Copyright (c) 2000, 2008 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2008 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.core.internal.expressions;

import org.w3c.dom.Element;

import org.eclipse.core.expressions.EvaluationResult;
import org.eclipse.core.expressions.Expression;
import org.eclipse.core.expressions.ExpressionInfo;
import org.eclipse.core.expressions.IEvaluationContext;

import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;

public class TestExpression extends Expression {

	private String fNamespace;
	private String fProperty;
	private Object[] fArgs;
	private Object fExpectedValue;
	private boolean fForcePluginActivation;

	private static final char PROP_SEP = '.';
	private static final String ATT_PROPERTY= "property"; //$NON-NLS-1$
	private static final String ATT_ARGS= "args"; //$NON-NLS-1$
	private static final String ATT_FORCE_PLUGIN_ACTIVATION= "forcePluginActivation"; //$NON-NLS-1$
	
The seed for the hash code for all test expressions.
/**
	 * The seed for the hash code for all test expressions.
	 */
	private static final int HASH_INITIAL= TestExpression.class.getName().hashCode();

	private static final TypeExtensionManager fgTypeExtensionManager= new TypeExtensionManager("propertyTesters"); //$NON-NLS-1$

	public TestExpression(IConfigurationElement element) throws CoreException {
		String property= element.getAttribute(ATT_PROPERTY);
		int pos= property.lastIndexOf(PROP_SEP);
		if (pos == -1) {
			throw new CoreException(new ExpressionStatus(
				ExpressionStatus.NO_NAMESPACE_PROVIDED,
				ExpressionMessages.TestExpression_no_name_space));
		}
		fNamespace= property.substring(0, pos);
		fProperty= property.substring(pos + 1);
		fArgs= Expressions.getArguments(element, ATT_ARGS);
		fExpectedValue= Expressions.convertArgument(element.getAttribute(ATT_VALUE));
		fForcePluginActivation= Expressions.getOptionalBooleanAttribute(element, ATT_FORCE_PLUGIN_ACTIVATION);
	}

	public TestExpression(Element element) throws CoreException {
		String property= element.getAttribute(ATT_PROPERTY);
		int pos= property.lastIndexOf(PROP_SEP);
		if (pos == -1) {
			throw new CoreException(new ExpressionStatus(
				ExpressionStatus.NO_NAMESPACE_PROVIDED,
				ExpressionMessages.TestExpression_no_name_space));
		}
		fNamespace= property.substring(0, pos);
		fProperty= property.substring(pos + 1);
		fArgs= Expressions.getArguments(element, ATT_ARGS);
		String value = element.getAttribute(ATT_VALUE);
		fExpectedValue = Expressions.convertArgument(value.isEmpty() ? null : value);
		fForcePluginActivation= Expressions.getOptionalBooleanAttribute(element, ATT_FORCE_PLUGIN_ACTIVATION);
	}

	public TestExpression(String namespace, String property, Object[] args, Object expectedValue) {
		this(namespace, property, args, expectedValue, false);
	}

	public TestExpression(String namespace, String property, Object[] args, Object expectedValue, boolean forcePluginActivation) {
		Assert.isNotNull(namespace);
		Assert.isNotNull(property);
		fNamespace= namespace;
		fProperty= property;
		fArgs= args != null ? args : Expressions.EMPTY_ARGS;
		fExpectedValue= expectedValue;
		fForcePluginActivation= forcePluginActivation;
	}

	@Override
	public EvaluationResult evaluate(IEvaluationContext context) throws CoreException {
		Object element= context.getDefaultVariable();
		if (System.class.equals(element)) {
			String str= System.getProperty(fProperty);
			if (str == null)
				return EvaluationResult.FALSE;
			return EvaluationResult.valueOf(str.equals(fArgs[0]));
		}
		Property property= fgTypeExtensionManager.getProperty(element, fNamespace, fProperty, context.getAllowPluginActivation() && fForcePluginActivation);
		if (!property.isInstantiated())
			return EvaluationResult.NOT_LOADED;
		return EvaluationResult.valueOf(property.test(element, fArgs, fExpectedValue));
	}

	@Override
	public void collectExpressionInfo(ExpressionInfo info) {
		info.markDefaultVariableAccessed();
		info.addAccessedPropertyName(fNamespace + PROP_SEP + fProperty);
	}

	@Override
	public boolean equals(final Object object) {
		if (!(object instanceof TestExpression))
			return false;

		final TestExpression that= (TestExpression)object;
		return this.fNamespace.equals(that.fNamespace) && this.fProperty.equals(that.fProperty)
			&& this.fForcePluginActivation == that.fForcePluginActivation
			&& equals(this.fArgs, that.fArgs) && equals(this.fExpectedValue, that.fExpectedValue);
	}

	@Override
	protected int computeHashCode() {
		return HASH_INITIAL * HASH_FACTOR + hashCode(fArgs)
			* HASH_FACTOR + hashCode(fExpectedValue)
			* HASH_FACTOR + fNamespace.hashCode()
			* HASH_FACTOR + fProperty.hashCode()
			* HASH_FACTOR + (fForcePluginActivation ? 1 : 0);
	}

	//---- Debugging ---------------------------------------------------

	@Override
	public String toString() {
		StringBuilder args= new StringBuilder();
		for (int i= 0; i < fArgs.length; i++) {
			Object arg= fArgs[i];
			if (arg instanceof String) {
				args.append('\'');
				args.append(arg);
				args.append('\'');
			} else {
				args.append(arg.toString());
			}
			if (i < fArgs.length - 1)
				args.append(", "); //$NON-NLS-1$
		}
		return "<test property=\"" + fProperty +  "\"" +//$NON-NLS-1$ //$NON-NLS-2$
		(fArgs.length != 0 ? " args=\"" + args + "\"" : "") + //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
		 (fExpectedValue != null ? " value=\"" + fExpectedValue + "\"" : "") + //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
		  " plug-in activation: " + (fForcePluginActivation ? "eager" : "lazy") +   //$NON-NLS-1$//$NON-NLS-2$//$NON-NLS-3$
		  "/>"; //$NON-NLS-1$
	}

	//---- testing ---------------------------------------------------

	public boolean testGetForcePluginActivation() {
		return fForcePluginActivation;
	}

	public static TypeExtensionManager testGetTypeExtensionManager() {
		return fgTypeExtensionManager;
	}
}