summaryrefslogtreecommitdiffstats
path: root/dom/xslt/xpath/txExprParser.cpp
blob: f8474004bd40f2dc2f552092e52736f155d5bf60 (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
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/**
 * ExprParser
 * This class is used to parse XSL Expressions
 * @see ExprLexer
**/

#include "mozilla/Move.h"
#include "txExprParser.h"
#include "txExprLexer.h"
#include "txExpr.h"
#include "txStack.h"
#include "nsGkAtoms.h"
#include "nsError.h"
#include "txIXPathContext.h"
#include "txStringUtils.h"
#include "txXPathNode.h"
#include "txXPathOptimizer.h"

using mozilla::Move;

/**
 * Creates an Attribute Value Template using the given value
 * This should move to XSLProcessor class
 */
nsresult
txExprParser::createAVT(const nsSubstring& aAttrValue,
                        txIParseContext* aContext,
                        Expr** aResult)
{
    *aResult = nullptr;
    nsresult rv = NS_OK;
    nsAutoPtr<Expr> expr;
    FunctionCall* concat = nullptr;

    nsAutoString literalString;
    bool inExpr = false;
    nsSubstring::const_char_iterator iter, start, end, avtStart;
    aAttrValue.BeginReading(iter);
    aAttrValue.EndReading(end);
    avtStart = iter;

    while (iter != end) {
        // Every iteration through this loop parses either a literal section
        // or an expression
        start = iter;
        nsAutoPtr<Expr> newExpr;
        if (!inExpr) {
            // Parse literal section
            literalString.Truncate();
            while (iter != end) {
                char16_t q = *iter;
                if (q == '{' || q == '}') {
                    // Store what we've found so far and set a new |start| to
                    // skip the (first) brace
                    literalString.Append(Substring(start, iter));
                    start = ++iter;
                    // Unless another brace follows we've found the start of
                    // an expression (in case of '{') or an unbalanced brace
                    // (in case of '}')
                    if (iter == end || *iter != q) {
                        if (q == '}') {
                            aContext->SetErrorOffset(iter - avtStart);
                            return NS_ERROR_XPATH_UNBALANCED_CURLY_BRACE;
                        }

                        inExpr = true;
                        break;
                    }
                    // We found a second brace, let that be part of the next
                    // literal section being parsed and continue looping
                }
                ++iter;
            }

            if (start == iter && literalString.IsEmpty()) {
                // Restart the loop since we didn't create an expression
                continue;
            }
            newExpr = new txLiteralExpr(literalString +
                                        Substring(start, iter));
        }
        else {
            // Parse expressions, iter is already past the initial '{' when
            // we get here.
            while (iter != end) {
                if (*iter == '}') {
                    rv = createExprInternal(Substring(start, iter),
                                            start - avtStart, aContext,
                                            getter_Transfers(newExpr));
                    NS_ENSURE_SUCCESS(rv, rv);

                    inExpr = false;
                    ++iter; // skip closing '}'
                    break;
                }
                else if (*iter == '\'' || *iter == '"') {
                    char16_t q = *iter;
                    while (++iter != end && *iter != q) {} /* do nothing */
                    if (iter == end) {
                        break;
                    }
                }
                ++iter;
            }

            if (inExpr) {
                aContext->SetErrorOffset(start - avtStart);
                return NS_ERROR_XPATH_UNBALANCED_CURLY_BRACE;
            }
        }
        
        // Add expression, create a concat() call if necessary
        if (!expr) {
            expr = Move(newExpr);
        }
        else {
            if (!concat) {
                concat = new txCoreFunctionCall(txCoreFunctionCall::CONCAT);
                rv = concat->addParam(expr.forget());
                expr = concat;
                NS_ENSURE_SUCCESS(rv, rv);
            }

            rv = concat->addParam(newExpr.forget());
            NS_ENSURE_SUCCESS(rv, rv);
        }
    }

    if (inExpr) {
        aContext->SetErrorOffset(iter - avtStart);
        return NS_ERROR_XPATH_UNBALANCED_CURLY_BRACE;
    }

    if (!expr) {
        expr = new txLiteralExpr(EmptyString());
    }

    *aResult = expr.forget();

