Use java.text.BreakIterator in DefaultTextDoubleClickStrategy

bundles/org.eclipse.jface.text/META-INF/MANIFEST.MF

@@ -38,7 +38,6 @@ Require-Bundle:
  org.eclipse.text;bundle-version="[3.8.0,4.0.0)";visibility:=reexport,
  org.eclipse.swt;bundle-version="[3.133.0,4.0.0)",
  org.eclipse.jface;bundle-version="[3.39.0,4.0.0)"
-Import-Package: com.ibm.icu.text
 Bundle-RequiredExecutionEnvironment: JavaSE-21
 Automatic-Module-Name: org.eclipse.jface.text
 Bundle-Activator: org.eclipse.jface.text.Activator

bundles/org.eclipse.jface.text/src/org/eclipse/jface/text/DefaultTextDoubleClickStrategy.java

@@ -14,12 +14,10 @@
 
 package org.eclipse.jface.text;
 
+import java.text.BreakIterator;
 import java.text.CharacterIterator;
 import java.util.Locale;
 
-import com.ibm.icu.text.BreakIterator;
-
-
 
 /**
  * Standard implementation of
@@ -223,9 +221,54 @@ protected IRegion findExtendedDoubleClickSelection(IDocument document, int offse
 	 * @since 3.5
 	 */
 	protected IRegion findWord(IDocument document, int offset) {
+		IRegion identifier= findIdentifierAt(document, offset);
+		if (identifier != null) {
+			return identifier;
+		}
 		return findWord(document, offset, getWordBreakIterator());
 	}
 
+	/**
+	 * If the offset lies on an ASCII identifier character ({@code [A-Za-z0-9_]}), or
+	 * just after one, returns the maximal contiguous identifier run. Otherwise
+	 * returns {@code null} so the caller falls back to the locale-aware
+	 * {@link BreakIterator}. This handles identifier-style words containing runs
+	 * of {@code '_'} (e.g. {@code foo__bar}, {@code __aaaa}) consistently across
+	 * JDK versions, since {@link BreakIterator#getWordInstance()} places word
+	 * boundaries between consecutive underscores while users expect such tokens
+	 * to be selected as a single word.
+	 */
+	private static IRegion findIdentifierAt(IDocument document, int offset) {
+		try {
+			IRegion line= document.getLineInformationOfOffset(offset);
+			int lineStart= line.getOffset();
+			int lineEnd= lineStart + line.getLength();
+			int probe;
+			if (offset < lineEnd && isIdentifierPart(document.getChar(offset))) {
+				probe= offset;
+			} else if (offset > lineStart && isIdentifierPart(document.getChar(offset - 1))) {
+				probe= offset - 1;
+			} else {
+				return null;
+			}
+			int start= probe;
+			while (start > lineStart && isIdentifierPart(document.getChar(start - 1))) {
+				start--;
+			}
+			int end= probe + 1;
+			while (end < lineEnd && isIdentifierPart(document.getChar(end))) {
+				end++;
+			}
+			return new Region(start, end - start);
+		} catch (BadLocationException e) {
+			return null;
+		}
+	}
+
+	private static boolean isIdentifierPart(char c) {
+		return c == '_' || (c < 128 && (c >= '0' && c <= '9' || c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z'));
+	}
+
 	/**
 	 * Returns the locale specific word break iterator.
 	 *

tests/org.eclipse.jface.text.tests/src/org/eclipse/jface/text/tests/DefaultTextDoubleClickStrategyTest.java

@@ -55,6 +55,70 @@ public void testClickAtLineEnd() throws Exception {
 		assertEquals("you", document.get(selection.getOffset(), selection.getLength()), "Unexpected selection");
 	}
 
+	@Test
+	public void testClickJustPastIdentifierSelectsThatIdentifier() throws Exception {
+		String content= "foo bar baz";
+		IDocument document= new Document(content);
+		TestSpecificDefaultTextDoubleClickStrategy strategy= new TestSpecificDefaultTextDoubleClickStrategy();
+		// Click at offset 3: the space right after "foo".
+		IRegion selection= strategy.findWord(document, 3);
+		assertNotNull(selection);
+		assertEquals("foo", document.get(selection.getOffset(), selection.getLength()));
+	}
+
+	@Test
+	public void testClickAtIdentifierStartSelectsWholeIdentifier() throws Exception {
+		String content= "foo __aaaa bar";
+		IDocument document= new Document(content);
+		TestSpecificDefaultTextDoubleClickStrategy strategy= new TestSpecificDefaultTextDoubleClickStrategy();
+		// Click at offset 4: the first '_' starting "__aaaa".
+		IRegion selection= strategy.findWord(document, 4);
+		assertNotNull(selection);
+		assertEquals("__aaaa", document.get(selection.getOffset(), selection.getLength()));
+	}
+
+	@Test
+	public void testIdentifierAtLineStartAndEnd() throws Exception {
+		String content= "_foo___\nbar_baz";
+		IDocument document= new Document(content);
+		TestSpecificDefaultTextDoubleClickStrategy strategy= new TestSpecificDefaultTextDoubleClickStrategy();
+		// First line: every offset 0..7 should yield "_foo___".
+		for (int offset= 0; offset <= 7; offset++) {
+			IRegion selection= strategy.findWord(document, offset);
+			assertNotNull(selection, "no selection at offset " + offset);
+			assertEquals("_foo___", document.get(selection.getOffset(), selection.getLength()),
+					"unexpected selection at offset " + offset);
+		}
+		// Second line.
+		IRegion selection= strategy.findWord(document, 11);
+		assertNotNull(selection);
+		assertEquals("bar_baz", document.get(selection.getOffset(), selection.getLength()));
+	}
+
+	@Test
+	public void testSingleLineDocument() throws Exception {
+		String content= "abc";
+		IDocument document= new Document(content);
+		TestSpecificDefaultTextDoubleClickStrategy strategy= new TestSpecificDefaultTextDoubleClickStrategy();
+		IRegion selection= strategy.findWord(document, 0);
+		assertNotNull(selection);
+		assertEquals("abc", document.get(selection.getOffset(), selection.getLength()));
+		selection= strategy.findWord(document, document.getLength());
+		assertNotNull(selection);
+		assertEquals("abc", document.get(selection.getOffset(), selection.getLength()));
+	}
+
+	@Test
+	public void testIdentifierSurroundedByPunctuation() throws Exception {
+		String content= "(foo_bar);";
+		IDocument document= new Document(content);
+		TestSpecificDefaultTextDoubleClickStrategy strategy= new TestSpecificDefaultTextDoubleClickStrategy();
+		// Click in the middle of the identifier.
+		IRegion selection= strategy.findWord(document, 4);
+		assertNotNull(selection);
+		assertEquals("foo_bar", document.get(selection.getOffset(), selection.getLength()));
+	}
+
 	private static final class TestSpecificDefaultTextDoubleClickStrategy extends DefaultTextDoubleClickStrategy {
 
 		@Override