BooleanType.cs

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// 
//  Copyright 2010-2015 Deveel
// 
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
// 
//        http://www.apache.org/licenses/LICENSE-2.0
// 
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
//

using System;
using System.Globalization;
using System.IO;

using Deveel.Data.Serialization;
using Deveel.Data.Sql.Objects;

namespace Deveel.Data.Types {
    [Serializable]
    public sealed class BooleanType : SqlType {
        public BooleanType(SqlTypeCode typeCode) 
            : base("BOOLEAN", typeCode) {
            AssertIsBoolean(typeCode);
        }

        private BooleanType(ObjectData data)
            : base(data) {
        }

        private static void AssertIsBoolean(SqlTypeCode sqlType) {
            if (!IsBooleanType(sqlType))
                throw new ArgumentException(String.Format("The SQL type {0} is not BOOLEAN.", sqlType));
        }

        internal static bool IsBooleanType(SqlTypeCode sqlType) {
            return (sqlType == SqlTypeCode.Bit ||
                    sqlType == SqlTypeCode.Boolean);
        }

        public override bool IsStorable {
            get { return true; }
        }

        public override bool IsCacheable(ISqlObject value) {
            return value is SqlBoolean || value is SqlNull;
        }

        public override Type GetObjectType() {
            return typeof (SqlBoolean);
        }

        public override Type GetRuntimeType() {
            return typeof(bool);
        }

        public override int Compare(ISqlObject x, ISqlObject y) {
            if (!(x is SqlBoolean))
                throw new ArgumentException();

            var a = (SqlBoolean) x;
            SqlBoolean b;

            if (y is SqlNumber) {
                b = ((SqlNumber) y) == SqlNumber.One ? SqlBoolean.True : ((SqlNumber) y) == SqlNumber.Zero ? SqlBoolean.False : SqlBoolean.Null;
            } else if (y is SqlBoolean) {
                b = (SqlBoolean) y;
            } else {
                throw new ArgumentException();
            }

            return a.CompareTo(b);
        }

        public override bool IsComparable(SqlType type) {
            return type is BooleanType || type is NumericType;
        }

        public override bool CanCastTo(SqlType destType) {
            return destType is StringType ||
                   destType is NumericType ||
                   destType is BinaryType ||
                   destType is BooleanType;
        }

        public override DataObject CastTo(DataObject value, SqlType destType) {
            var bValue = ((SqlBoolean) value.Value);
            if (destType is StringType) {
                var s = Convert.ToString(bValue);
                // TODO: Provide a method in StringType to build a string specific to the type
                return new DataObject(destType, new SqlString(s));
            }
            if (destType is NumericType) {
                SqlNumber num;
                if (bValue == SqlBoolean.Null) {
                    num = SqlNumber.Null;
                } else if (bValue) {
                    num = SqlNumber.One;
                } else {
                    num = SqlNumber.Zero;
                }

                return new DataObject(destType, num);
            }
            if (destType is BinaryType) {
                var bytes = (byte[]) Convert.ChangeType(bValue, typeof (byte[]), CultureInfo.InvariantCulture);
                return new DataObject(destType, new SqlBinary(bytes));
            }
            if (destType is BooleanType)
                return value;

            return base.CastTo(value, destType);
        }

        public override ISqlObject Negate(ISqlObject value) {
            var b = (SqlBoolean) value;
            return b.Not();
        }

        public override void SerializeObject(Stream stream, ISqlObject obj) {
            var writer = new BinaryWriter(stream);

            if (obj is SqlNull) {
                writer.Write((byte)0);
            } else if (obj is SqlBoolean) {
                var b = (SqlBoolean)obj;

                if (b.IsNull) {
                    writer.Write((byte)0);
                } else {
                    var value = (bool)b;
                    writer.Write((byte)1);
                    writer.Write((byte)(value ? 1 : 0));
                }
            } else {
                throw new ArgumentException("Cannot serialize an object that is not a BOOLEAN using a boolean type.");
            }
        }

        public override ISqlObject DeserializeObject(Stream stream) {
            var reader = new BinaryReader(stream);

            var type = reader.ReadByte();
            if (type == 0)
                return SqlBoolean.Null;

            var value = reader.ReadByte();
            return new SqlBoolean(value);
        }

        internal override int ColumnSizeOf(ISqlObject obj) {
            return obj.IsNull ? 1 : 1 + 1;
        }

        public override ISqlObject Reverse(ISqlObject value) {
            return Negate(value);
        }

        public override ISqlObject And(ISqlObject a, ISqlObject b) {
            if (a.IsNull || b.IsNull)
                return SqlBoolean.Null;

            var b1 = (SqlBoolean) a;
            var b2 = (SqlBoolean) b;

            return b1.And(b2);
        }

        public override ISqlObject Or(ISqlObject a, ISqlObject b) {
            if (a.IsNull || b.IsNull)
                return SqlBoolean.Null;

            var b1 = (SqlBoolean)a;
            var b2 = (SqlBoolean)b;

            return b1.Or(b2);
        }

        public override ISqlObject XOr(ISqlObject a, ISqlObject b) {
            if (a.IsNull || b.IsNull)
                return SqlBoolean.Null;

            var b1 = (SqlBoolean)a;
            var b2 = (SqlBoolean)b;

            return b1.And(b2);
        }
    }
}