2 * Copyright (c) 2018 Pantheon Technologies, s.r.o. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
8 package org.opendaylight.yangtools.yang.xpath.impl;
10 import static com.google.common.base.Preconditions.checkArgument;
11 import static com.google.common.base.Verify.verify;
12 import static com.google.common.base.Verify.verifyNotNull;
13 import static java.util.Objects.requireNonNull;
14 import static org.opendaylight.yangtools.yang.xpath.impl.ParseTreeUtils.getChild;
15 import static org.opendaylight.yangtools.yang.xpath.impl.ParseTreeUtils.illegalShape;
16 import static org.opendaylight.yangtools.yang.xpath.impl.ParseTreeUtils.verifyAtLeastChildren;
17 import static org.opendaylight.yangtools.yang.xpath.impl.ParseTreeUtils.verifyChildCount;
18 import static org.opendaylight.yangtools.yang.xpath.impl.ParseTreeUtils.verifyTerminal;
19 import static org.opendaylight.yangtools.yang.xpath.impl.ParseTreeUtils.verifyToken;
20 import static org.opendaylight.yangtools.yang.xpath.impl.ParseTreeUtils.verifyTree;
22 import com.google.common.collect.ImmutableList;
23 import com.google.common.collect.Iterators;
24 import com.google.common.collect.Maps;
25 import java.util.ArrayDeque;
26 import java.util.ArrayList;
27 import java.util.Arrays;
28 import java.util.Deque;
29 import java.util.Iterator;
30 import java.util.LinkedHashSet;
31 import java.util.List;
33 import java.util.Optional;
35 import javax.xml.xpath.XPathExpressionException;
36 import org.antlr.v4.runtime.CharStreams;
37 import org.antlr.v4.runtime.CommonTokenStream;
38 import org.antlr.v4.runtime.ParserRuleContext;
39 import org.antlr.v4.runtime.tree.ParseTree;
40 import org.antlr.v4.runtime.tree.TerminalNode;
41 import org.opendaylight.yangtools.yang.common.QName;
42 import org.opendaylight.yangtools.yang.common.QNameModule;
43 import org.opendaylight.yangtools.yang.common.QualifiedQName;
44 import org.opendaylight.yangtools.yang.common.UnqualifiedQName;
45 import org.opendaylight.yangtools.yang.common.YangConstants;
46 import org.opendaylight.yangtools.yang.common.YangNamespaceContext;
47 import org.opendaylight.yangtools.yang.common.YangVersion;
48 import org.opendaylight.yangtools.yang.xpath.antlr.xpathLexer;
49 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser;
50 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.AbbreviatedStepContext;
51 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.AbsoluteLocationPathNorootContext;
52 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.AdditiveExprContext;
53 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.AndExprContext;
54 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.AxisSpecifierContext;
55 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.EqualityExprContext;
56 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.ExprContext;
57 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.FilterExprContext;
58 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.FunctionCallContext;
59 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.FunctionNameContext;
60 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.LocationPathContext;
61 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.MultiplicativeExprContext;
62 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.NCNameContext;
63 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.NameTestContext;
64 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.NodeTestContext;
65 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.OrExprContext;
66 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.PathExprNoRootContext;
67 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.PredicateContext;
68 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.PrimaryExprContext;
69 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.QNameContext;
70 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.RelationalExprContext;
71 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.RelativeLocationPathContext;
72 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.StepContext;
73 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.UnaryExprNoRootContext;
