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1 /* | |
2 * Copyright (c) 2013, Opera Software ASA. All rights reserved. | |
3 * | |
4 * Redistribution and use in source and binary forms, with or without | |
5 * modification, are permitted provided that the following conditions | |
6 * are met: | |
7 * 1. Redistributions of source code must retain the above copyright | |
8 * notice, this list of conditions and the following disclaimer. | |
9 * 2. Redistributions in binary form must reproduce the above copyright | |
10 * notice, this list of conditions and the following disclaimer in the | |
11 * documentation and/or other materials provided with the distribution. | |
12 * 3. Neither the name of Opera Software ASA nor the names of its | |
13 * contributors may be used to endorse or promote products derived | |
14 * from this software without specific prior written permission. | |
15 * | |
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |
19 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE | |
20 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, | |
21 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | |
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | |
23 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
25 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
26 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
27 * OF THE POSSIBILITY OF SUCH DAMAGE. | |
28 */ | |
29 | |
30 #ifndef VTTScanner_h | |
31 #define VTTScanner_h | |
32 | |
33 #include "platform/ParsingUtilities.h" | |
34 #include "wtf/text/WTFString.h" | |
35 | |
36 namespace WebCore { | |
37 | |
38 // Helper class for "scanning" an input string and performing parsing of | |
39 // "micro-syntax"-like constructs. | |
40 // | |
41 // There's two primary operations: match and scan. | |
42 // | |
43 // The 'match' operation matches an explicitly or implicitly specified sequence | |
44 // against the characters ahead of the current input pointer, and returns true | |
45 // if the sequence can be matched. | |
46 // | |
47 // The 'scan' operation performs a 'match', and if the match is successful it | |
48 // advance the input pointer past the matched sequence. | |
49 class VTTScanner { | |
jochen (gone - plz use gerrit)
2014/01/03 11:02:24
can you make this class non-copiable as well?
| |
50 public: | |
51 VTTScanner(const String& line); | |
jochen (gone - plz use gerrit)
2014/01/03 11:02:24
explicit
| |
52 | |
53 typedef const LChar* Position; | |
54 | |
55 struct Run { | |
jochen (gone - plz use gerrit)
2014/01/03 11:02:24
this is really a class with all the fancy methods
| |
56 Run(Position start, Position end, bool is8Bit) | |
57 : start(start), end(end), is8Bit(is8Bit) { } | |
58 | |
59 bool isEmpty() const { return start == end; } | |
60 size_t length() const; | |
61 | |
62 Position start; | |
63 Position end; | |
64 bool is8Bit; | |
65 }; | |
66 | |
67 // Check if the input pointer points at the specified position. | |
68 bool isAt(Position checkPosition) const { return position() == checkPosition ; } | |
69 // Check if the input pointer points at the end of the input. | |
70 bool isAtEnd() const { return position() == end(); } | |
71 // Match the character |c| against the character at the input pointer (~look ahead). | |
72 bool match(char c) const { return !isAtEnd() && currentChar() == c; } | |
73 // Scan the character |c|. | |
74 bool scan(char); | |
75 // Scan the first |charactersCount| characters of the string |characters|. | |
76 bool scan(const LChar* characters, size_t charactersCount); | |
77 | |
78 // Scan the literal |characters|. | |
79 template<unsigned charactersCount> | |
80 bool scan(const char (&characters)[charactersCount]); | |
81 | |
82 // Skip (advance the input pointer) as long as the specified | |
83 // |characterPredicate| returns true, and the input pointer is not passed | |
84 // the end of the input. | |
85 template<bool characterPredicate(UChar)> | |
86 void skipWhile(); | |
87 | |
88 // Return the run of characters for which the specified | |
89 // |characterPredicate| returns true. The start of the run will be the | |
90 // current input pointer. | |
91 template<bool characterPredicate(UChar)> | |
92 Run collectWhile(); | |
93 | |
94 // Return a String constructed from the rest of the input (between input | |
95 // pointer and end of input), and advance the input pointer accordingly. | |
96 String restOfInputAsString(); | |
97 | |
