summaryrefslogtreecommitdiffstats
path: root/src/xmlpatterns/functions/qsequencefns_p.h
blob: 3f79a5f55e382a28324f1508429956e3fd8e0f81 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Qt Software Information (qt-info@nokia.com)
**
** This file is part of the QtXmlPatterns module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the either Technology Preview License Agreement or the
** Beta Release License Agreement.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain
** additional rights. These rights are described in the Nokia Qt LGPL
** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you are unsure which license is appropriate for your use, please
** contact the sales department at qt-sales@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/

//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.

#ifndef Patternist_SequenceFNs_H
#define Patternist_SequenceFNs_H

#include "qatomiccomparator_p.h"
#include "qcomparisonplatform_p.h"
#include "qliteral_p.h"
#include "qfunctioncall_p.h"

/**
 * @file
 * @short Contains classes implementing the functions found in
 * <a href="http://www.w3.org/TR/xpath-functions/#general-seq-funcs">XQuery 1.0 and
 * XPath 2.0 Functions and Operators, 15.1 General Functions and Operators on Sequences</a>.
 *
 * @todo document that some functions have both eval funcs implented.
 *
 * @ingroup Patternist_functions
 */

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist
{
    /**
     * @short Implements the function <tt>fn:boolean()</tt>.
     *
     * @see EBVExtractor
     * @ingroup Patternist_functions
     * @author Frans Englich <fenglich@trolltech.com>
     */
    class BooleanFN : public FunctionCall
    {
    public:
        virtual bool evaluateEBV(const DynamicContext::Ptr &context) const;

        /**
         * If @p reqType is CommonSequenceTypes::EBV, the type check of
         * the operand is returned. Hence, this removes redundant calls
         * to <tt>fn:boolean()</tt>.
         */
        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
                                          const SequenceType::Ptr &reqType);
    };

    /**
     * @short Implements the function <tt>fn:index-of()</tt>.
     *
     * @ingroup Patternist_functions
     * @author Frans Englich <fenglich@trolltech.com>
     */
    class IndexOfFN : public FunctionCall,
                      public ComparisonPlatform<IndexOfFN, false>
    {
    public:
        inline IndexOfFN() : ComparisonPlatform<IndexOfFN, false>()
        {
        }

        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
                                          const SequenceType::Ptr &reqType);

        inline AtomicComparator::Operator operatorID() const
        {
            return AtomicComparator::OperatorEqual;
        }
    };

    /**
     * @short Implements the functions <tt>fn:exists()</tt> and <tt>fn:empty()</tt>.
     *
     * Existence is a template value class. Appropriate implementations are achieved
     * by instantiating it with either IDExistsFN or IDEmptyFN.
     *
     * @ingroup Patternist_functions
     * @author Frans Englich <fenglich@trolltech.com>
     */
    template<const Expression::ID Id>
    class Existence : public FunctionCall
    {
    public:
        virtual bool evaluateEBV(const DynamicContext::Ptr &context) const
        {
            if(Id == IDExistsFN)
                return !m_operands.first()->evaluateSequence(context)->isEmpty();
            else
                return m_operands.first()->evaluateSequence(context)->isEmpty();
        }

        /**
         * Attempts to rewrite to @c false or @c true by looking at the static
         * cardinality of its operand.
         */
        virtual Expression::Ptr compress(const StaticContext::Ptr &context)
        {
            Q_ASSERT(Id == IDExistsFN || Id == IDEmptyFN);
            const Expression::Ptr me(FunctionCall::compress(context));

            if(me != this)
                return me;

            const Cardinality myCard((Id == IDExistsFN) ? Cardinality::oneOrMore() : Cardinality::empty());

            const Cardinality card(m_operands.first()->staticType()->cardinality());
            if(myCard.isMatch(card))
            { /* Since the dynamic type always is narrower than the static type or equal, and that the
                 static type is in scope, it means we will always be true. */
                return wrapLiteral(CommonValues::BooleanTrue, context, this);
            }
            else
            {
                /* Is it even possible to hit? */
                if(myCard.canMatch(card))
                {
                    return me;
                }
                else
                { /* We can never hit. */
                    return wrapLiteral(CommonValues::BooleanFalse, context, this);
                }
            }
        }
    };

    /**
     * @short Implements the function <tt>fn:distinct-values()</tt>.
     *
     * @ingroup Patternist_functions
     * @author Frans Englich <fenglich@trolltech.com>
     */
    class DistinctValuesFN : public FunctionCall,
                             public ComparisonPlatform<IndexOfFN, false>
    {
    public:
        inline DistinctValuesFN() : ComparisonPlatform<IndexOfFN, false>()
        {
        }

