1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 // This module computes snippets of queries based on hits in the documents 6 // for display in history search results. 7 8 #ifndef CHROME_BROWSER_HISTORY_SNIPPET_H__ 9 #define CHROME_BROWSER_HISTORY_SNIPPET_H__ 10 #pragma once 11 12 #include <vector> 13 14 #include "base/string16.h" 15 16 class Snippet { 17 public: 18 // Each MatchPosition is the [begin, end) positions of a match within a 19 // string. 20 typedef std::pair<size_t, size_t> MatchPosition; 21 typedef std::vector<MatchPosition> MatchPositions; 22 23 // Parses an offsets string as returned from a sqlite full text index. An 24 // offsets string encodes information about why a row matched a text query. 25 // The information is encoded in the string as a set of matches, where each 26 // match consists of the column, term-number, location, and length of the 27 // match. Each element of the match is separated by a space, as is each match 28 // from other matches. 29 // 30 // This method adds the start and end of each match whose column is 31 // column_num to match_positions. The pairs are ordered based on first, 32 // with no overlapping elements. 33 // 34 // NOTE: the positions returned are in terms of UTF8 encoding. To convert the 35 // offsets to wide, use ConvertMatchPositionsToWide. 36 static void ExtractMatchPositions(const std::string& offsets_str, 37 const std::string& column_num, 38 MatchPositions* match_positions); 39 40 // Converts match positions as returned from ExtractMatchPositions to be in 41 // terms of a wide string. 42 static void ConvertMatchPositionsToWide( 43 const std::string& utf8_string, 44 Snippet::MatchPositions* match_positions); 45 46 Snippet(); 47 ~Snippet(); 48 49 // Given |matches|, the match positions within |document|, compute the snippet 50 // for the document. 51 // Note that |document| is UTF-8 and the offsets in |matches| are byte 52 // offsets. 53 void ComputeSnippet(const MatchPositions& matches, 54 const std::string& document); 55 56 const string16& text() const { return text_; } 57 const MatchPositions& matches() const { return matches_; } 58 59 // Efficiently swaps the contents of this snippet with the other. 60 void Swap(Snippet* other); 61 62 private: 63 // The text of the snippet. 64 string16 text_; 65 66 // The matches within text_. 67 MatchPositions matches_; 68 }; 69 70 #endif // CHROME_BROWSER_HISTORY_SNIPPET_H__ 71