98 // Scan a set of ASCII digits from the input. Return the number of digits | |
99 // scanned, and set |number| to the computed value. If the digits make up a | |
100 // number that does not fit the 'int' type, |number| is set to INT_MAX. | |
101 // Note: Does not handle sign. | |
102 unsigned scanDigits(int& number); | |
103 | |
104 protected: | |
105 Position position() const { return m_data.characters8; } | |
106 Position end() const { return m_end.characters8; } | |
107 void seekTo(Position); | |
108 UChar currentChar() const; | |
109 void advance(unsigned amount = 1); | |
110 // Adapt a UChar-predicate to an LChar-predicate. | |
111 // (For use with skipWhile/Until from ParsingUtilities.h). | |
112 template<bool characterPredicate(UChar)> | |
113 static inline bool LCharPredicateAdapter(LChar c) { return characterPredicat e(c); } | |
114 union { | |
115 const LChar* characters8; | |
116 const UChar* characters16; | |
117 } m_data; | |
118 union { | |
119 const LChar* characters8; | |
120 const UChar* characters16; | |
121 } m_end; | |
122 bool m_is8Bit; | |
jochen (gone - plz use gerrit)
2014/01/03 11:02:24
it would be nicer if you had accessors and made th
| |
123 }; | |
124 | |
125 inline size_t VTTScanner::Run::length() const | |
126 { | |
127 if (is8Bit) | |
128 return end - start; | |
129 return reinterpret_cast<const UChar*>(end) - reinterpret_cast<const UChar*>( start); | |
130 } | |
131 | |
132 template<unsigned charactersCount> | |
133 inline bool VTTScanner::scan(const char (&characters)[charactersCount]) | |
134 { | |
135 return scan(reinterpret_cast<const LChar*>(characters), charactersCount - 1) ; | |
136 } | |
137 | |
138 template<bool characterPredicate(UChar)> | |
139 inline void VTTScanner::skipWhile() | |
140 { | |
141 if (m_is8Bit) | |
142 ::skipWhile<LChar, LCharPredicateAdapter<characterPredicate> >(m_data.ch aracters8, m_end.characters8); | |
143 else | |
144 ::skipWhile<UChar, characterPredicate>(m_data.characters16, m_end.charac ters16); | |
145 } | |
146 | |
147 template<bool characterPredicate(UChar)> | |
148 inline VTTScanner::Run VTTScanner::collectWhile() | |
149 { | |
150 Run run(position(), position(), m_is8Bit); | |
151 if (m_is8Bit) { | |
152 const LChar* current = m_data.characters8; | |
153 ::skipWhile<LChar, LCharPredicateAdapter<characterPredicate> >(current, m_end.characters8); | |
154 run.end = current; | |
155 } else { | |
156 const UChar* current = m_data.characters16; | |
157 ::skipWhile<UChar, characterPredicate>(current, m_end.characters16); | |
158 run.end = reinterpret_cast<Position>(current); | |
159 } | |
160 return run; | |
161 } | |
162 | |
163 inline void VTTScanner::seekTo(Position position) | |
164 { | |
165 ASSERT(position <= end()); | |
166 m_data.characters8 = position; | |
167 } | |
168 | |
169 inline UChar VTTScanner::currentChar() const | |
170 { | |
171 ASSERT(position() < end()); | |
172 return m_is8Bit ? *m_data.characters8 : *m_data.characters16; | |
173 } | |
174 | |
175 inline void VTTScanner::advance(unsigned amount) | |
176 { | |
177 ASSERT(position() < end()); | |
178 if (m_is8Bit) | |
179 m_data.characters8 += amount; | |
180 else | |
181 m_data.characters16 += amount; | |
182 } | |
183 | |
184 // Wrapper of VTTScanner that allows easy interaction with a parsing model | |
185 // where a <String, index> tuple is used. | |
186 class VTTLegacyScanner : public VTTScanner { | |
187 WTF_MAKE_NONCOPYABLE(VTTLegacyScanner); | |
188 public: | |
189 VTTLegacyScanner(const String& line, unsigned* outPosition) | |
190 : VTTScanner(line) | |
191 , m_outPosition(outPosition) | |
192 { | |
193 ASSERT(outPosition && *outPosition <= line.length()); | |
194 // Adjust state according to |*outPosition|. | |
195 advance(*outPosition); | |
196 // Save the start position to allow adjusting |*outPosition|. | |
197 if (m_is8Bit) | |
198 m_start.characters8 = m_data.characters8; | |
199 else | |
200 m_start.characters16 = m_data.characters16; | |
201 } | |
202 ~VTTLegacyScanner() | |
203 { | |
204 // "Export" the updated position. | |
205 unsigned advancedChars = m_is8Bit ? m_data.characters8 - m_start.charact ers8 : m_data.characters16 - m_start.characters16; | |
206 *m_outPosition += advancedChars; | |
207 } | |
208 | |
209 private: | |
210 unsigned* m_outPosition; | |
211 union { | |
212 const LChar* characters8; | |
213 const UChar* characters16; | |
214 } m_start; | |
215 }; | |
216 | |
217 } | |
218 | |
219 #endif | |
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