ParseElementCollection.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Speech / Src / Internal / SrgsCompiler / ParseElementCollection.cs / 1 / ParseElementCollection.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) Microsoft Corporation.  All rights reserved.
//  
//
// 
// Description: 
//
// History: 
//		11/15/2004	[....]		Created from the Kurosawa Code
//---------------------------------------------------------------------------

#region Using directives 

using System; 
using System.Collections.ObjectModel; 
using System.Speech.Internal.SrgsParser;
 
#endregion

namespace System.Speech.Internal.SrgsCompiler
{ 
    internal abstract class ParseElementCollection : ParseElement
    { 
        protected ParseElementCollection (Backend backend, Rule rule) 
            : base (rule)
        { 
            _backend = backend;
        }

        ///  
        /// Attach a semantic tag to word. If the word is a rule ref then an
        /// epsilon transition must be created 
        ///  
        /// 
        internal void AddSemanticInterpretationTag (CfgGrammar.CfgProperty propertyInfo) 
        {
            // If the word is a rule ref, an epsilon transition must be created
            if (_endArc != null && _endArc.RuleRef != null)
            { 
                Arc tagTransition = _backend.EpsilonTransition (1.0f);
                _backend.AddSemanticInterpretationTag (tagTransition, propertyInfo); 
 
                // Create a new state
                State state = _backend.CreateNewState (_rule); 

                // Connect the new state with the end arc
                tagTransition.Start = state;
                _endArc.End = state; 
                _endArc = tagTransition;
            } 
            else 
            {
                if (_startArc == null) 
                {
                    _startArc = _endArc = _backend.EpsilonTransition (1.0f);
                }
                _backend.AddSemanticInterpretationTag (_endArc, propertyInfo); 
            }
        } 
 

        // must add the rule Id 
        // _propInfo._ulId = (uint) ((ParseElement) parent).StartState._rule._iSerialize2;
        internal void AddSementicPropertyTag (CfgGrammar.CfgProperty propertyInfo)
        {
            if (_startArc == null) 
            {
                _startArc = _endArc = _backend.EpsilonTransition (1.0f); 
            } 
            _backend.AddPropertyTag (_startArc, _endArc, propertyInfo);
        } 

        /// 
        /// Insert an epsilon state either before or after the current arc
        ///  
        /// 
        ///  
        ///  
        /// 
        protected Arc InsertState (Arc arc, float weight, Position position) 
        {
            // If the arc is a epsilon, creating a new epsilon arc might not be needed
            if (arc.IsEpsilonTransition)
            { 
                if (position == Position.Before && arc.End != null && arc.End.InArcs.CountIsOne && Graph.MoveSemanticTagRight (arc))
                { 
                    return arc; 
                }
                if (position == Position.After && arc.Start != null && arc.Start.OutArcs.CountIsOne && Graph.MoveSemanticTagLeft (arc)) 
                {
                    return arc;
                }
            } 

            // Create an epsilon transition 
            Arc epsilon = _backend.EpsilonTransition (weight); 

            // Insert a state 
            State insertionState = _backend.CreateNewState (_rule);

            if (position == Position.Before)
            { 
                epsilon.End = insertionState;
                arc.Start = insertionState; 
            } 
            else
            { 
                arc.End = insertionState;
                epsilon.Start = insertionState;
            }
            return epsilon; 
        }
 
        ///  
        /// Remove all the epsilon transitions at the beginning of a sub graph
        ///  
        /// 
        /// 
        /// 
        protected static Arc TrimStart (Arc start, Backend backend) 
        {
            Arc startArc = start; 
 
            if (start.End != null)
            { 
                // Remove the added startState if possible, check done by MoveSemanticTagRight
                for (State startState = startArc.End; startArc.IsEpsilonTransition && startState != null && Graph.MoveSemanticTagRight (startArc) && startState.InArcs.CountIsOne && startState.OutArcs.CountIsOne; startState = startArc.End)
                {
                    // State has a single input epsilon transition 
                    // Delete the input epsilon transition and delete state.
                    System.Diagnostics.Debug.Assert (startArc.End == startState); 
                    startArc.End = null; 

                    // Reset the start Arc 
                    System.Diagnostics.Debug.Assert (startState.OutArcs.CountIsOne);
                    startArc = startState.OutArcs.First;
                    System.Diagnostics.Debug.Assert (startArc.Start == startState);
                    startArc.Start = null; 

                    // Delete the input epsilon transition and delete state if appropriate. 
                    backend.DeleteState (startState); 
                }
            } 
            return startArc;
        }

