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NumericUtils.cs
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NumericUtils.cs
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using J2N.Numerics;
using System;
using System.Runtime.CompilerServices;
namespace Lucene.Net.Util
{
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 FilteredTermsEnum = Lucene.Net.Index.FilteredTermsEnum;
using TermsEnum = Lucene.Net.Index.TermsEnum;
/// <summary>
/// This is a helper class to generate prefix-encoded representations for numerical values
/// and supplies converters to represent float/double values as sortable integers/longs.
///
/// <para/>To quickly execute range queries in Apache Lucene, a range is divided recursively
/// into multiple intervals for searching: The center of the range is searched only with
/// the lowest possible precision in the trie, while the boundaries are matched
/// more exactly. this reduces the number of terms dramatically.
///
/// <para/>This class generates terms to achieve this: First the numerical integer values need to
/// be converted to bytes. For that integer values (32 bit or 64 bit) are made unsigned
/// and the bits are converted to ASCII chars with each 7 bit. The resulting byte[] is
/// sortable like the original integer value (even using UTF-8 sort order). Each value is also
/// prefixed (in the first char) by the <c>shift</c> value (number of bits removed) used
/// during encoding.
///
/// <para/>To also index floating point numbers, this class supplies two methods to convert them
/// to integer values by changing their bit layout: <see cref="DoubleToSortableInt64(double)"/>,
/// <see cref="SingleToSortableInt32(float)"/>. You will have no precision loss by
/// converting floating point numbers to integers and back (only that the integer form
/// is not usable). Other data types like dates can easily converted to <see cref="long"/>s or <see cref="int"/>s (e.g.
/// date to long: <see cref="DateTime.Ticks"/>).
///
/// <para/>For easy usage, the trie algorithm is implemented for indexing inside
/// <see cref="Analysis.NumericTokenStream"/> that can index <see cref="int"/>, <see cref="long"/>,
/// <see cref="float"/>, and <see cref="double"/>. For querying,
/// <see cref="Search.NumericRangeQuery"/> and <see cref="Search.NumericRangeFilter"/> implement the query part
/// for the same data types.
///
/// <para/>This class can also be used, to generate lexicographically sortable (according to
/// <see cref="BytesRef.UTF8SortedAsUTF16Comparer"/>) representations of numeric data
/// types for other usages (e.g. sorting).
///
/// <para/>
/// @lucene.internal
/// @since 2.9, API changed non backwards-compliant in 4.0
/// </summary>
public static class NumericUtils // LUCENENET specific - changed to static
{
/// <summary>
/// The default precision step used by <see cref="Documents.Int32Field"/>,
/// <see cref="Documents.SingleField"/>, <see cref="Documents.Int64Field"/>,
/// <see cref="Documents.DoubleField"/>, <see cref="Analysis.NumericTokenStream"/>,
/// <see cref="Search.NumericRangeQuery"/>, and <see cref="Search.NumericRangeFilter"/>.
/// </summary>
public const int PRECISION_STEP_DEFAULT = 4;
/// <summary>
/// Longs are stored at lower precision by shifting off lower bits. The shift count is
/// stored as <c>SHIFT_START_INT64+shift</c> in the first byte
/// <para/>
/// NOTE: This was SHIFT_START_LONG in Lucene
/// </summary>
public const char SHIFT_START_INT64 = (char)0x20;
/// <summary>
/// The maximum term length (used for <see cref="T:byte[]"/> buffer size)
/// for encoding <see cref="long"/> values.
/// <para/>
/// NOTE: This was BUF_SIZE_LONG in Lucene
/// </summary>
/// <seealso cref="Int64ToPrefixCodedBytes(long, int, BytesRef)"/>
public const int BUF_SIZE_INT64 = 63 / 7 + 2;
/// <summary>
/// Integers are stored at lower precision by shifting off lower bits. The shift count is
/// stored as <c>SHIFT_START_INT32+shift</c> in the first byte
/// <para/>
/// NOTE: This was SHIFT_START_INT in Lucene
/// </summary>
public const byte SHIFT_START_INT32 = 0x60;
/// <summary>
/// The maximum term length (used for <see cref="T:byte[]"/> buffer size)
/// for encoding <see cref="int"/> values.
