Class TracingInterceptor

src/main/java/groovy/lang/TracingInterceptor.java:52–142

This Interceptor traces method calls on the proxied object to a log. By default, the log is simply System.out ; however, that can be changed with the setWriter(Writer) method. A message will be written to output before a method is invoked and after a method is invoke

 * </pre>
 */
public class TracingInterceptor implements Interceptor {

    /**
     * Writer used to emit trace output.
     */
    protected Writer writer = new PrintWriter(System.out);
    private int indent = 0;

    /**
    * Returns the writer associated with this interceptor.
    */
    public Writer getWriter() {
        return writer;
    }

    /**
    * Changes the writer associated with this interceptor.
    */
    public void setWriter(Writer writer) {
        this.writer = writer;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Object beforeInvoke(Object object, String methodName, Object[] arguments) {
        write(object, methodName, arguments, "before");
        indent++ ;
        return null;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Object afterInvoke(Object object, String methodName, Object[] arguments, Object result) {
        indent--;
        write(object, methodName, arguments, "after ");
        return result;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean doInvoke() {
        return true;
    }
    private String indent(){
        return "  ".repeat(Math.max(0, indent));
    }

    /**
     * Writes a formatted trace line for the supplied invocation stage.
     *
     * @param object the receiver object
     * @param methodName the invoked method name