    return NS_OK;
}

nsresult
txExprParser::createExprInternal(const nsSubstring& aExpression,
                                 uint32_t aSubStringPos,
                                 txIParseContext* aContext, Expr** aExpr)
{
    NS_ENSURE_ARG_POINTER(aExpr);
    *aExpr = nullptr;
    txExprLexer lexer;
    nsresult rv = lexer.parse(aExpression);
    if (NS_FAILED(rv)) {
        nsASingleFragmentString::const_char_iterator start;
        aExpression.BeginReading(start);
        aContext->SetErrorOffset(lexer.mPosition - start + aSubStringPos);
        return rv;
    }
    nsAutoPtr<Expr> expr;
    rv = createExpr(lexer, aContext, getter_Transfers(expr));
    if (NS_SUCCEEDED(rv) && lexer.peek()->mType != Token::END) {
        rv = NS_ERROR_XPATH_BINARY_EXPECTED;
    }
    if (NS_FAILED(rv)) {
        nsASingleFragmentString::const_char_iterator start;
        aExpression.BeginReading(start);
        aContext->SetErrorOffset(lexer.peek()->mStart - start + aSubStringPos);

        return rv;
    }

    txXPathOptimizer optimizer;
    Expr* newExpr = nullptr;
    rv = optimizer.optimize(expr, &newExpr);
    NS_ENSURE_SUCCESS(rv, rv);

    *aExpr = newExpr ? newExpr : expr.forget();

    return NS_OK;
}

/**
 * Private Methods
 */

/**
 * Creates a binary Expr for the given operator
 */
nsresult
txExprParser::createBinaryExpr(nsAutoPtr<Expr>& left, nsAutoPtr<Expr>& right,
                               Token* op, Expr** aResult)
{
    NS_ASSERTION(op, "internal error");
    *aResult = nullptr;

    Expr* expr = nullptr;
    switch (op->mType) {
        //-- math ops
        case Token::ADDITION_OP :
            expr = new txNumberExpr(left, right, txNumberExpr::ADD);
            break;
        case Token::SUBTRACTION_OP:
            expr = new txNumberExpr(left, right, txNumberExpr::SUBTRACT);
            break;
        case Token::DIVIDE_OP :
            expr = new txNumberExpr(left, right, txNumberExpr::DIVIDE);
            break;
        case Token::MODULUS_OP :
            expr = new txNumberExpr(left, right, txNumberExpr::MODULUS);
            break;
        case Token::MULTIPLY_OP :
            expr = new txNumberExpr(left, right, txNumberExpr::MULTIPLY);
            break;

        //-- case boolean ops
        case Token::AND_OP:
            expr = new BooleanExpr(left, right, BooleanExpr::AND);
            break;
        case Token::OR_OP:
            expr = new BooleanExpr(left, right, BooleanExpr::OR);
            break;

        //-- equality ops
        case Token::EQUAL_OP :
            expr = new RelationalExpr(left, right, RelationalExpr::EQUAL);
            break;
        case Token::NOT_EQUAL_OP :
            expr = new RelationalExpr(left, right, RelationalExpr::NOT_EQUAL);
            break;

        //-- relational ops
        case Token::LESS_THAN_OP:
            expr = new RelationalExpr(left, right, RelationalExpr::LESS_THAN);
            break;
        case Token::GREATER_THAN_OP:
            expr = new RelationalExpr(left, right,
                                      RelationalExpr::GREATER_THAN);
            break;
        case Token::LESS_OR_EQUAL_OP:
            expr = new RelationalExpr(left, right,
                                      RelationalExpr::LESS_OR_EQUAL);
            break;
        case Token::GREATER_OR_EQUAL_OP:
            expr = new RelationalExpr(left, right,
                                      RelationalExpr::GREATER_OR_EQUAL);
            break;

        default:
            NS_NOTREACHED("operator tokens should be already checked");
            return NS_ERROR_UNEXPECTED;
    }
    NS_ENSURE_TRUE(expr, NS_ERROR_OUT_OF_MEMORY);

    left.forget();
    right.forget();