/// <para/>
/// NOTE: This was BUF_SIZE_INT in Lucene
/// </summary>
/// <seealso cref="Int32ToPrefixCodedBytes(int, int, BytesRef)"/>
public const int BUF_SIZE_INT32 = 31 / 7 + 2;
/// <summary>
/// Returns prefix coded bits after reducing the precision by <paramref name="shift"/> bits.
/// This is method is used by <see cref="Analysis.NumericTokenStream"/>.
/// After encoding, <c>bytes.Offset</c> will always be 0.
/// <para/>
/// NOTE: This was longToPrefixCoded() in Lucene
/// </summary>
/// <param name="val"> The numeric value </param>
/// <param name="shift"> How many bits to strip from the right </param>
/// <param name="bytes"> Will contain the encoded value </param>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void Int64ToPrefixCoded(long val, int shift, BytesRef bytes)
{
Int64ToPrefixCodedBytes(val, shift, bytes);
}
/// <summary>
/// Returns prefix coded bits after reducing the precision by <paramref name="shift"/> bits.
/// This is method is used by <see cref="Analysis.NumericTokenStream"/>.
/// After encoding, <c>bytes.Offset</c> will always be 0.
/// <para/>
/// NOTE: This was intToPrefixCoded() in Lucene
/// </summary>
/// <param name="val"> The numeric value </param>
/// <param name="shift"> How many bits to strip from the right </param>
/// <param name="bytes"> Will contain the encoded value </param>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void Int32ToPrefixCoded(int val, int shift, BytesRef bytes)
{
Int32ToPrefixCodedBytes(val, shift, bytes);
}
/// <summary>
/// Returns prefix coded bits after reducing the precision by <paramref name="shift"/> bits.
/// This is method is used by <see cref="Analysis.NumericTokenStream"/>.
/// After encoding, <c>bytes.Offset</c> will always be 0.
/// <para/>
/// NOTE: This was longToPrefixCodedBytes() in Lucene
/// </summary>
/// <param name="val"> The numeric value </param>
/// <param name="shift"> How many bits to strip from the right </param>
/// <param name="bytes"> Will contain the encoded value </param>
public static void Int64ToPrefixCodedBytes(long val, int shift, BytesRef bytes)
{
if ((shift & ~0x3f) != 0) // ensure shift is 0..63
{
throw new ArgumentOutOfRangeException(nameof(shift), "Illegal shift value, must be 0..63"); // LUCENENET specific - changed from IllegalArgumentException to ArgumentOutOfRangeException (.NET convention)
}
int nChars = (((63 - shift) * 37) >> 8) + 1; // i/7 is the same as (i*37)>>8 for i in 0..63
bytes.Offset = 0;
bytes.Length = nChars + 1; // one extra for the byte that contains the shift info
if (bytes.Bytes.Length < bytes.Length)
{
bytes.Bytes = new byte[NumericUtils.BUF_SIZE_INT64]; // use the max
}
bytes.Bytes[0] = (byte)(SHIFT_START_INT64 + shift);
ulong sortableBits = BitConverter.ToUInt64(BitConverter.GetBytes(val), 0) ^ 0x8000000000000000L; // LUCENENET TODO: Performance - Benchmark this
sortableBits = sortableBits >> shift;
while (nChars > 0)
{
// Store 7 bits per byte for compatibility
// with UTF-8 encoding of terms
bytes.Bytes[nChars--] = (byte)(sortableBits & 0x7f);
sortableBits = sortableBits >> 7;
}
}
/// <summary>
/// Returns prefix coded bits after reducing the precision by <paramref name="shift"/> bits.
/// This is method is used by <see cref="Analysis.NumericTokenStream"/>.
/// After encoding, <c>bytes.Offset</c> will always be 0.
