LikeNode.cs

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using System.Data.Common;
using System.Data.SqlTypes;
using System.Diagnostics.CodeAnalysis;
 
namespace System.Data;
 
internal sealed class LikeNode : BinaryNode
{
    private static readonly char[] s_trimChars = new char[2] { ' ', '\u3000' };
 
    private int _kind;
 
    private string _pattern;
 
    internal LikeNode(DataTable table, int op, ExpressionNode left, ExpressionNode right)
        : base(table, op, left, right)
    {
    }
 
    [RequiresUnreferencedCode("Members from serialized types may be trimmed if not referenced directly.")]
    internal override object Eval(DataRow row, DataRowVersion version)
    {
        object obj = _left.Eval(row, version);
        if (obj == DBNull.Value || (_left.IsSqlColumn && DataStorage.IsObjectSqlNull(obj)))
        {
            return DBNull.Value;
        }
        string text;
        if (_pattern == null)
        {
            object obj2 = _right.Eval(row, version);
            if (!(obj2 is string) && !(obj2 is SqlString))
            {
                SetTypeMismatchError(_op, obj.GetType(), obj2.GetType());
            }
            if (obj2 == DBNull.Value || DataStorage.IsObjectSqlNull(obj2))
            {
                return DBNull.Value;
            }
            string pat = (string)SqlConvert.ChangeType2(obj2, StorageType.String, typeof(string), base.FormatProvider);
            text = AnalyzePattern(pat);
            if (_right.IsConstant())
            {
                _pattern = text;
            }
        }
        else
        {
            text = _pattern;
        }
        if (!(obj is string) && !(obj is SqlString))
        {
            SetTypeMismatchError(_op, obj.GetType(), typeof(string));
        }
        string text2 = ((obj is SqlString sqlString) ? sqlString.Value : ((string)obj));
        string s = text2.TrimEnd(s_trimChars);
        switch (_kind)
        {
        case 5:
            return true;
        case 4:
            return base.table.Compare(s, text) == 0;
        case 3:
            return 0 <= base.table.IndexOf(s, text);
        case 1:
            return base.table.IndexOf(s, text) == 0;
        case 2:
        {
            string s2 = text.TrimEnd(s_trimChars);
            return base.table.IsSuffix(s, s2);
        }
        default:
            return DBNull.Value;
        }
    }
 
    internal string AnalyzePattern(string pat)
    {
        int length = pat.Length;
        char[] array = new char[length + 1];
        pat.CopyTo(0, array, 0, length);
        array[length] = '\0';
        string text = null;
        char[] array2 = new char[length + 1];
        int num = 0;
        int num2 = 0;
        int i = 0;
        while (i < length)
        {
            if (array[i] == '*' || array[i] == '%')
            {
                for (; (array[i] == '*' || array[i] == '%') && i < length; i++)
                {
                }
                if ((i < length && num > 0) || num2 >= 2)
                {
                    throw ExprException.InvalidPattern(pat);
                }
                num2++;
            }
            else if (array[i] == '[')
            {
                i++;
                if (i >= length)
                {
                    throw ExprException.InvalidPattern(pat);
                }
                array2[num++] = array[i++];
                if (i >= length)
                {
                    throw ExprException.InvalidPattern(pat);
                }
                if (array[i] != ']')
                {
                    throw ExprException.InvalidPattern(pat);
                }
                i++;
            }
            else
            {
                array2[num++] = array[i];
                i++;
            }
        }
        text = new string(array2, 0, num);
        if (num2 == 0)
        {
            _kind = 4;
        }
        else if (num > 0)
        {
            if (array[0] == '*' || array[0] == '%')
            {
                if (array[length - 1] == '*' || array[length - 1] == '%')
                {
                    _kind = 3;
                }
                else
                {
                    _kind = 2;
                }
            }
            else
            {
                _kind = 1;
            }
        }
        else
        {
            _kind = 5;
        }
        return text;
    }
}