    *aResult = expr;
    return NS_OK;
}


nsresult
txExprParser::createExpr(txExprLexer& lexer, txIParseContext* aContext,
                         Expr** aResult)
{
    *aResult = nullptr;

    nsresult rv = NS_OK;
    bool done = false;

    nsAutoPtr<Expr> expr;

    txStack exprs;
    txStack ops;

    while (!done) {

        uint16_t negations = 0;
        while (lexer.peek()->mType == Token::SUBTRACTION_OP) {
            negations++;
            lexer.nextToken();
        }

        rv = createUnionExpr(lexer, aContext, getter_Transfers(expr));
        if (NS_FAILED(rv)) {
            break;
        }

        if (negations > 0) {
            if (negations % 2 == 0) {
                FunctionCall* fcExpr = new txCoreFunctionCall(txCoreFunctionCall::NUMBER);
                
                rv = fcExpr->addParam(expr);
                if (NS_FAILED(rv))
                    return rv;
                expr.forget();
                expr = fcExpr;
            }
            else {
                expr = new UnaryExpr(expr.forget());
            }
        }

        short tokPrecedence = precedence(lexer.peek());
        if (tokPrecedence != 0) {
            Token* tok = lexer.nextToken();
            while (!exprs.isEmpty() && tokPrecedence
                   <= precedence(static_cast<Token*>(ops.peek()))) {
                // can't use expr as argument due to order of evaluation
                nsAutoPtr<Expr> left(static_cast<Expr*>(exprs.pop()));
                nsAutoPtr<Expr> right(Move(expr));
                rv = createBinaryExpr(left, right,
                                      static_cast<Token*>(ops.pop()),
                                      getter_Transfers(expr));
                if (NS_FAILED(rv)) {
                    done = true;
                    break;
                }
            }
            exprs.push(expr.forget());
            ops.push(tok);
        }
        else {
            done = true;
        }
    }

    while (NS_SUCCEEDED(rv) && !exprs.isEmpty()) {
        nsAutoPtr<Expr> left(static_cast<Expr*>(exprs.pop()));
        nsAutoPtr<Expr> right(Move(expr));
        rv = createBinaryExpr(left, right, static_cast<Token*>(ops.pop()),
                              getter_Transfers(expr));
    }
    // clean up on error
    while (!exprs.isEmpty()) {
        delete static_cast<Expr*>(exprs.pop());
    }
    NS_ENSURE_SUCCESS(rv, rv);

    *aResult = expr.forget();
    return NS_OK;
}

nsresult
txExprParser::createFilterOrStep(txExprLexer& lexer, txIParseContext* aContext,
                                 Expr** aResult)
{
    *aResult = nullptr;

    nsresult rv = NS_OK;
    Token* tok = lexer.peek();

    nsAutoPtr<Expr> expr;
    switch (tok->mType) {
        case Token::FUNCTION_NAME_AND_PAREN:
            rv = createFunctionCall(lexer, aContext, getter_Transfers(expr));
            NS_ENSURE_SUCCESS(rv, rv);
            break;
        case Token::VAR_REFERENCE :
            lexer.nextToken();
            {
                nsCOMPtr<nsIAtom> prefix, lName;
                int32_t nspace;
                nsresult rv = resolveQName(tok->Value(), getter_AddRefs(prefix),
                                           aContext, getter_AddRefs(lName),
                                           nspace);
                NS_ENSURE_SUCCESS(rv, rv);
                expr = new VariableRefExpr(prefix, lName, nspace);
            }
            break;
        case Token::L_PAREN:
            lexer.nextToken();
            rv = createExpr(lexer, aContext, getter_Transfers(expr));
            NS_ENSURE_SUCCESS(rv, rv);

            if (lexer.peek()->mType != Token::R_PAREN) {
                return NS_ERROR_XPATH_PAREN_EXPECTED;
            }
            lexer.nextToken();
            break;
        case Token::LITERAL :
            lexer.nextToken();
            expr = new txLiteralExpr(tok->Value());
            break;
        case Token::NUMBER:
        {
            lexer.nextToken();
            expr = new txLiteralExpr(txDouble::toDouble(tok->Value()));
            break;
        }
        default:
            return createLocationStep(lexer, aContext, aResult);
    }

    if (lexer.peek()->mType == Token::L_BRACKET) {
        nsAutoPtr<FilterExpr> filterExpr(new FilterExpr(expr));

        expr.forget();

        //-- handle predicates
        rv = parsePredicates(filterExpr, lexer, aContext);
        NS_ENSURE_SUCCESS(rv, rv);
        expr = filterExpr.forget();
    }

    *aResult = expr.forget();
    return NS_OK;
}

nsresult
txExprParser::createFunctionCall(txExprLexer& lexer, txIParseContext* aContext,
                                 Expr** aResult)
{
    *aResult = nullptr;

    nsAutoPtr<FunctionCall> fnCall;