74 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.UnionExprNoRootContext;
75 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.VariableReferenceContext;
76 import org.opendaylight.yangtools.yang.xpath.api.YangBinaryOperator;
77 import org.opendaylight.yangtools.yang.xpath.api.YangBooleanConstantExpr;
78 import org.opendaylight.yangtools.yang.xpath.api.YangExpr;
79 import org.opendaylight.yangtools.yang.xpath.api.YangFilterExpr;
80 import org.opendaylight.yangtools.yang.xpath.api.YangFunction;
81 import org.opendaylight.yangtools.yang.xpath.api.YangFunctionCallExpr;
82 import org.opendaylight.yangtools.yang.xpath.api.YangLiteralExpr;
83 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath;
84 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath.AxisStep;
85 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath.QNameStep;
86 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath.ResolvedQNameStep;
87 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath.Step;
88 import org.opendaylight.yangtools.yang.xpath.api.YangNaryExpr;
89 import org.opendaylight.yangtools.yang.xpath.api.YangNaryOperator;
90 import org.opendaylight.yangtools.yang.xpath.api.YangNegateExpr;
91 import org.opendaylight.yangtools.yang.xpath.api.YangNumberExpr;
92 import org.opendaylight.yangtools.yang.xpath.api.YangPathExpr;
93 import org.opendaylight.yangtools.yang.xpath.api.YangVariableReferenceExpr;
94 import org.opendaylight.yangtools.yang.xpath.api.YangXPathAxis;
95 import org.opendaylight.yangtools.yang.xpath.api.YangXPathExpression;
96 import org.opendaylight.yangtools.yang.xpath.api.YangXPathMathMode;
97 import org.opendaylight.yangtools.yang.xpath.api.YangXPathMathSupport;
98 import org.opendaylight.yangtools.yang.xpath.api.YangXPathNodeType;
99 import org.opendaylight.yangtools.yang.xpath.api.YangXPathParser;
102 * ANTLR-based XPath parser. Uses {@code xpath.g4} ANTLR grammar.
104 * @author Robert Varga
106 abstract class AntlrXPathParser implements YangXPathParser {
107 static class Base extends AntlrXPathParser {
108 Base(final YangXPathMathMode mathMode) {
113 public YangXPathExpression parseExpression(final String xpath) throws XPathExpressionException {
114 final ParseExprResult result = parseExpr(xpath);
115 return new AntlrYangXPathExpression.Base(mathMode, result.minimumYangVersion, result.expression, xpath);
119 QNameStep createStep(final YangXPathAxis axis, final String localName,
120 final List<YangExpr> predicates) {
121 return axis.asStep(UnqualifiedQName.of(localName).intern(), predicates);
125 QNameStep createStep(final YangXPathAxis axis, final String prefix, final String localName,
126 final List<YangExpr> predicates) {
127 return axis.asStep(QualifiedQName.of(prefix, localName).intern(), predicates);
131 QName createQName(final String localName) {
132 throw new UnsupportedOperationException();
136 QName createQName(final String prefix, final String localName) {
137 throw new UnsupportedOperationException();
141 static class Qualified extends Base implements QualifiedBound {
142 final YangNamespaceContext namespaceContext;
144 Qualified(final YangXPathMathMode mathMode, final YangNamespaceContext namespaceContext) {
146 this.namespaceContext = requireNonNull(namespaceContext);
150 public YangXPathExpression.QualifiedBound parseExpression(final String xpath) throws XPathExpressionException {
151 final ParseExprResult result = parseExpr(xpath);
152 return new AntlrYangXPathExpression.Qualified(mathMode, result.minimumYangVersion, result.expression, xpath,
153 result.haveLiteral ? namespaceContext : null);
157 final QName createQName(final String prefix, final String localName) {
158 return namespaceContext.createQName(prefix, localName);
162 ResolvedQNameStep createStep(final YangXPathAxis axis, final String prefix, final String localName,
163 final List<YangExpr> predicates) {
164 return axis.asStep(createQName(prefix, localName), predicates);
168 static final class Unqualified extends Qualified implements UnqualifiedBound {
169 private final QNameModule defaultNamespace;
171 Unqualified(final YangXPathMathMode mathMode, final YangNamespaceContext namespaceContext,
172 final QNameModule defaultNamespace) {
