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.AbstractMap.SimpleImmutableEntry;
26 import java.util.ArrayDeque;
27 import java.util.ArrayList;
28 import java.util.Arrays;
29 import java.util.Deque;
30 import java.util.Iterator;
31 import java.util.LinkedHashSet;
32 import java.util.List;
34 import java.util.Map.Entry;
35 import java.util.Optional;
37 import javax.xml.xpath.XPathExpressionException;
38 import org.antlr.v4.runtime.CharStreams;
39 import org.antlr.v4.runtime.CommonTokenStream;
40 import org.antlr.v4.runtime.ParserRuleContext;
41 import org.antlr.v4.runtime.tree.ParseTree;
42 import org.antlr.v4.runtime.tree.TerminalNode;
43 import org.opendaylight.yangtools.yang.common.QName;
44 import org.opendaylight.yangtools.yang.common.QNameModule;
45 import org.opendaylight.yangtools.yang.common.QualifiedQName;
46 import org.opendaylight.yangtools.yang.common.UnqualifiedQName;
47 import org.opendaylight.yangtools.yang.common.YangConstants;
48 import org.opendaylight.yangtools.yang.common.YangNamespaceContext;
49 import org.opendaylight.yangtools.yang.common.YangVersion;
50 import org.opendaylight.yangtools.yang.xpath.api.YangBinaryOperator;
51 import org.opendaylight.yangtools.yang.xpath.api.YangBooleanConstantExpr;
52 import org.opendaylight.yangtools.yang.xpath.api.YangExpr;
53 import org.opendaylight.yangtools.yang.xpath.api.YangFilterExpr;
54 import org.opendaylight.yangtools.yang.xpath.api.YangFunction;
55 import org.opendaylight.yangtools.yang.xpath.api.YangFunctionCallExpr;
56 import org.opendaylight.yangtools.yang.xpath.api.YangLiteralExpr;
57 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath;
58 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath.AxisStep;
59 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath.QNameStep;
60 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath.ResolvedQNameStep;
61 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath.Step;
62 import org.opendaylight.yangtools.yang.xpath.api.YangNaryExpr;
63 import org.opendaylight.yangtools.yang.xpath.api.YangNaryOperator;
64 import org.opendaylight.yangtools.yang.xpath.api.YangNegateExpr;
65 import org.opendaylight.yangtools.yang.xpath.api.YangNumberExpr;
66 import org.opendaylight.yangtools.yang.xpath.api.YangPathExpr;
67 import org.opendaylight.yangtools.yang.xpath.api.YangVariableReferenceExpr;
68 import org.opendaylight.yangtools.yang.xpath.api.YangXPathAxis;
69 import org.opendaylight.yangtools.yang.xpath.api.YangXPathExpression;
70 import org.opendaylight.yangtools.yang.xpath.api.YangXPathMathMode;
71 import org.opendaylight.yangtools.yang.xpath.api.YangXPathMathSupport;
72 import org.opendaylight.yangtools.yang.xpath.api.YangXPathNodeType;
73 import org.opendaylight.yangtools.yang.xpath.api.YangXPathParser;
74 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.AbbreviatedStepContext;
75 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.AbsoluteLocationPathNorootContext;
76 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.AdditiveExprContext;
77 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.AndExprContext;
78 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.AxisSpecifierContext;
79 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.EqualityExprContext;
80 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.ExprContext;
81 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.FilterExprContext;
82 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.FunctionCallContext;
83 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.FunctionNameContext;
84 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.LocationPathContext;
85 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.MultiplicativeExprContext;
86 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.NCNameContext;
87 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.NameTestContext;
88 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.NodeTestContext;
89 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.OrExprContext;
90 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.PathExprNoRootContext;
91 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.PredicateContext;
92 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.PrimaryExprContext;