/// <para/>
/// NOTE: This was intToPrefixCodedBytes() in Lucene
/// </summary>
/// <param name="val"> The numeric value </param>
/// <param name="shift"> How many bits to strip from the right </param>
/// <param name="bytes"> Will contain the encoded value </param>
public static void Int32ToPrefixCodedBytes(int val, int shift, BytesRef bytes)
{
if ((shift & ~0x1f) != 0) // ensure shift is 0..31
{
throw new ArgumentOutOfRangeException(nameof(shift), "Illegal shift value, must be 0..31"); // LUCENENET specific - changed from IllegalArgumentException to ArgumentOutOfRangeException (.NET convention)
}
int nChars = (((31 - shift) * 37) >> 8) + 1; // i/7 is the same as (i*37)>>8 for i in 0..63
bytes.Offset = 0;
bytes.Length = nChars + 1; // one extra for the byte that contains the shift info
if (bytes.Bytes.Length < bytes.Length)
{
bytes.Bytes = new byte[NumericUtils.BUF_SIZE_INT64]; // use the max
}
bytes.Bytes[0] = (byte)(SHIFT_START_INT32 + shift);
int sortableBits = val ^ unchecked((int)0x80000000);
sortableBits = sortableBits.TripleShift(shift);
while (nChars > 0)
{
// Store 7 bits per byte for compatibility
// with UTF-8 encoding of terms
bytes.Bytes[nChars--] = (byte)(sortableBits & 0x7f);
sortableBits = sortableBits.TripleShift(7);
}
}
/// <summary>
/// Returns the shift value from a prefix encoded <see cref="long"/>.
/// <para/>
/// NOTE: This was getPrefixCodedLongShift() in Lucene
/// </summary>
/// <exception cref="FormatException"> if the supplied <see cref="BytesRef"/> is
/// not correctly prefix encoded. </exception>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static int GetPrefixCodedInt64Shift(BytesRef val)
{
int shift = val.Bytes[val.Offset] - SHIFT_START_INT64;
if (shift > 63 || shift < 0)
{
throw NumberFormatException.Create("Invalid shift value (" + shift + ") in prefixCoded bytes (is encoded value really an INT?)");
}
return shift;
}
/// <summary>
/// Returns the shift value from a prefix encoded <see cref="int"/>.
/// <para/>
/// NOTE: This was getPrefixCodedIntShift() in Lucene
/// </summary>
/// <exception cref="FormatException"> if the supplied <see cref="BytesRef"/> is
/// not correctly prefix encoded. </exception>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static int GetPrefixCodedInt32Shift(BytesRef val)
{
int shift = val.Bytes[val.Offset] - SHIFT_START_INT32;
if (shift > 31 || shift < 0)
{
throw NumberFormatException.Create("Invalid shift value in prefixCoded bytes (is encoded value really an INT?)");
}
return shift;
}
/// <summary>
/// Returns a <see cref="long"/> from prefixCoded bytes.
/// Rightmost bits will be zero for lower precision codes.
/// This method can be used to decode a term's value.
/// <para/>
/// NOTE: This was prefixCodedToLong() in Lucene
/// </summary>
/// <exception cref="FormatException"> if the supplied <see cref="BytesRef"/> is
/// not correctly prefix encoded. </exception>
/// <seealso cref="Int64ToPrefixCodedBytes(long, int, BytesRef)"/>
public static long PrefixCodedToInt64(BytesRef val)
{
long sortableBits = 0L;
for (int i = val.Offset + 1, limit = val.Offset + val.Length; i < limit; i++)
{
sortableBits <<= 7;
var b = val.Bytes[i];
if (b < 0)
{
throw NumberFormatException.Create("Invalid prefixCoded numerical value representation (byte " + (b & 0xff).ToString("x") + " at position " + (i - val.Offset) + " is invalid)");
}
sortableBits |= (byte)b;
}
return (long)((ulong)(sortableBits << GetPrefixCodedInt64Shift(val)) ^ 0x8000000000000000L); // LUCENENET TODO: Is the casting here necessary?
}
/// <summary>
/// Returns an <see cref="int"/> from prefixCoded bytes.