173 super(mathMode, namespaceContext);
174 this.defaultNamespace = requireNonNull(defaultNamespace);
178 public YangXPathExpression.UnqualifiedBound parseExpression(final String xpath)
179 throws XPathExpressionException {
180 final ParseExprResult result = parseExpr(xpath);
182 return new AntlrYangXPathExpression.Unqualified(mathMode, result.minimumYangVersion, result.expression,
183 xpath, result.haveLiteral ? namespaceContext : null, defaultNamespace);
187 QName createQName(final String localName) {
188 return QName.create(defaultNamespace, localName);
192 ResolvedQNameStep createStep(final YangXPathAxis axis, final String localName,
193 final List<YangExpr> predicates) {
194 return axis.asStep(QName.create(defaultNamespace, localName), predicates);
198 private static final class ParseExprResult {
199 final YangVersion minimumYangVersion;
200 final YangExpr expression;
201 final boolean haveLiteral;
203 ParseExprResult(final YangVersion minimumYangVersion, final YangExpr expression, final boolean haveLiteral) {
204 this.minimumYangVersion = requireNonNull(minimumYangVersion);
205 this.expression = requireNonNull(expression);
206 this.haveLiteral = haveLiteral;
210 private static final Map<String, YangBinaryOperator> BINARY_OPERATORS = Maps.uniqueIndex(
211 Arrays.asList(YangBinaryOperator.values()), YangBinaryOperator::toString);
212 private static final Map<String, YangXPathNodeType> NODE_TYPES = Maps.uniqueIndex(Arrays.asList(
213 YangXPathNodeType.values()), YangXPathNodeType::toString);
214 private static final Map<String, YangXPathAxis> XPATH_AXES = Maps.uniqueIndex(Arrays.asList(YangXPathAxis.values()),
215 YangXPathAxis::toString);
216 private static final Map<QName, YangFunction> YANG_FUNCTIONS = Maps.uniqueIndex(Arrays.asList(
217 YangFunction.values()), YangFunction::getIdentifier);
219 // Cached for checks in hot path
220 private static final AxisStep SELF_STEP = YangXPathAxis.SELF.asStep();
222 final YangXPathMathMode mathMode;
223 private final YangXPathMathSupport mathSupport;
224 private final FunctionSupport functionSupport;
226 private YangVersion minimumYangVersion = YangVersion.VERSION_1;
227 private boolean haveLiteral = false;
229 AntlrXPathParser(final YangXPathMathMode mathMode) {
230 this.mathMode = requireNonNull(mathMode);
231 this.mathSupport = mathMode.getSupport();
232 this.functionSupport = new FunctionSupport(mathSupport);
235 abstract QName createQName(String localName);
237 abstract QName createQName(String prefix, String localName);
239 abstract QNameStep createStep(YangXPathAxis axis, String localName, List<YangExpr> predicates);
241 abstract QNameStep createStep(YangXPathAxis axis, String prefix, String localName, List<YangExpr> predicates);
243 private QNameStep createStep(final YangXPathAxis axis, final QNameContext expr, final List<YangExpr> predicates) {
244 switch (expr.getChildCount()) {
246 return createStep(axis, getChild(expr, NCNameContext.class, 0).getText(), predicates);
248 return createStep(axis, getChild(expr, NCNameContext.class, 0).getText(),
249 getChild(expr, NCNameContext.class, 2).getText(), predicates);
251 throw illegalShape(expr);
255 @SuppressWarnings("checkstyle:illegalCatch")
256 final ParseExprResult parseExpr(final String xpath) throws XPathExpressionException {
257 // Create a parser and disconnect it from console error output
258 final xpathLexer lexer = new xpathLexer(CharStreams.fromString(xpath));
259 final xpathParser parser = new xpathParser(new CommonTokenStream(lexer));
261 final CapturingErrorListener listener = new CapturingErrorListener();
262 lexer.removeErrorListeners();
263 lexer.addErrorListener(listener);
264 parser.removeErrorListeners();
265 parser.addErrorListener(listener);
266 final ExprContext antlr = parser.main().expr();
267 listener.reportError();
269 // Reset our internal context
270 minimumYangVersion = YangVersion.VERSION_1;
275 expr = parseExpr(antlr);
276 } catch (RuntimeException e) {
277 throw new XPathExpressionException(e);
279 return new ParseExprResult(minimumYangVersion, expr, haveLiteral);
283 * Parse and simplify an XPath expression in {@link ExprContext} representation.
