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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_TypeChecker_H
51#define Patternist_TypeChecker_H
52
53#include <private/qstaticcontext_p.h>
54#include <private/qexpression_p.h>
55
56QT_BEGIN_NAMESPACE
57
58namespace QPatternist
59{
60 /**
61 * @short Contains functions that applies Function Conversion Rules and other
62 * kinds of compile-time type checking tasks.
63 *
64 * @ingroup Patternist_types
65 * @author Frans Englich <frans.englich@nokia.com>
66 */
67 class TypeChecker
68 {
69 public:
70 enum Option
71 {
72 /**
73 * @short When set, the function conversion rules are applied.
74 *
75 * For instance, this is type promotion and conversions from @c
76 * xs:untypedAtomic to @c xs:date. This is done for function calls,
77 * but not when binding an expression to a variable.
78 */
79 AutomaticallyConvert = 1,
80
81 /**
82 * @short Whether the focus should be checked or not.
83 *
84 * Sometimes the focus is unknown at the time
85 * applyFunctionConversion() is called, and therefore it is
86 * of interest to post pone the check to later on.
87 */
88 CheckFocus = 2,
89
90 /**
91 * When applyFunctionConversion() is passed AutomaticallyConvert
92 * and promotion is required, such as from @c xs:integer to
93 * @c xs:float, there will be no conversion performed, with the
94 * assumption that the receiver will call Numeric::toFloat() or
95 * similar.
96 *
97 * However, when GeneratePromotion is set, code will be generated
98 * that performs this conversion regardless of what any receiver
99 * do.
100 *
101 * This is useful in the case where one Expression only pipes the
102 * result of another. The only known case of that as of this
103 * writing is when UserFunctionCallsite evaluates its body.
104 */
105 GeneratePromotion
106 };
107 typedef QFlags<Option> Options;
108
109 /**
110 * @short Builds a pipeline of artificial AST nodes that ensures @p operand
111 * conforms to the type @p reqType by applying the Function
112 * Conversion Rules.
113 *
114 * This new Expression is returned, or, if no conversions were necessary,
115 * @p operand as it is.
116 *
117 * applyFunctionConversion() also performs various checks, such as if
118 * @p operand needs the focus and that the focus is defined in the
119 * @p context. These checks are largely guided by @p operand's
120 * Expression::properties().
121 *
122 * @see <a href="http://www.w3.org/TR/xpath20/\#id-function-calls">XML Path
123 * Language (XPath) 2.0, 3.1.5 Function Calls</a>, more specifically the
124 * Function Conversion Rules
125 */
126 static Expression::Ptr
127 applyFunctionConversion(const Expression::Ptr &operand,
128 const SequenceType::Ptr &reqType,
129 const StaticContext::Ptr &context,
130 const ReportContext::ErrorCode code = ReportContext::XPTY0004,
131 const Options = Options(AutomaticallyConvert | CheckFocus));
132 private:
133
134 static inline Expression::Ptr typeCheck(Expression *const op,
135 const StaticContext::Ptr &context,
136 const SequenceType::Ptr &reqType);
137 /**
138 * @short Implements the type checking and promotion part of the Function Conversion Rules.
139 */
140 static Expression::Ptr verifyType(const Expression::Ptr &operand,
141 const SequenceType::Ptr &reqSeqType,
142 const StaticContext::Ptr &context,
143 const ReportContext::ErrorCode code,
144 const Options options);
145
146 /**
147 * Determines whether type promotion is possible from one type to another. False
148 * is returned when a promotion is not possible or if a promotion is not needed(as when
149 * the types are identical), since that can be considered to not be type promotion.
150 *
151 * @returns @c true if @p fromType can be promoted to @p toType.
152 * @see <a href="http://www.w3.org/TR/xpath20/#promotion">XML Path Language
153 * (XPath) 2.0, B.1 Type Promotion</a>
154 */
155 static bool promotionPossible(const ItemType::Ptr &fromType,
156 const ItemType::Ptr &toType,
157 const StaticContext::Ptr &context);
158
159 /**
160 * @short Centralizes a message-string to reduce work for translators
161 * and increase consistency.
162 */
163 static inline QString wrongType(const NamePool::Ptr &np,
164 const ItemType::Ptr &reqType,
165 const ItemType::Ptr &opType);
166
167 /**
168 * No implementation is provided for this constructor. This class
169 * is not supposed to be instantiated.
170 */
171 inline TypeChecker();
172
173 Q_DISABLE_COPY(TypeChecker)
174 };
175}
176
177QT_END_NAMESPACE
178
179#endif
180

source code of qtxmlpatterns/src/xmlpatterns/type/qtypechecker_p.h