    Token* tok = lexer.nextToken();
    NS_ASSERTION(tok->mType == Token::FUNCTION_NAME_AND_PAREN,
                 "FunctionCall expected");

    //-- compare function names
    nsCOMPtr<nsIAtom> prefix, lName;
    int32_t namespaceID;
    nsresult rv = resolveQName(tok->Value(), getter_AddRefs(prefix), aContext,
                               getter_AddRefs(lName), namespaceID);
    NS_ENSURE_SUCCESS(rv, rv);

    txCoreFunctionCall::eType type;
    if (namespaceID == kNameSpaceID_None &&
        txCoreFunctionCall::getTypeFromAtom(lName, type)) {
        // It is a known built-in function.
        fnCall = new txCoreFunctionCall(type);
    }

    // check extension functions and xslt
    if (!fnCall) {
        rv = aContext->resolveFunctionCall(lName, namespaceID,
                                           getter_Transfers(fnCall));

        if (rv == NS_ERROR_NOT_IMPLEMENTED) {
            // this should just happen for unparsed-entity-uri()
            NS_ASSERTION(!fnCall, "Now is it implemented or not?");
            rv = parseParameters(0, lexer, aContext);
            NS_ENSURE_SUCCESS(rv, rv);

            *aResult = new txLiteralExpr(tok->Value() +
                                         NS_LITERAL_STRING(" not implemented."));

            return NS_OK;
        }

        NS_ENSURE_SUCCESS(rv, rv);
    }

    //-- handle parametes
    rv = parseParameters(fnCall, lexer, aContext);
    NS_ENSURE_SUCCESS(rv, rv);

    *aResult = fnCall.forget();
    return NS_OK;
}

nsresult
txExprParser::createLocationStep(txExprLexer& lexer, txIParseContext* aContext,
                                 Expr** aExpr)
{
    *aExpr = nullptr;

    //-- child axis is default
    LocationStep::LocationStepType axisIdentifier = LocationStep::CHILD_AXIS;
    nsAutoPtr<txNodeTest> nodeTest;

    //-- get Axis Identifier or AbbreviatedStep, if present
    Token* tok = lexer.peek();
    switch (tok->mType) {
        case Token::AXIS_IDENTIFIER:
        {
            //-- eat token
            lexer.nextToken();
            nsCOMPtr<nsIAtom> axis = NS_Atomize(tok->Value());
            if (axis == nsGkAtoms::ancestor) {
                axisIdentifier = LocationStep::ANCESTOR_AXIS;
            }
            else if (axis == nsGkAtoms::ancestorOrSelf) {
                axisIdentifier = LocationStep::ANCESTOR_OR_SELF_AXIS;
            }
            else if (axis == nsGkAtoms::attribute) {
                axisIdentifier = LocationStep::ATTRIBUTE_AXIS;
            }
            else if (axis == nsGkAtoms::child) {
                axisIdentifier = LocationStep::CHILD_AXIS;
            }
            else if (axis == nsGkAtoms::descendant) {
                axisIdentifier = LocationStep::DESCENDANT_AXIS;
            }
            else if (axis == nsGkAtoms::descendantOrSelf) {
                axisIdentifier = LocationStep::DESCENDANT_OR_SELF_AXIS;
            }
            else if (axis == nsGkAtoms::following) {
                axisIdentifier = LocationStep::FOLLOWING_AXIS;
            }
            else if (axis == nsGkAtoms::followingSibling) {
                axisIdentifier = LocationStep::FOLLOWING_SIBLING_AXIS;
            }
            else if (axis == nsGkAtoms::_namespace) {
                axisIdentifier = LocationStep::NAMESPACE_AXIS;
            }
            else if (axis == nsGkAtoms::parent) {
                axisIdentifier = LocationStep::PARENT_AXIS;
            }
            else if (axis == nsGkAtoms::preceding) {
                axisIdentifier = LocationStep::PRECEDING_AXIS;
            }
            else if (axis == nsGkAtoms::precedingSibling) {
                axisIdentifier = LocationStep::PRECEDING_SIBLING_AXIS;
            }
            else if (axis == nsGkAtoms::self) {
                axisIdentifier = LocationStep::SELF_AXIS;
            }
            else {
                return NS_ERROR_XPATH_INVALID_AXIS;
            }
            break;
        }
        case Token::AT_SIGN:
            //-- eat token
            lexer.nextToken();
            axisIdentifier = LocationStep::ATTRIBUTE_AXIS;
            break;
        case Token::PARENT_NODE :
            //-- eat token
            lexer.nextToken();
            axisIdentifier = LocationStep::PARENT_AXIS;
            nodeTest = new txNodeTypeTest(txNodeTypeTest::NODE_TYPE);
            break;
        case Token::SELF_NODE :
            //-- eat token
            lexer.nextToken();
            axisIdentifier = LocationStep::SELF_AXIS;
            nodeTest = new txNodeTypeTest(txNodeTypeTest::NODE_TYPE);
            break;
        default:
            break;
    }

