RaasAhsan/XmlParser.java

## XmlParser.java
package xml;

import java.util.ArrayList;
import java.util.List;

import com.jantox.xmlparser.Scanner;

/*
 * <xmlNode> ::= "<" ~ <name> ~ ">" ~ <body> ~ "</" ~ <name> ">"
 * <letter>  ::= [A-Za-z]
 * <name>    ::= <letter> | <letter> <name>
 * <body>    ::= <xmlNode> | <xmlNode> <body> | ""
 */

// In Scala, a Parser would just be a function S => ParseResult[S, S]
// Pass in a string, get back a ParseResult which can be a ParseSuccess[S, S]
// ParseSuccess[S, S] returns the unparsed string and the parsed value.

public class XmlParser {

	private Scanner scanner;

	public XmlParser() {

	}

	public XmlElement parse(String xmlString) {
		this.scanner = new Scanner(xmlString);

		return parseElement();
	}

	public XmlElement parseElement() {
		if (!this.scanner.expect("<")) {
			return null;
		}

		String name = this.parseName();

		if (!this.scanner.expect(">")) {
			return null;
		}

		List<XmlNode> body = this.parseBody();

		if (!this.scanner.expect("<")) {
			return null;
		}

		if (!this.scanner.expect("/")) {
			return null;
		}

		String endName = this.parseName();

		if (!this.scanner.expect(">")) {
			return null;
		}

		if (!name.equals(endName)) {
			return null;
		}

		return new XmlElement(name, new ArrayList<XmlAttribute>(), body);
	}

	public List<XmlNode> parseBody() {
		List<XmlNode> body = new ArrayList<XmlNode>();

		while (true) {
			if (!this.scanner.startsWith("</")) {
				XmlNode node = this.parseElement();

				body.add(node);
			} else {
				break;
			}
		}

		return body;
	}

	public String parseName() {
		if (this.isAlphabet()) {
			String letter = this.parseAlphabet();

			if (this.isAlphabet()) { // There's another letter, so we possible have a name
				return letter + this.parseName();
			} else { // There is no letter next
				return letter;
			}
		}

		return null;
	}

	public String parseLetter(String t) {
		if (this.scanner.length() > 0) {
			if (this.scanner.peek().equals(t)) {
				return this.scanner.take();
			}
		}

		return null;
	}

	public boolean isLetter(String l) {
		if (this.scanner.length() > 0) {
			String token = this.scanner.peek();

			if (token.equals(l)) {
				return true;
			}
		}

		return false;
	}

	public String parseAlphabet() {
		if (this.isAlphabet()) {
			return this.scanner.take();
		}

		return null;
	}

	public boolean isAlphabet() {
		if (this.scanner.length() > 0) {
			String token = this.scanner.peek();
			char charToken = token.charAt(0);

			if ((charToken >= 'A' && charToken <= 'Z') || (charToken >= 'a' && charToken <= 'z')) {
				return true;
			}
		}

		return false;
	}

}
	package xml;

	import java.util.ArrayList;
	import java.util.List;

	import com.jantox.xmlparser.Scanner;

	/*
	* <xmlNode> ::= "<" ~ <name> ~ ">" ~ <body> ~ "</" ~ <name> ">"
	* <letter> ::= [A-Za-z]
	* <name> ::= <letter> \| <letter> <name>
	* <body> ::= <xmlNode> \| <xmlNode> <body> \| ""
	*/

	// In Scala, a Parser would just be a function S => ParseResult[S, S]
	// Pass in a string, get back a ParseResult which can be a ParseSuccess[S, S]
	// ParseSuccess[S, S] returns the unparsed string and the parsed value.

	public class XmlParser {

	private Scanner scanner;

	public XmlParser() {

	}

	public XmlElement parse(String xmlString) {
	this.scanner = new Scanner(xmlString);

	return parseElement();
	}

	public XmlElement parseElement() {
	if (!this.scanner.expect("<")) {
	return null;
	}

	String name = this.parseName();

	if (!this.scanner.expect(">")) {
	return null;
	}

	List<XmlNode> body = this.parseBody();

	if (!this.scanner.expect("<")) {
	return null;
	}

	if (!this.scanner.expect("/")) {
	return null;
	}

	String endName = this.parseName();

	if (!this.scanner.expect(">")) {
	return null;
	}

	if (!name.equals(endName)) {
	return null;
	}

	return new XmlElement(name, new ArrayList<XmlAttribute>(), body);
	}

	public List<XmlNode> parseBody() {
	List<XmlNode> body = new ArrayList<XmlNode>();

	while (true) {
	if (!this.scanner.startsWith("</")) {
	XmlNode node = this.parseElement();

	body.add(node);
	} else {
	break;
	}
	}

	return body;
	}

	public String parseName() {
	if (this.isAlphabet()) {
	String letter = this.parseAlphabet();

	if (this.isAlphabet()) { // There's another letter, so we possible have a name
	return letter + this.parseName();
	} else { // There is no letter next
	return letter;
	}
	}

	return null;
	}

	public String parseLetter(String t) {
	if (this.scanner.length() > 0) {
	if (this.scanner.peek().equals(t)) {
	return this.scanner.take();
	}
	}

	return null;
	}

	public boolean isLetter(String l) {
	if (this.scanner.length() > 0) {
	String token = this.scanner.peek();

	if (token.equals(l)) {
	return true;
	}
	}

	return false;
	}

	public String parseAlphabet() {
	if (this.isAlphabet()) {
	return this.scanner.take();
	}

	return null;
	}

	public boolean isAlphabet() {
	if (this.scanner.length() > 0) {
	String token = this.scanner.peek();
	char charToken = token.charAt(0);

	if ((charToken >= 'A' && charToken <= 'Z') \|\| (charToken >= 'a' && charToken <= 'z')) {
	return true;
	}
	}

	return false;
	}

	}