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39
40//
41// W A R N I N G
42// -------------
43//
44// This file is not part of the Qt API. It exists purely as an
45// implementation detail. This header file may change from version to
46// version without notice, or even be removed.
47//
48// We mean it.
49
50#ifndef Patternist_DynamicContext_H
51#define Patternist_DynamicContext_H
52
53#include <private/qautoptr_p.h>
54#include <private/qcachecells_p.h>
55#include <private/qexternalvariableloader_p.h>
56#include <private/qitem_p.h>
57#include <private/qnamepool_p.h>
58#include <private/qnodebuilder_p.h>
59#include <private/qprimitives_p.h>
60#include <private/qreportcontext_p.h>
61#include <private/qresourceloader_p.h>
62
63QT_BEGIN_NAMESPACE
64
65class QDateTime;
66template<typename T> class QVector;
67
68namespace QPatternist
69{
70 class DayTimeDuration;
71 class Expression;
72 class TemplateMode;
73
74 /**
75 * @short Carries information and facilities used at runtime, and hence
76 * provides a state for that stage in a thread-safe manner.
77 *
78 * @see <a href="http://www.w3.org/TR/xquery/#eval_context">XQuery
79 * 1.0: An XML Query Language, 2.1.2 Dynamic Context</a>
80 * @see <a href="http://www.w3.org/TR/xquery/#id-dynamic-evaluation">XQuery
81 * 1.0: An XML Query Language, 2.2.3.2 Dynamic Evaluation Phase</a>
82 * @author Frans Englich <frans.englich@nokia.com>
83 */
84 class DynamicContext : public ReportContext
85 {
86 public:
87 /**
88 * @short Carries template parameters at runtime.
89 *
90 * The key is the name of the parameter, and the value the Expression
91 * which supplies the value.
92 */
93 typedef QHash<QXmlName, QExplicitlySharedDataPointer<Expression> > TemplateParameterHash;
94 typedef QExplicitlySharedDataPointer<DynamicContext> Ptr;
95
96 virtual ~DynamicContext()
97 {
98 }
99
100 /**
101 * This function intentionally returns by reference.
102 *
103 * @see globalItemCacheCell()
104 */
105 virtual ItemCacheCell &itemCacheCell(const VariableSlotID slot) = 0;
106
107 /**
108 * This function intentionally returns by reference.
109 *
110 * @see globalItemSequenceCacheCells
111 */
112 virtual ItemSequenceCacheCell::Vector &itemSequenceCacheCells(const VariableSlotID slot) = 0;
113
114 virtual xsInteger contextPosition() const = 0;
115 virtual Item contextItem() const = 0;
116 virtual xsInteger contextSize() = 0;
117
118 virtual void setRangeVariable(const VariableSlotID slot,
119 const Item &newValue) = 0;
120 virtual Item rangeVariable(const VariableSlotID slot) const = 0;
121 virtual void setExpressionVariable(const VariableSlotID slot,
122 const QExplicitlySharedDataPointer<Expression> &newValue) = 0;
123 virtual QExplicitlySharedDataPointer<Expression>
124 expressionVariable(const VariableSlotID slot) const = 0;
125
126 virtual Item::Iterator::Ptr positionIterator(const VariableSlotID slot) const = 0;
127 virtual void setPositionIterator(const VariableSlotID slot,
128 const Item::Iterator::Ptr &newValue) = 0;
129
130 virtual void setFocusIterator(const Item::Iterator::Ptr &it) = 0;
131 virtual Item::Iterator::Ptr focusIterator() const = 0;
132
133 virtual QExplicitlySharedDataPointer<DayTimeDuration> implicitTimezone() const = 0;
134 virtual QDateTime currentDateTime() const = 0;
135
136 virtual QAbstractXmlReceiver *outputReceiver() const = 0;
137 virtual NodeBuilder::Ptr nodeBuilder(const QUrl &baseURI) const = 0;
138 virtual ResourceLoader::Ptr resourceLoader() const = 0;
139 virtual ExternalVariableLoader::Ptr externalVariableLoader() const = 0;
140 virtual NamePool::Ptr namePool() const = 0;
141
142 /**
143 * @short Returns the item that @c fn:current() returns.
144 *
145 * Hence, this is not the focus, and very different from the focus.
146 *
147 * @see CurrentItemStore
148 * @see CurrentFN
149 */
150 virtual Item currentItem() const = 0;
151
152 DynamicContext::Ptr createFocus();
153 DynamicContext::Ptr createStack();
154 DynamicContext::Ptr createReceiverContext(QAbstractXmlReceiver *const receiver);
155
156 /**
157 * Whenever a tree gets built, this function is called. DynamicContext
158 * has the responsibility of keeping a copy of @p nm, such that it
159 * doesn't go out of scope, since no one else will reference @p nm.
160 *
161 * I think this is currently only used for temporary node trees. In
162 * other cases they are stored in the ExternalResourceLoader.
163 *
164 * The caller guarantees that @p nm is not @c null.
165 */
166 virtual void addNodeModel(const QAbstractXmlNodeModel::Ptr &nm) = 0;
167
168 /**
169 * Same as itemCacheCell(), but is only used for global varibles. This
170 * is needed because sometimes stack frames needs to be created for
171 * other kinds of variables(such as in the case of user function
172 * calls), while the global variable(s) needs to continue to use the
173 * same cache, instead of one for each new stack frame, typically an
174 * instance of StackContextBase.
175 *
176 * This has two effects:
177 *
178 * - It's an optimization. Instead of that a global variable gets evaluated each
179 * time a user function is called, think recursive functions, it's done
180 * only once.
181 * - Query stability, hence affects things like node identity and
182 * therefore conformance. Hence affects for instance what nodes a query
183 * returns, since node identity affect node deduplication.
184 */
185 virtual ItemCacheCell &globalItemCacheCell(const VariableSlotID slot) = 0;
186
187 /**
188 * @short When a template is called, this member carries the template
189 * parameters.
190 *
191 * Hence this is similar to the other variable stack functions such as
192 * rangeVariable() and expressionVariable(), the difference being that
193 * the order of template parameters as well as its arguments can appear
194 * in arbitrary order. Hence the name is used to make the order
195 * insignificant.
196 */
197 virtual TemplateParameterHash &templateParameterStore() = 0;
198
199 /**
200 * Same as itemSequenceCacheCells() but applies only for global
201 * variables.
202 *
203 * @see globalItemCacheCell()
204 */
205 virtual ItemSequenceCacheCell::Vector &globalItemSequenceCacheCells(const VariableSlotID slot) = 0;
206
207 /**
208 * @short Returns the previous DynamicContext. If this context is the
209 * top-level one, @c null is returned.
210 */
211 virtual DynamicContext::Ptr previousContext() const = 0;
212
213 /**
214 * @short Returns the current template mode that is in effect.
215 *
216 * If @c null is returned, it means that the default mode should be
217 * used as the current mode.
218 */
219 virtual QExplicitlySharedDataPointer<TemplateMode> currentTemplateMode() const = 0;
220 };
221}
222
223QT_END_NAMESPACE
224
225#endif
226

source code of qtxmlpatterns/src/xmlpatterns/environment/qdynamiccontext_p.h