Saxon.Api
Class XQueryCompiler
-
public class XQueryCompiler
The XQueryCompiler
object allows XQuery queries to be compiled.
To construct an XQueryCompiler
, use the factory method
NewXQueryCompiler
on the XQueryCompiler.Processor object.
The XQueryCompiler
holds information that represents the static context
for the queries that it compiles. This information remains intact after performing
a compilation. An XQueryCompiler
may therefore be used repeatedly to compile multiple
queries. Any changes made to the XQueryCompiler
(that is, to the
static context) do not affect queries that have already been compiled.
An XQueryCompiler
may be used concurrently in multiple threads, but
it should not then be modified once initialized.
Property Summary |
|
---|---|
Uri | BaseUri
The base URI of the query, which forms part of the static context
of the query. This is used for resolving any relative URIs appearing
within the query, for example in references to library modules, schema
locations, or as an argument to the |
bool | CompileWithTracing Property indicating that the query is to be compiled with tracing enabled. |
XdmItemType | ContextItemType The required context item type for the expression. This is used for optimizing the expression at compile time, and to check at run-time that the value supplied for the context item is the correct type. |
string | DefaultCollationName
The name of the default collation used by queries compiled using this |
ErrorReporter | ErrorReporter Set the |
bool | FastCompilation Property indicating that fast compilation is preferred. 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, the expression is only executed once against a document of modest size. |
Processor | Processor
Get the |
bool | SchemaAware Property indicating that the query is to be compiled to be schema-aware, even if it contains no "import schema" declarations. Normally a query is treated as schema-aware only if it contains one or more "import schema" declarations. |
bool | StreamingEnabled
Property indicating that the query is to be compiled to enable streaming, which is
necessary if the query is to be executed using the method |
bool | UpdatingEnabled This property indicates whether XQuery Update syntax is accepted. The default value is false. This property must be set to true before compiling a query that uses update syntax. |
string | XQueryLanguageVersion This property indicates which version of XQuery language syntax is accepted. The values accepted are "3.1" and "4.0". The default is "3.1". |
XQueryResolver | XQueryResolver
A user-supplied |
Method Summary |
|
---|---|
XQueryExecutable | Compile (Stream query)
Compile a query supplied as a |
XQueryExecutable | Compile (string query)
Compile a query supplied as a |
void | CompileLibrary (Stream query) Compile a library module supplied as a stream. The code generated by compiling the library is available for importing by all subsequent compilations using the same XQueryCompiler; it is identified by an "import module" declaration that specifies the module URI of the library module. No module location hint is required, and if one is present, it is ignored. |
void | CompileLibrary (string query) Compile a library module supplied as a string. The code generated by compiling the library is available for importing by all subsequent compilations using the same XQueryCompiler; it is identified by an "import module" declaration that specifies the module URI of the library module. No module location hint is required, and if one is present, it is ignored. |
void | DeclareNamespace (string prefix, string uri) Declare a namespace for use by the query. This has the same status as a namespace declaration appearing within the query prolog (though a declaration of the same prefix in the query prolog will take precedence). |
Property Detail
BaseUri
The base URI of the query, which forms part of the static context
of the query. This is used for resolving any relative URIs appearing
within the query, for example in references to library modules, schema
locations, or as an argument to the doc()
function.
CompileWithTracing
Property indicating that the query is to be compiled with tracing enabled.
This allows tracing to be switched on at run-time, but it has no effect unless run-time tracing is activated.
ContextItemType
The required context item type for the expression. This is used for optimizing the expression at compile time, and to check at run-time that the value supplied for the context item is the correct type.
DefaultCollationName
The name of the default collation used by queries compiled using this XQueryCompiler
.
This must be the name of a collation that is known to the Processor
.
ErrorReporter
Set the ErrorReporter
to be used when validating instance documents as a user defined IErrorReporter.
Requirements here is IErrorReport implementation with a user-written report()
method, it is possible to
intercept error conditions as they occur.
If this property is used then the ErrorList property and SetErrorList method is overriden.
The IErrorReporter
to be used
FastCompilation
Property indicating that fast compilation is preferred. 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, the expression is only executed once against a document of modest size.
The current implementation is equivalent to switching off all optimizations. Setting this option, however, indicates an intent rather than a mechanism, and the implementation details may change in future to reflect the intent.
Set to true to request fast compilation; set to false to revert to the optimization options defined in the Configuration.
Processor
Get the Processor
from which this XQueryCompiler
was constructed
SchemaAware
Property indicating that the query is to be compiled to be schema-aware, even if it contains no "import schema" declarations. Normally a query is treated as schema-aware only if it contains one or more "import schema" declarations.
If the query is not schema-aware, then all input documents must be untyped
(or xs:anyType
), and validation of temporary nodes is disallowed
(though validation of the final result tree is permitted). Setting the argument to
true
means that schema-aware code will be compiled regardless.
StreamingEnabled
Property indicating that the query is to be compiled to enable streaming, which is
necessary if the query is to be executed using the method XQueryEvaluator.RunStreamed()
.
In streaming mode, the source document is supplied as a stream, and no tree is built
in memory. The default is false.
When the value is set to true
, this has the additional side-effect of
setting the required context item type to document-node()
.
