xref: /external/antlr/antlr-3.4/runtime/CSharp3/Sources/Antlr3.Runtime/Tree/RewriteRuleSubtreeStream.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.Tree
{
    using IList = System.Collections.IList;

    [System.Serializable]
    public class RewriteRuleSubtreeStream : RewriteRuleElementStream
    {
        public RewriteRuleSubtreeStream( ITreeAdaptor adaptor, string elementDescription )
            : base( adaptor, elementDescription )
        {
        }

        /** <summary>Create a stream with one element</summary> */
        public RewriteRuleSubtreeStream( ITreeAdaptor adaptor, string elementDescription, object oneElement )
            : base( adaptor, elementDescription, oneElement )
        {
        }

        /** <summary>Create a stream, but feed off an existing list</summary> */
        public RewriteRuleSubtreeStream( ITreeAdaptor adaptor, string elementDescription, IList elements )
            : base( adaptor, elementDescription, elements )
        {
        }

        /** <summary>
         *  Treat next element as a single node even if it's a subtree.
         *  This is used instead of next() when the result has to be a
         *  tree root node.  Also prevents us from duplicating recently-added
         *  children; e.g., ^(type ID)+ adds ID to type and then 2nd iteration
         *  must dup the type node, but ID has been added.
         *  </summary>
         *
         *  <remarks>
         *  Referencing a rule result twice is ok; dup entire tree as
         *  we can't be adding trees as root; e.g., expr expr.
         *
         *  Hideous code duplication here with super.next().  Can't think of
         *  a proper way to refactor.  This needs to always call dup node
         *  and super.next() doesn't know which to call: dup node or dup tree.
         *  </remarks>
         */
        public virtual object NextNode()
        {
            //System.Console.WriteLine("nextNode: elements={0}, singleElement={1}", elements, ((ITree)singleElement).ToStringTree());
            int n = Count;
            if ( dirty || ( cursor >= n && n == 1 ) )
            {
                // if out of elements and size is 1, dup (at most a single node
                // since this is for making root nodes).
                object el = NextCore();
                return adaptor.DupNode( el );
            }
            // test size above then fetch
            object tree = NextCore();
            while (adaptor.IsNil(tree) && adaptor.GetChildCount(tree) == 1)
                tree = adaptor.GetChild(tree, 0);
            //System.Console.WriteLine("_next={0}", ((ITree)tree).ToStringTree());
            object el2 = adaptor.DupNode(tree); // dup just the root (want node here)
            return el2;
        }

        protected override object Dup( object el )
        {
            return adaptor.DupTree( el );
        }
    }
}