93 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.QNameContext;
94 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.RelationalExprContext;
95 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.RelativeLocationPathContext;
96 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.StepContext;
97 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.UnaryExprNoRootContext;
98 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.UnionExprNoRootContext;
99 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.VariableReferenceContext;
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 Entry<YangVersion, YangExpr> result = parseExpr(xpath);
115 return new AntlrYangXPathExpression.Base(mathMode, result.getKey(), result.getValue(), 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 Entry<YangVersion, YangExpr> result = parseExpr(xpath);
152 return new AntlrYangXPathExpression.Qualified(mathMode, result.getKey(), result.getValue(), xpath,
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 Entry<YangVersion, YangExpr> result = parseExpr(xpath);
182 return new AntlrYangXPathExpression.Unqualified(mathMode, result.getKey(), result.getValue(), xpath,
183 namespaceContext, 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 Map<String, YangBinaryOperator> BINARY_OPERATORS = Maps.uniqueIndex(
199 Arrays.asList(YangBinaryOperator.values()), YangBinaryOperator::toString);
200 private static final Map<String, YangXPathNodeType> NODE_TYPES = Maps.uniqueIndex(Arrays.asList(
201 YangXPathNodeType.values()), YangXPathNodeType::toString);
202 private static final Map<String, YangXPathAxis> XPATH_AXES = Maps.uniqueIndex(Arrays.asList(YangXPathAxis.values()),
203 YangXPathAxis::toString);
204 private static final Map<QName, YangFunction> YANG_FUNCTIONS = Maps.uniqueIndex(Arrays.asList(
205 YangFunction.values()), YangFunction::getIdentifier);
207 // Cached for checks in hot path
208 private static final AxisStep SELF_STEP = YangXPathAxis.SELF.asStep();
210 final YangXPathMathMode mathMode;
211 private final YangXPathMathSupport mathSupport;
212 private final FunctionSupport functionSupport;
214 private YangVersion minimumYangVersion = YangVersion.VERSION_1;
216 AntlrXPathParser(final YangXPathMathMode mathMode) {
217 this.mathMode = requireNonNull(mathMode);
218 this.mathSupport = mathMode.getSupport();
219 this.functionSupport = new FunctionSupport(mathSupport);
222 abstract QName createQName(String localName);
224 abstract QName createQName(String prefix, String localName);
226 abstract QNameStep createStep(YangXPathAxis axis, String localName, List<YangExpr> predicates);
228 abstract QNameStep createStep(YangXPathAxis axis, String prefix, String localName, List<YangExpr> predicates);
230 private QNameStep createStep(final YangXPathAxis axis, final QNameContext expr, final List<YangExpr> predicates) {
231 switch (expr.getChildCount()) {
233 return createStep(axis, getChild(expr, NCNameContext.class, 0).getText(), predicates);
235 return createStep(axis, getChild(expr, NCNameContext.class, 0).getText(),
236 getChild(expr, NCNameContext.class, 2).getText(), predicates);
238 throw illegalShape(expr);
242 @SuppressWarnings("checkstyle:illegalCatch")
243 final Entry<YangVersion, YangExpr> parseExpr(final String xpath) throws XPathExpressionException {
244 // Create a parser and disconnect it from console error output
245 final xpathLexer lexer = new xpathLexer(CharStreams.fromString(xpath));
246 final xpathParser parser = new xpathParser(new CommonTokenStream(lexer));
248 final CapturingErrorListener listener = new CapturingErrorListener();
249 lexer.removeErrorListeners();
250 lexer.addErrorListener(listener);
251 parser.removeErrorListeners();
252 parser.addErrorListener(listener);
253 final ExprContext antlr = parser.main().expr();
254 listener.reportError();
256 // Reset our internal context
257 minimumYangVersion = YangVersion.VERSION_1;
261 expr = parseExpr(antlr);
262 } catch (RuntimeException e) {
263 throw new XPathExpressionException(e);
265 return new SimpleImmutableEntry<>(minimumYangVersion, expr);
269 * Parse and simplify an XPath expression in {@link ExprContext} representation.
