| using System.Collections.Generic; |
| using System.Text; |
| using JCG = J2N.Collections.Generic; |
| |
| namespace Lucene.Net.Search.VectorHighlight |
| { |
| /* |
| * 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. |
| */ |
| |
| /// <summary> |
| /// Simple boundary scanner implementation that divides fragments |
| /// based on a set of separator characters. |
| /// </summary> |
| public class SimpleBoundaryScanner : IBoundaryScanner |
| { |
| public static readonly int DEFAULT_MAX_SCAN = 20; |
| public static readonly char[] DEFAULT_BOUNDARY_CHARS = { '.', ',', '!', '?', ' ', '\t', '\n' }; |
| |
| protected int m_maxScan; |
| protected ISet<char> m_boundaryChars; |
| |
| public SimpleBoundaryScanner() |
| : this(DEFAULT_MAX_SCAN, DEFAULT_BOUNDARY_CHARS) |
| { |
| } |
| |
| public SimpleBoundaryScanner(int maxScan) |
| : this(maxScan, DEFAULT_BOUNDARY_CHARS) |
| { |
| } |
| |
| public SimpleBoundaryScanner(char[] boundaryChars) |
| : this(DEFAULT_MAX_SCAN, boundaryChars) |
| { |
| } |
| |
| public SimpleBoundaryScanner(int maxScan, char[] boundaryChars) |
| { |
| this.m_maxScan = maxScan; |
| this.m_boundaryChars = new JCG.HashSet<char>(); |
| this.m_boundaryChars.UnionWith(boundaryChars); |
| } |
| |
| public SimpleBoundaryScanner(int maxScan, ISet<char> boundaryChars) |
| { |
| this.m_maxScan = maxScan; |
| this.m_boundaryChars = boundaryChars; |
| } |
| |
| public virtual int FindStartOffset(StringBuilder buffer, int start) |
| { |
| // avoid illegal start offset |
| if (start > buffer.Length || start < 1) return start; |
| int offset, count = m_maxScan; |
| for (offset = start; offset > 0 && count > 0; count--) |
| { |
| // found? |
| if (m_boundaryChars.Contains(buffer[offset - 1])) return offset; |
| offset--; |
| } |
| // if we scanned up to the start of the text, return it, its a "boundary" |
| if (offset == 0) |
| { |
| return 0; |
| } |
| // not found |
| return start; |
| } |
| |
| public virtual int FindEndOffset(StringBuilder buffer, int start) |
| { |
| // avoid illegal start offset |
| if (start > buffer.Length || start < 0) return start; |
| int offset, count = m_maxScan; |
| //for( offset = start; offset <= buffer.length() && count > 0; count-- ){ |
| for (offset = start; offset < buffer.Length && count > 0; count--) |
| { |
| // found? |
| if (m_boundaryChars.Contains(buffer[offset])) return offset; |
| offset++; |
| } |
| // not found |
| return start; |
| } |
| } |
| } |