antlr-3.4/runtime/CSharp3/Sources/Antlr3.Runtime.Debug/Tracer.cs

/*
 * [The "BSD licence"]
 * Copyright (c) 2005-2008 Terence Parr
 * All rights reserved.
 *
 * Conversion to C#:
 * Copyright (c) 2008-2009 Sam Harwell, Pixel Mine, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

namespace Antlr.Runtime.Debug
{
    using Antlr.Runtime.JavaExtensions;

    using Console = System.Console;

    /** <summary>
     *  The default tracer mimics the traceParser behavior of ANTLR 2.x.
     *  This listens for debugging events from the parser and implies
     *  that you cannot debug and trace at the same time.
     *  </summary>
     */
    public class Tracer : BlankDebugEventListener
    {
        public IIntStream input;
        protected int level = 0;

        public Tracer( IIntStream input )
        {
            this.input = input;
        }

        public virtual void EnterRule( string ruleName )
        {
            for ( int i = 1; i <= level; i++ )
            {
                Console.Out.Write( " " );
            }
            Console.Out.WriteLine( "> " + ruleName + " lookahead(1)=" + GetInputSymbol( 1 ) );
            level++;
        }

        public virtual void ExitRule( string ruleName )
        {
            level--;
            for ( int i = 1; i <= level; i++ )
            {
                Console.Out.Write( " " );
            }
            Console.Out.WriteLine( "< " + ruleName + " lookahead(1)=" + GetInputSymbol( 1 ) );
        }

        public virtual object GetInputSymbol( int k )
        {
            if ( input is ITokenStream )
            {
                return ( (ITokenStream)input ).LT( k );
            }
            return (char)input.LA( k );
        }
    }
}