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.Iterator;
29 import java.util.LinkedHashSet;
30 import java.util.List;
32 import java.util.Optional;
33 import javax.xml.xpath.XPathExpressionException;
34 import org.antlr.v4.runtime.CharStreams;
35 import org.antlr.v4.runtime.CommonTokenStream;
36 import org.antlr.v4.runtime.ParserRuleContext;
37 import org.antlr.v4.runtime.tree.ParseTree;
38 import org.antlr.v4.runtime.tree.TerminalNode;
39 import org.opendaylight.yangtools.yang.common.QName;
40 import org.opendaylight.yangtools.yang.common.QNameModule;
41 import org.opendaylight.yangtools.yang.common.UnresolvedQName;
42 import org.opendaylight.yangtools.yang.common.YangConstants;
43 import org.opendaylight.yangtools.yang.common.YangNamespaceContext;
44 import org.opendaylight.yangtools.yang.common.YangVersion;
45 import org.opendaylight.yangtools.yang.xpath.antlr.xpathLexer;
46 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser;
47 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.AbbreviatedStepContext;
48 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.AbsoluteLocationPathNorootContext;
49 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.AdditiveExprContext;
50 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.AndExprContext;
51 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.AxisSpecifierContext;
52 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.EqualityExprContext;
53 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.ExprContext;
54 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.FilterExprContext;
55 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.FunctionCallContext;
56 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.FunctionNameContext;
57 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.LocationPathContext;
58 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.MultiplicativeExprContext;
59 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.NCNameContext;
60 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.NameTestContext;
61 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.NodeTestContext;
62 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.PathExprNoRootContext;
63 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.PredicateContext;
64 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.PrimaryExprContext;
65 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.QNameContext;
66 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.RelationalExprContext;
67 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.RelativeLocationPathContext;
68 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.StepContext;
69 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.UnaryExprNoRootContext;
70 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.UnionExprNoRootContext;
71 import org.opendaylight.yangtools.yang.xpath.antlr.xpathParser.VariableReferenceContext;
72 import org.opendaylight.yangtools.yang.xpath.api.YangBinaryOperator;
73 import org.opendaylight.yangtools.yang.xpath.api.YangBooleanConstantExpr;
74 import org.opendaylight.yangtools.yang.xpath.api.YangExpr;
75 import org.opendaylight.yangtools.yang.xpath.api.YangFilterExpr;
76 import org.opendaylight.yangtools.yang.xpath.api.YangFunction;
77 import org.opendaylight.yangtools.yang.xpath.api.YangFunctionCallExpr;
78 import org.opendaylight.yangtools.yang.xpath.api.YangLiteralExpr;
79 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath;
80 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath.AxisStep;
81 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath.QNameStep;
82 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath.ResolvedQNameStep;
83 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath.Step;
84 import org.opendaylight.yangtools.yang.xpath.api.YangNaryExpr;
85 import org.opendaylight.yangtools.yang.xpath.api.YangNaryOperator;
86 import org.opendaylight.yangtools.yang.xpath.api.YangNegateExpr;
87 import org.opendaylight.yangtools.yang.xpath.api.YangNumberExpr;
88 import org.opendaylight.yangtools.yang.xpath.api.YangPathExpr;
89 import org.opendaylight.yangtools.yang.xpath.api.YangVariableReferenceExpr;
90 import org.opendaylight.yangtools.yang.xpath.api.YangXPathAxis;
91 import org.opendaylight.yangtools.yang.xpath.api.YangXPathExpression;
92 import org.opendaylight.yangtools.yang.xpath.api.YangXPathMathMode;
93 import org.opendaylight.yangtools.yang.xpath.api.YangXPathMathSupport;
94 import org.opendaylight.yangtools.yang.xpath.api.YangXPathNodeType;
95 import org.opendaylight.yangtools.yang.xpath.api.YangXPathParser;
98 * ANTLR-based XPath parser. Uses {@code xpath.g4} ANTLR grammar.
