The java.pattern.composite option

The java.pattern.composite option adds a composite facility for Relaxer objects.

The composite facility, which is a kind of Composite pattern from the GoF's (Gang of Four) Design Patter book, enables a uniform interface for manipulating a generic tree structure.

Parameters

The java.pattern.composite option takes one of the following values as a parameter:

true

Enables a composite facility.

false

Disables a composite facility.

The default configuration is false. No parameter implies that the parameter is true.

Artifacts

The java.pattern.composite option generates an additional class as follows:

• IRNode

The IRNode is an interface to access child nodes uniformly.

The java.pattern.composite option adds the following methods to Relaxer objects:

• rGetParentRNode
• rSetParentRNode
• rGetRNodes

The rGetParentRNode method and The rSetParentRNode method are setter and getter of the property 'parentRNode', which refer a parent node.

The rGetRNodes method notifies all child nodes.

Example

List 7.19.3.1[javaPatternComposite.rng] is a sample schema for the java.pattern.composite option.

<grammar xmlns="http://relaxng.org/ns/structure/1.0"
         datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
  <start>
    <ref name="account"/>
  </start>
  <define name="account">
    <element name="account">
      <attribute name="accountNo">
        <data type="token"/>
      </attribute>
      <element name="balance">
        <data type="int"/>
      </element>
      <element name="owner">
        <data type="token"/>
      </element>
      <ref name="address"/>
      <zeroOrMore>
        <ref name="phone"/>
      </zeroOrMore>
    </element>
  </define>
  <define name="address">
    <element name="address">
      <attribute name="zip">
        <data type="token"/>
      </attribute>
      <text/>
    </element>
  </define>
  <define name="phone">
    <element name="phone">
      <attribute name="area">
        <data type="token"/>
      </attribute>
        <data type="token"/>
    </element>
  </define>
</grammar>

Build

Execution of Relaxer with the java.pattern.composite option is as follows:

$ relaxer -java -java.pattern.composite javaPatternComposite.rng

Because the Java generator is a default generator, execution of Relaxer as shown below has the same effect:

$ relaxer -java.pattern.composite javaPatternComposite.rng

As a result, Relaxer generates six files:

• Account.java
• Address.java
• Phone.java
• URelaxer.java
• RStack.java
• UJAXP.java

List 7.19.3.1.1[JavaPatternComposite.java] is a sample program for the java.pattern.composite option.

import java.io.IOException;
import javax.xml.parsers.ParserConfigurationException;
import org.xml.sax.SAXException;

public class JavaPatternComposite {
    public static void main(String[] args)
	throws IOException, SAXException, ParserConfigurationException {

	String uri = args[0];
	Account account = makeAccount(uri);
	printAccount(account);
	printChildren(account);
    }

    private static Account makeAccount(String uri)
	throws IOException, SAXException, ParserConfigurationException {

	System.out.println("*** makeAccount ***");
	Account account = new Account(uri);
	return (account);
    }

    private static void printAccount(Account account) {
	System.out.println("*** printAccount ***");
	String accountNo = account.getAccountNo();
	long balance = account.getBalance();
	String owner = account.getOwner();
	Address address = account.getAddress();
	String zip = address.getZip();
	String place = address.getContent();
	System.out.println("AccountNo:" + accountNo);
	System.out.println("Balance:" + balance);
	System.out.println("Owner:" + owner);
	System.out.println("Address: [" + zip + "] " + place);
	Phone[] phones = account.getPhone();
	for (int i = 0;i < phones.length;i++) {
	    Phone phone = phones[i];
	    String area = phone.getArea();
	    String number = phone.getContent();
	    System.out.println("Phone: [" + area + "] " + number);
	}
	System.out.println("XML:" + account);
    }

    private static void printChildren(Account account) {
	System.out.println("*** printChildren ***");
	IRNode[] children = account.rGetRNodes();
	for (int i = 0;i < children.length;i++) {
	    IRNode child = children[i];
	    if (child instanceof Address) {
		Address address = (Address)child;
		String zip = address.getZip();
		String place = address.getContent();
		System.out.println("Address: [" + zip + "] " + place);
	    } else if (child instanceof Phone) {
		Phone phone = (Phone)child;
		String area = phone.getArea();
		String number = phone.getContent();
		System.out.println("Phone: [" + area + "] " + number);
	    } else {
		throw (new InternalError());
	    }
	}
    }
}

Compilation of JavaPatternComposite.java is shown here:

$ javac JavaPatternComposite.java

Execution

List 7.19.3.2.1[javapatternComposite.xml] is an XML document for testing.

<account accountNo="12345">
  <balance>102030</balance>
  <owner>XML Taro</owner>
  <address zip="213">Yokohama</address>
  <phone area="123">456-7890</phone>
  <phone area="090">123-4567</phone>
</account>

Execution of the JavaPatternComposite class is shown here:

$ java JavaPatternComposite javaPatternComposite.xml
*** makeAccount ***
*** printAccount ***
AccountNo:12345
Balance:102030
Owner:XML Taro
Address: [213] Yokohama
Phone: [123] 456-7890
Phone: [090] 123-4567
XML:<account \
    accountNo="12345"><balance>102030</balance><owner>XML \
    Taro</owner><address zip="213">Yokohama</address><phone \
    area="123">456-7890</phone><phone \
    area="090">123-4567</phone></account>
*** printChildren ***
Address: [213] Yokohama
Phone: [123] 456-7890
Phone: [090] 123-4567

The printAccount method demonstrates the composite facility of Relaxer objects.