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39
40#include "qcardinalityverifier_p.h"
41#include "qcommonsequencetypes_p.h"
42#include "qemptysequence_p.h"
43#include "qabstractxmlforwarditerator_p.h"
44#include "qliteral_p.h"
45#include "qsequencemappingiterator_p.h"
46
47#include "qexpressionsequence_p.h"
48
49#include <algorithm>
50#include <iterator>
51
52QT_BEGIN_NAMESPACE
53
54using namespace QPatternist;
55
56ExpressionSequence::ExpressionSequence(const Expression::List &ops) : UnlimitedContainer(ops)
57{
58 Q_ASSERT_X(1 < ops.count(), Q_FUNC_INFO,
59 "It makes no sense to have an ExpressionSequence containing less than two expressions.");
60}
61
62Item::Iterator::Ptr ExpressionSequence::mapToSequence(const Expression::Ptr &expr,
63 const DynamicContext::Ptr &context) const
64{
65 return expr->evaluateSequence(context);
66}
67
68Item::Iterator::Ptr ExpressionSequence::evaluateSequence(const DynamicContext::Ptr &context) const
69{
70 return makeSequenceMappingIterator<Item>(mapper: ConstPtr(this),
71 source: makeListIterator(list: m_operands),
72 context);
73}
74
75void ExpressionSequence::evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const
76{
77 Expression::List::const_iterator it(m_operands.constBegin());
78 const Expression::List::const_iterator end(m_operands.constEnd());
79 Expression::List result;
80
81 for(; it != end; ++it)
82 (*it)->evaluateToSequenceReceiver(context);
83}
84
85Expression::Ptr ExpressionSequence::compress(const StaticContext::Ptr &context)
86{
87 const Expression::Ptr me(UnlimitedContainer::compress(context));
88
89 if(me != this)
90 return me;
91
92 Expression::List::const_iterator it(m_operands.constBegin());
93 const Expression::List::const_iterator end(m_operands.constEnd());
94 Expression::List result;
95
96 for(; it != end; ++it)
97 {
98 const ID Id = (*it)->id();
99
100 /* Remove empty sequences. This is rather important because we have some steps in the parser that
101 * intentionally, unconditionally and for temporary reasons create expressions like (expr, ()). Of course,
102 * empty sequences also occur as part of optimizations.
103 *
104 * User function call sites that are of type empty-sequence() must be avoided since
105 * they may contain calls to fn:error(), which we would rewrite away otherwise. */
106 if(Id != IDUserFunctionCallsite && (*it)->staticType()->cardinality().isEmpty())
107 {
108 /* Rewrite "(1, (), 2)" into "(1, 2)" by not
109 * adding (*it) to result. */
110 continue;
111 }
112 else if(Id == IDExpressionSequence)
113 {
114 /* Rewrite "(1, (2, 3), 4)" into "(1, 2, 3, 4)" */
115 const auto &operands = (*it)->operands();
116 std::copy(first: operands.cbegin(), last: operands.cend(), result: std::back_inserter(x&: result));
117 } else if (Id == IDLiteralSequence) {
118 /* Rewrite "(1, (2, 3), 4)" into "(1, 2, 3, 4)" */
119 // Note: LiteralSequence does not use the dynamic context, so we pass in a nullptr.
120 Item::Iterator::Ptr seqIt = (*it)->evaluateSequence(context: DynamicContext::Ptr(nullptr));
121
122 while (!seqIt->next().isNull())
123 result.append(t: Literal::Ptr(new Literal(seqIt->current())));
124 }
125 else
126 result.append(t: *it);
127 }
128
129 if(result.isEmpty())
130 return EmptySequence::create(replacementFor: this, context);
131 else if(result.count() == 1)
132 return result.first();
133 else
134 {
135 m_operands = result;
136 return me;
137 }
138}
139
140Expression::Ptr ExpressionSequence::typeCheck(const StaticContext::Ptr &context,
141 const SequenceType::Ptr &reqType)
142{
143 Q_ASSERT(reqType);
144 Expression::List::iterator it(m_operands.begin());
145 const Expression::List::iterator end(m_operands.end());
146
147 /* We treat the cardinality differently here by allowing the empty sequence
148 * for each individual Expression, since the Cardinality can be conformed to by
149 * the ExpressionSequence as a whole(which we check for at the end). */
150 const SequenceType::Ptr testOnlyIT(makeGenericSequenceType(itemType: reqType->itemType(),
151 cardinality: Cardinality::empty() |
152 reqType->cardinality()));
153
154 for(; it != end; ++it)
155 *it = (*it)->typeCheck(context, reqType: testOnlyIT);
156
157 /* The above loop is only guaranteed to find item type errors, but the cardinality
158 * can still be wrong since the operands were treated individually. */
159 return CardinalityVerifier::verifyCardinality(operand: Expression::Ptr(this), card: reqType->cardinality(), context);
160}
161
162Expression::Properties ExpressionSequence::properties() const
163{
164 const Expression::List::const_iterator end(m_operands.constEnd());
165 Expression::List::const_iterator it;
166 bool allEvaled = true;
167 Expression::Properties props(DisableElimination); /* Why do we have this flag? */
168
169 for(it = m_operands.constBegin(); it != end; ++it)
170 {
171 const Expression::Properties newp((*it)->properties());
172 props |= newp;
173
174 if((newp & IsEvaluated) != IsEvaluated)
175 {
176 allEvaled = false;
177 break;
178 }
179 }
180
181 if(!allEvaled)
182 props &= ~IsEvaluated; /* Remove IsEvaluated. */
183
184 /* One of our children might need the focus, but we don't, so
185 * cut it out. */
186 return props & ~RequiresFocus;
187}
188
189SequenceType::Ptr ExpressionSequence::staticType() const
190{
191 return operandsUnionType<ProductOfCardinality>();
192}
193
194SequenceType::List ExpressionSequence::expectedOperandTypes() const
195{
196 SequenceType::List result;
197 /* ExpressionSequence is a bit strange type wise since it has an
198 * infinite amount of operands. */
199 result.append(t: CommonSequenceTypes::ZeroOrMoreItems);
200 return result;
201}
202
203ExpressionVisitorResult::Ptr ExpressionSequence::accept(const ExpressionVisitor::Ptr &visitor) const
204{
205 return visitor->visit(this);
206}
207
208Expression::ID ExpressionSequence::id() const
209{
210 return IDExpressionSequence;
211}
212
213QT_END_NAMESPACE
214

source code of qtxmlpatterns/src/xmlpatterns/expr/qexpressionsequence.cpp