stgsharp/StgSharp.RegularAnalysis/TextRegex/RegexAstNode.cs

//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// file="RegexAstNode.cs"
// Project: StgSharp
// AuthorGroup: Nitload Space
// Copyright (c) Nitload Space. All rights reserved.
//     
// Permission is hereby granted, free of charge, to any person 
// obtaining a copy of this software and associated documentation 
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// and to permit persons to whom the Software is furnished to do so, 
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// The above copyright notice and 
// this permission notice shall be included in all copies 
// or substantial portions of the Software.
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using StgSharp.RegularAnalysis.Abstraction;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

namespace StgSharp.RegularAnalysis.TextRegex
{
    internal class RegexAstNode : ISyntaxNode<RegexAstNode, RegexElementLabel>
    {

        private RegexAstNode _left, _right;

        public RegexAstNode(Token<RegexElementLabel> source)
        {
            Source = source;
        }

        public int EnumState { get; set; }

        public long NodeFlag => (long)Source.Flag;

        public static RegexAstNode Empty
        {
            get => new EmptyRegexAstNode();
        }

        public RegexAstNode Previous { get; set; }

        public RegexAstNode Next { get; set; }

        public RegexAstNode Parent { get; set; }

        public RegexAstNode Left
        {
            get;
            set
            {
                field?.Parent = null;
                field = value;
                value.Parent = this;
            }
        }

        public RegexAstNode Right
        {
            get;
            set
            {
                field?.Parent = null;
                field = value;
                value.Parent = this;
            }
        }

        public RegexElementLabel EqualityTypeConvert
        {
            get => Source.Flag;
        }

        public string CodeConvertTemplate { get; }

        public Token<RegexElementLabel> Source { get; }

        public void AppendNode(RegexAstNode nextToken) { }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static (bool Valid,int Value) ComparePrecedence(RegexElementLabel left, RegexElementLabel right)
        {
            left |= RegexElementLabel.OPERATOR;
            right |= RegexElementLabel.OPERATOR;
            int v_left = (int)left, v_right = (int)right;
            if (v_left == 0 || v_right == 0) {
                return (false,0);
            }
            return (true,v_left - v_right);
        }

        public void PrependNode(RegexAstNode previousNode) { }

        public static bool TryMergeUnit(RegexAstNode prev, RegexAstNode next, out RegexAstNode result)
        {
            Token<RegexElementLabel> pSource = prev.Source;
            Token<RegexElementLabel> nSource = next.Source;
            if (pSource.IsAccurateChar() &&
                nSource.IsAccurateChar() &&
                pSource.Column + pSource.Value.Length == nSource.Column)
            {
                // both are unit types and adjacent
                // and are all accurate unit
                Token<RegexElementLabel> newToken = new Token<RegexElementLabel>($"{pSource.Value}{nSource.Value}",
                                                                                 pSource.Line,
                                                                                 pSource.Column,
                                                                                 RegexElementLabel.UNIT_SPAN);
                result = new RegexAstNode(newToken);
                return true;
            }
            result = Empty;
            return false;
        }

        private class EmptyRegexAstNode : RegexAstNode

        {

            public EmptyRegexAstNode() : base(Token<RegexElementLabel>.Empty) { }

        }

    }
}