100 * @author Robert Varga
102 abstract class AntlrXPathParser implements YangXPathParser {
103 static class Base extends AntlrXPathParser {
104 Base(final YangXPathMathMode mathMode) {
109 public YangXPathExpression parseExpression(final String xpath) throws XPathExpressionException {
110 final var result = parseExpr(xpath);
111 return new AntlrYangXPathExpression.Base(mathMode, result.minimumYangVersion, result.expression, xpath);
115 QNameStep createStep(final YangXPathAxis axis, final String localName, final List<YangExpr> predicates) {
116 return axis.asStep(UnresolvedQName.Unqualified.of(localName).intern(), predicates);
120 QNameStep createStep(final YangXPathAxis axis, final String prefix, final String localName,
121 final List<YangExpr> predicates) {
122 return axis.asStep(UnresolvedQName.Qualified.of(prefix, localName).intern(), predicates);
126 QName createQName(final String localName) {
127 throw new UnsupportedOperationException();
131 QName createQName(final String prefix, final String localName) {
132 throw new UnsupportedOperationException();
136 static class Qualified extends Base implements QualifiedBound {
137 final YangNamespaceContext namespaceContext;
139 Qualified(final YangXPathMathMode mathMode, final YangNamespaceContext namespaceContext) {
141 this.namespaceContext = requireNonNull(namespaceContext);
145 public YangXPathExpression.QualifiedBound parseExpression(final String xpath) throws XPathExpressionException {
146 final var result = parseExpr(xpath);
147 return new AntlrYangXPathExpression.Qualified(mathMode, result.minimumYangVersion, result.expression, xpath,
148 result.haveLiteral ? namespaceContext : null);
152 final QName createQName(final String prefix, final String localName) {
153 return namespaceContext.createQName(prefix, localName);
157 ResolvedQNameStep createStep(final YangXPathAxis axis, final String prefix, final String localName,
158 final List<YangExpr> predicates) {
159 return axis.asStep(createQName(prefix, localName), predicates);
163 static final class Unqualified extends Qualified implements UnqualifiedBound {
164 private final QNameModule defaultNamespace;
166 Unqualified(final YangXPathMathMode mathMode, final YangNamespaceContext namespaceContext,
167 final QNameModule defaultNamespace) {
168 super(mathMode, namespaceContext);
169 this.defaultNamespace = requireNonNull(defaultNamespace);
173 public YangXPathExpression.UnqualifiedBound parseExpression(final String xpath)
174 throws XPathExpressionException {
175 final var result = parseExpr(xpath);
176 return new AntlrYangXPathExpression.Unqualified(mathMode, result.minimumYangVersion, result.expression,
177 xpath, result.haveLiteral ? namespaceContext : null, defaultNamespace);
181 QName createQName(final String localName) {
182 return QName.create(defaultNamespace, localName);
186 ResolvedQNameStep createStep(final YangXPathAxis axis, final String localName,
187 final List<YangExpr> predicates) {
188 return axis.asStep(QName.create(defaultNamespace, localName), predicates);
192 private static final class ParseExprResult {
193 final YangVersion minimumYangVersion;
194 final YangExpr expression;
195 final boolean haveLiteral;
197 ParseExprResult(final YangVersion minimumYangVersion, final YangExpr expression, final boolean haveLiteral) {
198 this.minimumYangVersion = requireNonNull(minimumYangVersion);
199 this.expression = requireNonNull(expression);
200 this.haveLiteral = haveLiteral;
204 private static final Map<String, YangBinaryOperator> BINARY_OPERATORS = Maps.uniqueIndex(
205 Arrays.asList(YangBinaryOperator.values()), YangBinaryOperator::toString);
206 private static final Map<String, YangXPathNodeType> NODE_TYPES = Maps.uniqueIndex(Arrays.asList(
207 YangXPathNodeType.values()), YangXPathNodeType::toString);
208 private static final Map<String, YangXPathAxis> XPATH_AXES = Maps.uniqueIndex(Arrays.asList(YangXPathAxis.values()),