285 * @param ctx Current parsing context
286 * @param expr ANTLR ExprContext
287 * @return A {@link YangExpr}
288 * @throws NullPointerException if {@code expr} is null
289 * @throws IllegalArgumentException if {@code expr} references an unbound prefix
291 private YangExpr parseExpr(final ExprContext expr) {
292 final OrExprContext or = expr.orExpr();
293 final int size = or.getChildCount();
295 return parseAnd(getChild(or, AndExprContext.class, 0));
297 final List<YangExpr> tmp = new ArrayList<>((size + 1) / 2);
298 for (int i = 0; i < size; i += 2) {
299 tmp.add(parseAnd(getChild(or, AndExprContext.class, i)));
301 return YangNaryOperator.OR.exprWith(tmp);
304 private YangExpr parseAdditive(final AdditiveExprContext expr) {
305 final Iterator<ParseTree> it = expr.children.iterator();
306 final YangExpr first = parseMultiplicative(nextContext(it, MultiplicativeExprContext.class));
307 return it.hasNext() ? parseAdditiveExpr(first, it) : first;
310 private YangExpr parseAnd(final AndExprContext expr) {
311 final int size = expr.getChildCount();
313 return parseEquality(getChild(expr, EqualityExprContext.class, 0));
315 final List<YangExpr> tmp = new ArrayList<>((size + 1) / 2);
316 for (int i = 0; i < size; i += 2) {
317 tmp.add(parseEquality(getChild(expr, EqualityExprContext.class, i)));
319 return YangNaryOperator.AND.exprWith(tmp);
322 private YangExpr parseEquality(final EqualityExprContext expr) {
323 final Iterator<ParseTree> it = expr.children.iterator();
324 final YangExpr first = parseRelational(nextContext(it, RelationalExprContext.class));
325 return it.hasNext() ? parseEqualityExpr(first, it) : first;
328 private YangExpr parseFilter(final FilterExprContext expr) {
329 final Iterator<ParseTree> it = expr.children.iterator();
330 final YangExpr first = parsePrimary(nextContext(it, PrimaryExprContext.class));
331 return it.hasNext() ? YangFilterExpr.of(first, ImmutableList.copyOf(Iterators.transform(it,
332 tree -> parsePredicate(verifyTree(PredicateContext.class, tree)))))
336 private YangExpr parseFunctionCall(final FunctionCallContext expr) {
337 // We are mapping functions to RFC7950 YIN namespace, to keep us consistent with type/statement definitions
339 final FunctionNameContext name = getChild(expr, FunctionNameContext.class, 0);
341 switch (name.getChildCount()) {
343 parsed = QName.create(YangConstants.RFC6020_YIN_MODULE, name.getChild(0).getText());
346 parsed = createQName(name.getChild(0).getText(), name.getChild(2).getText());
349 throw illegalShape(name);
352 final List<YangExpr> args = expr.expr().stream().map(this::parseExpr).collect(ImmutableList.toImmutableList());
353 final YangFunction func = YANG_FUNCTIONS.get(parsed);
355 if (minimumYangVersion.compareTo(func.getYangVersion()) < 0) {
356 minimumYangVersion = func.getYangVersion();
359 final YangExpr funcExpr = functionSupport.functionToExpr(func, args);
360 if (funcExpr instanceof YangLiteralExpr) {
366 checkArgument(!YangConstants.RFC6020_YIN_MODULE.equals(parsed.getModule()), "Unknown default function %s",
368 return YangFunctionCallExpr.of(parsed, args);
371 private YangLocationPath parseLocationPath(final LocationPathContext expr) {
372 verifyChildCount(expr, 1);
373 final ParseTree first = expr.getChild(0);
374 if (first instanceof RelativeLocationPathContext) {
375 return YangLocationPath.relative(parseLocationPathSteps((RelativeLocationPathContext) first));