    //-- get NodeTest unless an AbbreviatedStep was found
    nsresult rv = NS_OK;
    if (!nodeTest) {
        tok = lexer.peek();

        if (tok->mType == Token::CNAME) {
            lexer.nextToken();
            // resolve QName
            nsCOMPtr<nsIAtom> prefix, lName;
            int32_t nspace;
            rv = resolveQName(tok->Value(), getter_AddRefs(prefix),
                              aContext, getter_AddRefs(lName),
                              nspace, true);
            NS_ENSURE_SUCCESS(rv, rv);

            nodeTest =
              new txNameTest(prefix, lName, nspace,
                             axisIdentifier == LocationStep::ATTRIBUTE_AXIS ?
                             static_cast<uint16_t>(txXPathNodeType::ATTRIBUTE_NODE) :
                             static_cast<uint16_t>(txXPathNodeType::ELEMENT_NODE));
        }
        else {
            rv = createNodeTypeTest(lexer, getter_Transfers(nodeTest));
            NS_ENSURE_SUCCESS(rv, rv);
        }
    }
    
    nsAutoPtr<LocationStep> lstep(new LocationStep(nodeTest, axisIdentifier));

    nodeTest.forget();

    //-- handle predicates
    rv = parsePredicates(lstep, lexer, aContext);
    NS_ENSURE_SUCCESS(rv, rv);

    *aExpr = lstep.forget();
    return NS_OK;
}

/**
 * This method only handles comment(), text(), processing-instructing()
 * and node()
 */
nsresult
txExprParser::createNodeTypeTest(txExprLexer& lexer, txNodeTest** aTest)
{
    *aTest = 0;
    nsAutoPtr<txNodeTypeTest> nodeTest;

    Token* nodeTok = lexer.peek();

    switch (nodeTok->mType) {
        case Token::COMMENT_AND_PAREN:
            lexer.nextToken();
            nodeTest = new txNodeTypeTest(txNodeTypeTest::COMMENT_TYPE);
            break;
        case Token::NODE_AND_PAREN:
            lexer.nextToken();
            nodeTest = new txNodeTypeTest(txNodeTypeTest::NODE_TYPE);
            break;
        case Token::PROC_INST_AND_PAREN:
            lexer.nextToken();
            nodeTest = new txNodeTypeTest(txNodeTypeTest::PI_TYPE);
            break;
        case Token::TEXT_AND_PAREN:
            lexer.nextToken();
            nodeTest = new txNodeTypeTest(txNodeTypeTest::TEXT_TYPE);
            break;
        default:
            return NS_ERROR_XPATH_NO_NODE_TYPE_TEST;
    }

    NS_ENSURE_TRUE(nodeTest, NS_ERROR_OUT_OF_MEMORY);

    if (nodeTok->mType == Token::PROC_INST_AND_PAREN &&
        lexer.peek()->mType == Token::LITERAL) {
        Token* tok = lexer.nextToken();
        nodeTest->setNodeName(tok->Value());
    }
    if (lexer.peek()->mType != Token::R_PAREN) {
        return NS_ERROR_XPATH_PAREN_EXPECTED;
    }
    lexer.nextToken();

    *aTest = nodeTest.forget();
    return NS_OK;
}

/**
 * Creates a PathExpr using the given txExprLexer
 * @param lexer the txExprLexer for retrieving Tokens
 */
nsresult
txExprParser::createPathExpr(txExprLexer& lexer, txIParseContext* aContext,
                             Expr** aResult)
{
    *aResult = nullptr;

    nsAutoPtr<Expr> expr;

    Token* tok = lexer.peek();

    // is this a root expression?
    if (tok->mType == Token::PARENT_OP) {
        if (!isLocationStepToken(lexer.peekAhead())) {
            lexer.nextToken();
            *aResult = new RootExpr();
            return NS_OK;
        }
    }