271 * @param ctx Current parsing context
272 * @param expr ANTLR ExprContext
273 * @return A {@link YangExpr}
274 * @throws NullPointerException if {@code expr} is null
275 * @throws IllegalArgumentException if {@code expr} references an unbound prefix
277 private YangExpr parseExpr(final ExprContext expr) {
278 final OrExprContext or = expr.orExpr();
279 final int size = or.getChildCount();
281 return parseAnd(getChild(or, AndExprContext.class, 0));
283 final List<YangExpr> tmp = new ArrayList<>((size + 1) / 2);
284 for (int i = 0; i < size; i += 2) {
285 tmp.add(parseAnd(getChild(or, AndExprContext.class, i)));
287 return YangNaryOperator.OR.exprWith(tmp);
290 private YangExpr parseAdditive(final AdditiveExprContext expr) {
291 final Iterator<ParseTree> it = expr.children.iterator();
292 final YangExpr first = parseMultiplicative(nextContext(it, MultiplicativeExprContext.class));
293 return it.hasNext() ? parseAdditiveExpr(first, it) : first;
296 private YangExpr parseAnd(final AndExprContext expr) {
297 final int size = expr.getChildCount();
299 return parseEquality(getChild(expr, EqualityExprContext.class, 0));
301 final List<YangExpr> tmp = new ArrayList<>((size + 1) / 2);
302 for (int i = 0; i < size; i += 2) {
303 tmp.add(parseEquality(getChild(expr, EqualityExprContext.class, i)));
305 return YangNaryOperator.AND.exprWith(tmp);
308 private YangExpr parseEquality(final EqualityExprContext expr) {
309 final Iterator<ParseTree> it = expr.children.iterator();
310 final YangExpr first = parseRelational(nextContext(it, RelationalExprContext.class));
311 return it.hasNext() ? parseEqualityExpr(first, it) : first;
314 private YangExpr parseFilter(final FilterExprContext expr) {
315 final Iterator<ParseTree> it = expr.children.iterator();
316 final YangExpr first = parsePrimary(nextContext(it, PrimaryExprContext.class));
317 return it.hasNext() ? YangFilterExpr.of(first, ImmutableList.copyOf(Iterators.transform(it,
318 tree -> parsePredicate(verifyTree(PredicateContext.class, tree)))))
322 private YangExpr parseFunctionCall(final FunctionCallContext expr) {
323 // We are mapping functions to RFC7950 YIN namespace, to keep us consistent with type/statement definitions
325 final FunctionNameContext name = getChild(expr, FunctionNameContext.class, 0);
327 switch (name.getChildCount()) {
329 parsed = QName.create(YangConstants.RFC6020_YIN_MODULE, name.getChild(0).getText());
332 parsed = createQName(name.getChild(0).getText(), name.getChild(2).getText());
335 throw illegalShape(name);
338 final List<YangExpr> args = expr.expr().stream().map(this::parseExpr).collect(ImmutableList.toImmutableList());
339 final YangFunction func = YANG_FUNCTIONS.get(parsed);
341 if (minimumYangVersion.compareTo(func.getYangVersion()) < 0) {
342 minimumYangVersion = func.getYangVersion();
344 return functionSupport.functionToExpr(func, args);
347 checkArgument(!YangConstants.RFC6020_YIN_MODULE.equals(parsed.getModule()), "Unknown default function %s",
349 return YangFunctionCallExpr.of(parsed, args);
352 private YangLocationPath parseLocationPath(final LocationPathContext expr) {
353 verifyChildCount(expr, 1);
354 final ParseTree first = expr.getChild(0);
355 if (first instanceof RelativeLocationPathContext) {
356 return YangLocationPath.relative(parseLocationPathSteps((RelativeLocationPathContext) first));
359 final AbsoluteLocationPathNorootContext abs = verifyTree(AbsoluteLocationPathNorootContext.class, first);
