org.opendaylight.yangtools.yang.data.util.XpathStringParsingPathArgumentBuilder Maven / Gradle / Ivy
/*
* Copyright (c) 2015 Cisco Systems, Inc. and others. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 which accompanies this distribution,
* and is available at http://www.eclipse.org/legal/epl-v10.html
*/
package org.opendaylight.yangtools.yang.data.util;
import static java.util.Objects.requireNonNull;
import com.google.common.base.CharMatcher;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import java.util.ArrayList;
import java.util.List;
import org.eclipse.jdt.annotation.NonNull;
import org.opendaylight.yangtools.concepts.Mutable;
import org.opendaylight.yangtools.yang.common.QName;
import org.opendaylight.yangtools.yang.common.QNameModule;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeIdentifier;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeIdentifierWithPredicates;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeWithValue;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument;
import org.opendaylight.yangtools.yang.data.util.DataSchemaContext.Composite;
import org.opendaylight.yangtools.yang.data.util.DataSchemaContext.PathMixin;
import org.opendaylight.yangtools.yang.data.util.DataSchemaContext.SimpleValue;
import org.opendaylight.yangtools.yang.model.api.TypeDefinition;
import org.opendaylight.yangtools.yang.model.api.type.LeafrefTypeDefinition;
import org.opendaylight.yangtools.yang.model.util.SchemaInferenceStack;
/**
* Iterator which lazily parses {@link PathArgument} from string representation.
*
*
* Note that invocation of {@link #hasNext()} or {@link #next()} may result in
* throwing of {@link IllegalArgumentException} if underlying string representation
* is not correctly serialized or does not represent instance identifier valid
* for associated schema context.
*/
final class XpathStringParsingPathArgumentBuilder implements Mutable {
/**
* Matcher matching WSP YANG ABNF token.
*/
private static final CharMatcher WSP = CharMatcher.anyOf(" \t");
/**
* Matcher matching IDENTIFIER first char token.
*/
private static final CharMatcher IDENTIFIER_FIRST_CHAR = CharMatcher.inRange('a', 'z')
.or(CharMatcher.inRange('A', 'Z')).or(CharMatcher.is('_')).precomputed();
/**
* Matcher matching IDENTIFIER token.
*/
private static final CharMatcher IDENTIFIER = IDENTIFIER_FIRST_CHAR.or(CharMatcher.inRange('0', '9'))
.or(CharMatcher.anyOf(".-")).precomputed();
private static final char SLASH = '/';
private static final char BACKSLASH = '\\';
private static final char COLON = ':';
private static final char DOT = '.';
private static final char EQUALS = '=';
private static final char PRECONDITION_START = '[';
private static final char PRECONDITION_END = ']';
private static final char SQUOT = '\'';
private static final char DQUOT = '"';
private final List product = new ArrayList<>();
private final AbstractStringInstanceIdentifierCodec codec;
private final SchemaInferenceStack stack;
private final String data;
private DataSchemaContext current;
private QNameModule lastModule;
private int offset;
XpathStringParsingPathArgumentBuilder(final AbstractStringInstanceIdentifierCodec codec, final String data) {
this.codec = requireNonNull(codec);
this.data = requireNonNull(data);
offset = 0;
final DataSchemaContextTree tree = codec.getDataContextTree();
stack = SchemaInferenceStack.of(tree.modelContext());
current = tree.getRoot();
}
/**
* Parse input string and return the corresponding list of {@link PathArgument}s.
