com.saxonica.functions.json

Class XMLToJsonFn

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.FunctionCall

net.sf.saxon.functions.SystemFunctionCall

com.saxonica.functions.json.XMLToJsonFn

All Implemented Interfaces:

SourceLocator, Callable, IdentityComparable, InstructionInfo

public class XMLToJsonFn
extends SystemFunctionCall
implements Callable

Implement the XML to JSON conversion as a built-in function - fn:xml-to-json()

This exploits the stylesheets xml-to-json.xsl and xml-to-json-indent.xsl, to perform the actual conversion. These are held as resources within the Saxon jar and compiled when needed.

Field Summary

Fields inherited from class net.sf.saxon.functions.SystemFunctionCall

operation

Fields inherited from class net.sf.saxon.expr.FunctionCall

argument

Fields inherited from class net.sf.saxon.expr.Expression

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD

Constructor Summary

Constructors

Constructor and Description
XMLToJsonFn()

Method Summary

Methods

Modifier and Type	Method and Description
Sequence	call(XPathContext context, Sequence[] arguments) Call the Callable.
StringValue	evaluateItem(XPathContext context) Evaluate the function to produce a single item or an empty sequence
Expression	preEvaluate(ExpressionVisitor visitor) preEvaluate: this method suppresses compile-time evaluation by doing nothing (because the value of the expression depends on the runtime context)

Methods inherited from class net.sf.saxon.functions.SystemFunctionCall

addContextDocumentArgument, addDocToPathMap, bindStaticContext, checkArguments, computeCardinality, computeSpecialProperties, copy, equalOrNull, equals, getContextNode, getConvertingCallable, getDefaultArgumentNode, getDetails, getErrorCodeForTypeErrors, getFunctionItemType, getImplementationMethod, getItemType, getOperation, getRequiredType, makeSystemFunction, operands, optimize, setDetails, toShortString, useContextItemAsDefault

Methods inherited from class net.sf.saxon.expr.FunctionCall

addExternalFunctionCallToPathMap, checkArgumentCount, explain, getArguments, getDisplayName, getExpressionName, getFunctionName, getNumberOfArguments, hashCode, promote, replaceOperand, setArguments, setFunctionName, simplifyArguments, toString, typeCheck

Methods inherited from class net.sf.saxon.expr.Expression

addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, clearStreamabilityData, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getConfiguration, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExpressionCompiler, getHostLanguage, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLocationId, getObjectName, getPosture, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getStreamability, getStreamingAdjunct, getSweep, getSystemId, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isIdentical, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, makeStreamingAdjunct, markTailFunctionCalls, operandList, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, setPostureAndSweep, simplify, staticTypeCheck, suppressValidation, toPattern, toStreamingPattern, typeError, unordered

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

XMLToJsonFn

public XMLToJsonFn()

Method Detail

call

public Sequence call(XPathContext context,
            Sequence[] arguments)
              throws XPathException

Description copied from interface: Callable

Call the Callable.

Specified by:

call in interface Callable

Parameters:

context - the dynamic evaluation context

arguments - the values of the arguments, supplied as Sequences.

Generally it is advisable, if calling iterate() to process a supplied sequence, to call it only once; if the value is required more than once, it should first be converted to a GroundedValue by calling the utility methd SequenceTool.toGroundedValue().

If the expected value is a single item, the item should be obtained by calling Sequence.head(): it cannot be assumed that the item will be passed as an instance of Item or AtomicValue.

It is the caller's responsibility to perform any type conversions required to convert arguments to the type expected by the callee. An exception is where this Callable is explicitly an argument-converting wrapper around the original Callable.

Returns:

the result of the evaluation, in the form of a Sequence. It is the responsibility of the callee to ensure that the type of result conforms to the expected result type.

Throws:

XPathException - if a dynamic error occurs during the evaluation of the expression

evaluateItem

public StringValue evaluateItem(XPathContext context)
                         throws XPathException

Evaluate the function to produce a single item or an empty sequence

The first argument is the XML tree to convert. The second, optional, is a map of parameters. Valid entries in this map have the following string-valued keys, and corresponding typed entry values:

• 'indent' as xs:boolean - whether to produce an indented result - default false()
• 'indent-spaces' as xs:integer - the number of spaces to indent by - default 3
• 'start-array' as xs:string - the string to use to mark the start of an array - default '['
• 'array-separator' as xs:string = the string to separate array elements - default ','
• 'end-array' as xs:string - the string to use to mark the end of an array - default ']'
• 'start-map' as xs:string - the string to use to mark the start of an map - default '{'
• 'key-delimiter' as xs:string - the string to delimit start and end of map keys - default '"'
• 'key-value-separator' as xs:string - the string to separate map keys from values - default ':'
• 'map-separator' as xs:string = the string to separate map entries - default ','
• 'end-map' as xs:string - the string to use to mark the end of an map - default '}'
• 'string-delimiter' as xs:string - the string to delimit start and end of string values - default '"'

Overrides:

evaluateItem in class Expression

Parameters:

context - the context in which the expression is to be evaluated

Returns:

either an item, or null to denote the empty sequence

Throws:

XPathException - if a failure occurs, e.g. bad JSON syntax

preEvaluate

public Expression preEvaluate(ExpressionVisitor visitor)

preEvaluate: this method suppresses compile-time evaluation by doing nothing (because the value of the expression depends on the runtime context)

Overrides:

preEvaluate in class FunctionCall

Parameters:

visitor - an expression visitor

Returns:

the result of the early evaluation, or the original expression, or potentially a simplified expression