Extend Elements to update the backing DOM on set(), remove(), et al

CHANGES

@@ -1,5 +1,10 @@
 jsoup changelog
 
+Release 1.17.1 [PENDING]
+  * Improvement: in the Elements list, added direct support for `#set(index, element)`, `#remove(index)`,
+    `#remove(object)`, `#clear()`, `#removeAll(collection)`, `#retainAll(collection)`, `#removeIf(filter)`,
+    `#replaceAll(operator)`. These methods update the original DOM, as well as the Elements list.
+
 Release 1.16.2 [20-Oct-2023]
   * Improvement: optimized the performance of complex CSS selectors, by adding a cost-based query planner. Evaluators
     are sorted by their relative execution cost, and executed in order of lower to higher cost. This speeds the

src/main/java/org/jsoup/select/Elements.java

@@ -14,14 +14,17 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashSet;
+import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.function.Predicate;
+import java.util.function.UnaryOperator;
 
 /**
  A list of {@link Element}s, with methods that act on every element in the list.
- <p>
- To get an {@code Elements} object, use the {@link Element#select(String)} method.
- </p>
+ <p>To get an {@code Elements} object, use the {@link Element#select(String)} method.</p>
+ <p>Methods that {@link #set(int, Element) set}, {@link #remove(int) remove}, or {@link #replaceAll(UnaryOperator)
+ replace} Elements in the list will also act on the underlying {@link org.jsoup.nodes.Document DOM}.</p>
 
  @author Jonathan Hedley, [email protected] */
 public class Elements extends ArrayList<Element> {
@@ -431,6 +434,7 @@ public Elements empty() {
 
     /**
      * Remove each matched element from the DOM. This is similar to setting the outer HTML of each element to nothing.
+     * <p>The elements will still be retained in this list, in case further processing of them is desired.</p>
      * <p>
      * E.g. HTML: {@code <div><p>Hello</p> <p>there</p> <img /></div>}<br>
      * <code>doc.select("p").remove();</code><br>
@@ -440,6 +444,7 @@ public Elements empty() {
      * @return this, for chaining
      * @see Element#empty()
      * @see #empty()
+     * @see #clear()
      */
     public Elements remove() {
         for (Element element : this) {
@@ -683,4 +688,121 @@ private <T extends Node> List<T> childNodesOfType(Class<T> tClass) {
         return nodes;
     }
 
+    // list methods that update the DOM:
+
+    /**
+     Replace the Element at the specified index in this list, and in the DOM.
+     * @param index index of the element to replace
+     * @param element element to be stored at the specified position
+     * @return the old Element at this index
+     * @since 1.17.1
+     */
+    @Override public Element set(int index, Element element) {
+        Validate.notNull(element);
+        Element old = super.set(index, element);
+        old.replaceWith(element);
+        return old;
+    }
+
+    /**
+     Remove the Element at the specified index in this ist, and from the DOM.
+     * @param index the index of the element to be removed
+     * @return the old element at this index
+     * @since 1.17.1
+     */
+    @Override public Element remove(int index) {
+        Element old = super.remove(index);
+        old.remove();
+        return old;
+    }
+
+    /**
+     Remove the specified Element from this list, and from th DOM
+     * @param o element to be removed from this list, if present
+     * @return if this list contained the Element
+     * @since 1.17.1
+     */
+    @Override public boolean remove(Object o) {
+        int index = super.indexOf(o);
+        if (index == -1) {
+            return false;
+        } else {
+            remove(index);
+            return true;
+        }
+    }
+
+    /**
+     Removes all the elements from this list, and each of them from the DOM.
+     * @since 1.17.1
+     * @see #remove()
+     */
+    @Override public void clear() {
+        remove();
+        super.clear();
+    }
+
+    /**
+     Removes from this list, and from the DOM, each of the elements that are contained in the specified collection and
+     are in this list.
+     * @param c collection containing elements to be removed from this list
+     * @return {@code true} if elements were removed from this list
+     * @since 1.17.1
+     */
+    @Override public boolean removeAll(Collection<?> c) {
+        boolean anyRemoved = false;
+        for (Object o : c) {
+            anyRemoved |= this.remove(o);
+        }
+        return anyRemoved;
+    }
+
+    /**
+     Retain in this list, and in the DOM, only the elements that are in the specified collection and are in this list.
+     In other words, remove elements from this list and the DOM any item that is in this list but not in the specified
+     collection.
+     * @param c collection containing elements to be retained in this list
+     * @return {@code true} if elements were removed from this list
+     * @since 1.17.1
+     */
+    @Override public boolean retainAll(Collection<?> c) {
+        boolean anyRemoved = false;
+        for (Iterator<Element> it = this.iterator(); it.hasNext(); ) {
+            Element el = it.next();
+            if (!c.contains(el)) {
+                it.remove();
+                anyRemoved = true;
+            }
+        }
+        return anyRemoved;
+    }
+
+    /**
+     Remove from the list, and from the DOM, all elements in this list that mach the given filter.
+     * @param filter a predicate which returns {@code true} for elements to be removed
+     * @return {@code true} if elements were removed from this list
+     * @since 1.17.1
+     */
+    @Override public boolean removeIf(Predicate<? super Element> filter) {
+        boolean anyRemoved = false;
+        for (Iterator<Element> it = this.iterator(); it.hasNext(); ) {
+            Element el = it.next();
+            if (filter.test(el)) {
+                it.remove();
+                anyRemoved = true;
+            }
+        }
+        return anyRemoved;
+    }
+
+    /**
+     Replace each element in this list with the result of the operator, and update the DOM.
+     * @param operator the operator to apply to each element
+     * @since 1.17.1
+     */
+    @Override public void replaceAll(UnaryOperator<Element> operator) {
+        for (int i = 0; i < this.size(); i++) {
+            this.set(i, operator.apply(this.get(i)));
+        }
+    }
 }

