package org.jsoup.select;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.jsoup.helper.StringUtil;
import org.jsoup.helper.Validate;
import org.jsoup.parser.TokenQueue;
/**
* Parses a CSS selector into an Evaluator tree.
*/
class QueryParser {
private final static String[] combinators = {",", ">", "+", "~", " "};
private TokenQueue tq;
private String query;
private List<Evaluator> evals = new ArrayList<Evaluator>();
/**
* Create a new QueryParser.
* @param query CSS query
*/
private QueryParser(String query) {
this.query = query;
this.tq = new TokenQueue(query);
}
/**
* Parse a CSS query into an Evaluator.
* @param query CSS query
* @return Evaluator
*/
public static Evaluator parse(String query) {
QueryParser p = new QueryParser(query);
return p.parse();
}
/**
* Parse the query
* @return Evaluator
*/
Evaluator parse() {
tq.consumeWhitespace();
if (tq.matchesAny(combinators)) { // if starts with a combinator, use root as elements
evals.add(new StructuralEvaluator.Root());
combinator(tq.consume());
} else {
findElements();
}
while (!tq.isEmpty()) {
// hierarchy and extras
boolean seenWhite = tq.consumeWhitespace();
if (tq.matchesAny(combinators)) {
combinator(tq.consume());
} else if (seenWhite) {
combinator(' ');
} else { // E.class, E#id, E[attr] etc. AND
findElements(); // take next el, #. etc off queue
}
}
if (evals.size() == 1)
return evals.get(0);
return new CombiningEvaluator.And(evals);
}
private void combinator(char combinator) {
tq.consumeWhitespace();
String subQuery = consumeSubQuery(); // support multi > childs
Evaluator rootEval; // the new topmost evaluator
Evaluator currentEval; // the evaluator the new eval will be combined to. could be root, or rightmost or.
Evaluator newEval = parse(subQuery); // the evaluator to add into target evaluator
boolean replaceRightMost = false;
if (evals.size() == 1) {
rootEval = currentEval = evals.get(0);
// make sure OR (,) has precedence:
if (rootEval instanceof CombiningEvaluator.Or && combinator != ',') {
currentEval = ((CombiningEvaluator.Or) currentEval).rightMostEvaluator();
replaceRightMost = true;
}
}
else {
rootEval = currentEval = new CombiningEvaluator.And(evals);
}
evals.clear();
// for most combinators: change the current eval into an AND of the current eval and the new eval
if (combinator == '>')
currentEval = new CombiningEvaluator.And(newEval, new StructuralEvaluator.ImmediateParent(currentEval));
else if (combinator == ' ')
currentEval = new CombiningEvaluator.And(newEval, new StructuralEvaluator.Parent(currentEval));
else if (combinator == '+')
currentEval = new CombiningEvaluator.And(newEval, new StructuralEvaluator.ImmediatePreviousSibling(currentEval));
else if (combinator == '~')
currentEval = new CombiningEvaluator.And(newEval, new StructuralEvaluator.PreviousSibling(currentEval));
else if (combinator == ',') { // group or.
CombiningEvaluator.Or or;
if (currentEval instanceof CombiningEvaluator.Or) {
or = (CombiningEvaluator.Or) currentEval;
or.add(newEval);
} else {
or = new CombiningEvaluator.Or();
or.add(currentEval);
or.add(newEval);
}
currentEval = or;
}
else
throw new Selector.SelectorParseException("Unknown combinator: " + combinator);
if (replaceRightMost)
((CombiningEvaluator.Or) rootEval).replaceRightMostEvaluator(currentEval);
else rootEval = currentEval;
evals.add(rootEval);
}
private String consumeSubQuery() {
StringBuilder sq = new StringBuilder();
while (!tq.isEmpty()) {
if (tq.matches("("))
sq.append("(").append(tq.chompBalanced('(', ')')).append(")");
else if (tq.matches("["))
sq.append("[").append(tq.chompBalanced('[', ']')).append("]");
else if (tq.matchesAny(combinators))
break;
else
sq.append(tq.consume());
}
return sq.toString();
}
private void findElements() {
if (tq.matchChomp("#"))
byId();
else if (tq.matchChomp("."))
