, the return value is null. If the expression returns a sequence of more than one item, any items after the first are ignored.
        Throws:
        SaxonApiException - if any static error is detected while analyzing the expression, or if any dynamic error is detected while evaluating it.
        Since:
        9.3. Changed in 11.0 to use FastCompilation (i.e., to suppress most optimizations)

      • compilePattern

        public XPathExecutable compilePattern​(java.lang.String source)
                               throws SaxonApiException
        Compile an XSLT 2.0 pattern, supplied as a character string. The compiled pattern behaves as a boolean expression which, when evaluated in a particular context, returns true if the context node matches the pattern, and false if it does not. An error is reported if there is no context item or it the context item is not a node.
        Parameters:
        source - A non-null string conforming to the syntax of XSLT 2.0 patterns
        Returns:
        An XPathExecutable representing an expression which evaluates to true when the context node matches the pattern, and false when it does not.
        Throws:
        SaxonApiException - if the pattern contains static errors: for example, if its syntax is incorrect, or if it refers to undeclared variables or namespaces
        Since:
        9.1

      • setDecimalFormatProperty

        public void setDecimalFormatProperty​(QName format,
                                     java.lang.String property,
                                     java.lang.String value)
                              throws SaxonApiException
        Registers the required decimal format properties, for use in calls to the fn:format-number() function. The values for different properties may be supplied incrementally; they are only checked for consistency when an XPath expression is compiled.
        Parameters:
        format - The name of the decimal format. (Note: it is not possible to set properties for the default unnamed decimal format.)
        property - The decimal symbols name to update, for example "grouping-separator"
        value - The value to update the decimal symbol property
        Throws:
        SaxonApiException - if an invalid value is supplied for a decimal format property
        java.lang.IllegalArgumentException - if the value of property is not one of the recognized decimal format properties
        Since:
        9.4

      • getUnderlyingStaticContext

        public StaticContext getUnderlyingStaticContext()
        Escape-hatch method to get the underlying static context object used by the implementation.
        Returns:
        the underlying static context object. In the current implementation this will always be an instance of IndependentContext.

        This method provides an escape hatch to internal Saxon implementation objects that offer a finer and lower-level degree of control than the s9api classes and methods. Some of these classes and methods may change from release to release.

        Since:
        9.1