360 verifyChildCount(abs, 2);
362 final Deque<Step> steps = parseLocationPathSteps(getChild(abs, RelativeLocationPathContext.class, 1));
363 parseStepShorthand(abs.getChild(0)).ifPresent(steps::addFirst);
365 return YangLocationPath.absolute(steps);
368 private YangExpr parseMultiplicative(final MultiplicativeExprContext expr) {
369 final ParseTree first = expr.getChild(0);
371 if (first instanceof UnaryExprNoRootContext) {
372 left = parseUnary((UnaryExprNoRootContext) first);
374 left = YangLocationPath.root();
376 if (expr.getChildCount() == 1) {
380 verifyChildCount(expr, 3);
381 final YangBinaryOperator operator = parseOperator(expr.getChild(1));
382 final YangExpr right = parseMultiplicative(getChild(expr, MultiplicativeExprContext.class, 2));
383 final Optional<YangExpr> simple = simplifyNumbers(operator, left, right);
384 return simple.isPresent() ? simple.get() : operator.exprWith(left, right);
387 private YangExpr parsePathExpr(final PathExprNoRootContext expr) {
388 final ParseTree first = expr.getChild(0);
389 if (first instanceof LocationPathContext) {
390 return parseLocationPath((LocationPathContext) first);
393 final YangExpr filter = parseFilter(verifyTree(FilterExprContext.class, first));
394 if (expr.getChildCount() == 1) {
398 verifyChildCount(expr, 3);
399 final Deque<Step> steps = parseLocationPathSteps(getChild(expr, RelativeLocationPathContext.class, 2));
400 parseStepShorthand(expr.getChild(1)).ifPresent(steps::addFirst);
401 return YangPathExpr.of(filter, YangLocationPath.relative(steps));
404 private YangExpr parsePredicate(final PredicateContext expr) {
405 verifyChildCount(expr, 3);
406 return parseExpr(getChild(expr, ExprContext.class, 1));
409 private YangExpr parsePrimary(final PrimaryExprContext expr) {
410 if (expr.getChildCount() == 3) {
411 return parseExpr(getChild(expr, ExprContext.class, 1));
414 verifyChildCount(expr, 1);
415 final ParseTree first = expr.getChild(0);
416 if (first instanceof TerminalNode) {
417 return parseTerminal((TerminalNode) first);
419 if (first instanceof FunctionCallContext) {
420 return parseFunctionCall((FunctionCallContext) first);
422 if (first instanceof VariableReferenceContext) {
423 return YangVariableReferenceExpr.of(parseQName(((VariableReferenceContext) first).qName()));
425 throw illegalShape(first);
428 private YangExpr parseRelational(final RelationalExprContext expr) {
429 final Iterator<ParseTree> it = expr.children.iterator();
430 final YangExpr first = parseAdditive(nextContext(it, AdditiveExprContext.class));
431 return it.hasNext() ? parseRelationalExpr(first, it) : first;
434 private Deque<Step> parseLocationPathSteps(final RelativeLocationPathContext expr) {
435 final Deque<Step> steps = new ArrayDeque<>(expr.getChildCount());
436 final Iterator<ParseTree> it = expr.children.iterator();
437 addNotSelfStep(steps, parseStep(nextContext(it, StepContext.class)));
439 while (it.hasNext()) {
440 parseStepShorthand(it.next()).ifPresent(steps::add);
442 // Parse step and add it if it's not SELF_STEP
443 addNotSelfStep(steps, parseStep(nextContext(it, StepContext.class)));
449 private static void addNotSelfStep(final Deque<Step> steps, final Step step) {
450 if (!SELF_STEP.equals(step)) {
455 private YangExpr parseTerminal(final TerminalNode term) {
456 final String text = term.getText();
457 switch (term.getSymbol().getType()) {
458 case xpathParser.Literal:
459 // We have to strip quotes
