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.Lists;
25 import com.google.common.collect.Maps;
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.Optional;
36 import javax.xml.xpath.XPathExpressionException;
37 import org.antlr.v4.runtime.CharStreams;
38 import org.antlr.v4.runtime.CommonTokenStream;
39 import org.antlr.v4.runtime.ParserRuleContext;
40 import org.antlr.v4.runtime.tree.ParseTree;
41 import org.antlr.v4.runtime.tree.TerminalNode;
42 import org.opendaylight.yangtools.yang.common.QName;
43 import org.opendaylight.yangtools.yang.common.YangConstants;
44 import org.opendaylight.yangtools.yang.common.YangNamespaceContext;
45 import org.opendaylight.yangtools.yang.xpath.api.YangBinaryOperator;
46 import org.opendaylight.yangtools.yang.xpath.api.YangBooleanConstantExpr;
47 import org.opendaylight.yangtools.yang.xpath.api.YangExpr;
48 import org.opendaylight.yangtools.yang.xpath.api.YangFilterExpr;
49 import org.opendaylight.yangtools.yang.xpath.api.YangFunction;
50 import org.opendaylight.yangtools.yang.xpath.api.YangFunctionCallExpr;
51 import org.opendaylight.yangtools.yang.xpath.api.YangLiteralExpr;
52 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath;
53 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath.AxisStep;
54 import org.opendaylight.yangtools.yang.xpath.api.YangLocationPath.Step;
55 import org.opendaylight.yangtools.yang.xpath.api.YangNaryExpr;
56 import org.opendaylight.yangtools.yang.xpath.api.YangNaryOperator;
57 import org.opendaylight.yangtools.yang.xpath.api.YangNegateExpr;
58 import org.opendaylight.yangtools.yang.xpath.api.YangNumberExpr;
59 import org.opendaylight.yangtools.yang.xpath.api.YangPathExpr;
60 import org.opendaylight.yangtools.yang.xpath.api.YangVariableReferenceExpr;
61 import org.opendaylight.yangtools.yang.xpath.api.YangXPathAxis;
62 import org.opendaylight.yangtools.yang.xpath.api.YangXPathExpression;
63 import org.opendaylight.yangtools.yang.xpath.api.YangXPathMathMode;
64 import org.opendaylight.yangtools.yang.xpath.api.YangXPathMathSupport;
65 import org.opendaylight.yangtools.yang.xpath.api.YangXPathNodeType;
66 import org.opendaylight.yangtools.yang.xpath.api.YangXPathParser;
67 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.AbbreviatedStepContext;
68 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.AbsoluteLocationPathNorootContext;
69 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.AdditiveExprContext;
70 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.AndExprContext;
71 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.AxisSpecifierContext;
72 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.EqualityExprContext;
73 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.ExprContext;
74 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.FilterExprContext;
75 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.FunctionCallContext;
76 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.FunctionNameContext;
77 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.LocationPathContext;
78 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.MultiplicativeExprContext;
79 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.NCNameContext;
80 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.NameTestContext;
81 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.NodeTestContext;
82 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.OrExprContext;
83 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.PathExprNoRootContext;
84 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.PredicateContext;
85 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.PrimaryExprContext;
86 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.QNameContext;
87 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.RelationalExprContext;
88 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.RelativeLocationPathContext;
89 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.StepContext;
90 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.UnaryExprNoRootContext;
91 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.UnionExprNoRootContext;
92 import org.opendaylight.yangtools.yang.xpath.impl.xpathParser.VariableReferenceContext;
93 import org.slf4j.Logger;
94 import org.slf4j.LoggerFactory;
97 * ANTLR-based XPath parser. Uses {@code xpath.g4} ANTLR grammar.
