native_capability ( ';' ( 'os.name' | 'os.version' | 'os.processor' ) '=' STRING )*

/**
 * <p>
 * Generates a Capability string, in the format specified by the OSGi
 * Provide-Capability header, representing the current native platform
 * according to OSGi RFC 188. For example on Windows7 running on an x86_64
 * processor it should generate the following:
 * </p>
 * 
 * <pre>
 * osgi.native;osgi.native.osname:List&lt;String&gt;="Windows7,Windows 7,Win32";osgi.native.osversion:Version=6.1.0;osgi.native.processor:List&lt;String&gt;="x86-64,amd64,em64t,x86_64"
 * </pre>
 * 
 * @param args
 *            The array of properties. For example: the macro invocation of
 *            "${native_capability;osversion=3.2.4;osname=Linux}" results in
 *            an args array of
 *            [native_capability,&nbsp;osversion=3.2.4,&nbsp;osname=Linux]
 */

public String _native_capability(String[] args) throws IllegalArgumentException {
	StringBuilder builder = new StringBuilder().append(OSGI_NATIVE);

	String processorNames = null;
	OSInformation osInformation = null;
	IllegalArgumentException osInformationException = null;
	/*
	 * Determine the processor information
	 */
	String[] aliases = OSInformation.getProcessorAliases(System.getProperty("os.arch"));
	if (aliases != null)
		processorNames = Strings.join(aliases);

	/*
	 * Determine the OS information
	 */

	try {
		osInformation = new OSInformation();
	}
	catch (IllegalArgumentException e) {
		osInformationException = e;
	}

	/*
	 * Determine overrides
	 */

	String osnameOverride = null;
	Version osversionOverride = null;
	String processorNamesOverride = null;

	if (args.length > 1) {
		assert ("native_capability".equals(args[0]));
		for (int i = 1; i < args.length; i++) {
			String arg = args[i];
			String[] fields = arg.split("=", 2);
			if (fields.length != 2) {
				throw new IllegalArgumentException("Illegal property syntax in \"" + arg + "\", use \"key=value\"");
			}
			String key = fields[0];
			String value = fields[1];
			if (OS_NAME.equals(key)) {
				osnameOverride = value;
			} else if (OS_VERSION.equals(key)) {
				osversionOverride = new Version(value);
			} else if (OS_PROCESSOR.equals(key)) {
				processorNamesOverride = value;
			} else {
				throw new IllegalArgumentException("Unrecognised/unsupported property. Supported: " + OS_NAME
						+ ", " + OS_VERSION + ", " + OS_PROCESSOR + ".");
			}
		}
	}

	/*
	 * Determine effective values: put determined value into override if
	 * there is no override
	 */

	if (osnameOverride == null && osInformation != null) {
		osnameOverride = osInformation.osnames;
	}
	if (osversionOverride == null && osInformation != null) {
		osversionOverride = osInformation.osversion;
	}
	if (processorNamesOverride == null && processorNames != null) {
		processorNamesOverride = processorNames;
	}

	/*
	 * Construct result string
	 */

	builder.append(";" + OSGI_NATIVE + "." + OS_NAME + ":List<String>=\"").append(osnameOverride).append('"');
	builder.append(";" + OSGI_NATIVE + "." + OS_VERSION + ":Version=").append(osversionOverride);
	builder.append(";" + OSGI_NATIVE + "." + OS_PROCESSOR + ":List<String>=\"").append(processorNamesOverride)
			.append('"');

	/*
	 * Report error if needed
	 */

	if (osnameOverride == null || osversionOverride == null || processorNamesOverride == null) {
		throw new IllegalArgumentException(
				"At least one of the required parameters could not be detected; specify an override. Detected: "
						+ builder.toString(), osInformationException);
	}

	return builder.toString();
}