byClass();
else if (tq.matchesWord())
byTag();
else if (tq.matches("["))
byAttribute();
else if (tq.matchChomp("*"))
allElements();
else if (tq.matchChomp(":lt("))
indexLessThan();
else if (tq.matchChomp(":gt("))
indexGreaterThan();
else if (tq.matchChomp(":eq("))
indexEquals();
else if (tq.matches(":has("))
has();
else if (tq.matches(":contains("))
contains(false);
else if (tq.matches(":containsOwn("))
contains(true);
else if (tq.matches(":matches("))
matches(false);
else if (tq.matches(":matchesOwn("))
matches(true);
else if (tq.matches(":not("))
not();
else if (tq.matchChomp(":nth-child("))
cssNthChild(false, false);
else if (tq.matchChomp(":nth-last-child("))
cssNthChild(true, false);
else if (tq.matchChomp(":nth-of-type("))
cssNthChild(false, true);
else if (tq.matchChomp(":nth-last-of-type("))
cssNthChild(true, true);
else if (tq.matchChomp(":first-child"))
evals.add(new Evaluator.IsFirstChild());
else if (tq.matchChomp(":last-child"))
evals.add(new Evaluator.IsLastChild());
else if (tq.matchChomp(":first-of-type"))
evals.add(new Evaluator.IsFirstOfType());
else if (tq.matchChomp(":last-of-type"))
evals.add(new Evaluator.IsLastOfType());
else if (tq.matchChomp(":only-child"))
evals.add(new Evaluator.IsOnlyChild());
else if (tq.matchChomp(":only-of-type"))
evals.add(new Evaluator.IsOnlyOfType());
else if (tq.matchChomp(":empty"))
evals.add(new Evaluator.IsEmpty());
else if (tq.matchChomp(":root"))
evals.add(new Evaluator.IsRoot());
else // unhandled
throw new Selector.SelectorParseException("Could not parse query '%s': unexpected token at '%s'", query, tq.remainder());
}
private void byId() {
String id = tq.consumeCssIdentifier();
Validate.notEmpty(id);
evals.add(new Evaluator.Id(id));
}
private void byClass() {
String className = tq.consumeCssIdentifier();
Validate.notEmpty(className);
evals.add(new Evaluator.Class(className.trim().toLowerCase()));
}
private void byTag() {
String tagName = tq.consumeElementSelector();
Validate.notEmpty(tagName);
// namespaces: if element name is "abc:def", selector must be "abc|def", so flip:
if (tagName.contains("|"))
tagName = tagName.replace("|", ":");
evals.add(new Evaluator.Tag(tagName.trim().toLowerCase()));
}
private void byAttribute() {
TokenQueue cq = new TokenQueue(tq.chompBalanced('[', ']')); // content queue
String key = cq.consumeToAny("=", "!=", "^=", "$=", "*=", "~="); // eq, not, start, end, contain, match, (no val)
Validate.notEmpty(key);
cq.consumeWhitespace();
if (cq.isEmpty()) {
if (key.startsWith("^"))
evals.add(new Evaluator.AttributeStarting(key.substring(1)));
else
evals.add(new Evaluator.Attribute(key));
} else {
if (cq.matchChomp("="))
evals.add(new Evaluator.AttributeWithValue(key, cq.remainder()));
else if (cq.matchChomp("!="))
evals.add(new Evaluator.AttributeWithValueNot(key, cq.remainder()));
else if (cq.matchChomp("^="))
evals.add(new Evaluator.AttributeWithValueStarting(key, cq.remainder()));
else if (cq.matchChomp("$="))
evals.add(new Evaluator.AttributeWithValueEnding(key, cq.remainder()));
else if (cq.matchChomp("*="))
evals.add(new Evaluator.AttributeWithValueContaining(key, cq.remainder()));
else if (cq.matchChomp("~="))
evals.add(new Evaluator.AttributeWithValueMatching(key, Pattern.compile(cq.remainder())));
else
throw new Selector.SelectorParseException("Could not parse attribute query '%s': unexpected token at '%s'", query, cq.remainder());
}
}
private void allElements() {
evals.add(new Evaluator.AllElements());
}
// pseudo selectors :lt, :gt, :eq
private void indexLessThan() {
evals.add(new Evaluator.IndexLessThan(consumeIndex()));
}
private void indexGreaterThan() {
evals.add(new Evaluator.IndexGreaterThan(consumeIndex()));
}
private void indexEquals() {
evals.add(new Evaluator.IndexEquals(consumeIndex()));
}
//pseudo selectors :first-child, :last-child, :nth-child, ...