99 * @author Robert Varga
101 final class AntlrXPathParser implements YangXPathParser {
102 private static final Logger LOG = LoggerFactory.getLogger(AntlrXPathParser.class);
103 private static final Map<String, YangBinaryOperator> BINARY_OPERATORS = Maps.uniqueIndex(
104 Arrays.asList(YangBinaryOperator.values()), YangBinaryOperator::toString);
105 private static final Map<String, YangXPathNodeType> NODE_TYPES = Maps.uniqueIndex(Arrays.asList(
106 YangXPathNodeType.values()), YangXPathNodeType::toString);
107 private static final Map<String, YangXPathAxis> XPATH_AXES = Maps.uniqueIndex(Arrays.asList(YangXPathAxis.values()),
108 YangXPathAxis::toString);
109 private static final Map<QName, YangFunction> YANG_FUNCTIONS = Maps.uniqueIndex(Arrays.asList(
110 YangFunction.values()), YangFunction::getIdentifier);
112 // Cached for checks in hot path
113 private static final AxisStep SELF_STEP = YangXPathAxis.SELF.asStep();
115 private final YangXPathMathMode mathMode;
116 private final YangXPathMathSupport mathSupport;
117 private final YangNamespaceContext namespaceContext;
118 private final FunctionSupport functionSupport;
120 AntlrXPathParser(final YangXPathMathMode mathMode, final YangNamespaceContext namespaceContext) {
121 this.mathMode = requireNonNull(mathMode);
122 this.mathSupport = mathMode.getSupport();
123 this.namespaceContext = requireNonNull(namespaceContext);
124 this.functionSupport = new FunctionSupport(namespaceContext, mathSupport);
128 public YangXPathExpression parseExpression(final String xpath) throws XPathExpressionException {
129 // Create a parser and disconnect it from console error output
130 final xpathLexer lexer = new xpathLexer(CharStreams.fromString(xpath));
131 final xpathParser parser = new xpathParser(new CommonTokenStream(lexer));
133 final CapturingErrorListener listener = new CapturingErrorListener();
134 lexer.removeErrorListeners();
135 lexer.addErrorListener(listener);
136 parser.removeErrorListeners();
137 parser.addErrorListener(listener);
139 final YangExpr expr = parseExpr(parser.main().expr());
140 listener.reportError();
141 return new AntlrYangXPathExpression(namespaceContext, mathMode, expr, xpath);
145 * Parse and simplify an XPath expression in {@link ExprContext} representation.
147 * @param expr ANTLR ExprContext
148 * @return A {@link YangExpr}
149 * @throws NullPointerException if {@code expr} is null
150 * @throws IllegalArgumentException if {@code expr} references an unbound prefix
152 private YangExpr parseExpr(final ExprContext expr) {
153 final OrExprContext or = expr.orExpr();
154 final int size = or.getChildCount();
156 return parseAnd(getChild(or, AndExprContext.class, 0));
158 final List<YangExpr> tmp = new ArrayList<>((size + 1) / 2);
159 for (int i = 0; i < size; i += 2) {
160 tmp.add(parseAnd(getChild(or, AndExprContext.class, i)));
162 return YangNaryOperator.OR.exprWith(tmp);
165 private YangExpr parseAdditive(final AdditiveExprContext expr) {
166 final Iterator<ParseTree> it = expr.children.iterator();
167 final YangExpr first = parseMultiplicative(nextContext(it, MultiplicativeExprContext.class));
168 return it.hasNext() ? parseAdditiveExpr(first, it) : first;
171 private YangExpr parseAnd(final AndExprContext expr) {
172 final int size = expr.getChildCount();
174 return parseEquality(getChild(expr, EqualityExprContext.class, 0));
176 final List<YangExpr> tmp = new ArrayList<>((size + 1) / 2);
177 for (int i = 0; i < size; i += 2) {
178 tmp.add(parseEquality(getChild(expr, EqualityExprContext.class, i)));
180 return YangNaryOperator.AND.exprWith(tmp);
183 private YangExpr parseEquality(final EqualityExprContext expr) {
184 final Iterator<ParseTree> it = expr.children.iterator();
185 final YangExpr first = parseRelational(nextContext(it, RelationalExprContext.class));
186 return it.hasNext() ? parseEqualityExpr(first, it) : first;
189 private YangExpr parseFilter(final FilterExprContext expr) {
190 final Iterator<ParseTree> it = expr.children.iterator();
