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org.mycore.common.xml.MCRNodeBuilder Maven / Gradle / Ivy
/*
* This file is part of *** M y C o R e ***
* See http://www.mycore.de/ for details.
*
* MyCoRe is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* MyCoRe is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with MyCoRe. If not, see variables;
private Object firstNodeBuilt = null;
public MCRNodeBuilder() {
}
public MCRNodeBuilder(Map variables) {
this.variables = variables;
}
public Object getFirstNodeBuilt() {
return firstNodeBuilt;
}
public Element buildElement(String xPath, String value, Parent parent) throws JaxenException {
return (Element) buildNode(xPath, value, parent);
}
public Attribute buildAttribute(String xPath, String value, Parent parent) throws JaxenException {
return (Attribute) buildNode(xPath, value, parent);
}
public Object buildNode(String xPath, String value, Parent parent) throws JaxenException {
BaseXPath baseXPath = new BaseXPath(xPath, new DocumentNavigator());
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("start building {} relative to {}", simplify(xPath), MCRXPathBuilder.buildXPath(parent));
}
return buildExpression(baseXPath.getRootExpr(), value, parent);
}
private Object buildExpression(Expr expression, String value, Parent parent) throws JaxenException {
if (expression instanceof EqualityExpr) {
return buildEqualityExpression((EqualityExpr) expression, parent);
} else if (expression instanceof LocationPath) {
return buildLocationPath((LocationPath) expression, value, parent);
} else {
return canNotBuild(expression);
}
}
@SuppressWarnings("unchecked")
private Object buildLocationPath(LocationPath locationPath, String value, Parent parent) throws JaxenException {
Object existingNode = null;
List steps = locationPath.getSteps();
int i, indexOfLastStep = steps.size() - 1;
for (i = indexOfLastStep; i >= 0; i--) {
String xPath = buildXPath(steps.subList(0, i + 1));
existingNode = evaluateFirst(xPath, parent);
if (existingNode instanceof Element) {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("element already existing");
}
parent = (Element) existingNode;
break;
} else if (existingNode instanceof Attribute) {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("attribute already existing");
}
break;
} else if (LOGGER.isDebugEnabled()) {
LOGGER.debug("{} does not exist or is not a node, will try to build it", xPath);
}
}
if (i == indexOfLastStep) {
return existingNode;
} else {
return buildLocationSteps(steps.subList(i + 1, steps.size()), value, parent);
}
}
private Object evaluateFirst(String xPath, Parent parent) {
return new MCRXPathEvaluator(variables, parent).evaluateFirst(xPath);
}
private String buildXPath(List steps) {
StringBuilder path = new StringBuilder();
for (Step step : steps) {
path.append("/").append(step.getText());
}
return simplify(path.substring(1));
}
private Object buildLocationSteps(List steps, String value, Parent parent) throws JaxenException {
Object built = null;
for (Iterator iterator = steps.iterator(); iterator.hasNext();) {
Step step = iterator.next();
built = buildStep(step, iterator.hasNext() ? null : value, parent);
if (built == null) {
return parent;
} else if (firstNodeBuilt == null) {
firstNodeBuilt = built;
}
if (built instanceof Parent) {
parent = (Parent) built;
}
}
return built;
}
private Object buildStep(Step step, String value, Parent parent) throws JaxenException {
if (step instanceof NameStep) {
return buildNameStep((NameStep) step, value, parent);
} else {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("ignoring step, can not be built: {} {}", step.getClass().getName(),
simplify(step.getText()));
}
return null;
}
}
@SuppressWarnings("unchecked")
private Object buildNameStep(NameStep nameStep, String value, Parent parent) throws JaxenException {
String name = nameStep.getLocalName();
String prefix = nameStep.getPrefix();
Namespace ns = prefix.isEmpty() ? Namespace.NO_NAMESPACE : MCRConstants.getStandardNamespace(prefix);
if (nameStep.getAxis() == Axis.CHILD) {