209 YangXPathAxis::toString);
210 private static final Map<QName, YangFunction> YANG_FUNCTIONS = Maps.uniqueIndex(Arrays.asList(
211 YangFunction.values()), YangFunction::getIdentifier);
213 // Cached for checks in hot path
214 private static final AxisStep SELF_STEP = YangXPathAxis.SELF.asStep();
216 final YangXPathMathMode mathMode;
217 private final YangXPathMathSupport mathSupport;
218 private final FunctionSupport functionSupport;
220 private YangVersion minimumYangVersion = YangVersion.VERSION_1;
221 private boolean haveLiteral = false;
223 AntlrXPathParser(final YangXPathMathMode mathMode) {
224 this.mathMode = requireNonNull(mathMode);
225 mathSupport = mathMode.getSupport();
226 functionSupport = new FunctionSupport(mathSupport);
229 abstract QName createQName(String localName);
231 abstract QName createQName(String prefix, String localName);
233 abstract QNameStep createStep(YangXPathAxis axis, String localName, List<YangExpr> predicates);
235 abstract QNameStep createStep(YangXPathAxis axis, String prefix, String localName, List<YangExpr> predicates);
237 private QNameStep createStep(final YangXPathAxis axis, final QNameContext expr, final List<YangExpr> predicates) {
238 return switch (expr.getChildCount()) {
239 case 1 -> createStep(axis, getChild(expr, NCNameContext.class, 0).getText(), predicates);
240 case 3 -> createStep(axis, getChild(expr, NCNameContext.class, 0).getText(),
241 getChild(expr, NCNameContext.class, 2).getText(), predicates);
242 default -> throw illegalShape(expr);
246 @SuppressWarnings("checkstyle:illegalCatch")
247 final ParseExprResult parseExpr(final String xpath) throws XPathExpressionException {
248 // Create a parser and disconnect it from console error output
249 final var lexer = new xpathLexer(CharStreams.fromString(xpath));
250 final var parser = new xpathParser(new CommonTokenStream(lexer));
252 final var listener = new CapturingErrorListener();
253 lexer.removeErrorListeners();
254 lexer.addErrorListener(listener);
255 parser.removeErrorListeners();
256 parser.addErrorListener(listener);
257 final var antlr = parser.main().expr();
258 listener.reportError();
260 // Reset our internal context
261 minimumYangVersion = YangVersion.VERSION_1;
266 expr = parseExpr(antlr);
267 } catch (RuntimeException e) {
268 throw new XPathExpressionException(e);
270 return new ParseExprResult(minimumYangVersion, expr, haveLiteral);
274 * Parse and simplify an XPath expression in {@link ExprContext} representation.
276 * @param ctx Current parsing context
277 * @param expr ANTLR ExprContext
278 * @return A {@link YangExpr}
279 * @throws NullPointerException if {@code expr} is null
280 * @throws IllegalArgumentException if {@code expr} references an unbound prefix
282 private YangExpr parseExpr(final ExprContext expr) {
283 final var or = expr.orExpr();
284 final int size = or.getChildCount();
286 return parseAnd(getChild(or, AndExprContext.class, 0));
288 final var tmp = new ArrayList<YangExpr>((size + 1) / 2);
289 for (int i = 0; i < size; i += 2) {
290 tmp.add(parseAnd(getChild(or, AndExprContext.class, i)));
292 return YangNaryOperator.OR.exprWith(tmp);
295 private YangExpr parseAdditive(final AdditiveExprContext expr) {
296 final var it = expr.children.iterator();
297 final var first = parseMultiplicative(nextContext(it, MultiplicativeExprContext.class));
298 return it.hasNext() ? parseAdditiveExpr(first, it) : first;
301 private YangExpr parseAnd(final AndExprContext expr) {
302 final int size = expr.getChildCount();
304 return parseEquality(getChild(expr, EqualityExprContext.class, 0));
306 final var tmp = new ArrayList<YangExpr>((size + 1) / 2);
307 for (int i = 0; i < size; i += 2) {
308 tmp.add(parseEquality(getChild(expr, EqualityExprContext.class, i)));
310 return YangNaryOperator.AND.exprWith(tmp);
313 private YangExpr parseEquality(final EqualityExprContext expr) {
314 final var it = expr.children.iterator();
