ParserHandler.java

/*
 * Copyright (C) 2014 The Context Engine Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package uk.ac.tvu.mdse.contextengine.parser;

import java.util.ArrayList;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import uk.ac.tvu.mdse.contextengine.ContextEngineCore;

import android.util.Log;

public class ParserHandler extends DefaultHandler {

	// Unique application indentifier
	private static final String APP_ID = "AppKey";
	// Root for all context definitions
	private static final String CONTEXT_DEFINITION = "ContextDefinition";
	// Context container
	private static final String CONTEXT = "Context";
	// Name of Context
	private static final String CONTEXT_NAME = "ContextName";
	// Context Values
	private static final String CONTEXT_VALUE = "ContextValue";
	// Specific Context Values, for example for comparing locations
	private static final String SPECIFIC_CVALUE = "SpecificContextValue";
	// Name of Specific Context Value
	private static final String SPECIFIC_CNAME = "SpecificName";
	// Numeric value, part of specific context values
	private static final String NUMERIC_VALUE1 = "NumericValue1";
	// Second Numeric value, part of specific context values
	private static final String NUMERIC_VALUE2 = "NumericValue2";
	// Context Range container
	private static final String CONTEXT_RANGE = "Range";
	// Context Range Name
	private static final String CONTEXT_RANGE_NAME = "RangeName";
	// Minimum value in Context Range
	private static final String RANGE_MIN_VALUE = "Min";
	// Maximum value in Context Range
	private static final String RANGE_MAX_VALUE = "Max";
	// Specific Context Value
	private static final String SPECIFIC_CONTEXT_VALUE = "SpeicificContextValue";
	// Numeric value 1 to describe Specific Context Value
	private static final String NUMERIC_VALUE_1 = "NumericValue1";
	// Numeric value 2 to describe Specific Context Value
	private static final String NUMERIC_VALUE_2 = "NumericValue2";
	// Composite Context container
	private static final String COMPOSITE_CONTEXT = "CompositeContext";
	// Context needed for the composite composition
	private static final String CONTEXT_CHILD = "ContextChild";
	// Value of the Child context
	private static final String CONTEXT_CHILD_VALUE = "ChildValue";
	// The value of the composite if rule is currect
	private static final String CONTEXT_PARENT_VALUE = "ParentValue";
	// Composite Context Rule container
	private static final String COMPOSITE_RULE = "Rule";

	private String appid;
	private String currentElementValue;
	private String currentElement;
	private String contextName;
	private XMLSCV scv;
	private XMLRange range;
	ArrayList<String> ruleCondition;
	String ruleParentValue;
	private ContextEngineCore ce;

	public boolean setContextEngine(ContextEngineCore contextEngineCore) {
		this.ce = contextEngineCore;
		return true;
	}

	@Override
	public void startDocument() throws SAXException {
		Log.v("ContextEngineParser", "Beginning XML Document");

	}

	@Override
	public void endDocument() throws SAXException {
		Log.v("ContextEngineParser", "Finished XML Document");
	}

	@Override
	public void startElement(String namespaceURI, String localName,
			String qName, Attributes atts) throws SAXException {

		if (localName.equals(CONTEXT_RANGE))
			range = new XMLRange();
		if (localName.equals(SPECIFIC_CVALUE))
			scv = new XMLSCV();

		currentElement = localName;
	}

	@Override
	public void endElement(String namespaceURI, String localName, String qName)
			throws SAXException {
		if (localName.equals(APP_ID))
			appid = currentElementValue;
		if (localName.equals(CONTEXT_DEFINITION))
			Log.v("ContextEngine", "End of Contexts");
		if (localName.equals(CONTEXT_NAME))
			ce.newComponent(appid, currentElementValue);
		if (localName.equals(CONTEXT_RANGE_NAME))
			range.name = currentElementValue;
		if (localName.equals(RANGE_MAX_VALUE))
			range.max = currentElementValue;
		if (localName.equals(RANGE_MIN_VALUE))
			range.min = currentElementValue;
		if (localName.equals(CONTEXT_RANGE))
			ce.newRange(appid, contextName, range.min, range.max, range.name);
		if (localName.equals(CONTEXT_CHILD))
			ce.addToCompositeM(appid, currentElementValue, contextName);
		if (localName.equals(CONTEXT_CHILD_VALUE))
			ruleCondition.add(currentElementValue);
		if (localName.equals(CONTEXT_PARENT_VALUE))
			ruleParentValue = currentElementValue;
		if (localName.equals(COMPOSITE_RULE))
			ce.newRule(contextName, (String[]) ruleCondition.toArray(),
					ruleParentValue);
		if (localName.equals(COMPOSITE_CONTEXT))
			ce.compositeReady(contextName);
		if (localName.equals(SPECIFIC_CVALUE))
			ce.newSpecificContextValue(appid, contextName, scv.name,
					scv.value1, scv.value2);
		if (localName.equals(SPECIFIC_CNAME))
			scv.name = currentElementValue;
		if (localName.equals(NUMERIC_VALUE1))
			scv.value1 = currentElementValue;
		if (localName.equals(NUMERIC_VALUE2))
			scv.value2 = currentElementValue;

	}

	@Override
	public void characters(char ch[], int start, int length) {
		currentElementValue = new String(ch, start, length);
	}

	static class XMLRange {
		String name;
		String min;
		String max;
	}

	static class XMLSCV {
		String name;
		String value1;
		String value2;
	}
}