summaryrefslogtreecommitdiff
path: root/src/xmlpatterns/expr/qexpressionsequence.cpp
blob: 193e15feb7e1f5a31677c3e5bf1995ebe764b62c (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
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtXmlPatterns module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qcardinalityverifier_p.h"
#include "qcommonsequencetypes_p.h"
#include "qemptysequence_p.h"
#include "qabstractxmlforwarditerator_p.h"
#include "qliteral_p.h"
#include "qsequencemappingiterator_p.h"

#include "qexpressionsequence_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

ExpressionSequence::ExpressionSequence(const Expression::List &ops) : UnlimitedContainer(ops)
{
    Q_ASSERT_X(1 < ops.count(), Q_FUNC_INFO,
               "It makes no sense to have an ExpressionSequence containing less than two expressions.");
}

Item::Iterator::Ptr ExpressionSequence::mapToSequence(const Expression::Ptr &expr,
                                                      const DynamicContext::Ptr &context) const
{
    return expr->evaluateSequence(context);
}

Item::Iterator::Ptr ExpressionSequence::evaluateSequence(const DynamicContext::Ptr &context) const
{
    return makeSequenceMappingIterator<Item>(ConstPtr(this),
                                             makeListIterator(m_operands),
                                             context);
}

void ExpressionSequence::evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const
{
    Expression::List::const_iterator it(m_operands.constBegin());
    const Expression::List::const_iterator end(m_operands.constEnd());
    Expression::List result;

    for(; it != end; ++it)
        (*it)->evaluateToSequenceReceiver(context);
}

Expression::Ptr ExpressionSequence::compress(const StaticContext::Ptr &context)
{
    const Expression::Ptr me(UnlimitedContainer::compress(context));

    if(me != this)
        return me;

    Expression::List::const_iterator it(m_operands.constBegin());
    const Expression::List::const_iterator end(m_operands.constEnd());
    Expression::List result;

    for(; it != end; ++it)
    {
        const ID Id = (*it)->id();

        /* Remove empty sequences. This is rather important because we have some steps in the parser that
         * intentionally, unconditionally and for temporary reasons create expressions like (expr, ()). Of course,
         * empty sequences also occur as part of optimizations.
         *
         * User function call sites that are of type empty-sequence() must be avoided since
         * they may contain calls to fn:error(), which we would rewrite away otherwise. */
        if(Id != IDUserFunctionCallsite && (*it)->staticType()->cardinality().isEmpty())
        {
            /* Rewrite "(1, (), 2)" into "(1, 2)" by not
             * adding (*it) to result. */
            continue;
        }
        else if(Id == IDExpressionSequence)
        {
            /* Rewrite "(1, (2, 3), 4)" into "(1, 2, 3, 4)" */
            Expression::List::const_iterator seqIt((*it)->operands().constBegin());
            const Expression::List::const_iterator seqEnd((*it)->operands().constEnd());

            for(; seqIt != seqEnd; ++seqIt)
                result.append(*seqIt);
        } else if (Id == IDLiteralSequence) {
            /* Rewrite "(1, (2, 3), 4)" into "(1, 2, 3, 4)" */
            // Note: LiteralSequence does not use the dynamic context, so we pass in a nullptr.
            Item::Iterator::Ptr seqIt = (*it)->evaluateSequence(DynamicContext::Ptr(Q_NULLPTR));

            while (!seqIt->next().isNull())
                result.append(Literal::Ptr(new Literal(seqIt->current())));
        }
        else
            result.append(*it);
    }

    if(result.isEmpty())
        return EmptySequence::create(this, context);
    else if(result.count() == 1)
        return result.first();
    else
    {
        m_operands = result;
        return me;
    }
}

Expression::Ptr ExpressionSequence::typeCheck(const StaticContext::Ptr &context,
                                              const SequenceType::Ptr &reqType)
{
    Q_ASSERT(reqType);
    Expression::List::iterator it(m_operands.begin());
    const Expression::List::iterator end(m_operands.end());

    /* We treat the cardinality differently here by allowing the empty sequence
     * for each individual Expression, since the Cardinality can be conformed to by
     * the ExpressionSequence as a whole(which we check for at the end). */
    const SequenceType::Ptr testOnlyIT(makeGenericSequenceType(reqType->itemType(),
                                                               Cardinality::empty() |
                                                               reqType->cardinality()));

    for(; it != end; ++it)
        *it = (*it)->typeCheck(context, testOnlyIT);

    /* The above loop is only guaranteed to find item type errors, but the cardinality
     * can still be wrong since the operands were treated individually. */
    return CardinalityVerifier::verifyCardinality(Expression::Ptr(this), reqType->cardinality(), context);
}

Expression::Properties ExpressionSequence::properties() const
{
    const Expression::List::const_iterator end(m_operands.constEnd());
    Expression::List::const_iterator it;
    bool allEvaled = true;
    Expression::Properties props(DisableElimination); /* Why do we have this flag? */

    for(it = m_operands.constBegin(); it != end; ++it)
    {
        const Expression::Properties newp((*it)->properties());
        props |= newp;

        if((newp & IsEvaluated) != IsEvaluated)
        {
            allEvaled = false;
            break;
        }
    }

    if(!allEvaled)
        props &= ~IsEvaluated; /* Remove IsEvaluated. */

    /* One of our children might need the focus, but we don't, so
     * cut it out. */
    return props & ~RequiresFocus;
}

SequenceType::Ptr ExpressionSequence::staticType() const
{
    return operandsUnionType<ProductOfCardinality>();
}

SequenceType::List ExpressionSequence::expectedOperandTypes() const
{
    SequenceType::List result;
    /* ExpressionSequence is a bit strange type wise since it has an
     * infinite amount of operands. */
    result.append(CommonSequenceTypes::ZeroOrMoreItems);
    return result;
}

ExpressionVisitorResult::Ptr ExpressionSequence::accept(const ExpressionVisitor::Ptr &visitor) const
{
    return visitor->visit(this);
}

Expression::ID ExpressionSequence::id() const
{
    return IDExpressionSequence;
}

QT_END_NAMESPACE