378 final AbsoluteLocationPathNorootContext abs = verifyTree(AbsoluteLocationPathNorootContext.class, first);
379 verifyChildCount(abs, 2);
381 final Deque<Step> steps = parseLocationPathSteps(getChild(abs, RelativeLocationPathContext.class, 1));
382 parseStepShorthand(abs.getChild(0)).ifPresent(steps::addFirst);
384 return YangLocationPath.absolute(steps);
387 private YangExpr parseMultiplicative(final MultiplicativeExprContext expr) {
388 final ParseTree first = expr.getChild(0);
390 if (first instanceof UnaryExprNoRootContext) {
391 left = parseUnary((UnaryExprNoRootContext) first);
393 left = YangLocationPath.root();
395 if (expr.getChildCount() == 1) {
399 verifyChildCount(expr, 3);
400 final YangBinaryOperator operator = parseOperator(expr.getChild(1));
401 final YangExpr right = parseMultiplicative(getChild(expr, MultiplicativeExprContext.class, 2));
402 final Optional<YangExpr> simple = simplifyNumbers(operator, left, right);
403 return simple.isPresent() ? simple.get() : operator.exprWith(left, right);
406 private YangExpr parsePathExpr(final PathExprNoRootContext expr) {
407 final ParseTree first = expr.getChild(0);
408 if (first instanceof LocationPathContext) {
409 return parseLocationPath((LocationPathContext) first);
412 final YangExpr filter = parseFilter(verifyTree(FilterExprContext.class, first));
413 if (expr.getChildCount() == 1) {
417 verifyChildCount(expr, 3);
418 final Deque<Step> steps = parseLocationPathSteps(getChild(expr, RelativeLocationPathContext.class, 2));
419 parseStepShorthand(expr.getChild(1)).ifPresent(steps::addFirst);
420 return YangPathExpr.of(filter, YangLocationPath.relative(steps));
423 private YangExpr parsePredicate(final PredicateContext expr) {
424 verifyChildCount(expr, 3);
425 return parseExpr(getChild(expr, ExprContext.class, 1));
428 private YangExpr parsePrimary(final PrimaryExprContext expr) {
429 if (expr.getChildCount() == 3) {
430 return parseExpr(getChild(expr, ExprContext.class, 1));
433 verifyChildCount(expr, 1);
434 final ParseTree first = expr.getChild(0);
435 if (first instanceof TerminalNode) {
436 return parseTerminal((TerminalNode) first);
438 if (first instanceof FunctionCallContext) {
439 return parseFunctionCall((FunctionCallContext) first);
441 if (first instanceof VariableReferenceContext) {
442 return YangVariableReferenceExpr.of(parseQName(((VariableReferenceContext) first).qName()));
444 throw illegalShape(first);
447 private YangExpr parseRelational(final RelationalExprContext expr) {
448 final Iterator<ParseTree> it = expr.children.iterator();
449 final YangExpr first = parseAdditive(nextContext(it, AdditiveExprContext.class));
450 return it.hasNext() ? parseRelationalExpr(first, it) : first;
453 private Deque<Step> parseLocationPathSteps(final RelativeLocationPathContext expr) {
454 final Deque<Step> steps = new ArrayDeque<>(expr.getChildCount());
455 final Iterator<ParseTree> it = expr.children.iterator();
456 addNotSelfStep(steps, parseStep(nextContext(it, StepContext.class)));
458 while (it.hasNext()) {
459 parseStepShorthand(it.next()).ifPresent(steps::add);
461 // Parse step and add it if it's not SELF_STEP
462 addNotSelfStep(steps, parseStep(nextContext(it, StepContext.class)));
468 private static void addNotSelfStep(final Deque<Step> steps, final Step step) {
469 if (!SELF_STEP.equals(step)) {
474 private YangExpr parseTerminal(final TerminalNode term) {
475 final String text = term.getText();
476 switch (term.getSymbol().getType()) {
477 case xpathParser.Literal:
