stgsharp/StgSharp.RegularAnalysis/RegularExpression.StateMachine.cs

//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// file="RegularExpression.StateMachine"
// Project: StgSharp
// AuthorGroup: Nitload
// Copyright (c) Nitload. All rights reserved.
//     
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// -----------------------------------------------------------------------
// -----------------------------------------------------------------------
using StgSharp.Internal;
using StgSharp.State;

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Threading.Tasks;

namespace StgSharp.RegularAnalysis
{
    public partial class RegularExpression
    {

        private readonly RegularExpressionState _state;

        private class RegularExpressionState : ISimpleStateMachine<RegularExpressionStateNode, int, RegularExpressionStateContext>
        {

            private List<RegularExpressionStateNode> _nodes;
            private RegularExpressionStateNode _currentState;

            public RegularExpressionStateNode this[
                                              int label
            ] => _nodes[label];

            public ref readonly RegularExpressionStateNode GetCurrentStateNode()
            {
                throw new NotImplementedException();
            }

            public void Reset()
            {
                throw new NotImplementedException();
            }

            public bool TryMoveNext(
                        RegularExpressionStateContext ctx
            )
            {
                throw new NotImplementedException();
            }

            #region node factory

            public RegularExpressionCharNode AddChar(
                                             char c
            )
            {
                RegularExpressionCharNode node = new RegularExpressionCharNode(c);
                int index = _nodes.Count;
                _nodes.Add(node);
                node.FailNodeIndex = index; // Point to self by default
                return node;
            }

            public RegularExpressionCharsetNode AddCharset(
                                                ReadOnlySpan<char> chars,
                                                bool isNegate
            )
            {
                RegularExpressionCharsetNode node = new RegularExpressionCharsetNode(chars, isNegate);
                int index = _nodes.Count;
                _nodes.Add(node);
                node.FailNodeIndex = index; // Point to self by default
                return node;
            }

            public (RegularExpressionLeftBoarderNode left) AddBoarder(string groupName, int groupIndex)
            { 
                RegularExpressionLeftBoarderNode leftNode = new RegularExpressionLeftBoarderNode(new GroupIndex(groupName, groupIndex));
                int leftIndex = _nodes.Count;
                _nodes.Add(leftNode);
                leftNode.FailNodeIndex = leftIndex; // Point to self by default
                return (left: leftNode);
            }

            public RegularExpressionCounterNode AddCounter(
                                                int minCount,
                                                bool isEager
            )
            {
                RegularExpressionCounterNode node = new RegularExpressionCounterNode(minCount, isEager);
                int index = _nodes.Count;
                _nodes.Add(node);
                node.FailNodeIndex = index; // Point to self by default
                return node;
            }

            #endregion
        }

        private abstract class RegularExpressionStateNode : SimpleStateMachineNode<RegularExpressionStateNode, int, RegularExpressionStateContext>
        {

            public int FailNodeIndex { get; set; }

            public abstract NodeState Type { get; }

            public override bool TryTransaction(
                                 ReadOnlySpan<RegularExpressionStateNode> nodeSpan,
                                 RegularExpressionStateContext context,
                                 out int label
            )
            {
                context.Position++;
                int pos = context.Position;
                if (pos < 0)
                {
                    label = FailNodeIndex;
                    return true;
                }
                char c = context.CurrentCharSpan[pos];
                foreach (int index in AvailableNodes)
                {
                    if (nodeSpan[index].IsValidateFrom(this, context))
                    {
                        label = index;
                        return true;
                    }
                }
                label = FailNodeIndex;
                return true;
            }

        }

        private class RegularExpressionStateContext : StateContext
        {

            public int Begin { get; set; }

            public int Position { get; set; } = -1;

            public ReadOnlySpan<char> CurrentCharSpan => Source.AsSpan()[Begin..Position];

            public string Source { get; init; }

        }

    }
}