/// Rightmost bits will be zero for lower precision codes.
/// This method can be used to decode a term's value.
/// <para/>
/// NOTE: This was prefixCodedToInt() in Lucene
/// </summary>
/// <exception cref="FormatException"> if the supplied <see cref="BytesRef"/> is
/// not correctly prefix encoded. </exception>
/// <seealso cref="Int32ToPrefixCodedBytes(int, int, BytesRef)"/>
public static int PrefixCodedToInt32(BytesRef val)
{
long sortableBits = 0;
for (int i = val.Offset, limit = val.Offset + val.Length; i < limit; i++)
{
sortableBits <<= 7;
var b = val.Bytes[i];
if (b < 0)
{
throw NumberFormatException.Create("Invalid prefixCoded numerical value representation (byte " + (b & 0xff).ToString("x") + " at position " + (i - val.Offset) + " is invalid)");
}
sortableBits |= b;
}
return (int)((sortableBits << GetPrefixCodedInt32Shift(val)) ^ 0x80000000);
}
/// <summary>
/// Converts a <see cref="double"/> value to a sortable signed <see cref="long"/>.
/// The value is converted by getting their IEEE 754 floating-point "double format"
/// bit layout and then some bits are swapped, to be able to compare the result as <see cref="long"/>.
/// By this the precision is not reduced, but the value can easily used as a <see cref="long"/>.
/// The sort order (including <see cref="double.NaN"/>) is defined by
/// <see cref="double.CompareTo(double)"/>; <c>NaN</c> is greater than positive infinity.
/// <para/>
/// NOTE: This was doubleToSortableLong() in Lucene
/// </summary>
/// <seealso cref="SortableInt64ToDouble(long)"/>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static long DoubleToSortableInt64(double val)
{
long f = J2N.BitConversion.DoubleToInt64Bits(val);
if (f < 0)
{
f ^= 0x7fffffffffffffffL;
}
return f;
}
/// <summary>
/// Converts a sortable <see cref="long"/> back to a <see cref="double"/>.
/// <para/>
/// NOTE: This was sortableLongToDouble() in Lucene
/// </summary>
/// <seealso cref="DoubleToSortableInt64(double)"/>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static double SortableInt64ToDouble(long val)
{
if (val < 0)
{
val ^= 0x7fffffffffffffffL;
}
return J2N.BitConversion.Int64BitsToDouble(val);
}
/// <summary>
/// Converts a <see cref="float"/> value to a sortable signed <see cref="int"/>.
/// The value is converted by getting their IEEE 754 floating-point "float format"
/// bit layout and then some bits are swapped, to be able to compare the result as <see cref="int"/>.
/// By this the precision is not reduced, but the value can easily used as an <see cref="int"/>.
/// The sort order (including <see cref="float.NaN"/>) is defined by
/// <seealso cref="float.CompareTo(float)"/>; <c>NaN</c> is greater than positive infinity.
/// <para/>
/// NOTE: This was floatToSortableInt() in Lucene
/// </summary>
/// <seealso cref="SortableInt32ToSingle(int)"/>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static int SingleToSortableInt32(float val)
{
int f = J2N.BitConversion.SingleToInt32Bits(val);
if (f < 0)
{
f ^= 0x7fffffff;
}
return f;
}
/// <summary>
/// Converts a sortable <see cref="int"/> back to a <see cref="float"/>.
/// <para/>
/// NOTE: This was sortableIntToFloat() in Lucene
/// </summary>
/// <seealso cref="SingleToSortableInt32"/>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static float SortableInt32ToSingle(int val)
{
if (val < 0)
{
val ^= 0x7fffffff;
}
return J2N.BitConversion.Int32BitsToSingle(val);
}
/// <summary>
/// Splits a long range recursively.
/// You may implement a builder that adds clauses to a
/// <see cref="Lucene.Net.Search.BooleanQuery"/> for each call to its
/// <see cref="Int64RangeBuilder.AddRange(BytesRef, BytesRef)"/>
/// method.
/// <para/>
/// This method is used by <see cref="Search.NumericRangeQuery"/>.