478 // We have to strip quotes
480 return YangLiteralExpr.of(text.substring(1, text.length() - 1));
481 case xpathParser.Number:
482 return mathSupport.createNumber(text);
484 throw illegalShape(term);
488 private YangExpr parseUnary(final UnaryExprNoRootContext expr) {
489 // any number of '-' and an union expr
490 final int size = verifyAtLeastChildren(expr, 1);
491 final YangExpr ret = parseUnion(getChild(expr, UnionExprNoRootContext.class, size - 1));
493 // Even number of '-' tokens cancel out
496 return ret instanceof YangNumberExpr ? mathSupport.negateNumber((YangNumberExpr) ret) : YangNegateExpr.of(ret);
499 private YangExpr parseUnion(final UnionExprNoRootContext expr) {
500 final ParseTree first = expr.getChild(0);
502 if (first instanceof PathExprNoRootContext) {
503 path = parsePathExpr((PathExprNoRootContext) first);
504 if (expr.getChildCount() == 1) {
508 path = YangLocationPath.root();
511 verifyChildCount(expr, 3);
512 final YangExpr union = parseUnion(getChild(expr, UnionExprNoRootContext.class, 2));
514 // Deduplicate expressions so we do not perform useless unioning
515 final Set<YangExpr> expressions = new LinkedHashSet<>();
516 expressions.add(path);
517 if (union instanceof YangNaryExpr) {
518 // If the result is a union expression, integrate it into this expression
519 final YangNaryExpr nary = (YangNaryExpr) union;
520 if (nary.getOperator() == YangNaryOperator.UNION) {
521 expressions.addAll(nary.getExpressions());
523 expressions.add(union);
526 expressions.add(union);
529 return YangNaryOperator.UNION.exprWith(expressions);
532 private YangExpr parseAdditiveExpr(final YangExpr left, final Iterator<ParseTree> it) {
535 final YangBinaryOperator operator = nextOperator(it);
536 final YangExpr right = parseMultiplicative(nextContext(it, MultiplicativeExprContext.class));
537 final Optional<YangExpr> simple = simplifyNumbers(operator, ret, right);
538 ret = simple.isPresent() ? simple.get() : operator.exprWith(ret, right);
539 } while (it.hasNext());
544 private Optional<YangExpr> simplifyNumbers(final YangBinaryOperator operator, final YangExpr left,
545 final YangExpr right) {
546 if (left instanceof YangNumberExpr && right instanceof YangNumberExpr) {
547 // Constant folding on numbers -- precision plays a role here
548 return mathSupport.tryEvaluate(operator, (YangNumberExpr)left, (YangNumberExpr)right);
550 return Optional.empty();
553 private YangExpr parseEqualityExpr(final YangExpr left, final Iterator<ParseTree> it) {
556 final YangBinaryOperator operator = nextOperator(it);
557 final YangExpr right = parseRelational(nextContext(it, RelationalExprContext.class));
559 if (left.equals(right)) {
560 // Constant folding on expression level: equal expressions are result in equal results
563 return YangBooleanConstantExpr.TRUE;
565 return YangBooleanConstantExpr.FALSE;
571 final Optional<YangExpr> simple = simplifyNumbers(operator, ret, right);
572 ret = simple.isPresent() ? simple.get() : operator.exprWith(ret, right);
573 } while (it.hasNext());
578 private YangExpr parseRelationalExpr(final YangExpr left, final Iterator<ParseTree> it) {
581 final YangBinaryOperator operator = nextOperator(it);
582 final YangExpr right = parseAdditive(nextContext(it, AdditiveExprContext.class));
583 final Optional<YangExpr> simple = simplifyNumbers(operator, ret, right);
584 ret = simple.isPresent() ? simple.get() : operator.exprWith(ret, right);
585 } while (it.hasNext());
