| using Lucene.Net.Diagnostics; |
| using System; |
| |
| namespace Lucene.Net.Util.Fst |
| { |
| /* |
| * 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 DataInput = Lucene.Net.Store.DataInput; |
| using DataOutput = Lucene.Net.Store.DataOutput; |
| |
| /// <summary> |
| /// An FST <see cref="Outputs{T}"/> implementation where each output |
| /// is a sequence of characters. |
| /// <para/> |
| /// @lucene.experimental |
| /// </summary> |
| public sealed class CharSequenceOutputs : Outputs<CharsRef> |
| { |
| private static readonly CharsRef NO_OUTPUT = new CharsRef(); |
| private static readonly CharSequenceOutputs singleton = new CharSequenceOutputs(); |
| |
| private CharSequenceOutputs() |
| { |
| } |
| |
| public static CharSequenceOutputs Singleton => singleton; |
| |
| public override CharsRef Common(CharsRef output1, CharsRef output2) |
| { |
| if (Debugging.AssertsEnabled) |
| { |
| Debugging.Assert(output1 != null); |
| Debugging.Assert(output2 != null); |
| } |
| |
| int pos1 = output1.Offset; |
| int pos2 = output2.Offset; |
| int stopAt1 = pos1 + Math.Min(output1.Length, output2.Length); |
| while (pos1 < stopAt1) |
| { |
| if (output1.Chars[pos1] != output2.Chars[pos2]) |
| { |
| break; |
| } |
| pos1++; |
| pos2++; |
| } |
| |
| if (pos1 == output1.Offset) |
| { |
| // no common prefix |
| return NO_OUTPUT; |
| } |
| else if (pos1 == output1.Offset + output1.Length) |
| { |
| // output1 is a prefix of output2 |
| return output1; |
| } |
| else if (pos2 == output2.Offset + output2.Length) |
| { |
| // output2 is a prefix of output1 |
| return output2; |
| } |
| else |
| { |
| return new CharsRef(output1.Chars, output1.Offset, pos1 - output1.Offset); |
| } |
| } |
| |
| public override CharsRef Subtract(CharsRef output, CharsRef inc) |
| { |
| if (Debugging.AssertsEnabled) |
| { |
| Debugging.Assert(output != null); |
| Debugging.Assert(inc != null); |
| } |
| if (inc == NO_OUTPUT) |
| { |
| // no prefix removed |
| return output; |
| } |
| else if (inc.Length == output.Length) |
| { |
| // entire output removed |
| return NO_OUTPUT; |
| } |
| else |
| { |
| if (Debugging.AssertsEnabled) |
| { |
| Debugging.Assert(inc.Length < output.Length,"inc.Length={0} vs output.Length={1}", inc.Length, output.Length); |
| Debugging.Assert(inc.Length > 0); |
| } |
| return new CharsRef(output.Chars, output.Offset + inc.Length, output.Length - inc.Length); |
| } |
| } |
| |
| public override CharsRef Add(CharsRef prefix, CharsRef output) |
| { |
| if (Debugging.AssertsEnabled) |
| { |
| Debugging.Assert(prefix != null); |
| Debugging.Assert(output != null); |
| } |
| if (prefix == NO_OUTPUT) |
| { |
| return output; |
| } |
| else if (output == NO_OUTPUT) |
| { |
| return prefix; |
| } |
| else |
| { |
| if (Debugging.AssertsEnabled) |
| { |
| Debugging.Assert(prefix.Length > 0); |
| Debugging.Assert(output.Length > 0); |
| } |
| var result = new CharsRef(prefix.Length + output.Length); |
| Array.Copy(prefix.Chars, prefix.Offset, result.Chars, 0, prefix.Length); |
| Array.Copy(output.Chars, output.Offset, result.Chars, prefix.Length, output.Length); |
| result.Length = prefix.Length + output.Length; |
| return result; |
| } |
| } |
| |
| public override void Write(CharsRef prefix, DataOutput @out) |
| { |
| if (Debugging.AssertsEnabled) Debugging.Assert(prefix != null); |
| @out.WriteVInt32(prefix.Length); |
| // TODO: maybe UTF8? |
| for (int idx = 0; idx < prefix.Length; idx++) |
| { |
| @out.WriteVInt32(prefix.Chars[prefix.Offset + idx]); |
| } |
| } |
| |
| public override CharsRef Read(DataInput @in) |
| { |
| int len = @in.ReadVInt32(); |
| if (len == 0) |
| { |
| return NO_OUTPUT; |
| } |
| else |
| { |
| CharsRef output = new CharsRef(len); |
| for (int idx = 0; idx < len; idx++) |
| { |
| output.Chars[idx] = (char)@in.ReadVInt32(); |
| } |
| output.Length = len; |
| return output; |
| } |
| } |
| |
| public override CharsRef NoOutput => NO_OUTPUT; |
| |
| public override string OutputToString(CharsRef output) |
| { |
| return output.ToString(); |
| } |
| } |
| } |