1 // Copyright (c) 2011 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.
5 #ifndef CHROME_BROWSER_HISTORY_QUERY_PARSER_H_
6 #define CHROME_BROWSER_HISTORY_QUERY_PARSER_H_
10 #include "base/basictypes.h"
11 #include "base/strings/string16.h"
12 #include "chrome/browser/history/snippet.h"
16 // Used by HasMatchIn.
18 // The work to match against.
21 // The starting position of the word in the original text.
25 // QueryNode is used by QueryParser to represent the elements that constitute a
26 // query. While QueryNode is exposed by way of ParseQuery, it really isn't meant
27 // for external usage.
30 virtual ~QueryNode() {}
32 // Serialize ourselves out to a string that can be passed to SQLite. Returns
33 // the number of words in this node.
34 virtual int AppendToSQLiteQuery(string16* query) const = 0;
36 // Return true if this is a QueryNodeWord, false if it's a QueryNodeList.
37 virtual bool IsWord() const = 0;
39 // Returns true if this node matches |word|. If |exact| is true, the string
40 // must exactly match. Otherwise, this uses a starts with comparison.
41 virtual bool Matches(const string16& word, bool exact) const = 0;
43 // Returns true if this node matches at least one of the words in |words|. An
44 // entry is added to |match_positions| for all matching words giving the
46 virtual bool HasMatchIn(const std::vector<QueryWord>& words,
47 Snippet::MatchPositions* match_positions) const = 0;
49 // Returns true if this node matches at least one of the words in |words|.
50 virtual bool HasMatchIn(const std::vector<QueryWord>& words) const = 0;
52 // Appends the words that make up this node in |words|.
53 virtual void AppendWords(std::vector<string16>* words) const = 0;
56 // This class is used to parse queries entered into the history search into more
57 // normalized queries that can be passed to the SQLite backend.
62 // For CJK ideographs and Korean Hangul, even a single character
63 // can be useful in prefix matching, but that may give us too many
64 // false positives. Moreover, the current ICU word breaker gives us
65 // back every single Chinese character as a word so that there's no
66 // point doing anything for them and we only adjust the minimum length
67 // to 2 for Korean Hangul while using 3 for others. This is a temporary
68 // hack until we have a segmentation support.
69 static bool IsWordLongEnoughForPrefixSearch(const string16& word);
71 // Parse a query into a SQLite query. The resulting query is placed in
72 // |sqlite_query| and the number of words is returned.
73 int ParseQuery(const string16& query, string16* sqlite_query);
75 // Parses |query|, returning the words that make up it. Any words in quotes
76 // are put in |words| without the quotes. For example, the query text
77 // "foo bar" results in two entries being added to words, one for foo and one
79 void ParseQueryWords(const string16& query, std::vector<string16>* words);
81 // Parses |query|, returning the nodes that constitute the valid words in the
82 // query. This is intended for later usage with DoesQueryMatch. Ownership of
83 // the nodes passes to the caller.
84 void ParseQueryNodes(const string16& query, std::vector<QueryNode*>* nodes);
86 // Returns true if the string text matches the query nodes created by a call
87 // to ParseQuery. If the query does match, each of the matching positions in
88 // the text is added to |match_positions|.
89 bool DoesQueryMatch(const string16& text,
90 const std::vector<QueryNode*>& nodes,
91 Snippet::MatchPositions* match_positions);
93 // Returns true if all of the |words| match the query |nodes| created by a
94 // call to ParseQuery.
95 bool DoesQueryMatch(const std::vector<QueryWord>& words,
96 const std::vector<QueryNode*>& nodes);
98 // Extracts the words from |text|, placing each word into |words|.
99 void ExtractQueryWords(const string16& text, std::vector<QueryWord>* words);
102 // Does the work of parsing |query|; creates nodes in |root| as appropriate.
103 // This is invoked from both of the ParseQuery methods.
104 bool ParseQueryImpl(const string16& query, QueryNodeList* root);
106 DISALLOW_COPY_AND_ASSIGN(QueryParser);
109 #endif // CHROME_BROWSER_HISTORY_QUERY_PARSER_H_