590 private Step parseStep(final StepContext expr) {
591 if (expr.getChildCount() == 1) {
592 final AbbreviatedStepContext abbrev = getChild(expr, AbbreviatedStepContext.class, 0);
593 verifyChildCount(abbrev, 1);
594 switch (getTerminalType(abbrev, 0)) {
595 case xpathParser.DOT:
596 return YangXPathAxis.SELF.asStep();
597 case xpathParser.DOTDOT:
598 return YangXPathAxis.PARENT.asStep();
600 throw illegalShape(abbrev);
604 final int size = verifyAtLeastChildren(expr, 2);
605 final List<YangExpr> predicates = new ArrayList<>(size - 2);
606 for (int i = 2; i < size; ++i) {
607 predicates.add(parsePredicate(getChild(expr, PredicateContext.class, i)));
610 final YangXPathAxis axis = parseAxis(getChild(expr, AxisSpecifierContext.class, 0));
611 final NodeTestContext nodeTest = getChild(expr, NodeTestContext.class, 1);
612 switch (nodeTest.getChildCount()) {
614 final NameTestContext nameChild = getChild(nodeTest, NameTestContext.class, 0);
615 final ParseTree first = nameChild.getChild(0);
616 if (first instanceof TerminalNode) {
617 verify(((TerminalNode) first).getSymbol().getType() == xpathParser.MUL);
618 return axis.asStep(predicates);
620 return createStep(axis, verifyTree(QNameContext.class, first), predicates);
622 return axis.asStep(parseNodeType(nodeTest.getChild(0)), predicates);
624 final String text = verifyToken(nodeTest, 2, xpathParser.Literal).getText();
625 return axis.asStep(text.substring(1, text.length() - 1), predicates);
627 throw illegalShape(nodeTest);
631 private static YangXPathAxis parseAxis(final AxisSpecifierContext expr) {
632 switch (expr.getChildCount()) {
634 return YangXPathAxis.CHILD;
636 verify(getTerminalType(expr, 0) == xpathParser.AT, "Unhandled axis specifier shape %s", expr);
637 return YangXPathAxis.ATTRIBUTE;
639 final String str = verifyTerminal(expr.getChild(0)).getText();
640 return verifyNotNull(XPATH_AXES.get(str), "Unhandled axis %s", str);
642 throw illegalShape(expr);
646 private QName parseQName(final QNameContext expr) {
647 switch (expr.getChildCount()) {
649 return createQName(getChild(expr, NCNameContext.class, 0).getText());
651 return createQName(getChild(expr, NCNameContext.class, 0).getText(),
652 getChild(expr, NCNameContext.class, 2).getText());
654 throw illegalShape(expr);
658 private static <T extends ParserRuleContext> T nextContext(final Iterator<ParseTree> it, final Class<T> type) {
659 return verifyTree(type, it.next());
662 private static YangBinaryOperator nextOperator(final Iterator<ParseTree> it) {
663 return parseOperator(it.next());
666 private static int getTerminalType(final ParseTree parent, final int offset) {
667 return verifyTerminal(parent.getChild(offset)).getSymbol().getType();
670 private static YangXPathNodeType parseNodeType(final ParseTree tree) {
671 final String str = verifyTerminal(tree).getText();
672 return verifyNotNull(NODE_TYPES.get(str), "Unhandled node type %s", str);
675 private static YangBinaryOperator parseOperator(final ParseTree tree) {
676 final String str = verifyTerminal(tree).getText();
677 return verifyNotNull(BINARY_OPERATORS.get(str), "Unhandled operator %s", str);
680 private static Optional<Step> parseStepShorthand(final ParseTree tree) {
681 switch (verifyTerminal(tree).getSymbol().getType()) {
682 case xpathParser.PATHSEP:
683 return Optional.empty();
684 case xpathParser.ABRPATH:
685 return Optional.of(YangXPathAxis.DESCENDANT_OR_SELF.asStep());
687 throw illegalShape(tree);