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matlab.io.xml.xpath.CompiledExpression class

Package: matlab.io.xml.xpath

Compiled XPath expression

Description

An object of the matlab.io.xml.xpath.CompiledExpression class represents a compiled XPath expression. You can provide a CompiledExpression object, instead of the source XPath expression, to the evaluate method of a matlab.io.xml.xpath.Evaluator object.

The matlab.io.xml.xpath.CompiledExpression class is a handle class.

Class Attributes

ConstructOnLoad
true
HandleCompatible
true

For information on class attributes, see Class Attributes.

Creation

To create a matlab.io.xml.xpath.CompiledExpression object, call the compileExpression method of a matlab.io.xml.xpath.Evaluator object.

Properties

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Source XPath expression, specified as a character vector.

Attributes:

GetAccess
public
SetAccess
immutable
Transient
true
NonCopyable
true

Examples

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This examples compiles an XPath expression and passes the compiled expression to an XPath expression evaluator.

The example uses the file music.xml, which contains this XML markup:

<MusicalEnsemble>
	<Ensemble>
		<Music>Jazz</Music>
            <BandName>Kool Katz</BandName>
		<Instrumentation>
			<Instrument type="wind">Trumpet
            </Instrument>
			<Instrument type="percussion">Piano
                <pianotype>concert grand</pianotype>
            </Instrument>
			<Instrument type="percussion">Drums
                <drumkit>Bass drum</drumkit>
                <drumkit>Floor tom</drumkit>
                <drumkit>Snare drum</drumkit>
                <drumkit>Hi-hat</drumkit>
                <drumkit>Ride cymbal</drumkit>
            </Instrument>
			<Instrument type="string">Bass
                <basstype>upright</basstype>
            </Instrument>
		</Instrumentation>
	</Ensemble>
    <Musicians>
        <Name role="trumpeter">Miles</Name>
        <Name role="vocalist">Roger</Name>
        <Name role="pianist">Diana</Name>
        <Name role="drummer">George</Name>
        <Name role="bassist">John</Name>
    </Musicians>
</MusicalEnsemble>

Compile the XPath expression //Instrument by calling the compileExpression method of a matlab.io.xml.xpath.Evaluator object.

import matlab.io.xml.xpath.*

evalObj = Evaluator();
compExpObj = compileExpression(evalObj,"//Instrument");

Evaluate the compiled expression in the context of music.xml and return the resulting nodes as a vector of node objects.

xmlFilePath = "music.xml";
data = evaluate(evalObj,compExpObj,xmlFilePath,EvalResultType.NodeSet)
data=1×4 object
  1x4 Element array with properties:

    TagName
    HasAttributes
    TextContent
    Children

Introduced in R2021a