if (parent instanceof Document) {
return buildPredicates(nameStep.getPredicates(), ((Document) parent).getRootElement());
} else {
return buildPredicates(nameStep.getPredicates(), buildElement(ns, name, value, (Element) parent));
}
} else if (nameStep.getAxis() == Axis.ATTRIBUTE) {
return buildAttribute(ns, name, value, (Element) parent);
} else {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("ignoring axis, can not be built: {} {}{}", nameStep.getAxis(),
prefix.isEmpty() ? "" : prefix + ":", name);
}
return null;
}
}
private Element buildPredicates(List predicates, Element parent) throws JaxenException {
for (Predicate predicate : predicates) {
new MCRNodeBuilder(variables).buildExpression(predicate.getExpr(), null, parent);
}
return parent;
}
private Object buildEqualityExpression(EqualityExpr ee, Parent parent) throws JaxenException {
if (ee.getOperator().equals("=")) {
if ((ee.getLHS() instanceof LocationPath) && (ee.getRHS() instanceof LiteralExpr)) {
return assignLiteral(ee.getLHS(), (LiteralExpr) (ee.getRHS()), parent);
} else if ((ee.getRHS() instanceof LocationPath) && (ee.getLHS() instanceof LiteralExpr)) {
return assignLiteral(ee.getRHS(), (LiteralExpr) (ee.getLHS()), parent);
} else if (ee.getLHS() instanceof LocationPath) {
String value = getValueOf(ee.getRHS().getText(), parent);
if (value != null) {
return assignLiteral(ee.getLHS(), value, parent);
}
}
}
return canNotBuild(ee);
}
/**
* Resolves the first match for the given XPath and returns its value as a String
*
* @param xPath the XPath expression
* @param parent the context element or document
* @return the value of the element or attribute as a String
*/
public String getValueOf(String xPath, Parent parent) {
Object result = evaluateFirst(xPath, parent);
if (result instanceof String) {
return (String) result;
} else if (result instanceof Element) {
return ((Element) result).getText();
} else if (result instanceof Attribute) {
return ((Attribute) result).getValue();
} else {
return null;
}
}
private Object assignLiteral(Expr expression, LiteralExpr literal, Parent parent) throws JaxenException {
String xPath = simplify(expression.getText()) + "[.=" + literal.getText() + "]";
return assignLiteral(expression, literal.getLiteral(), parent, xPath);
}
private Object assignLiteral(Expr expression, String literal, Parent parent) throws JaxenException {
String delimiter = literal.contains("'") ? "\"" : "'";
String xPath = simplify(expression.getText()) + "[.=" + delimiter + literal + delimiter + "]";
return assignLiteral(expression, literal, parent, xPath);
}
private Object assignLiteral(Expr expression, String literal, Parent parent, String xPath) throws JaxenException {
Object result = evaluateFirst(xPath, parent);
if ((result instanceof Element) || (result instanceof Attribute)) {
return result;
} else {
xPath = simplify(expression.getText()) + "[9999]";
return buildNode(xPath, literal, parent);
}
}
private Element buildElement(Namespace ns, String name, String value, Element parent) {
Element element = new Element(name, ns);
if ((value != null) && !value.isEmpty()) {
element.setText(value);
}
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("building new element {}", element.getName());
}
if (parent != null) {
parent.addContent(element);
}
return element;
}
private Attribute buildAttribute(Namespace ns, String name, String value, Element parent) {
Attribute attribute = new Attribute(name, value == null ? "" : value, ns);
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("building new attribute {}", attribute.getName());
}
if (parent != null) {
parent.setAttribute(attribute);
}
return attribute;
}
/**
* Removes obsolete child:: and attribute:: axis prefixes from given XPath
*/
public static String simplify(String xPath) {
return xPath.replaceAll("child::", "").replaceAll("attribute::", "@");
}
private Object canNotBuild(Expr expression) {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("ignoring expression, can not be built: {} {}", expression.getClass().getName(),
simplify(expression.getText()));
}
return null;
}
}