191 final YangExpr first = parsePrimary(nextContext(it, PrimaryExprContext.class));
192 return it.hasNext() ? YangFilterExpr.of(first, ImmutableList.copyOf(Iterators.transform(it,
193 tree -> parsePredicate(verifyTree(PredicateContext.class, tree)))))
197 private YangExpr parseFunctionCall(final FunctionCallContext expr) {
198 // We are mapping functions to RFC7950 YIN namespace, to keep us consistent with type/statement definitions
200 final FunctionNameContext name = getChild(expr, FunctionNameContext.class, 0);
202 switch (name.getChildCount()) {
204 parsed = QName.create(YangConstants.RFC6020_YIN_MODULE, name.getChild(0).getText());
207 parsed = namespaceContext.createQName(name.getChild(0).getText(), name.getChild(2).getText());
210 throw illegalShape(name);
213 final List<YangExpr> args = ImmutableList.copyOf(Lists.transform(expr.expr(), this::parseExpr));
214 final YangFunction func = YANG_FUNCTIONS.get(parsed);
216 return functionSupport.functionToExpr(func, args);
219 checkArgument(!YangConstants.RFC6020_YIN_MODULE.equals(parsed.getModule()), "Unknown default function %s",
221 return YangFunctionCallExpr.of(parsed, args);
224 private YangLocationPath parseLocationPath(final LocationPathContext expr) {
225 verifyChildCount(expr, 1);
226 final ParseTree first = expr.getChild(0);
227 if (first instanceof RelativeLocationPathContext) {
228 return parseRelativeLocationPath((RelativeLocationPathContext) first);
231 final AbsoluteLocationPathNorootContext abs = verifyTree(AbsoluteLocationPathNorootContext.class, first);
232 verifyChildCount(abs, 2);
234 final Deque<Step> steps = parseLocationPathSteps(getChild(abs, RelativeLocationPathContext.class, 1));
235 parseStepShorthand(abs.getChild(0)).ifPresent(steps::addFirst);
237 return YangLocationPath.of(true, steps);
240 private YangExpr parseMultiplicative(final MultiplicativeExprContext expr) {
241 final ParseTree first = expr.getChild(0);
243 if (first instanceof UnaryExprNoRootContext) {
244 left = parseUnary((UnaryExprNoRootContext) first);
246 left = YangLocationPath.root();
248 if (expr.getChildCount() == 1) {
252 verifyChildCount(expr, 3);
253 final YangBinaryOperator operator = parseOperator(expr.getChild(1));
254 final YangExpr right = parseMultiplicative(getChild(expr, MultiplicativeExprContext.class, 2));
255 final Optional<YangExpr> simple = simplifyNumbers(operator, left, right);
256 return simple.isPresent() ? simple.get() : operator.exprWith(left, right);
259 private YangExpr parsePathExpr(final PathExprNoRootContext expr) {
260 final ParseTree first = expr.getChild(0);
261 if (first instanceof LocationPathContext) {
262 return parseLocationPath((LocationPathContext) first);
265 final YangExpr filter = parseFilter(verifyTree(FilterExprContext.class, first));
266 if (expr.getChildCount() == 1) {
270 verifyChildCount(expr, 3);
271 final Deque<Step> steps = parseLocationPathSteps(getChild(expr, RelativeLocationPathContext.class, 2));
272 parseStepShorthand(expr.getChild(1)).ifPresent(steps::addFirst);
273 return YangPathExpr.of(filter, YangLocationPath.of(false, steps));
276 private YangExpr parsePredicate(final PredicateContext expr) {
277 verifyChildCount(expr, 3);
278 return parseExpr(getChild(expr, ExprContext.class, 1));
281 private YangExpr parsePrimary(final PrimaryExprContext expr) {
282 if (expr.getChildCount() == 3) {
283 return parseExpr(getChild(expr, ExprContext.class, 1));
286 verifyChildCount(expr, 1);
287 final ParseTree first = expr.getChild(0);
288 if (first instanceof TerminalNode) {
289 return parseTerminal((TerminalNode) first);
291 if (first instanceof FunctionCallContext) {
292 return parseFunctionCall((FunctionCallContext) first);
294 if (first instanceof VariableReferenceContext) {
295 return YangVariableReferenceExpr.of(parseQName(((VariableReferenceContext) first).qName()));
297 throw illegalShape(first);
300 private YangExpr parseRelational(final RelationalExprContext expr) {
301 final Iterator<ParseTree> it = expr.children.iterator();