        ///  
        /// Remove all the epsilon transition at the end
        ///  
        ///  
        /// 
        ///  
        protected static Arc TrimEnd (Arc end, Backend backend)
        {
            Arc endArc = end;
 
            if (endArc != null)
            { 
                // Remove the end arc if possible, check done by MoveSemanticTagRight 
                for (State endState = endArc.Start; endArc.IsEpsilonTransition && endState != null && Graph.MoveSemanticTagLeft (endArc) && endState.InArcs.CountIsOne && endState.OutArcs.CountIsOne; endState = endArc.Start)
                { 
                    // State has a single input epsilon transition
                    // Delete the input epsilon transition and delete state.
                    System.Diagnostics.Debug.Assert (endArc.Start == endState);
                    endArc.Start = null; 

                    // Reset the end Arc 
                    System.Diagnostics.Debug.Assert (endState.InArcs.CountIsOne); 
                    endArc = endState.InArcs.First;
                    System.Diagnostics.Debug.Assert (endArc.End == endState); 
                    endArc.End = null;

                    // Delete the input epsilon transition and delete state if appropriate.
                    backend.DeleteState (endState); 
                }
            } 
            return endArc; 
        }
 
        protected void PostParse (ParseElementCollection parent)
        {
            if (_startArc != null)
            { 
                parent.AddArc (_startArc, _endArc);
            } 
        } 

        internal void AddArc (Arc arc) { AddArc (arc, arc); } 
        //internal virtual void AddArc (Arc startArc, Arc endArc) { throw new NotImplementedException (); }

        internal enum Position
        { 
            Before,
            After 
        } 

        ///  
        /// New sets of arcs are added after the last arc
        /// 
        /// 
        ///  
        internal virtual void AddArc (Arc start, Arc end)
        { 
            State state = null; 
            if (_startArc == null)
            { 
                _startArc = start;
                _endArc = end;
            }
            else 
            {
                bool done = false; 
 
                // Successive  have 2 epsilon transition
                if (_endArc.IsEpsilonTransition && start.IsEpsilonTransition) 
                {
                    // Trim the start tag.
                    start = TrimStart (start, _backend);
 
                    // If Trimming didn't create a non epsilon, try to trim the end
                    if (start.IsEpsilonTransition) 
                    { 
                        _endArc = TrimEnd (_endArc, _backend);
 
                        // start and end are still epsilon transition
                        if (_endArc.IsEpsilonTransition)
                        {
                            // we do the merging 
                            State from = _endArc.Start;
                            State to = start.End; 
                            done = true; 

                            if (from == null) 
                            {
                                // Ignore the current _start _end
                                Arc.CopyTags (_endArc, start, Direction.Right);
                                _startArc = start; 
                            }
                            else if (to == null) 
                            { 
                                // Ignore the old _startArc _endArc
                                Arc.CopyTags (start, _endArc, Direction.Left); 
                                end = _endArc;
                            }
                            else
                            { 
                                // No tags, just fold the start and end state
                                if (_endArc.IsPropertylessTransition && start.IsPropertylessTransition) 
                                { 
                                    // Move the end arc
                                    start.End = null; 
                                    _endArc.Start = null;
                                    _backend.MoveInputTransitionsAndDeleteState (from, to);
                                }
                                else 
                                {
                                    // Discard the endstate and replace it with the startArc 
                                    Arc.CopyTags (start, _endArc, Direction.Left); 
                                    start.End = null;
                                    _endArc.End = to; 
                                }
                            }
                        }
                    } 
                }
 
                if (!done) 
                {
                    // If the last arc is an epsilon value then there is no need to create a new state 
                    if (_endArc.IsEpsilonTransition && Graph.CanTagsBeMoved (_endArc, start))
                    {
                        // Copy the tags from "endArc" to the "start"
                        Arc.CopyTags (_endArc, start, Direction.Right); 

                        if (_endArc.Start != null) 
                        { 
                            // Discard the endstate and replace it with the startArc
                            state = _endArc.Start; 
                            _endArc.Start = null;

                            // Connexion between the state end the start is done below
                            //state.OutArcs.Add (start); 
                            //start.Start = state;
                        } 
                        if (_endArc == _startArc) 
                        {
                            _startArc = start; 
                        }
                    }
                    else
                    { 
                        // If the first arc is an epsilon value then there is no need to create a new state
                        if (start.IsEpsilonTransition && Graph.CanTagsBeMoved (start, _endArc)) 
                        { 
                            // Copy the tags from "endArc" to the "start"
                            Arc.CopyTags (start, _endArc, Direction.Left); 

                            if (start.End != null)
                            {
                                // Discard the endstate and replace it with the startArc 
                                state = start.End;
                                start.End = null; 
                                _endArc.End = state; 
                                state = null;
                            } 
                            if (start == end)
                            {
                                end = _endArc;
                            } 
                        }
                        else 
                        { 
                            // Create a new state
                            state = _backend.CreateNewState (_rule); 

                            // Connect the new state with the end arc
                            _endArc.End = state;
                        } 

                    } 
                    // connect the arcs 
                    if (state != null)
                    { 
                        start.Start = state;
                    }
                }
                _endArc = end; 
            }
        } 
 
        protected Backend _backend;
        protected Arc _startArc; 
        protected Arc _endArc;
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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