    // parse first step (possibly a FilterExpr)
    nsresult rv = NS_OK;
    if (tok->mType != Token::PARENT_OP &&
        tok->mType != Token::ANCESTOR_OP) {
        rv = createFilterOrStep(lexer, aContext, getter_Transfers(expr));
        NS_ENSURE_SUCCESS(rv, rv);

        // is this a singlestep path expression?
        tok = lexer.peek();
        if (tok->mType != Token::PARENT_OP &&
            tok->mType != Token::ANCESTOR_OP) {
            *aResult = expr.forget();
            return NS_OK;
        }
    }
    else {
        expr = new RootExpr();

#ifdef TX_TO_STRING
        static_cast<RootExpr*>(expr.get())->setSerialize(false);
#endif
    }
    
    // We have a PathExpr containing several steps
    nsAutoPtr<PathExpr> pathExpr(new PathExpr());

    rv = pathExpr->addExpr(expr, PathExpr::RELATIVE_OP);
    NS_ENSURE_SUCCESS(rv, rv);

    expr.forget();

    // this is ugly
    while (1) {
        PathExpr::PathOperator pathOp;
        switch (lexer.peek()->mType) {
            case Token::ANCESTOR_OP :
                pathOp = PathExpr::DESCENDANT_OP;
                break;
            case Token::PARENT_OP :
                pathOp = PathExpr::RELATIVE_OP;
                break;
            default:
                *aResult = pathExpr.forget();
                return NS_OK;
        }
        lexer.nextToken();

        rv = createLocationStep(lexer, aContext, getter_Transfers(expr));
        NS_ENSURE_SUCCESS(rv, rv);

        rv = pathExpr->addExpr(expr, pathOp);
        NS_ENSURE_SUCCESS(rv, rv);

        expr.forget();
    }
    NS_NOTREACHED("internal xpath parser error");
    return NS_ERROR_UNEXPECTED;
}

/**
 * Creates a PathExpr using the given txExprLexer
 * @param lexer the txExprLexer for retrieving Tokens
 */
nsresult
txExprParser::createUnionExpr(txExprLexer& lexer, txIParseContext* aContext,
                              Expr** aResult)
{
    *aResult = nullptr;

    nsAutoPtr<Expr> expr;
    nsresult rv = createPathExpr(lexer, aContext, getter_Transfers(expr));
    NS_ENSURE_SUCCESS(rv, rv);
    
    if (lexer.peek()->mType != Token::UNION_OP) {
        *aResult = expr.forget();
        return NS_OK;
    }

    nsAutoPtr<UnionExpr> unionExpr(new UnionExpr());

    rv = unionExpr->addExpr(expr);
    NS_ENSURE_SUCCESS(rv, rv);

    expr.forget();

    while (lexer.peek()->mType == Token::UNION_OP) {
        lexer.nextToken(); //-- eat token

        rv = createPathExpr(lexer, aContext, getter_Transfers(expr));
        NS_ENSURE_SUCCESS(rv, rv);

        rv = unionExpr->addExpr(expr.forget());
        NS_ENSURE_SUCCESS(rv, rv);
    }

    *aResult = unionExpr.forget();
    return NS_OK;
}

bool
txExprParser::isLocationStepToken(Token* aToken)
{
    // We could put these in consecutive order in ExprLexer.h for speed
    return aToken->mType == Token::AXIS_IDENTIFIER ||
           aToken->mType == Token::AT_SIGN ||
           aToken->mType == Token::PARENT_NODE ||
           aToken->mType == Token::SELF_NODE ||
           aToken->mType == Token::CNAME ||
           aToken->mType == Token::COMMENT_AND_PAREN ||
           aToken->mType == Token::NODE_AND_PAREN ||
           aToken->mType == Token::PROC_INST_AND_PAREN ||
           aToken->mType == Token::TEXT_AND_PAREN;
}