*
* @return List of PathArguments
* @throws IllegalArgumentException if the input string is not valid
*/
@NonNull List build() {
while (!allCharactersConsumed()) {
product.add(computeNextArgument());
}
return ImmutableList.copyOf(product);
}
private PathArgument computeNextArgument() {
checkValid(SLASH == currentChar(), "Identifier must start with '/'.");
skipCurrentChar();
checkValid(!allCharactersConsumed(), "Identifier cannot end with '/'.");
final QName name = nextQName();
// Memoize module
lastModule = name.getModule();
if (allCharactersConsumed() || SLASH == currentChar()) {
return computeIdentifier(name);
}
checkValid(PRECONDITION_START == currentChar(), "Last element must be identifier, predicate or '/'");
return computeIdentifierWithPredicate(name);
}
private DataSchemaContext nextContextNode(final QName qname) {
current = getChild(current, qname);
checkValid(current != null, "%s is not correct schema node identifier.", qname);
while (current instanceof PathMixin mixin) {
product.add(mixin.mixinPathStep());
current = getChild(current, qname);
}
stack.enterDataTree(qname);
return current;
}
private static DataSchemaContext getChild(final DataSchemaContext parent, final QName qname) {
return parent instanceof Composite composite ? composite.childByQName(qname) : null;
}
/**
* Creates path argument with predicates and sets offset
* to end of path argument.
*
* {@code
* predicate = "[" *WSP (predicate-expr / pos) *WSP "]"
* predicate-expr = (node-identifier / ".") *WSP "=" *WSP
* ((DQUOTE string DQUOTE) /
* (SQUOTE string SQUOTE))
* pos = non-negative-integer-value
* }
*
* @param name QName of node, for which predicates are computed.
* @return PathArgument representing node selection with predictes
*/
private PathArgument computeIdentifierWithPredicate(final QName name) {
final var currentNode = nextContextNode(name);
if (currentNode.pathStep() != null) {
throw iae("Entry %s does not allow specifying predicates.", name);
}
final var keyValues = ImmutableMap.builder();
while (!allCharactersConsumed() && PRECONDITION_START == currentChar()) {
skipCurrentChar();
skipWhitespaces();
final QName key;
if (DOT == currentChar()) {
key = null;
skipCurrentChar();
} else {
key = nextQName();
}
skipWhitespaces();
checkCurrentAndSkip(EQUALS, "Precondition must contain '='");
skipWhitespaces();
final String keyValue = nextQuotedValue();
skipWhitespaces();
checkCurrentAndSkip(PRECONDITION_END, "Precondition must ends with ']'");
// Break-out from method for leaf-list case
if (key == null && currentNode instanceof SimpleValue) {
checkValid(offset == data.length(), "Leaf argument must be last argument of instance identifier.");
final var currentSchema = currentNode.dataSchemaNode();
final Object value = codec.deserializeKeyValue(currentSchema,
type -> resolveLeafref(currentSchema.getQName(), type), keyValue);
return new NodeWithValue<>(name, value);
}
final var keyNode = currentNode instanceof Composite composite ? composite.childByQName(key) : null;
if (keyNode == null) {
throw iae("%s is not correct schema node identifier.", key);
}
final Object value = codec.deserializeKeyValue(keyNode.dataSchemaNode(),
type -> resolveLeafref(key, type), keyValue);
keyValues.put(key, value);
}
return NodeIdentifierWithPredicates.of(name, keyValues.build());
}
private @NonNull TypeDefinition resolveLeafref(final QName qname, final LeafrefTypeDefinition type) {
final SchemaInferenceStack tmp = stack.copy();
tmp.enterDataTree(qname);
return tmp.resolveLeafref(type);
}
private @NonNull NodeIdentifier computeIdentifier(final QName name) {
final var currentNode = nextContextNode(name);
final var currentArg = currentNode.pathStep();
if (currentArg == null) {
throw iae("Entry %s requires key or value predicate to be present", name);
}
return currentArg;
}
/**
* Returns following QName and sets offset to end of QName.
*
* @return following QName.
*/
private @NonNull QName nextQName() {
// Consume prefix or identifier
final String maybePrefix = nextIdentifier();
if (!allCharactersConsumed() && COLON == currentChar()) {
// previous token is prefix
skipCurrentChar();
return codec.createQName(maybePrefix, nextIdentifier());
}
return codec.createQName(lastModule, maybePrefix);
}
/**
* Returns true if all characters from input string were consumed.
*
* @return true if all characters from input string were consumed.
*/
private boolean allCharactersConsumed() {
return offset == data.length();
}
/**
* Skips current char if it equals expected otherwise fails parsing.