        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
        /**
         * Performs necessary type checks, but also implements the optimization
         * of rewriting to its operand if the operand's cardinality is zero-or-one
         * or exactly-one.
         */
        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
                                          const SequenceType::Ptr &reqType);
        /**
         * @returns a type whose item type is the type of the first operand, and
         * a cardinality which is non-empty if the first operand's type is non-empty
         * and allows exactly-one. The latter is needed for operands which has the
         * cardinality 2+, since distinct-values possibly removes items from the
         * source sequence.
         */
        virtual SequenceType::Ptr staticType() const;

    protected:
        inline AtomicComparator::Operator operatorID() const
        {
            return AtomicComparator::OperatorEqual;
        }
    };

    /**
     * @short Implements the function <tt>fn:insert-before()</tt>.
     *
     * @todo docs, explain why evaluateSequence and evaluateSingleton is implemented
     *
     * @ingroup Patternist_functions
     * @author Frans Englich <fenglich@trolltech.com>
     */
    class InsertBeforeFN : public FunctionCall
    {
    public:
        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
        virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;

        /**
         * Implements the static enferences rules. The function's static item type
         * is the union type of the first and third argument, and the cardinality is
         * the cardinalities of the two operands added together. For example,
         * insert-before((1, "str"), 1, xs:double(0)) has the static type xs:anyAtomicType+.
         *
         * @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_insert_before">XQuery 1.0
         * and XPath 2.0 Formal Semantics, 7.2.15 The fn:insert-before function</a>
         */
        virtual SequenceType::Ptr staticType() const;
    };

    /**
     * @short Implements the function <tt>fn:remove()</tt>.
     *
     * @ingroup Patternist_functions
     * @author Frans Englich <fenglich@trolltech.com>
     */
    class RemoveFN : public FunctionCall
    {
    public:
        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
        virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;

        /**
         * Implements the static enferences rules, "Since one item may be removed
         * from the sequence, the resulting type is made optional:"
         *
         * <tt>statEnv |-  (FN-URI,"remove")(Type, Type1) : prime(Type) * quantifier(Type)?</tt>
         *
         * However, because Patternist's type system is more fine grained than Formal Semantics,
         * the sequence isn't made optional. Instead its minimum length is reduced with one.
         *
         * @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_remove">XQuery 1.0
         * and XPath 2.0 Formal Semantics, 7.2.11 The fn:remove function</a>
         */
        virtual SequenceType::Ptr staticType() const;
    };

    /**
     * @short Implements the function <tt>fn:reverse()</tt>.
     *
     * @ingroup Patternist_functions
     * @author Frans Englich <fenglich@trolltech.com>
     */
    class ReverseFN : public FunctionCall
    {
    public:

        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
                                          const SequenceType::Ptr &reqType);

        /**
         * Formally speaking, the type inference is:
         *
@verbatim
statEnv |-  (FN-URI,"reverse")(Type) : prime(Type) * quantifier(Type)
@endverbatim
         *
         * @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_reverse">XQuery 1.0
         * and XPath 2.0 Formal Semantics, 7.2.12 The fn:reverse function</a>
         * @returns the static type of the function's first argument.
         */
        virtual SequenceType::Ptr staticType() const;
    };

    /**
     * @short Implements the function <tt>fn:subsequence()</tt>.
     *
     * @ingroup Patternist_functions
     * @author Frans Englich <fenglich@trolltech.com>
     * @todo Type inference can be made stronger for this function
     */
    class SubsequenceFN : public FunctionCall
    {
    public:
        SubsequenceFN();
        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
        virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;

        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
                                          const SequenceType::Ptr &reqType);

        /**
         * This function implements rewrites the SubsequenceFN instance into an
         * empty sequence if its third argument, the sequence length argument, is
         * evaluated and is effectively equal or less than zero.
         */
        virtual Expression::Ptr compress(const StaticContext::Ptr &context);

        /**
         * Partially implements the static type inference rules.
         *
         * @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_subsequence">XQuery 1.0
         * and XPath 2.0 Formal Semantics, 7.2.13 The fn:subsequence function</a>
         */
        virtual SequenceType::Ptr staticType() const;

    private:
        bool m_hasTypeChecked;
    };
}

QT_END_NAMESPACE

QT_END_HEADER

#endif