/**
 * Using the given lexer, parses the tokens if they represent a predicate list
 * If an error occurs a non-zero String pointer will be returned containing the
 * error message.
 * @param predicateList, the PredicateList to add predicate expressions to
 * @param lexer the txExprLexer to use for parsing tokens
 * @return 0 if successful, or a String pointer to the error message
 */
nsresult
txExprParser::parsePredicates(PredicateList* aPredicateList,
                              txExprLexer& lexer, txIParseContext* aContext)
{
    nsAutoPtr<Expr> expr;
    nsresult rv = NS_OK;
    while (lexer.peek()->mType == Token::L_BRACKET) {
        //-- eat Token
        lexer.nextToken();

        rv = createExpr(lexer, aContext, getter_Transfers(expr));
        NS_ENSURE_SUCCESS(rv, rv);

        rv = aPredicateList->add(expr);
        NS_ENSURE_SUCCESS(rv, rv);

        expr.forget();

        if (lexer.peek()->mType != Token::R_BRACKET) {
            return NS_ERROR_XPATH_BRACKET_EXPECTED;
        }
        lexer.nextToken();
    }
    return NS_OK;
}


/**
 * Using the given lexer, parses the tokens if they represent a parameter list
 * If an error occurs a non-zero String pointer will be returned containing the
 * error message.
 * @param list, the List to add parameter expressions to
 * @param lexer the txExprLexer to use for parsing tokens
 * @return NS_OK if successful, or another rv otherwise
 */
nsresult
txExprParser::parseParameters(FunctionCall* aFnCall, txExprLexer& lexer,
                              txIParseContext* aContext)
{
    if (lexer.peek()->mType == Token::R_PAREN) {
        lexer.nextToken();
        return NS_OK;
    }

    nsAutoPtr<Expr> expr;
    nsresult rv = NS_OK;
    while (1) {
        rv = createExpr(lexer, aContext, getter_Transfers(expr));
        NS_ENSURE_SUCCESS(rv, rv);

        if (aFnCall) {
            rv = aFnCall->addParam(expr.forget());
            NS_ENSURE_SUCCESS(rv, rv);
        }
                    
        switch (lexer.peek()->mType) {
            case Token::R_PAREN :
                lexer.nextToken();
                return NS_OK;
            case Token::COMMA: //-- param separator
                lexer.nextToken();
                break;
            default:
                return NS_ERROR_XPATH_PAREN_EXPECTED;
        }
    }

    NS_NOTREACHED("internal xpath parser error");
    return NS_ERROR_UNEXPECTED;
}

short
txExprParser::precedence(Token* aToken)
{
    switch (aToken->mType) {
        case Token::OR_OP:
            return 1;
        case Token::AND_OP:
            return 2;
        //-- equality
        case Token::EQUAL_OP:
        case Token::NOT_EQUAL_OP:
            return 3;
        //-- relational
        case Token::LESS_THAN_OP:
        case Token::GREATER_THAN_OP:
        case Token::LESS_OR_EQUAL_OP:
        case Token::GREATER_OR_EQUAL_OP:
            return 4;
        //-- additive operators
        case Token::ADDITION_OP:
        case Token::SUBTRACTION_OP:
            return 5;
        //-- multiplicative
        case Token::DIVIDE_OP:
        case Token::MULTIPLY_OP:
        case Token::MODULUS_OP:
            return 6;
        default:
            break;
    }
    return 0;
}

nsresult
txExprParser::resolveQName(const nsAString& aQName,
                           nsIAtom** aPrefix, txIParseContext* aContext,
                           nsIAtom** aLocalName, int32_t& aNamespace,
                           bool aIsNameTest)
{
    aNamespace = kNameSpaceID_None;
    int32_t idx = aQName.FindChar(':');
    if (idx > 0) {
        *aPrefix = NS_Atomize(StringHead(aQName, (uint32_t)idx)).take();
        if (!*aPrefix) {
            return NS_ERROR_OUT_OF_MEMORY;
        }
        *aLocalName = NS_Atomize(Substring(aQName, (uint32_t)idx + 1,
                                           aQName.Length() - (idx + 1))).take();
        if (!*aLocalName) {
            NS_RELEASE(*aPrefix);
            return NS_ERROR_OUT_OF_MEMORY;
        }
        return aContext->resolveNamespacePrefix(*aPrefix, aNamespace);
    }
    // the lexer dealt with idx == 0
    *aPrefix = 0;
    if (aIsNameTest && aContext->caseInsensitiveNameTests()) {
        nsAutoString lcname;
        nsContentUtils::ASCIIToLower(aQName, lcname);
        *aLocalName = NS_Atomize(lcname).take();
    }
    else {
        *aLocalName = NS_Atomize(aQName).take();
    }
    if (!*aLocalName) {
        return NS_ERROR_OUT_OF_MEMORY;
    }
    return NS_OK;
}