runtime/CSharp3/Sources/Antlr3.Runtime/Tree/ITreeNodeStream.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,
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

namespace Antlr.Runtime.Tree
{
    /** <summary>A stream of tree nodes, accessing nodes from a tree of some kind</summary> */
    public interface ITreeNodeStream : IIntStream
    {
        /** <summary>
         *  Get a tree node at an absolute index i; 0..n-1.
         *  If you don't want to buffer up nodes, then this method makes no
         *  sense for you.
         *  </summary>
         */
        object this[int i]
        {
            get;
        }

        /** <summary>
         * Get tree node at current input pointer + {@code k} ahead where
         * {@code k==1} is next node. {@code k<0} indicates nodes in the past. So
         * {@code LT(-1)} is previous node, but implementations are not required to
         * provide results for {@code k < -1}. {@code LT(0)} is undefined. For
         * {@code k<=n}, return {@code null}. Return {@code null} for {@code LT(0)}
         * and any index that results in an absolute address that is negative.
         *  </summary>
         *
         *  <remarks>
         * This is analogous to {@link TokenStream#LT}, but this returns a tree node
         * instead of a {@link Token}. Makes code generation identical for both
         * parser and tree grammars.
         *  </remarks>
         */
        object LT( int k );

        /** <summary>
         *  Where is this stream pulling nodes from?  This is not the name, but
         *  the object that provides node objects.
         *  </summary>
         */
        object TreeSource
        {
            get;
        }

        /** <summary>
         * If the tree associated with this stream was created from a
         * {@link TokenStream}, you can specify it here. Used to do rule
         * {@code $text} attribute in tree parser. Optional unless you use tree
         * parser rule {@code $text} attribute or {@code output=template} and
         * {@code rewrite=true} options.
         *  </summary>
         */
        ITokenStream TokenStream
        {
            get;
        }

        /** <summary>
         *  What adaptor can tell me how to interpret/navigate nodes and
         *  trees.  E.g., get text of a node.
         *  </summary>
         */
        ITreeAdaptor TreeAdaptor
        {
            get;
        }

        /** <summary>
         * As we flatten the tree, we use {@link Token#UP}, {@link Token#DOWN} nodes
         * to represent the tree structure. When debugging we need unique nodes so
         * we have to instantiate new ones. When doing normal tree parsing, it's
         * slow and a waste of memory to create unique navigation nodes. Default
         * should be {@code false}.
         *  </summary>
         */
        bool UniqueNavigationNodes
        {
            get;
            set;
        }

        /** <summary>
         * Return the text of all nodes from {@code start} to {@code stop},
         * inclusive. If the stream does not buffer all the nodes then it can still
         * walk recursively from start until stop. You can always return
         * {@code null} or {@code ""} too, but users should not access
         * {@code $ruleLabel.text} in an action of course in that case.
         *  </summary>
         */
        string ToString( object start, object stop );


        #region REWRITING TREES (used by tree parser)

        /** <summary>
         * Replace children of {@code parent} from index {@code startChildIndex} to
         * {@code stopChildIndex} with {@code t}, which might be a list. Number of
         * children may be different after this call. The stream is notified because
         * it is walking the tree and might need to know you are monkeying with the
         * underlying tree. Also, it might be able to modify the node stream to
         * avoid restreaming for future phases.
         *  </summary>
         *
         *  <remarks>
         * If {@code parent} is {@code null}, don't do anything; must be at root of
         * overall tree. Can't replace whatever points to the parent externally. Do
         * nothing.
         *  </remarks>
         */
        void ReplaceChildren( object parent, int startChildIndex, int stopChildIndex, object t );

        #endregion

    }
}