315 final var first = parseRelational(nextContext(it, RelationalExprContext.class));
316 return it.hasNext() ? parseEqualityExpr(first, it) : first;
319 private YangExpr parseFilter(final FilterExprContext expr) {
320 final var it = expr.children.iterator();
321 final var first = parsePrimary(nextContext(it, PrimaryExprContext.class));
322 return it.hasNext() ? YangFilterExpr.of(first, ImmutableList.copyOf(Iterators.transform(it,
323 tree -> parsePredicate(verifyTree(PredicateContext.class, tree)))))
327 private YangExpr parseFunctionCall(final FunctionCallContext expr) {
328 // We are mapping functions to RFC7950 YIN namespace, to keep us consistent with type/statement definitions
330 final var name = getChild(expr, FunctionNameContext.class, 0);
331 final var parsed = switch (name.getChildCount()) {
332 case 1 -> QName.create(YangConstants.RFC6020_YIN_MODULE, name.getChild(0).getText());
333 case 3 -> createQName(name.getChild(0).getText(), name.getChild(2).getText());
334 default -> throw illegalShape(name);
336 final var args = expr.expr().stream().map(this::parseExpr).collect(ImmutableList.toImmutableList());
337 final var func = YANG_FUNCTIONS.get(parsed);
339 if (minimumYangVersion.compareTo(func.getYangVersion()) < 0) {
340 minimumYangVersion = func.getYangVersion();
343 final var funcExpr = functionSupport.functionToExpr(func, args);
344 if (funcExpr instanceof YangLiteralExpr) {
350 checkArgument(!YangConstants.RFC6020_YIN_MODULE.equals(parsed.getModule()), "Unknown default function %s",
352 return YangFunctionCallExpr.of(parsed, args);
355 private YangLocationPath parseLocationPath(final LocationPathContext expr) {
356 verifyChildCount(expr, 1);
357 final var first = expr.getChild(0);
358 if (first instanceof RelativeLocationPathContext relativeLocation) {
359 return YangLocationPath.relative(parseLocationPathSteps(relativeLocation));
362 final var abs = verifyTree(AbsoluteLocationPathNorootContext.class, first);
363 verifyChildCount(abs, 2);
365 final var steps = parseLocationPathSteps(getChild(abs, RelativeLocationPathContext.class, 1));
366 parseStepShorthand(abs.getChild(0)).ifPresent(steps::addFirst);
368 return YangLocationPath.absolute(steps);
371 private YangExpr parseMultiplicative(final MultiplicativeExprContext expr) {
372 final var first = expr.getChild(0);
373 final var left = first instanceof UnaryExprNoRootContext unary ? parseUnary(unary) : YangLocationPath.root();
374 if (expr.getChildCount() == 1) {
378 verifyChildCount(expr, 3);
379 final var operator = parseOperator(expr.getChild(1));
380 final var right = parseMultiplicative(getChild(expr, MultiplicativeExprContext.class, 2));
381 final var simple = simplifyNumbers(operator, left, right);
382 return simple.isPresent() ? simple.orElseThrow() : operator.exprWith(left, right);
385 private YangExpr parsePathExpr(final PathExprNoRootContext expr) {
386 final var first = expr.getChild(0);
387 if (first instanceof LocationPathContext location) {
388 return parseLocationPath(location);
391 final var filter = parseFilter(verifyTree(FilterExprContext.class, first));
392 if (expr.getChildCount() == 1) {
396 verifyChildCount(expr, 3);
397 final var steps = parseLocationPathSteps(getChild(expr, RelativeLocationPathContext.class, 2));
398 parseStepShorthand(expr.getChild(1)).ifPresent(steps::addFirst);
399 return YangPathExpr.of(filter, YangLocationPath.relative(steps));
402 private YangExpr parsePredicate(final PredicateContext expr) {
403 verifyChildCount(expr, 3);
404 return parseExpr(getChild(expr, ExprContext.class, 1));
407 private YangExpr parsePrimary(final PrimaryExprContext expr) {
408 if (expr.getChildCount() == 3) {
409 return parseExpr(getChild(expr, ExprContext.class, 1));
412 verifyChildCount(expr, 1);
413 final var first = expr.getChild(0);
414 return switch (first) {
415 case TerminalNode terminal -> parseTerminal(terminal);
416 case FunctionCallContext function -> parseFunctionCall(function);