460 return YangLiteralExpr.of(text.substring(1, text.length() - 1));
461 case xpathParser.Number:
462 return mathSupport.createNumber(text);
464 throw illegalShape(term);
468 private YangExpr parseUnary(final UnaryExprNoRootContext expr) {
469 // any number of '-' and an union expr
470 final int size = verifyAtLeastChildren(expr, 1);
471 final YangExpr ret = parseUnion(getChild(expr, UnionExprNoRootContext.class, size - 1));
473 // Even number of '-' tokens cancel out
476 return ret instanceof YangNumberExpr ? mathSupport.negateNumber((YangNumberExpr) ret) : YangNegateExpr.of(ret);
479 private YangExpr parseUnion(final UnionExprNoRootContext expr) {
480 final ParseTree first = expr.getChild(0);
482 if (first instanceof PathExprNoRootContext) {
483 path = parsePathExpr((PathExprNoRootContext) first);
484 if (expr.getChildCount() == 1) {
488 path = YangLocationPath.root();
491 verifyChildCount(expr, 3);
492 final YangExpr union = parseUnion(getChild(expr, UnionExprNoRootContext.class, 2));
494 // Deduplicate expressions so we do not perform useless unioning
495 final Set<YangExpr> expressions = new LinkedHashSet<>();
496 expressions.add(path);
497 if (union instanceof YangNaryExpr) {
498 // If the result is a union expression, integrate it into this expression
499 final YangNaryExpr nary = (YangNaryExpr) union;
500 if (nary.getOperator() == YangNaryOperator.UNION) {
501 expressions.addAll(nary.getExpressions());
503 expressions.add(union);
506 expressions.add(union);
509 return YangNaryOperator.UNION.exprWith(expressions);
512 private YangExpr parseAdditiveExpr(final YangExpr left, final Iterator<ParseTree> it) {
515 final YangBinaryOperator operator = nextOperator(it);
516 final YangExpr right = parseMultiplicative(nextContext(it, MultiplicativeExprContext.class));
517 final Optional<YangExpr> simple = simplifyNumbers(operator, ret, right);
518 ret = simple.isPresent() ? simple.get() : operator.exprWith(ret, right);
519 } while (it.hasNext());
524 private Optional<YangExpr> simplifyNumbers(final YangBinaryOperator operator, final YangExpr left,
525 final YangExpr right) {
526 if (left instanceof YangNumberExpr && right instanceof YangNumberExpr) {
527 // Constant folding on numbers -- precision plays a role here
528 return mathSupport.tryEvaluate(operator, (YangNumberExpr)left, (YangNumberExpr)right);
530 return Optional.empty();
533 private YangExpr parseEqualityExpr(final YangExpr left, final Iterator<ParseTree> it) {
536 final YangBinaryOperator operator = nextOperator(it);
537 final YangExpr right = parseRelational(nextContext(it, RelationalExprContext.class));
539 if (left.equals(right)) {
540 // Constant folding on expression level: equal expressions are result in equal results
543 return YangBooleanConstantExpr.TRUE;
545 return YangBooleanConstantExpr.FALSE;
551 final Optional<YangExpr> simple = simplifyNumbers(operator, ret, right);
552 ret = simple.isPresent() ? simple.get() : operator.exprWith(ret, right);
553 } while (it.hasNext());
558 private YangExpr parseRelationalExpr(final YangExpr left, final Iterator<ParseTree> it) {
561 final YangBinaryOperator operator = nextOperator(it);
562 final YangExpr right = parseAdditive(nextContext(it, AdditiveExprContext.class));
563 final Optional<YangExpr> simple = simplifyNumbers(operator, ret, right);
564 ret = simple.isPresent() ? simple.get() : operator.exprWith(ret, right);
565 } while (it.hasNext());