*
* @param expected Expected character
* @param errorMsg Error message if {@link #currentChar()} does not match expected.
*/
private void checkCurrentAndSkip(final char expected, final String errorMsg) {
checkValid(expected == currentChar(), errorMsg);
offset++;
}
/**
* Fails parsing if a condition is not met.
*
*
* In case of error provides pointer to failed instance identifier,
* offset on which failure occurred with explanation.
*
* @param condition Fails parsing if {@code condition} is false
* @param errorMsg Error message which will be provided to user.
*/
private void checkValid(final boolean condition, final String errorMsg, final Object... attributes) {
if (!condition) {
throw iae(errorMsg, attributes);
}
}
private @NonNull IllegalArgumentException iae(final String errorMsg, final Object... attributes) {
return new IllegalArgumentException("Could not parse Instance Identifier '%s'. Offset: %s : Reason: %s"
.formatted(data, offset, errorMsg.formatted(attributes)));
}
/**
* Returns following value of quoted literal (without quotes) and sets offset after literal.
*
* @return String literal
*/
private String nextQuotedValue() {
return switch (currentChar()) {
case SQUOT -> nextSingleQuotedValue();
case DQUOT -> nextDoubleQuotedValue();
default -> throw iae("Value must be quote escaped with ''' or '\"'.");
};
}
// Simple: just look for the matching single quote and return substring
private String nextSingleQuotedValue() {
skipCurrentChar();
final int start = offset;
final int end = data.indexOf(SQUOT, start);
checkValid(end != -1, "Closing single quote not found");
offset = end;
skipCurrentChar();
return data.substring(start, end);
}
// Complicated: we need to potentially un-escape
private String nextDoubleQuotedValue() {
skipCurrentChar();
final int maxIndex = data.length() - 1;
final var sb = new StringBuilder();
while (true) {
final int nextStart = offset;
// Find next double quotes
final int nextEnd = data.indexOf(DQUOT, nextStart);
checkValid(nextEnd != -1, "Closing double quote not found");
offset = nextEnd;
// Find next backslash
final int nextBackslash = data.indexOf(BACKSLASH, nextStart);
if (nextBackslash == -1 || nextBackslash > nextEnd) {
// No backslash between nextStart and nextEnd -- just copy characters and terminate
offset = nextEnd;
skipCurrentChar();
return sb.append(data, nextStart, nextEnd).toString();
}
// Validate escape completeness and append buffer
checkValid(nextBackslash != maxIndex, "Incomplete escape");
sb.append(data, nextStart, nextBackslash);
// Adjust offset before potentially referencing it and
offset = nextBackslash;
sb.append(unescape(data.charAt(nextBackslash + 1)));
// Rinse and repeat
offset = nextBackslash + 2;
}
}
// As per https://www.rfc-editor.org/rfc/rfc7950#section-6.1.3
private char unescape(final char escape) {
return switch (escape) {
case 'n' -> '\n';
case 't' -> '\t';
case DQUOT -> DQUOT;
case BACKSLASH -> BACKSLASH;
default -> throw iae("Unrecognized escape");
};
}
/**
* Returns character at current offset.
*
* @return character at current offset.
*/
private char currentChar() {
return data.charAt(offset);
}
/**
* Increases processing offset by 1.
*/
private void skipCurrentChar() {
offset++;
}
/**
* Skip whitespace characters, sets offset to first following non-whitespace character.
*/
private void skipWhitespaces() {
nextSequenceEnd(WSP);
}
/**
* Returns string which matches IDENTIFIER YANG ABNF token
* and sets processing offset after end of identifier.
*
* @return string which matches IDENTIFIER YANG ABNF token
*/
private String nextIdentifier() {
checkValid(IDENTIFIER_FIRST_CHAR.matches(currentChar()),
"Identifier must start with character from set 'a-zA-Z_'");
final int start = offset;
nextSequenceEnd(IDENTIFIER);
return data.substring(start, offset);
}
private void nextSequenceEnd(final CharMatcher matcher) {
while (!allCharactersConsumed() && matcher.matches(data.charAt(offset))) {
offset++;
}
}
}