com.streamsets.pipeline.lib.xml.xpath.XPathValidatorUtil.java Source code

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Here is the source code for com.streamsets.pipeline.lib.xml.xpath.XPathValidatorUtil.java

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/*
 * Copyright 2017 StreamSets Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.streamsets.pipeline.lib.xml.xpath;

import com.google.common.base.Strings;
import com.streamsets.pipeline.api.impl.XMLChar;
import com.streamsets.pipeline.lib.xml.Constants;

import java.util.HashSet;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public abstract class XPathValidatorUtil {
    private static final String VALID_PREDICATE = "\\[(?:(?:[0-9]+)|(?:@([^=]+)='[^']*'))\\]";
    private static final java.util.regex.Pattern VALID_PREDICATE_PATTERN = Pattern.compile(VALID_PREDICATE);

    public static String getXPathValidationError(String expression) {
        if (Strings.isNullOrEmpty(expression)) {
            return Constants.ERROR_EMPTY_EXPRESSION;
        } else if (expression.charAt(0) != Constants.PATH_SEPARATOR_CHAR) {
            if (expression.indexOf(Constants.PATH_SEPARATOR_CHAR) < 0) {
                // "legacy" expression
                if (XMLChar.isValidName(expression)) {
                    return null;
                } else {
                    return Constants.ERROR_INVALID_ELEMENT_NAME_PREFIX + expression;
                }
            } else {
                // expression that does not start with separator but is otherwise an XPath - not allowed
                return Constants.ERROR_XPATH_MUST_START_WITH_SEP + Constants.PATH_SEPARATOR_CHAR;
            }
        }

        boolean firstEmptyStringSeen = false;
        for (String str : expression.split(Constants.PATH_SEPARATOR)) {
            if (Strings.isNullOrEmpty(str)) {
                if (firstEmptyStringSeen) {
                    return Constants.ERROR_DESCENDENT_OR_SELF_NOT_SUPPORTED;
                }
                firstEmptyStringSeen = true;
                continue;
            }
            final int predicateStartInd = str.indexOf('[');
            String elementName = str;
            if (predicateStartInd > 0) {
                elementName = str.substring(0, predicateStartInd);
                final String predicate = str.substring(predicateStartInd);
                final Matcher matcher = VALID_PREDICATE_PATTERN.matcher(predicate);
                if (!matcher.matches()) {
                    return Constants.ERROR_INVALID_PREDICATE_PREFIX + predicate;
                } else {
                    final String attributeName = matcher.group(1);
                    if (!Strings.isNullOrEmpty(attributeName) && !XMLChar.isValidName(attributeName)) {
                        return Constants.ERROR_INVALID_ATTRIBUTE_PREFIX + attributeName;
                    }
                }
            }
            if (!Constants.WILDCARD.equals(elementName) && !XMLChar.isValidName(elementName)) {
                return Constants.ERROR_INVALID_ELEMENT_NAME_PREFIX + elementName;
            }
        }
        return null;
    }

    public static Set<String> getNamespacePrefixes(String expression) {

        final Set<String> prefixes = new HashSet<>();

        for (String str : expression.split(Constants.PATH_SEPARATOR)) {
            final int prefixSeparatorInd = str.indexOf(Constants.NAMESPACE_PREFIX_SEPARATOR);
            if (prefixSeparatorInd >= 0) {
                prefixes.add(str.substring(0, prefixSeparatorInd));
            }
        }

        return prefixes;
    }
}