570 private Step parseStep(final StepContext expr) {
571 if (expr.getChildCount() == 1) {
572 final AbbreviatedStepContext abbrev = getChild(expr, AbbreviatedStepContext.class, 0);
573 verifyChildCount(abbrev, 1);
574 switch (getTerminalType(abbrev, 0)) {
575 case xpathParser.DOT:
576 return YangXPathAxis.SELF.asStep();
577 case xpathParser.DOTDOT:
578 return YangXPathAxis.PARENT.asStep();
580 throw illegalShape(abbrev);
584 final int size = verifyAtLeastChildren(expr, 2);
585 final List<YangExpr> predicates = new ArrayList<>(size - 2);
586 for (int i = 2; i < size; ++i) {
587 predicates.add(parsePredicate(getChild(expr, PredicateContext.class, i)));
590 final YangXPathAxis axis = parseAxis(getChild(expr, AxisSpecifierContext.class, 0));
591 final NodeTestContext nodeTest = getChild(expr, NodeTestContext.class, 1);
592 switch (nodeTest.getChildCount()) {
594 final NameTestContext nameChild = getChild(nodeTest, NameTestContext.class, 0);
595 final ParseTree first = nameChild.getChild(0);
596 if (first instanceof TerminalNode) {
597 verify(((TerminalNode) first).getSymbol().getType() == xpathParser.MUL);
598 return axis.asStep(predicates);
600 return createStep(axis, verifyTree(QNameContext.class, first), predicates);
602 return axis.asStep(parseNodeType(nodeTest.getChild(0)), predicates);
604 final String text = verifyToken(nodeTest, 2, xpathParser.Literal).getText();
605 return axis.asStep(text.substring(1, text.length() - 1), predicates);
607 throw illegalShape(nodeTest);
611 private static YangXPathAxis parseAxis(final AxisSpecifierContext expr) {
612 switch (expr.getChildCount()) {
614 return YangXPathAxis.CHILD;
616 verify(getTerminalType(expr, 0) == xpathParser.AT, "Unhandled axis specifier shape %s", expr);
617 return YangXPathAxis.ATTRIBUTE;
619 final String str = verifyTerminal(expr.getChild(0)).getText();
620 return verifyNotNull(XPATH_AXES.get(str), "Unhandled axis %s", str);
622 throw illegalShape(expr);
626 private QName parseQName(final QNameContext expr) {
627 switch (expr.getChildCount()) {
629 return createQName(getChild(expr, NCNameContext.class, 0).getText());
631 return createQName(getChild(expr, NCNameContext.class, 0).getText(),
632 getChild(expr, NCNameContext.class, 2).getText());
634 throw illegalShape(expr);
638 private static <T extends ParserRuleContext> T nextContext(final Iterator<ParseTree> it, final Class<T> type) {
639 return verifyTree(type, it.next());
642 private static YangBinaryOperator nextOperator(final Iterator<ParseTree> it) {
643 return parseOperator(it.next());
646 private static int getTerminalType(final ParseTree parent, final int offset) {
647 return verifyTerminal(parent.getChild(offset)).getSymbol().getType();
650 private static YangXPathNodeType parseNodeType(final ParseTree tree) {
651 final String str = verifyTerminal(tree).getText();
652 return verifyNotNull(NODE_TYPES.get(str), "Unhandled node type %s", str);
655 private static YangBinaryOperator parseOperator(final ParseTree tree) {
656 final String str = verifyTerminal(tree).getText();
657 return verifyNotNull(BINARY_OPERATORS.get(str), "Unhandled operator %s", str);
660 private static Optional<Step> parseStepShorthand(final ParseTree tree) {
661 switch (verifyTerminal(tree).getSymbol().getType()) {
662 case xpathParser.PATHSEP:
663 return Optional.empty();
664 case xpathParser.ABRPATH:
665 return Optional.of(YangXPathAxis.DESCENDANT_OR_SELF.asStep());
667 throw illegalShape(tree);