417 case VariableReferenceContext variable -> YangVariableReferenceExpr.of(parseQName(variable.qName()));
418 default -> throw illegalShape(first);
422 private YangExpr parseRelational(final RelationalExprContext expr) {
423 final var it = expr.children.iterator();
424 final var first = parseAdditive(nextContext(it, AdditiveExprContext.class));
425 return it.hasNext() ? parseRelationalExpr(first, it) : first;
428 private ArrayDeque<Step> parseLocationPathSteps(final RelativeLocationPathContext expr) {
429 final var steps = new ArrayDeque<Step>(expr.getChildCount());
430 final var it = expr.children.iterator();
431 addNotSelfStep(steps, parseStep(nextContext(it, StepContext.class)));
433 while (it.hasNext()) {
434 parseStepShorthand(it.next()).ifPresent(steps::add);
436 // Parse step and add it if it's not SELF_STEP
437 addNotSelfStep(steps, parseStep(nextContext(it, StepContext.class)));
443 private static void addNotSelfStep(final ArrayDeque<Step> steps, final Step step) {
444 if (!SELF_STEP.equals(step)) {
449 private YangExpr parseTerminal(final TerminalNode term) {
450 final var text = term.getText();
451 return switch (term.getSymbol().getType()) {
452 case xpathParser.Literal -> {
453 // We have to strip quotes
455 yield YangLiteralExpr.of(text.substring(1, text.length() - 1));
457 case xpathParser.Number -> mathSupport.createNumber(text);
458 default -> throw illegalShape(term);
462 private YangExpr parseUnary(final UnaryExprNoRootContext expr) {
463 // any number of '-' and an union expr
464 final int size = verifyAtLeastChildren(expr, 1);
465 final var ret = parseUnion(getChild(expr, UnionExprNoRootContext.class, size - 1));
467 // Even number of '-' tokens cancel out
470 return ret instanceof YangNumberExpr number ? mathSupport.negateNumber(number) : YangNegateExpr.of(ret);
473 private YangExpr parseUnion(final UnionExprNoRootContext expr) {
474 final var first = expr.getChild(0);
476 if (first instanceof PathExprNoRootContext noRoot) {
477 path = parsePathExpr(noRoot);
478 if (expr.getChildCount() == 1) {
482 path = YangLocationPath.root();
485 verifyChildCount(expr, 3);
486 final var union = parseUnion(getChild(expr, UnionExprNoRootContext.class, 2));
488 // Deduplicate expressions so we do not perform useless unioning
489 final var expressions = new LinkedHashSet<YangExpr>();
490 expressions.add(path);
491 if (union instanceof YangNaryExpr nary && nary.getOperator() == YangNaryOperator.UNION) {
492 expressions.addAll(nary.getExpressions());
494 expressions.add(union);
497 return YangNaryOperator.UNION.exprWith(expressions);
500 private YangExpr parseAdditiveExpr(final YangExpr left, final Iterator<ParseTree> it) {
503 final var operator = nextOperator(it);
504 final var right = parseMultiplicative(nextContext(it, MultiplicativeExprContext.class));
505 final var simple = simplifyNumbers(operator, ret, right);
506 ret = simple.isPresent() ? simple.orElseThrow() : operator.exprWith(ret, right);
507 } while (it.hasNext());
512 private Optional<YangExpr> simplifyNumbers(final YangBinaryOperator operator, final YangExpr left,
513 final YangExpr right) {
514 if (left instanceof YangNumberExpr leftNumber && right instanceof YangNumberExpr rightNumber) {
515 // Constant folding on numbers -- precision plays a role here
516 return mathSupport.tryEvaluate(operator, leftNumber, rightNumber);
518 return Optional.empty();
521 private YangExpr parseEqualityExpr(final YangExpr left, final Iterator<ParseTree> it) {
524 final var operator = nextOperator(it);
525 final var right = parseRelational(nextContext(it, RelationalExprContext.class));
527 if (left.equals(right)) {
528 // Constant folding on expression level: equal expressions are result in equal results
531 return YangBooleanConstantExpr.TRUE;
533 return YangBooleanConstantExpr.FALSE;
539 final var simple = simplifyNumbers(operator, ret, right);