src/test/java/org/jsoup/select/ElementsTest.java

@@ -11,9 +11,11 @@
 import org.jsoup.nodes.TextNode;
 import org.junit.jupiter.api.Test;
 
+import java.util.Iterator;
 import java.util.List;
 
 import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 
 /**
  Tests for ElementList.
@@ -435,4 +437,166 @@ public void tail(Node node, int depth) {
         assertEquals("http://example.com/bar", absAttrs.get(1));
         assertEquals("http://example.com", absAttrs.get(2));
     }
+
+    @Test public void setElementByIndex() {
+        Document doc = Jsoup.parse("<p>One<p>Two<p>Three");
+        Element newP = doc.createElement("p").text("New").attr("id", "new");
+
+        Elements ps = doc.select("p");
+        Element two = ps.get(1);
+        Element old = ps.set(1, newP);
+        assertSame(old, two);
+        assertSame(newP, ps.get(1)); // replaced in list
+        assertEquals("<p>One</p>\n<p id=\"new\">New</p>\n<p>Three</p>", doc.body().html()); // replaced in dom
+    }
+
+    @Test public void removeElementByIndex() {
+        Document doc = Jsoup.parse("<p>One<p>Two<p>Three");
+
+        Elements ps = doc.select("p");
+        Element two = ps.get(1);
+        assertTrue(ps.contains(two));
+        Element old = ps.remove(1);
+        assertSame(old, two);
+
+        assertEquals(2, ps.size()); // removed from list
+        assertFalse(ps.contains(old));
+        assertEquals("<p>One</p>\n<p>Three</p>", doc.body().html()); // removed from dom
+    }
+
+    @Test public void removeElementByObject() {
+        Document doc = Jsoup.parse("<p>One<p>Two<p>Three");
+
+        Elements ps = doc.select("p");
+        Element two = ps.get(1);
+        assertTrue(ps.contains(two));
+        boolean removed = ps.remove(two);
+        assertTrue(removed);
+
+        assertEquals(2, ps.size()); // removed from list
+        assertFalse(ps.contains(two));
+        assertEquals("<p>One</p>\n<p>Three</p>", doc.body().html()); // removed from dom
+    }
+
+    @Test public void removeElementObjectNoops() {
+        Document doc = Jsoup.parse("<p>One<p>Two<p>Three");
+        String origHtml = doc.html();
+        Element newP = doc.createElement("p").text("New");
+
+        Elements ps = doc.select("p");
+        int size = ps.size();
+        assertFalse(ps.remove(newP));
+        assertFalse(ps.remove(newP.childNodes()));
+        assertEquals(origHtml, doc.html());
+        assertEquals(size, ps.size());
+    }
+
+    @Test public void clear() {
+        Document doc = Jsoup.parse("<p>One</p><p>Two</p><div>Three</div>");
+        Elements ps = doc.select("p");
+        assertEquals(2, ps.size());
+        ps.clear();
+        assertEquals(0, ps.size());
+
+        assertEquals(0, doc.select("p").size());
+    }
+
+    @Test public void removeAll() {
+        Document doc = Jsoup.parse("<p>One<p>Two<p>Three<p>Four</p><div>Div");
+        Elements ps = doc.select("p");
+        assertEquals(4, ps.size());
+        Elements midPs = doc.select("p:gt(0):lt(3)"); //Two and Three
+        assertEquals(2, midPs.size());
+
+        boolean removed = ps.removeAll(midPs);
+        assertEquals(2, ps.size());
+        assertTrue(removed);