302 final YangExpr first = parseAdditive(nextContext(it, AdditiveExprContext.class));
303 return it.hasNext() ? parseRelationalExpr(first, it) : first;
306 private Deque<Step> parseLocationPathSteps(final RelativeLocationPathContext expr) {
307 final Deque<Step> steps = new ArrayDeque<>(expr.getChildCount());
308 final Iterator<ParseTree> it = expr.children.iterator();
309 steps.add(parseStep(nextContext(it, StepContext.class)));
311 while (it.hasNext()) {
312 parseStepShorthand(it.next()).ifPresent(steps::add);
314 // Parse step and add it if it's not SELF_STEP
315 final Step step = parseStep(nextContext(it, StepContext.class));
316 if (!SELF_STEP.equals(step)) {
324 private YangLocationPath parseRelativeLocationPath(final RelativeLocationPathContext expr) {
325 return YangLocationPath.of(false, parseLocationPathSteps(expr));
328 private YangExpr parseTerminal(final TerminalNode term) {
329 final String text = term.getText();
330 switch (term.getSymbol().getType()) {
331 case xpathParser.Literal:
332 // We have to strip quotes
333 return YangLiteralExpr.of(text.substring(1, text.length() - 1));
334 case xpathParser.Number:
335 return mathSupport.createNumber(text);
337 throw illegalShape(term);
341 private YangExpr parseUnary(final UnaryExprNoRootContext expr) {
342 // any number of '-' and an union expr
343 final int size = verifyAtLeastChildren(expr, 1);
344 final YangExpr ret = parseUnion(getChild(expr, UnionExprNoRootContext.class, size - 1));
346 // Even number of '-' tokens cancel out
349 return ret instanceof YangNumberExpr ? mathSupport.negateNumber((YangNumberExpr) ret) : YangNegateExpr.of(ret);
352 private YangExpr parseUnion(final UnionExprNoRootContext expr) {
353 final ParseTree first = expr.getChild(0);
355 if (first instanceof PathExprNoRootContext) {
356 path = parsePathExpr((PathExprNoRootContext) first);
357 if (expr.getChildCount() == 1) {
361 path = YangLocationPath.root();
364 verifyChildCount(expr, 3);
365 final YangExpr union = parseUnion(getChild(expr, UnionExprNoRootContext.class, 2));
367 // Deduplicate expressions so we do not perform useless unioning
368 final Set<YangExpr> expressions = new LinkedHashSet<>();
369 expressions.add(path);
370 if (union instanceof YangNaryExpr) {
371 // If the result is a union expression, integrate it into this expression
372 final YangNaryExpr nary = (YangNaryExpr) union;
373 if (nary.getOperator() == YangNaryOperator.UNION) {
374 expressions.addAll(nary.getExpressions());
376 expressions.add(union);
379 expressions.add(union);
382 return YangNaryOperator.UNION.exprWith(expressions);
385 private YangExpr parseAdditiveExpr(final YangExpr left, final Iterator<ParseTree> it) {
388 final YangBinaryOperator operator = nextOperator(it);
389 final YangExpr right = parseMultiplicative(nextContext(it, MultiplicativeExprContext.class));
390 final Optional<YangExpr> simple = simplifyNumbers(operator, ret, right);
391 ret = simple.isPresent() ? simple.get() : operator.exprWith(ret, right);
392 } while (it.hasNext());
397 private Optional<YangExpr> simplifyNumbers(final YangBinaryOperator operator, final YangExpr left,
398 final YangExpr right) {
399 if (left instanceof YangNumberExpr && right instanceof YangNumberExpr) {
400 // Constant folding on numbers -- precision plays a role here
401 return mathSupport.tryEvaluate(operator, (YangNumberExpr)left, (YangNumberExpr)right);
403 return Optional.empty();
406 private YangExpr parseEqualityExpr(final YangExpr left, final Iterator<ParseTree> it) {
409 final YangBinaryOperator operator = nextOperator(it);
410 final YangExpr right = parseRelational(nextContext(it, RelationalExprContext.class));
412 if (left.equals(right)) {
413 // Constant folding on expression level: equal expressions are result in equal results
416 return YangBooleanConstantExpr.TRUE;
418 return YangBooleanConstantExpr.FALSE;
424 final Optional<YangExpr> simple = simplifyNumbers(operator, ret, right);
