IndexRange.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.Text;

using Deveel.Data.Sql.Objects;
using Deveel.Data.Types;

namespace Deveel.Data.Index {
    public struct IndexRange {
        public static readonly DataObject FirstInSet = new DataObject(PrimitiveTypes.Null(), new SqlString("FirstInSet"));

        public static readonly DataObject LastInSet = new DataObject(PrimitiveTypes.Null(), new SqlString("LastInSet"));

        public IndexRange(RangeFieldOffset startOffset, DataObject firstValue, RangeFieldOffset lastOffset, DataObject endValue)
            : this(false) {
            StartOffset = startOffset;
            StartValue = firstValue;
            EndOffset = lastOffset;
            EndValue = endValue;
        }

        private IndexRange(bool isNull)
            : this() {
            IsNull = isNull;
        }

        public bool IsNull { get; private set; }

        public static readonly IndexRange FullRange = new IndexRange(RangeFieldOffset.FirstValue, FirstInSet,
            RangeFieldOffset.LastValue, LastInSet);

        public static readonly IndexRange FullRangeNotNull = new IndexRange(RangeFieldOffset.AfterLastValue, DataObject.Null(),
            RangeFieldOffset.LastValue, LastInSet);

        public static readonly IndexRange Null = new IndexRange(true);

        public RangeFieldOffset StartOffset { get; private set; }

        public DataObject StartValue { get; private set; }

        public RangeFieldOffset EndOffset { get; private set; }

        public DataObject EndValue { get; private set; }

        public override bool Equals(object obj) {
            var destRange = (IndexRange)obj;
            if (IsNull && destRange.IsNull)
                return true;
            if (IsNull && !destRange.IsNull)
                return false;
            if (!IsNull && destRange.IsNull)
                return false;

            return (StartValue.Value.Equals(destRange.StartValue.Value) &&
                    EndValue.Value.Equals(destRange.EndValue.Value) &&
                    StartOffset == destRange.StartOffset &&
                    EndOffset == destRange.EndOffset);
        }

        public override int GetHashCode() {
            return base.GetHashCode();
        }

        public override string ToString() {
            var sb = new StringBuilder();
            if (StartOffset == RangeFieldOffset.FirstValue) {
                sb.Append("FIRST_VALUE ");
            } else if (StartOffset == RangeFieldOffset.AfterLastValue) {
                sb.Append("AFTER_LAST_VALUE ");
            }

            sb.Append(StartValue.ToString());
            sb.Append(" -> ");
            if (EndOffset == RangeFieldOffset.LastValue) {
                sb.Append("LAST_VALUE ");
            } else if (EndOffset == RangeFieldOffset.BeforeFirstValue) {
                sb.Append("BEFORE_FIRST_VALUE ");
            }
            sb.Append(EndValue.ToString());
            return sb.ToString();
        }

        public static bool operator ==(IndexRange a, IndexRange b) {
            return a.Equals(b);
        }

        public static bool operator !=(IndexRange a, IndexRange b) {
            return !(a == b);
        }
    }
}