+        assertEquals(2, midPs.size());
+
+        Elements divs = doc.select("div");
+        assertEquals(1, divs.size());
+        assertFalse(ps.removeAll(divs));
+        assertEquals(2, ps.size());
+
+        assertEquals("<p>One</p>\n<p>Four</p>\n<div>\n Div\n</div>", doc.body().html());
+    }
+
+    @Test public void retainAll() {
+        Document doc = Jsoup.parse("<p>One<p>Two<p>Three<p>Four</p><div>Div");
+        Elements ps = doc.select("p");
+        assertEquals(4, ps.size());
+        Elements midPs = doc.select("p:gt(0):lt(3)"); //Two and Three
+        assertEquals(2, midPs.size());
+
+        boolean removed = ps.retainAll(midPs);
+        assertEquals(2, ps.size());
+        assertTrue(removed);
+        assertEquals(2, midPs.size());
+
+        assertEquals("<p>Two</p>\n<p>Three</p>\n<div>\n Div\n</div>", doc.body().html());
+
+        Elements psAgain = doc.select("p");
+        assertFalse(midPs.retainAll(psAgain));
+
+        assertEquals("<p>Two</p>\n<p>Three</p>\n<div>\n Div\n</div>", doc.body().html());
+    }
+
+    @Test public void iteratorRemovesFromDom() {
+        Document doc = Jsoup.parse("<p>One<p>Two<p>Three<p>Four");
+        Elements ps = doc.select("p");
+
+        assertEquals(4, ps.size());
+        for (Iterator<Element> it = ps.iterator(); it.hasNext(); ) {
+            Element el = it.next();
+            if (el.text().contains("Two"))
+                it.remove();
+        }
+        assertEquals(3, ps.size());
+        assertEquals("<p>One</p>\n<p>Three</p>\n<p>Four</p>", doc.body().html());
+    }
+
+    @Test public void removeIf() {
+        Document doc = Jsoup.parse("<p>One<p>Two<p>Three<p>Four");
+        Elements ps = doc.select("p");
+
+        assertEquals(4, ps.size());
+        boolean removed = ps.removeIf(el -> el.text().contains("Two"));
+        assertTrue(removed);
+        assertEquals(3, ps.size());
+        assertEquals("<p>One</p>\n<p>Three</p>\n<p>Four</p>", doc.body().html());
+
+        assertFalse(ps.removeIf(el -> el.text().contains("Five")));
+        assertEquals("<p>One</p>\n<p>Three</p>\n<p>Four</p>", doc.body().html());
+    }
+
+    @Test public void removeIfSupportsConcurrentRead() {
+        Document doc = Jsoup.parse("<p>One<p>Two<p>Three<p>Four");
+        Elements ps = doc.select("p");
+        assertEquals(4, ps.size());
+
+        boolean removed = ps.removeIf(el -> ps.contains(el));
+        assertTrue(removed);
+        assertEquals(0, ps.size());
+        assertEquals("", doc.body().html());
+    }
+
+    @Test public void replaceAll() {
+        Document doc = Jsoup.parse("<p>One<p>Two<p>Three<p>Four");
+        Elements ps = doc.select("p");
+        assertEquals(4, ps.size());
+
+        ps.replaceAll(el -> {
+            Element div = doc.createElement("div");
+            div.text(el.text());
+            return div;
+        });
+
+        // Check Elements
+        for (Element p : ps) {
+            assertEquals("div", p.tagName());
+        }
+
+        // check dom
+        assertEquals("<div> One</div><div> Two</div><div> Three</div><div> Four</div>", TextUtil.normalizeSpaces(doc.body().html()));
+    }
 }