//Dstl (c) Crown Copyright 2017 package uk.gov.dstl.baleen.uima.utils.select; import java.util.ArrayList; import java.util.Collection; import java.util.IdentityHashMap; import org.apache.commons.lang.Validate; /** * CSS-like node selector, that finds nodes matching a query. * * <h2>Selector syntax</h2> * <p> * A selector is a chain of simple selectors, separated by combinators. Selectors are <b>case * insensitive</b> (including against nodes, attributes, and attribute values). * </p> * <p> * The universal selector (*) is implicit when no node selector is supplied (i.e. {@code *.header} * and {@code .header} is equivalent). * </p> * <table summary=""> * <tr> * <th align="left">Pattern</th> * <th align="left">Matches</th> * <th align="left">Example</th> * </tr> * <tr> * <td><code>*</code></td> * <td>any node</td> * <td><code>*</code></td> * </tr> * <tr> * <td><code>type</code></td> * <td>nodes with the given type name</td> * <td><code>Paragraph</code></td> * </tr> * <tr> * <tr> * <td><code>#id</code></td> * <td>nodes with attribute id with value "id"</td> * <td><code>Paragraph#wrap</code>, <code>#logo</code></td> * </tr> * <tr> * <td><code>.class</code></td> * <td>nodes with a class name of "class"</td> * <td><code>Section.left</code>, <code>.result</code></td> * </tr> * <tr> * <td><code>[attr]</code></td> * <td>nodes with an attribute named "attr" (with any value)</td> * <td><code>Link[target]</code>, <code>[level]</code></td> * </tr> * <tr> * <td><code>[^attrPrefix]</code></td> * <td>nodes with an attribute name starting with "attrPrefix".</td> * <td><code>[^level]</code>, <code>Style[^d]</code></td> * </tr> * <tr> * <td><code>[attr=val]</code></td> * <td>nodes with an attribute named "attr", and value equal to "val"</td> * <td><code>Figure[width=500]</code>, <code>Link[target=test]</code></td> * </tr> * <tr> * <td><code>[attr="val"]</code></td> * <td>nodes with an attribute named "attr", and value equal to "val"</td> * <td><code>Aside[hello="Cleveland"][goodbye="Columbus"]</code>, * <code>Link[target="example.com"]</code></td> * </tr> * <tr> * <td><code>[attr^=valPrefix]</code></td> * <td>nodes with an attribute named "attr", and value starting with "valPrefix"</td> * <td><code>Link[target^=http:]</code></td> * </tr> * <tr> * <td><code>[attr$=valSuffix]</code></td> * <td>nodes with an attribute named "attr", and value ending with "valSuffix"</td> * <td><code>Figure[target$=.png]</code></td> * </tr> * <tr> * <td><code>[attr*=valContaining]</code></td> * <td>nodes with an attribute named "attr", and value containing "valContaining"</td> * <td><code>Link[target*=/search/]</code></td> * </tr> * <tr> * <td><code>[attr~=<em>regex</em>]</code></td> * <td>nodes with an attribute named "attr", and value matching the regular expression</td> * <td><code>Figure[target~=(?i)\\.(png|jpe?g)]</code></td> * </tr> * <tr> * <td></td> * <td>The above may be combined in any order</td> * <td><code>Section.header[title]</code></td> * </tr> * <tr> * <td> * <td colspan="3"> * <h3>Combinators</h3></td> * </tr> * <tr> * <td><code>E F</code></td> * <td>an F node descended from an E node</td> * <td><code>Section Paragraph</code>, <code>.logo Heading</code></td> * </tr> * <tr> * <td><code>E {@literal >} F</code></td> * <td>an F direct child of E</td> * <td><code>Ordered {@literal >} ListItem</code></td> * </tr> * <tr> * <td><code>E + F</code></td> * <td>an F node immediately preceded by sibling E</td> * <td><code>ListItem + ListItem</code>, <code>Section.head + Section</code></td> * </tr> * <tr> * <td><code>E ~ F</code></td> * <td>an F node preceded by sibling E</td> * <td><code>HEADING ~ paragraph</code></td> * </tr> * <tr> * <td><code>E, F, G</code></td> * <td>all matching nodes E, F, or G</td> * <td><code>Link[target^=http], Section, Heading</code></td> * </tr> * <tr> * <td> * <td colspan="3"> * <h3>Pseudo selectors</h3></td> * </tr> * <tr> * <td><code>:lt(<em>n</em>)</code></td> * <td>nodes whose sibling index is less than <em>n</em></td> * <td><code>TableCell:lt(3)</code> finds the first 3 cells of each row</td> * </tr> * <tr> * <td><code>:gt(<em>n</em>)</code></td> * <td>nodes whose sibling index is greater than <em>n</em></td> * <td><code>TableCell:gt(1)</code> finds cells after skipping the first two</td> * </tr> * <tr> * <td><code>:eq(<em>n</em>)</code></td> * <td>nodes whose sibling index is equal to <em>n</em></td> * <td><code>TableCell:eq(0)</code> finds the first cell of each