540 ret = simple.isPresent() ? simple.orElseThrow() : operator.exprWith(ret, right);
541 } while (it.hasNext());
546 private YangExpr parseRelationalExpr(final YangExpr left, final Iterator<ParseTree> it) {
549 final var operator = nextOperator(it);
550 final var right = parseAdditive(nextContext(it, AdditiveExprContext.class));
551 final var simple = simplifyNumbers(operator, ret, right);
552 ret = simple.isPresent() ? simple.orElseThrow() : operator.exprWith(ret, right);
553 } while (it.hasNext());
558 private Step parseStep(final StepContext expr) {
559 if (expr.getChildCount() == 1) {
560 final var abbrev = getChild(expr, AbbreviatedStepContext.class, 0);
561 verifyChildCount(abbrev, 1);
562 return switch (getTerminalType(abbrev, 0)) {
563 case xpathParser.DOT -> YangXPathAxis.SELF.asStep();
564 case xpathParser.DOTDOT -> YangXPathAxis.PARENT.asStep();
565 default -> throw illegalShape(abbrev);
569 final int size = verifyAtLeastChildren(expr, 2);
570 final var predicates = new ArrayList<YangExpr>(size - 2);
571 for (int i = 2; i < size; ++i) {
572 predicates.add(parsePredicate(getChild(expr, PredicateContext.class, i)));
575 final var axis = parseAxis(getChild(expr, AxisSpecifierContext.class, 0));
576 final var nodeTest = getChild(expr, NodeTestContext.class, 1);
577 return switch (nodeTest.getChildCount()) {
579 final var nameChild = getChild(nodeTest, NameTestContext.class, 0);
580 final var first = nameChild.getChild(0);
581 if (first instanceof TerminalNode terminal) {
582 verify(terminal.getSymbol().getType() == xpathParser.MUL);
583 yield axis.asStep(predicates);
585 yield createStep(axis, verifyTree(QNameContext.class, first), predicates);
587 case 3 -> axis.asStep(parseNodeType(nodeTest.getChild(0)), predicates);
589 final var text = verifyToken(nodeTest, 2, xpathParser.Literal).getText();
590 yield axis.asStep(text.substring(1, text.length() - 1), predicates);
592 default -> throw illegalShape(nodeTest);
596 private static YangXPathAxis parseAxis(final AxisSpecifierContext expr) {
597 return switch (expr.getChildCount()) {
598 case 0 -> YangXPathAxis.CHILD;
600 verify(getTerminalType(expr, 0) == xpathParser.AT, "Unhandled axis specifier shape %s", expr);
601 yield YangXPathAxis.ATTRIBUTE;
604 final var str = verifyTerminal(expr.getChild(0)).getText();
605 yield verifyNotNull(XPATH_AXES.get(str), "Unhandled axis %s", str);
607 default -> throw illegalShape(expr);
611 private QName parseQName(final QNameContext expr) {
612 return switch (expr.getChildCount()) {
613 case 1 -> createQName(getChild(expr, NCNameContext.class, 0).getText());
614 case 3 -> createQName(getChild(expr, NCNameContext.class, 0).getText(),
615 getChild(expr, NCNameContext.class, 2).getText());
616 default -> throw illegalShape(expr);
620 private static <T extends ParserRuleContext> T nextContext(final Iterator<ParseTree> it, final Class<T> type) {
621 return verifyTree(type, it.next());
624 private static YangBinaryOperator nextOperator(final Iterator<ParseTree> it) {
625 return parseOperator(it.next());
628 private static int getTerminalType(final ParseTree parent, final int offset) {
629 return verifyTerminal(parent.getChild(offset)).getSymbol().getType();
632 private static YangXPathNodeType parseNodeType(final ParseTree tree) {
633 final var str = verifyTerminal(tree).getText();
634 return verifyNotNull(NODE_TYPES.get(str), "Unhandled node type %s", str);
637 private static YangBinaryOperator parseOperator(final ParseTree tree) {
638 final var str = verifyTerminal(tree).getText();
639 return verifyNotNull(BINARY_OPERATORS.get(str), "Unhandled operator %s", str);
642 private static Optional<Step> parseStepShorthand(final ParseTree tree) {
643 return switch (verifyTerminal(tree).getSymbol().getType()) {
644 case xpathParser.PATHSEP -> Optional.empty();
645 case xpathParser.ABRPATH -> Optional.of(YangXPathAxis.DESCENDANT_OR_SELF.asStep());
646 default -> throw illegalShape(tree);