UpdatingEnabled
This property indicates whether XQuery Update syntax is accepted. The default value is false. This property must be set to true before compiling a query that uses update syntax.
This property must be set to true before any query can be compiled that uses updating syntax. This applies even if the query is not actually an updating query (for example, a copy-modify expression). XQuery Update syntax is accepted only by Saxon-EE. Non-updating queries are accepted regardless of the value of this property.
XQueryLanguageVersion
This property indicates which version of XQuery language syntax is accepted. The values accepted are "3.1" and "4.0". The default is "3.1".
XQuery 4.0 is work in progress, and the specification is far from stable.
XQueryResolver
A user-supplied XQueryResolver
used to resolve the URIs appearing in an
import module
declaration.
If an import module
declaration identifies a module URI that has already been loaded,
then the existing module is used (regardless of location hints and regardless of the
XQueryResolver
),
unless the configuration option XQUERY_MULTIPLE_MODULE_IMPORTS
is set. If this option is set, then an existing
module will be reused if the location hint matches; otherwise a new module is loaded
(which can
potentially cause a failure if it results in duplicate variables or functions having
the same name).
The XQueryResolver
can return multiple library modules; if it does so, they are all
imported. If it returns an empty array, nothing is imported.
If the XQueryResolver
returns null (as distinct from returning an empty array),
then the import module
declaration is resolved as if there were no user-supplied
XQueryResolver
.
If there is no user-supplied XQueryResolver
, and if the module has not already been
loaded, then an import module
declaration is interpreted as follows. First, if there are no location hints,
then a static error is reported. Otherwise, each URI listed in the location hints
is
resolved using the default resolution algorithm for the Processor
, and this is expected
to deliver an input stream containing an XQuery library module.
The interface changed in Saxon 11.1 so that the XQueryResolver
now returns one or more
TextResource
objects. The previous class XQueryModuleSource
no longer exists.
Method Detail
Compile
throws
SaxonApiException
Compile
throws
SaxonApiException
Compile a query supplied as a string
.
Using this method the query processor is provided with a string of Unicode characters, so no decoding is necessary. Any encoding information present in the version declaration is therefore ignored.
Parameters:
query
- A string containing the source text of the queryReturns:
XQueryExecutable
which represents the compiled query object.
The XQueryExecutable
may be run as many times as required, in the same or a different
thread. The XQueryExecutable
is not affected by any changes made to the XQueryCompiler
once it has been compiled.Throws:
SaxonApiException
if errors were detected
during static analysis of the query. Details of the errors will be reported to the
ErrorReporter
if supplied; otherwise they will be written to the standard
error stream. The exception that is returned from this method is merely a summary
indicating the
status, and is not useful for diagnosing the actual error.Example:
XQueryExecutable q = compiler.Compile("distinct-values(//*/node-name()");CompileLibrary
throws
Compile a library module supplied as a stream. The code generated by compiling the library is available for importing by all subsequent compilations using the same XQueryCompiler; it is identified by an "import module" declaration that specifies the module URI of the library module. No module location hint is required, and if one is present, it is ignored.
The base URI of the query should be supplied by setting the BaseURI
property of the QueryCompiler
.
Parameters:
query
- A stream delivering the text of the queryThrows:
CompileLibrary
throws
Compile a library module supplied as a string. The code generated by compiling the library is available for importing by all subsequent compilations using the same XQueryCompiler; it is identified by an "import module" declaration that specifies the module URI of the library module. No module location hint is required, and if one is present, it is ignored.
The base URI of the query should be supplied by setting the BaseURI
property of the QueryCompiler
.
Parameters:
query
- The text of the queryThrows:
DeclareNamespace
Declare a namespace for use by the query. This has the same status as a namespace declaration appearing within the query prolog (though a declaration of the same prefix in the query prolog will take precedence).
Parameters:
prefix
- The namespace prefix to be declared. Use
a zero-length string to declare the default namespace (that is, the
default namespace for elements and types).uri
- The namespace URI. It is possible to specify
a zero-length string to "undeclare" a namespace.
Compile a query supplied as a
Stream
.The XQuery processor attempts to deduce the encoding of the query by looking for a byte-order-mark, or if none is present, by looking for the encoding declaration in the XQuery version declaration. For this to work, the stream must have the
CanSeek
property. If no encoding information is present, UTF-8 is assumed.The base URI of the query is set to the value of the
BaseUri
property. If this has not been set, then the base URI will be undefined, which means that any use of an expression that depends on the base URI will cause an error.Parameters:
query
- A stream containing the source text of the queryReturns:
XQueryExecutable
which represents the compiled query object. TheXQueryExecutable
may be run as many times as required, in the same or a different thread. TheXQueryExecutable
is not affected by any changes made to theXQueryCompiler
once it has been compiled.Throws:
SaxonApiException
if errors were detected during static analysis of the query. Details of the errors will be reported to theErrorReporter
if supplied; otherwise they will be written to the standard error stream. The exception that is returned from this method is merely a summary indicating the status, and is not useful for diagnosing the actual error.Example:
XQueryExecutable q = compiler.Compile(new FileStream("input.xq", FileMode.Open, FileAccess.Read));