source: trunk/src/xmlpatterns/expr/qexpression.cpp@ 98

Last change on this file since 98 was 2, checked in by Dmitry A. Kuminov, 16 years ago

Initially imported qt-all-opensource-src-4.5.1 from Trolltech.
File size: 13.3 KB
Line 
1/****************************************************************************
2**
3** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
4** Contact: Qt Software Information ([email protected])
5**
6** This file is part of the QtXmlPatterns module of the Qt Toolkit.
7**
8** $QT_BEGIN_LICENSE:LGPL$
9** Commercial Usage
10** Licensees holding valid Qt Commercial licenses may use this file in
11** accordance with the Qt Commercial License Agreement provided with the
12** Software or, alternatively, in accordance with the terms contained in
13** a written agreement between you and Nokia.
14**
15** GNU Lesser General Public License Usage
16** Alternatively, this file may be used under the terms of the GNU Lesser
17** General Public License version 2.1 as published by the Free Software
18** Foundation and appearing in the file LICENSE.LGPL included in the
19** packaging of this file. Please review the following information to
20** ensure the GNU Lesser General Public License version 2.1 requirements
21** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
22**
23** In addition, as a special exception, Nokia gives you certain
24** additional rights. These rights are described in the Nokia Qt LGPL
25** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
26** package.
27**
28** GNU General Public License Usage
29** Alternatively, this file may be used under the terms of the GNU
30** General Public License version 3.0 as published by the Free Software
31** Foundation and appearing in the file LICENSE.GPL included in the
32** packaging of this file. Please review the following information to
33** ensure the GNU General Public License version 3.0 requirements will be
34** met: http://www.gnu.org/copyleft/gpl.html.
35**
36** If you are unsure which license is appropriate for your use, please
37** contact the sales department at [email protected].
38** $QT_END_LICENSE$
39**
40****************************************************************************/
41
42#include "qboolean_p.h"
43#include "qcommonvalues_p.h"
44#include "qemptysequence_p.h"
45#include "qliteral_p.h"
46#include "qliteralsequence_p.h"
47#include "qoperandsiterator_p.h"
48#include "qoptimizerframework_p.h"
49#include "qstaticfocuscontext_p.h"
50#include "qtypechecker_p.h"
51
52#include "qexpression_p.h"
53
54QT_BEGIN_NAMESPACE
55
56using namespace QPatternist;
57
58Expression::~Expression()
59{
60}
61
62StaticContext::Ptr Expression::finalizeStaticContext(const StaticContext::Ptr &context) const
63{
64 Q_ASSERT(context);
65 const ItemType::Ptr focusType(newFocusType());
66 Q_ASSERT(focusType);
67 return StaticContext::Ptr(new StaticFocusContext(focusType, context));
68}
69
70Expression::Ptr Expression::typeCheck(const StaticContext::Ptr &context,
71 const SequenceType::Ptr &reqType)
72{
73 Q_ASSERT(reqType);
74 typeCheckOperands(context);
75 return TypeChecker::applyFunctionConversion(Expression::Ptr(this), reqType, context);
76}
77
78void Expression::typeCheckOperands(const StaticContext::Ptr &context)
79{
80 const Expression::List ops(operands());
81
82 /* Check if this expression has any operands at all. */
83 if(ops.isEmpty())
84 return; /* We're done, early exit. */
85
86 const SequenceType::List opTypes(expectedOperandTypes());
87 Expression::List result;
88
89 /* If we create a focus, we handle the last one specially, so avoid it in the loop. */
90 const bool createsFocus = has(CreatesFocusForLast);
91 const SequenceType::List::const_iterator typeEnd(createsFocus ? --opTypes.constEnd()
92 : opTypes.constEnd());
93 const Expression::List::const_iterator end(createsFocus ? --ops.constEnd()
94 : ops.constEnd());
95
96 SequenceType::List::const_iterator reqType(opTypes.constBegin());
97 SequenceType::Ptr t(*reqType);
98 // TODO we assign twice to t here(also below in loop) when ops.size() > 1
99
100 Expression::List::const_iterator it(ops.constBegin());
101
102 for(; it != end; ++it)
103 {
104 /* This ensures that the last expectedOperandType stays, and is
105 * used for all other operands. This is used for expressions that
106 * have an infinite amount of operands, such as the concat() function. */
107 if(reqType != typeEnd)
108 {
109 t = *reqType;
110 ++reqType;
111 }
112
113 /* Let the child & its children typecheck. */
114 result.append((*it)->typeCheck(context, t));