row</td> * </tr> * <tr> * <td><code>:has(<em>selector</em>)</code></td> * <td>nodes that contains at least one node matching the <em>selector</em></td> * <td><code>Section:has(paragraph)</code> finds Sections that contain Paragraph nodes</td> * </tr> * <tr> * <td><code>:not(<em>selector</em>)</code></td> * <td>nodes that do not match the <em>selector</em>. See also {@link Nodes#not(String)}</td> * <td><code>Section:not(.logo)</code> finds all Sections that do not have the "logo" class. * <p> * <code>Section:not(:has(Section))</code> finds Sections that do not contain Sectionss. * </p> * </td> * </tr> * <tr> * <td><code>:contains(<em>text</em>)</code></td> * <td>nodes that contains the specified text. The search is case insensitive. The text may appear * in the found node, or any of its descendants.</td> * <td><code>paragraph:contains(baleen)</code> finds Paragraph nodes containing the text * "baleen".</td> * </tr> * <tr> * <td><code>:matches(<em>regex</em>)</code></td> * <td>nodes whose text matches the specified regular expression. The text may appear in the found * node, or any of its descendants.</td> * <td><code>TableRow:matches(\\d+)</code> finds table rows containing digits. * <code>Section:matches((?i)login)</code> finds Sections containing the text, case * insensitively.</td> * </tr> * <tr> * <td><code>:containsOwn(<em>text</em>)</code></td> * <td>nodes that directly contain the specified text. The search is case insensitive. The text must * appear in the found node, not any of its descendants.</td> * <td><code>paragraph:containsOwn(baleen)</code> finds Paragraph nodes with own text "baleen".</td> * </tr> * <tr> * <td><code>:matchesOwn(<em>regex</em>)</code></td> * <td>nodes whose own text matches the specified regular expression. The text must appear in the * found node, not any of its descendants.</td> * <td><code>tablecell:matchesOwn(\\d+)</code> finds table cells directly containing digits. * <code>section:matchesOwn((?i)login)</code> finds Section containing the text, case * insensitively.</td> * </tr> * <tr> * <td></td> * <td>The above may be combined in any order and with other selectors</td> * <td><code>.light:contains(name):eq(0)</code></td> * </tr> * <tr> * <td colspan="3"> * <h3>Structural pseudo selectors</h3></td> * </tr> * <tr> * <td><code>:root</code></td> * <td>The node that is the root of the structure. This is the artificial root of all structure and * the only node that does not contain a structure.</td> * <td><code>:root</code></td> * </tr> * <tr> * <td><code>:nth-child(<em>a</em>n+<em>b</em>)</code></td> * <td> * <p> * nodes that have <code><em>a</em>n+<em>b</em>-1</code> siblings <b>before</b> it in the structure * tree, for any positive integer or zero value of <code>n</code>, and has a parent node. For values * of <code>a</code> and <code>b</code> greater than zero, this effectively divides the node's * children into groups of a nodes (the last group taking the remainder), and selecting the * <em>b</em>th node of each group. For example, this allows the selectors to address every other * row in a table, and could be used to select alternating paragraphs text in a cycle of four. The * <code>a</code> and <code>b</code> values must be integers (positive, negative, or zero). The * index of the first child of an node is 1. * </p> * In addition to this, <code>:nth-child()</code> can take <code>odd</code> and <code>even</code> as * arguments instead. <code>odd</code> has the same signification as <code>2n+1</code>, and * <code>even</code> has the same signification as <code>2n</code>.</td> * <td><code>tr:nth-child(2n+1)</code> finds every odd row of a table. * <code>:nth-child(10n-1)</code> the 9th, 19th, 29th, etc, node. <code>li:nth-child(5)</code> the * 5h li</td> * </tr> * <tr> * <td><code>:nth-last-child(<em>a</em>n+<em>b</em>)</code></td> * <td>nodes that have <code><em>a</em>n+<em>b</em>-1</code> siblings <b>after</b> it in the * document tree. Otherwise like <code>:nth-child()</code></td> * <td><code>tr:nth-last-child(-n+2)</code> the last two rows of a table</td> * </tr> * <tr> * <td><code>:nth-of-type(<em>a</em>n+<em>b</em>)</code></td> * <td>pseudo-class notation represents a node that has <code><em>a</em>n+<em>b</em>-1</code> * siblings with the same expanded node name <em>before</em> it in the document tree, for any zero * or positive integer value of n, and has a parent node</td> * <td><code>Figure:nth-of-type(2n+1)</code></td> * </tr> * <tr> * <td><code>:nth-last-of-type(<em>a</em>n+<em>b</em>)</code></td> * <td>pseudo-class notation represents an node that has <code><em>a</em>n+<em>b</em>-1</code> * siblings with the same expanded node name <em>after</em> it in the structure tree, for any zero * or positive integer value of n, and has a parent node</td> * <td><code>Figure:nth-last-of-type(2n+1)</code></td> * </tr> * <tr> * <td><code>:first-child</code></td> * <td>nodes that are the first child of some other node.