1/****************************************************************************
2**
3** Copyright (C) 2016 The Qt Company Ltd.
4** Copyright (C) 2014 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
5** Contact: https://www.qt.io/licensing/
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39****************************************************************************/
40
41#ifndef QSTRINGITERATOR_H
42#define QSTRINGITERATOR_H
43
44//
45// W A R N I N G
46// -------------
47//
48// This file is not part of the Qt API. It exists purely as an
49// implementation detail. This header file may change from version to
50// version without notice, or even be removed.
51//
52// We mean it.
53//
54
55#include <QtCore/private/qglobal_p.h>
56#include <QtCore/qstring.h>
57
58QT_BEGIN_NAMESPACE
59
60class QStringIterator
61{
62 QString::const_iterator i, pos, e;
63 static_assert((std::is_same<QString::const_iterator, const QChar *>::value));
64public:
65 explicit QStringIterator(QStringView string, qsizetype idx = 0)
66 : i(string.begin()),
67 pos(i + idx),
68 e(string.end())
69 {
70 }
71
72 inline explicit QStringIterator(const QChar *begin, const QChar *end)
73 : i(begin),
74 pos(begin),
75 e(end)
76 {
77 }
78
79 inline explicit QStringIterator(const QChar *begin, int idx, const QChar *end)
80 : i(begin),
81 pos(begin + idx),
82 e(end)
83 {
84 }
85
86 inline QString::const_iterator position() const
87 {
88 return pos;
89 }
90
91 inline int index() const
92 {
93 return int(pos - i);
94 }
95
96 inline void setPosition(QString::const_iterator position)
97 {
98 Q_ASSERT_X(i <= position && position <= e, Q_FUNC_INFO, "position out of bounds");
99 pos = position;
100 }
101
102 // forward iteration
103
104 inline bool hasNext() const
105 {
106 return pos < e;
107 }
108
109 inline void advance()
110 {
111 Q_ASSERT_X(hasNext(), Q_FUNC_INFO, "iterator hasn't a next item");
112
113 if (Q_UNLIKELY((pos++)->isHighSurrogate())) {
114 if (Q_LIKELY(pos != e && pos->isLowSurrogate()))
115 ++pos;
116 }
117 }
118
119 inline void advanceUnchecked()
120 {
121 Q_ASSERT_X(hasNext(), Q_FUNC_INFO, "iterator hasn't a next item");
122
123 if (Q_UNLIKELY((pos++)->isHighSurrogate()))
124 ++pos;
125 }
126
127 inline char32_t peekNextUnchecked() const
128 {
129 Q_ASSERT_X(hasNext(), Q_FUNC_INFO, "iterator hasn't a next item");
130
131 if (Q_UNLIKELY(pos->isHighSurrogate()))
132 return QChar::surrogateToUcs4(pos[0], pos[1]);
133
134 return pos->unicode();
135 }
136
137 inline char32_t peekNext(char32_t invalidAs = QChar::ReplacementCharacter) const
138 {
139 Q_ASSERT_X(hasNext(), Q_FUNC_INFO, "iterator hasn't a next item");
140
141 if (Q_UNLIKELY(pos->isSurrogate())) {
142 if (Q_LIKELY(pos->isHighSurrogate())) {
143 const QChar *low = pos + 1;
144 if (Q_LIKELY(low != e && low->isLowSurrogate()))
145 return QChar::surrogateToUcs4(*pos, *low);
146 }
147 return invalidAs;
148 }
149
150 return pos->unicode();
151 }
152
153 inline char32_t nextUnchecked()
154 {
155 Q_ASSERT_X(hasNext(), Q_FUNC_INFO, "iterator hasn't a next item");
156
157 const QChar cur = *pos++;
158 if (Q_UNLIKELY(cur.isHighSurrogate()))
159 return QChar::surrogateToUcs4(cur, *pos++);
160 return cur.unicode();
161 }
162
163 inline char32_t next(char32_t invalidAs = QChar::ReplacementCharacter)
164 {
165 Q_ASSERT_X(hasNext(), Q_FUNC_INFO, "iterator hasn't a next item");
166
167 const QChar uc = *pos++;
168 if (Q_UNLIKELY(uc.isSurrogate())) {
169 if (Q_LIKELY(uc.isHighSurrogate() && pos < e && pos->isLowSurrogate()))
170 return QChar::surrogateToUcs4(uc, *pos++);
171 return invalidAs;
172 }
173
174 return uc.unicode();
175 }
176
177 // backwards iteration
178
179 inline bool hasPrevious() const
180 {
181 return pos > i;
182 }
183
184 inline void recede()
185 {
186 Q_ASSERT_X(hasPrevious(), Q_FUNC_INFO, "iterator hasn't a previous item");
187
188 if (Q_UNLIKELY((--pos)->isLowSurrogate())) {
189 const QChar *high = pos - 1;
190 if (Q_LIKELY(high != i - 1 && high->isHighSurrogate()))
191 --pos;
192 }
193 }
194
195 inline void recedeUnchecked()
196 {
197 Q_ASSERT_X(hasPrevious(), Q_FUNC_INFO, "iterator hasn't a previous item");
198
199 if (Q_UNLIKELY((--pos)->isLowSurrogate()))
200 --pos;
201 }
202
203 inline char32_t peekPreviousUnchecked() const
204 {
205 Q_ASSERT_X(hasPrevious(), Q_FUNC_INFO, "iterator hasn't a previous item");
206
207 if (Q_UNLIKELY(pos[-1].isLowSurrogate()))
208 return QChar::surrogateToUcs4(pos[-2], pos[-1]);
209 return pos[-1].unicode();
210 }
211
212 inline char32_t peekPrevious(char32_t invalidAs = QChar::ReplacementCharacter) const
213 {
214 Q_ASSERT_X(hasPrevious(), Q_FUNC_INFO, "iterator hasn't a previous item");
215
216 if (Q_UNLIKELY(pos[-1].isSurrogate())) {
217 if (Q_LIKELY(pos[-1].isLowSurrogate())) {
218 const QChar *high = pos - 2;
219 if (Q_LIKELY(high != i - 1 && high->isHighSurrogate()))
220 return QChar::surrogateToUcs4(*high, pos[-1]);
221 }
222 return invalidAs;
223 }
224
225 return pos[-1].unicode();
226 }
227
228 inline char32_t previousUnchecked()
229 {
230 Q_ASSERT_X(hasPrevious(), Q_FUNC_INFO, "iterator hasn't a previous item");
231
232 const QChar cur = *--pos;
233 if (Q_UNLIKELY(cur.isLowSurrogate()))
234 return QChar::surrogateToUcs4(*--pos, cur);
235 return cur.unicode();
236 }
237
238 inline char32_t previous(char32_t invalidAs = QChar::ReplacementCharacter)
239 {
240 Q_ASSERT_X(hasPrevious(), Q_FUNC_INFO, "iterator hasn't a previous item");
241
242 const QChar uc = *--pos;
243 if (Q_UNLIKELY(uc.isSurrogate())) {
244 if (Q_LIKELY(uc.isLowSurrogate() && pos > i && pos[-1].isHighSurrogate()))
245 return QChar::surrogateToUcs4(*--pos, uc);
246 return invalidAs;
247 }
248
249 return uc.unicode();
250 }
251};
252
253QT_END_NAMESPACE
254
255#endif // QSTRINGITERATOR_H
256