115 }
116
117 if(createsFocus)
118 {
119 const StaticContext::Ptr newContext(finalizeStaticContext(context));
120 result.append(ops.last()->typeCheck(newContext, opTypes.last()));
121 }
122
123 setOperands(result);
124}
125
126Expression::Ptr Expression::invokeOptimizers(const Expression::Ptr &expr,
127 const StaticContext::Ptr &context)
128{
129 Q_ASSERT(expr);
130
131 const OptimizationPass::List opts(expr->optimizationPasses());
132
133 if(opts.isEmpty()) /* Early exit. */
134 {
135 return expr;
136 }
137
138 const OptimizationPass::List::const_iterator passEnd(opts.constEnd());
139 const OptimizationPass::List::const_iterator end(opts.constEnd());
140 OptimizationPass::List::const_iterator passIt(opts.constBegin());
141
142 for(; passIt != passEnd; ++passIt) /* Invoke each optimization pass. */
143 {
144 const OptimizationPass::Ptr pass(*passIt); /* Alias, for readability. */
145 OptimizationPass::ExpressionMarker sourceMarker(pass->sourceExpression);
146
147 if(pass->startIdentifier && !pass->startIdentifier->matches(expr))
148 {
149 /* This pass specified a start identifier and it did
150 * not match -- let's try the next OptimizationPass. */
151 continue;
152 }
153
154 const ExpressionIdentifier::List::const_iterator idEnd(pass->operandIdentifiers.constEnd());
155 ExpressionIdentifier::List::const_iterator idIt(pass->operandIdentifiers.constBegin());
156 const Expression::List ops(expr->operands());
157 const Expression::List::const_iterator opEnd(ops.constEnd());
158 Expression::List::const_iterator opIt(ops.constBegin());
159
160 switch(pass->operandsMatchMethod)
161 {
162 case OptimizationPass::Sequential:
163 {
164 for(; opIt != opEnd; ++opIt)
165 {
166 const Expression::Ptr operand(*opIt); /* Alias, for readability. */
167 const ExpressionIdentifier::Ptr opIdentifier(*idIt); /* Alias, for readability. */
168 if(opIdentifier && !opIdentifier->matches(operand))
169 {
170 break;
171 }
172
173 ++idIt;
174 }
175
176 if(opIt == opEnd)
177 break; /* All operands matched, so this pass matched. */
178 else
179 {
180 /* The loop above did not finish which means all operands did not match.
181 Therefore, this OptimizationPass did not match -- let's try the next one. */
182 continue;
183 }
184 }
185 case OptimizationPass::AnyOrder:
186 {
187 Q_ASSERT_X(ops.count() == 2, Q_FUNC_INFO,
188 "AnyOrder is currently only supported for Expressions with two operands.");
189 if(pass->operandIdentifiers.first()->matches(ops.first()) &&
190 pass->operandIdentifiers.last()->matches(ops.last()))
191 {
192 break;
193 }
194 else if(pass->operandIdentifiers.first()->matches(ops.last()) &&
195 pass->operandIdentifiers.last()->matches(ops.first()))
196 {
197 sourceMarker.first() = 1;
198 sourceMarker[1] = 0;
199 break; /* This pass matched. */
200 }
201 else
202 continue; /* This pass didn't match, let's loop through the next pass. */
203 }
204 }
205
206 /* Figure out the source Expression, if any. */
207 Expression::List operands;
208 Expression::Ptr sourceExpr;
209
210 if(!sourceMarker.isEmpty())
211 {
212 const OptimizationPass::ExpressionMarker::const_iterator mEnd(sourceMarker.constEnd());
213 OptimizationPass::ExpressionMarker::const_iterator mIt(sourceMarker.constBegin());
214 sourceExpr = expr;
215
216 for(; mIt != mEnd; ++mIt)
217 {
218 Q_ASSERT(*mIt >= 0);
219 sourceExpr = sourceExpr->operands().at(*mIt);
220 }
221
222 operands.append(sourceExpr);
223 }
224
225 if(operands.isEmpty())
226 {
227 Q_ASSERT(pass->resultCreator);
228 return pass->resultCreator->create(Expression::List(), context, expr.data())->compress(context);
229 }
230 else if(pass->resultCreator)
231 return pass->resultCreator->create(operands, context, expr.data())->compress(context);
232 else
233 {
234 return sourceExpr;
235 }
236 }
237
238 return expr;
239}
240
241Expression::Ptr Expression::compress(const StaticContext::Ptr &context)
242{
243 if(!compressOperands(context))
244 {
245 /* At least one of the operands cannot be evaluated at compile, so
246 * 'this' Expression cannot const fold. */
247 return invokeOptimizers(Expression::Ptr(this), context);
248 }
249
250 Expression::Ptr retval;
251
252 if(hasDependency(DisableElimination))
253 retval = Expression::Ptr(this);
254 else
255 retval = constantPropagate(context);
256
257 return invokeOptimizers(retval, context);
258}
259
260Expression::Ptr Expression::constantPropagate(const StaticContext::Ptr &context) const
261{
262 Q_ASSERT(context);
263
264 /* Optimization: We rewrite literals to literals here, which is pointless.