425 ret = simple.isPresent() ? simple.get() : operator.exprWith(ret, right);
426 } while (it.hasNext());
431 private YangExpr parseRelationalExpr(final YangExpr left, final Iterator<ParseTree> it) {
434 final YangBinaryOperator operator = nextOperator(it);
435 final YangExpr right = parseAdditive(nextContext(it, AdditiveExprContext.class));
436 final Optional<YangExpr> simple = simplifyNumbers(operator, ret, right);
437 ret = simple.isPresent() ? simple.get() : nextOperator(it).exprWith(ret, right);
438 } while (it.hasNext());
443 private QName parseQName(final QNameContext expr) {
444 switch (expr.getChildCount()) {
446 return namespaceContext.createQName(getChild(expr, NCNameContext.class, 0).getText());
448 return namespaceContext.createQName(getChild(expr, NCNameContext.class, 0).getText(),
449 getChild(expr, NCNameContext.class, 2).getText());
451 throw illegalShape(expr);
455 private Step parseStep(final StepContext expr) {
456 if (expr.getChildCount() == 1) {
457 final AbbreviatedStepContext abbrev = getChild(expr, AbbreviatedStepContext.class, 0);
458 verifyChildCount(abbrev, 1);
459 switch (getTerminalType(abbrev, 0)) {
460 case xpathParser.DOT:
461 return YangXPathAxis.SELF.asStep();
462 case xpathParser.DOTDOT:
463 return YangXPathAxis.PARENT.asStep();
465 throw illegalShape(abbrev);
469 final int size = verifyAtLeastChildren(expr, 2);
470 final List<YangExpr> predicates = new ArrayList<>(size - 2);
471 for (int i = 2; i < size; ++i) {
472 predicates.add(parsePredicate(getChild(expr, PredicateContext.class, i)));
475 final YangXPathAxis axis = parseAxis(getChild(expr, AxisSpecifierContext.class, 0));
476 final NodeTestContext nodeTest = getChild(expr, NodeTestContext.class, 1);
477 switch (nodeTest.getChildCount()) {
479 final NameTestContext nameChild = getChild(nodeTest, NameTestContext.class, 0);
480 final ParseTree first = nameChild.getChild(0);
481 if (first instanceof TerminalNode) {
482 verify(((TerminalNode) first).getSymbol().getType() == xpathParser.MUL);
483 return axis.asStep(predicates);
485 return axis.asStep(parseQName(verifyTree(QNameContext.class, first)), predicates);
487 return axis.asStep(parseNodeType(nodeTest.getChild(0)), predicates);
489 final String text = verifyToken(nodeTest, 2, xpathParser.Literal).getText();
490 return axis.asStep(text.substring(1, text.length() - 1), predicates);
492 throw illegalShape(nodeTest);
496 private static YangXPathAxis parseAxis(final AxisSpecifierContext expr) {
497 switch (expr.getChildCount()) {
499 return YangXPathAxis.CHILD;
501 verify(getTerminalType(expr, 0) == xpathParser.AT, "Unhandled axis specifier shape %s", expr);
502 return YangXPathAxis.ATTRIBUTE;
504 final String str = verifyTerminal(expr.getChild(0)).getText();
505 return verifyNotNull(XPATH_AXES.get(str), "Unhandled axis %s", str);
507 throw illegalShape(expr);
511 private static <T extends ParserRuleContext> T nextContext(final Iterator<ParseTree> it, final Class<T> type) {
512 return verifyTree(type, it.next());
515 private static YangBinaryOperator nextOperator(final Iterator<ParseTree> it) {
516 return parseOperator(it.next());
519 private static int getTerminalType(final ParseTree parent, final int offset) {
520 return verifyTerminal(parent.getChild(offset)).getSymbol().getType();
523 private static YangXPathNodeType parseNodeType(final ParseTree tree) {
524 final String str = verifyTerminal(tree).getText();
525 return verifyNotNull(NODE_TYPES.get(str), "Unhandled node type %s", str);
528 private static YangBinaryOperator parseOperator(final ParseTree tree) {
529 final String str = verifyTerminal(tree).getText();
530 return verifyNotNull(BINARY_OPERATORS.get(str), "Unhandled operator %s", str);
533 private static Optional<Step> parseStepShorthand(final ParseTree tree) {
534 switch (verifyTerminal(tree).getSymbol().getType()) {
535 case xpathParser.PATHSEP:
536 return Optional.empty();
537 case xpathParser.ABRPATH:
538 return Optional.of(YangXPathAxis.DESCENDANT_OR_SELF.asStep());
540 throw illegalShape(tree);