</td> * <td><code>Section {@literal >} Paragraph:first-child</code></td> * </tr> * <tr> * <td><code>:last-child</code></td> * <td>nodes that are the last child of some other node.</td> * <td><code>Ordered {@literal >} ListItem:last-child</code></td> * </tr> * <tr> * <td><code>:first-of-type</code></td> * <td>nodes that are the first sibling of its type in the list of children of its parent node</td> * <td><code>DefinitionList DefinitionItem:first-of-type</code></td> * </tr> * <tr> * <td><code>:last-of-type</code></td> * <td>nodes that are the last sibling of its type in the list of children of its parent node</td> * <td><code>TableRow {@literal >} TableCell:last-of-type</code></td> * </tr> * <tr> * <td><code>:only-child</code></td> * <td>nodes that have a parent node and whose parent node have no other node children</td> * <td>Quotation:only-child</td> * </tr> * <tr> * <td><code>:only-of-type</code></td> * <td>a node that has a parent node and whose parent node has no other node children with the same * expanded node name</td> * <td>Aside:only-of-type</td> * </tr> * <tr> * <td><code>:empty</code></td> * <td>nodes that have no children at all</td> * <td>Paragraph:empty</td> * </tr> * </table> * * @see Node#select(String) */ public class Selector<T> { private final Evaluator<T> evaluator; private final Node<T> root; private Selector(String query, Node<T> root) { Validate.notNull(query); query = query.trim(); Validate.notEmpty(query); Validate.notNull(root); evaluator = QueryParser.parse(query); this.root = root; } private Selector(Evaluator<T> evaluator, Node<T> root) { Validate.notNull(evaluator); Validate.notNull(root); this.evaluator = evaluator; this.root = root; } private Nodes<T> select() { return Collector.collect(evaluator, root); } /** * Find nodes matching selector. * * @param query CSS selector * @param root root node to descend into * @return matching nodes, empty if none * @throws Selector.SelectorParseException (unchecked) on an invalid CSS query. */ public static <T> Nodes<T> select(String query, Node<T> root) { return new Selector<>(query, root).select(); } /** * Find nodes matching selector. * * @param evaluator CSS selector * @param root root node to descend into * @return matching nodes, empty if none */ public static <T> Nodes<T> select(Evaluator<T> evaluator, Node<T> root) { return new Selector<>(evaluator, root).select(); } /** * Find nodes matching selector. * * @param query CSS selector * @param roots root nodes to descend into * @return matching nodes, empty if none */ public static <T> Nodes<T> select(String query, Iterable<Node<T>> roots) { Validate.notEmpty(query); Validate.notNull(roots); Evaluator<T> evaluator = QueryParser.parse(query); ArrayList<Node<T>> nodes = new ArrayList<>(); IdentityHashMap<Node<T>, Boolean> seenNodes = new IdentityHashMap<>(); // dedupe nodes by identity, not equality for (Node<T> root : roots) { final Nodes<T> found = select(evaluator, root); for (Node<T> el : found) { if (!seenNodes.containsKey(el)) { nodes.add(el); seenNodes.put(el, Boolean.TRUE); } } } return new Nodes<>(nodes); } // exclude set. package open so that Nodes can implement .not() selector. protected static <T> Nodes<T> filterOut(Collection<Node<T>> nodes, Collection<Node<T>> outs) { Nodes<T> output = new Nodes<>(); for (Node<T> el : nodes) { boolean found = false; for (Node<T> out : outs) { if (el.equals(out)) { found = true; break; } } if (!found) { output.add(el); } } return output; } /** * Selector Parse Exception, for when the given selecotr query fails to parse. * */ public static class SelectorParseException extends IllegalStateException { private static final long serialVersionUID = 1L; /** * Constructor for the selector parse exception. * * @param msg the (templated) message for the exception * @param params the parameters for the (templated) message * */ public SelectorParseException(String msg, Object... params) { super(String.format(msg, params)); } } }