265 * Maybe we should have a property which says "doesn't disable elimination
266 * but don't eliminate me." */
267 if(staticType()->cardinality().allowsMany())
268 {
269 Item::Iterator::Ptr it(evaluateSequence(context->dynamicContext()));
270 Item::List result;
271 Item item(it->next());
272
273 while(item)
274 {
275 result.append(item);
276 item = it->next();
277 }
278
279 switch(result.count())
280 {
281 case 0:
282 return EmptySequence::create(this, context);
283 case 1:
284 return rewrite(Expression::Ptr(new Literal(result.first())), context);
285 default:
286 return rewrite(Expression::Ptr(new LiteralSequence(result)), context);
287 }
288 }
289 else
290 {
291 const Item item(evaluateSingleton(context->dynamicContext()));
292
293 if(item)
294 return rewrite(Expression::Ptr(new Literal(item)), context);
295 else
296 return EmptySequence::create(this, context);
297 }
298}
299
300Item::Iterator::Ptr Expression::evaluateSequence(const DynamicContext::Ptr &context) const
301{
302 const Item item(evaluateSingleton(context));
303
304 if(item)
305 return makeSingletonIterator(item);
306 else
307 return CommonValues::emptyIterator;
308}
309
310Item Expression::evaluateSingleton(const DynamicContext::Ptr &context) const
311{
312 return Boolean::fromValue(evaluateEBV(context));
313}
314
315bool Expression::evaluateEBV(const DynamicContext::Ptr &context) const
316{
317 return Boolean::evaluateEBV(evaluateSequence(context), context);
318}
319
320void Expression::evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const
321{
322 QAbstractXmlReceiver *const receiver = context->outputReceiver();
323 const Item::Iterator::Ptr it(evaluateSequence(context));
324 Item next(it->next());
325
326 while(next)
327 {
328 receiver->item(next);
329 next = it->next();
330 }
331}
332
333ItemType::Ptr Expression::expectedContextItemType() const
334{
335 Q_ASSERT_X(false, Q_FUNC_INFO,
336 "expectedContextItemType() must be overridden when RequiresContextItem is set.");
337 return ItemType::Ptr();
338}
339
340Expression::Properties Expression::properties() const
341{
342 return Properties();
343}
344
345Expression::Properties Expression::dependencies() const
346{
347 OperandsIterator it(Ptr(const_cast<Expression *>(this)), OperandsIterator::ExcludeParent);
348 Expression::Ptr next(it.next());
349
350 Properties dependencies(properties());
351
352 while(next)
353 {
354 dependencies |= next->dependencies();
355 next = it.next();
356 }
357
358 return dependencies & (Expression::RequiresFocus | Expression::IsEvaluated | Expression::DisableElimination);
359}
360
361void Expression::announceFocusType(const ItemType::Ptr &itemType)
362{
363 const Expression::List ops(operands());
364 const int len = ops.count();
365
366 for(int i = 0; i < len; ++i)
367 ops.at(i)->announceFocusType(itemType);
368}
369
370Expression::Properties Expression::deepProperties() const
371{
372 Properties props(properties());
373 const Expression::List ops(operands());
374 const int len = ops.count();
375
376 for(int i = 0; i < len; ++i)
377 props |= ops.at(i)->deepProperties();
378
379 return props;
380}
381
382Expression::ID Expression::id() const
383{
384 return IDIgnorableExpression;
385}
386
387OptimizationPass::List Expression::optimizationPasses() const
388{
389 return OptimizationPass::List();
390}
391
392ItemType::Ptr Expression::newFocusType() const
393{
394 Q_ASSERT_X(false, Q_FUNC_INFO,
395 "This function must be overridden when CreatesFocusForLast is set.");
396 return ItemType::Ptr();
397}
398
399const SourceLocationReflection *Expression::actualReflection() const
400{
401 return this;
402}
403
404QString Expression::description() const
405{
406 return QString::fromLatin1("Expression, id: %1").arg(QString::number(id()));
407}
408
409PatternPriority Expression::patternPriority() const
410{
411 return 0.5;
412}
413
414QT_END_NAMESPACE
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