/// <para/>
/// NOTE: This was splitLongRange() in Lucene
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void SplitInt64Range(Int64RangeBuilder builder, int precisionStep, long minBound, long maxBound)
{
SplitRange(builder, 64, precisionStep, minBound, maxBound);
}
/// <summary>
/// Splits an <see cref="int"/> range recursively.
/// You may implement a builder that adds clauses to a
/// <see cref="Lucene.Net.Search.BooleanQuery"/> for each call to its
/// <see cref="Int32RangeBuilder.AddRange(BytesRef, BytesRef)"/>
/// method.
/// <para/>
/// This method is used by <see cref="Search.NumericRangeQuery"/>.
/// <para/>
/// NOTE: This was splitIntRange() in Lucene
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void SplitInt32Range(Int32RangeBuilder builder, int precisionStep, int minBound, int maxBound)
{
SplitRange(builder, 32, precisionStep, minBound, maxBound);
}
/// <summary>
/// This helper does the splitting for both 32 and 64 bit. </summary>
private static void SplitRange(object builder, int valSize, int precisionStep, long minBound, long maxBound)
{
if (precisionStep < 1)
{
throw new ArgumentOutOfRangeException(nameof(precisionStep), "precisionStep must be >=1"); // LUCENENET specific - changed from IllegalArgumentException to ArgumentOutOfRangeException (.NET convention)
}
if (minBound > maxBound)
{
return;
}
for (int shift = 0; ; shift += precisionStep)
{
// calculate new bounds for inner precision
long diff = 1L << (shift + precisionStep), mask = ((1L << precisionStep) - 1L) << shift;
bool hasLower = (minBound & mask) != 0L, hasUpper = (maxBound & mask) != mask;
long nextMinBound = (hasLower ? (minBound + diff) : minBound) & ~mask, nextMaxBound = (hasUpper ? (maxBound - diff) : maxBound) & ~mask;
bool lowerWrapped = nextMinBound < minBound, upperWrapped = nextMaxBound > maxBound;
if (shift + precisionStep >= valSize || nextMinBound > nextMaxBound || lowerWrapped || upperWrapped)
{
// We are in the lowest precision or the next precision is not available.
AddRange(builder, valSize, minBound, maxBound, shift);
// exit the split recursion loop
break;
}
if (hasLower)
{
AddRange(builder, valSize, minBound, minBound | mask, shift);
}
if (hasUpper)
{
AddRange(builder, valSize, maxBound & ~mask, maxBound, shift);
}
// recurse to next precision
minBound = nextMinBound;
maxBound = nextMaxBound;
}
}
/// <summary>
/// Helper that delegates to correct range builder. </summary>
private static void AddRange(object builder, int valSize, long minBound, long maxBound, int shift)
{
// for the max bound set all lower bits (that were shifted away):
// this is important for testing or other usages of the splitted range
// (e.g. to reconstruct the full range). The prefixEncoding will remove
// the bits anyway, so they do not hurt!
maxBound |= (1L << shift) - 1L;
// delegate to correct range builder
switch (valSize)
{
case 64:
((Int64RangeBuilder)builder).AddRange(minBound, maxBound, shift);
break;
case 32:
((Int32RangeBuilder)builder).AddRange((int)minBound, (int)maxBound, shift);
break;
default:
// Should not happen!
throw new ArgumentException("valSize must be 32 or 64.");
}
}
/// <summary>
/// Callback for <see cref="SplitInt64Range(Int64RangeBuilder, int, long, long)"/>.
/// You need to override only one of the methods.
/// <para/>
/// NOTE: This was LongRangeBuilder in Lucene
/// <para/>
/// @lucene.internal
/// @since 2.9, API changed non backwards-compliant in 4.0
/// </summary>
public abstract class Int64RangeBuilder
{
/// <summary>
/// Override this method, if you like to receive the already prefix encoded range bounds.
/// You can directly build classical (inclusive) range queries from them.