private static final Pattern NTH_AB = Pattern.compile("((\\+|-)?(\\d+)?)n(\\s*(\\+|-)?\\s*\\d+)?", Pattern.CASE_INSENSITIVE);
private static final Pattern NTH_B = Pattern.compile("(\\+|-)?(\\d+)");
private void cssNthChild(boolean backwards, boolean ofType) {
String argS = tq.chompTo(")").trim().toLowerCase();
Matcher mAB = NTH_AB.matcher(argS);
Matcher mB = NTH_B.matcher(argS);
final int a, b;
if ("odd".equals(argS)) {
a = 2;
b = 1;
} else if ("even".equals(argS)) {
a = 2;
b = 0;
} else if (mAB.matches()) {
a = mAB.group(3) != null ? Integer.parseInt(mAB.group(1)
.replaceFirst("^\\+", "")) : 1;
b = mAB.group(4) != null ? Integer.parseInt(mAB.group(4)
.replaceFirst("^\\+", "")) : 0;
} else if (mB.matches()) {
a = 0;
b = Integer.parseInt(mB.group().replaceFirst("^\\+", ""));
} else {
throw new Selector.SelectorParseException(
"Could not parse nth-index '%s': unexpected format", argS);
}
if (ofType)
if (backwards)
evals.add(new Evaluator.IsNthLastOfType(a, b));
else
evals.add(new Evaluator.IsNthOfType(a, b));
else {
if (backwards)
evals.add(new Evaluator.IsNthLastChild(a, b));
else
evals.add(new Evaluator.IsNthChild(a, b));
}
}
private int consumeIndex() {
String indexS = tq.chompTo(")").trim();
Validate.isTrue(StringUtil.isNumeric(indexS), "Index must be numeric");
return Integer.parseInt(indexS);
}
// pseudo selector :has(el)
private void has() {
tq.consume(":has");
String subQuery = tq.chompBalanced('(', ')');
Validate.notEmpty(subQuery, ":has(el) subselect must not be empty");
evals.add(new StructuralEvaluator.Has(parse(subQuery)));
}
// pseudo selector :contains(text), containsOwn(text)
private void contains(boolean own) {
tq.consume(own ? ":containsOwn" : ":contains");
String searchText = TokenQueue.unescape(tq.chompBalanced('(', ')'));
Validate.notEmpty(searchText, ":contains(text) query must not be empty");
if (own)
evals.add(new Evaluator.ContainsOwnText(searchText));
else
evals.add(new Evaluator.ContainsText(searchText));
}
// :matches(regex), matchesOwn(regex)
private void matches(boolean own) {
tq.consume(own ? ":matchesOwn" : ":matches");
String regex = tq.chompBalanced('(', ')'); // don't unescape, as regex bits will be escaped
Validate.notEmpty(regex, ":matches(regex) query must not be empty");
if (own)
evals.add(new Evaluator.MatchesOwn(Pattern.compile(regex)));
else
evals.add(new Evaluator.Matches(Pattern.compile(regex)));
}
// :not(selector)
private void not() {
tq.consume(":not");
String subQuery = tq.chompBalanced('(', ')');
Validate.notEmpty(subQuery, ":not(selector) subselect must not be empty");
evals.add(new StructuralEvaluator.Not(parse(subQuery)));
}
}