/// </summary>
public virtual void AddRange(BytesRef minPrefixCoded, BytesRef maxPrefixCoded)
{
throw UnsupportedOperationException.Create();
}
/// <summary>
/// Override this method, if you like to receive the raw long range bounds.
/// You can use this for e.g. debugging purposes (print out range bounds).
/// </summary>
public virtual void AddRange(long min, long max, int shift)
{
BytesRef minBytes = new BytesRef(BUF_SIZE_INT64), maxBytes = new BytesRef(BUF_SIZE_INT64);
Int64ToPrefixCodedBytes(min, shift, minBytes);
Int64ToPrefixCodedBytes(max, shift, maxBytes);
AddRange(minBytes, maxBytes);
}
}
/// <summary>
/// Callback for <see cref="SplitInt32Range(Int32RangeBuilder, int, int, int)"/>.
/// You need to override only one of the methods.
/// <para/>
/// NOTE: This was IntRangeBuilder in Lucene
///
/// @lucene.internal
/// @since 2.9, API changed non backwards-compliant in 4.0
/// </summary>
public abstract class Int32RangeBuilder
{
/// <summary>
/// Override this method, if you like to receive the already prefix encoded range bounds.
/// You can directly build classical range (inclusive) queries from them.
/// </summary>
public virtual void AddRange(BytesRef minPrefixCoded, BytesRef maxPrefixCoded)
{
throw UnsupportedOperationException.Create();
}
/// <summary>
/// Override this method, if you like to receive the raw int range bounds.
/// You can use this for e.g. debugging purposes (print out range bounds).
/// </summary>
public virtual void AddRange(int min, int max, int shift)
{
BytesRef minBytes = new BytesRef(BUF_SIZE_INT32), maxBytes = new BytesRef(BUF_SIZE_INT32);
Int32ToPrefixCodedBytes(min, shift, minBytes);
Int32ToPrefixCodedBytes(max, shift, maxBytes);
AddRange(minBytes, maxBytes);
}
}
/// <summary>
/// Filters the given <see cref="TermsEnum"/> by accepting only prefix coded 64 bit
/// terms with a shift value of <c>0</c>.
/// <para/>
/// NOTE: This was filterPrefixCodedLongs() in Lucene
/// </summary>
/// <param name="termsEnum">
/// The terms enum to filter </param>
/// <returns> A filtered <see cref="TermsEnum"/> that only returns prefix coded 64 bit
/// terms with a shift value of <c>0</c>. </returns>
public static TermsEnum FilterPrefixCodedInt64s(TermsEnum termsEnum)
{
return new FilteredTermsEnumAnonymousClass(termsEnum);
}
private class FilteredTermsEnumAnonymousClass : FilteredTermsEnum
{
public FilteredTermsEnumAnonymousClass(TermsEnum termsEnum)
: base(termsEnum, false)
{
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
protected override AcceptStatus Accept(BytesRef term)
{
return NumericUtils.GetPrefixCodedInt64Shift(term) == 0 ? AcceptStatus.YES : AcceptStatus.END;
}
}
/// <summary>
/// Filters the given <see cref="TermsEnum"/> by accepting only prefix coded 32 bit
/// terms with a shift value of <c>0</c>.
/// <para/>
/// NOTE: This was filterPrefixCodedInts() in Lucene
/// </summary>
/// <param name="termsEnum">
/// The terms enum to filter </param>
/// <returns> A filtered <see cref="TermsEnum"/> that only returns prefix coded 32 bit
/// terms with a shift value of <c>0</c>. </returns>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static TermsEnum FilterPrefixCodedInt32s(TermsEnum termsEnum)
{
return new FilteredTermsEnumAnonymousClass2(termsEnum);
}
private class FilteredTermsEnumAnonymousClass2 : FilteredTermsEnum
{
public FilteredTermsEnumAnonymousClass2(TermsEnum termsEnum)
: base(termsEnum, false)
{
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
protected override AcceptStatus Accept(BytesRef term)
{
return NumericUtils.GetPrefixCodedInt32Shift(term) == 0 ? AcceptStatus.YES : AcceptStatus.END;
}
}
}
}