Config.removeSection() telling whether it changed the config

Add a variant of unsetSection() that returns whether it did indeed
change the config. This can be used in to skip saving the config if
it was not changed.

Also fix the iteration over the entries: lastWasMatch was never reset,
and thus all empty lines after a match would be removed.

Change-Id: Iea9e84aa74b1e4bb3c89efe3936fa3a8a09532e5
Signed-off-by: Thomas Wolf <twolf@apache.org>

org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/ConfigTest.java

@@ -506,6 +506,35 @@ public void testBooleanWithNoValue() throws ConfigInvalidException {
 		assertEquals("[my]\n\tempty\n", c.toText());
 	}
 
+	@Test
+	public void testRemoveBranchSection() throws ConfigInvalidException {
+		Config c = parse("" //
+				+ "[branch \"keep\"]\n"
+				+ "  merge = master.branch.to.keep.in.the.file\n"
+				+ "\n"
+				+ "[branch \"remove\"]\n"
+				+ "  merge = this.will.get.deleted\n"
+				+ "  remote = origin-for-some-long-gone-place\n"
+				+ "\n"
+				+ "\n"
+				+ "[core-section-not-to-remove-in-test]\n"
+				+ "  packedGitLimit = 14\n"
+				+ "\n"
+				+ "[other]\n"
+				+ "  foo = bar\n");
+		assertFalse(c.removeSection("branch", "does.not.exist"));
+		assertTrue(c.removeSection("branch", "remove"));
+		assertEquals("" //
+				+ "[branch \"keep\"]\n"
+				+ "  merge = master.branch.to.keep.in.the.file\n"
+				+ "\n"
+				+ "[core-section-not-to-remove-in-test]\n"
+				+ "  packedGitLimit = 14\n"
+				+ "\n"
+				+ "[other]\n"
+				+ "  foo = bar\n", c.toText());
+	}
+
 	@Test
 	public void testUnsetBranchSection() throws ConfigInvalidException {
 		Config c = parse("" //
@@ -516,8 +545,12 @@ public void testUnsetBranchSection() throws ConfigInvalidException {
 				+ "  merge = this.will.get.deleted\n"
 				+ "  remote = origin-for-some-long-gone-place\n"
 				+ "\n"
+				+ "\n"
 				+ "[core-section-not-to-remove-in-test]\n"
-				+ "  packedGitLimit = 14\n");
+				+ "  packedGitLimit = 14\n"
+				+ "\n"
+				+ "[other]\n"
+				+ "  foo = bar\n");
 		c.unsetSection("branch", "does.not.exist");
 		c.unsetSection("branch", "remove");
 		assertEquals("" //
@@ -525,7 +558,10 @@ public void testUnsetBranchSection() throws ConfigInvalidException {
 				+ "  merge = master.branch.to.keep.in.the.file\n"
 				+ "\n"
 				+ "[core-section-not-to-remove-in-test]\n"
-				+ "  packedGitLimit = 14\n", c.toText());
+				+ "  packedGitLimit = 14\n"
+				+ "\n"
+				+ "[other]\n"
+				+ "  foo = bar\n", c.toText());
 	}
 
 	@Test

org.eclipse.jgit/src/org/eclipse/jgit/lib/Config.java

@@ -30,6 +30,7 @@
 import java.util.Locale;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 
 import org.eclipse.jgit.annotations.NonNull;
@@ -921,29 +922,52 @@ public void unset(final String section, final String subsection,
 	 *            optional subsection value, e.g. a branch name
 	 */
 	public void unsetSection(String section, String subsection) {
-		ConfigSnapshot src, res;
-		do {
-			src = state.get();
-			res = unsetSection(src, section, subsection);
-		} while (!state.compareAndSet(src, res));
+		removeSection(section, subsection);
 	}
 
-	private ConfigSnapshot unsetSection(final ConfigSnapshot srcState,
-			final String section,
-			final String subsection) {
+	/**
+	 * Removes all configuration values under a single section.
+	 *
+	 * @param section
+	 *            section name, e.g "branch"
+	 * @param subsection
+	 *            optional subsection value, e.g. a branch name
+	 * @return {@code true} if a section was present and was removed;
+	 *         {@code false} if the config was not changed (i.e., no such
+	 *         section was present)
+	 * @since 6.8
+	 */
+	public boolean removeSection(String section, String subsection) {
+		ConfigSnapshot src, res;
+		AtomicBoolean changed = new AtomicBoolean();
+		do {
+			src = state.get();
+			changed.set(false);
+			res = unsetSection(src, section, subsection, changed);
+		} while (!state.compareAndSet(src, res));
+		return changed.get();
+	}
+
+	private ConfigSnapshot unsetSection(ConfigSnapshot srcState, String section,
+			String subsection, AtomicBoolean changed) {
 		final int max = srcState.entryList.size();
 		final ArrayList<ConfigLine> r = new ArrayList<>(max);
 
 		boolean lastWasMatch = false;
 		for (ConfigLine e : srcState.entryList) {
-			if (e.includedFrom == null && e.match(section, subsection)) {
-				// Skip this record, it's for the section we are removing.
-				lastWasMatch = true;
+			if (e.includedFrom != null) {
+				r.add(e);
 				continue;
 			}
-
-			if (lastWasMatch && e.section == null && e.subsection == null)
+			if (lastWasMatch && e.section == null && e.subsection == null) {
 				continue; // skip this padding line in the section.
+			}
+			lastWasMatch = e.match(section, subsection);
+			if (lastWasMatch) {
+				// Skip this record, it's for the section we are removing.
+				changed.set(true);
+				continue;
+			}
 			r.add(e);
 		}
 

org.eclipse.jgit/src/org/eclipse/jgit/storage/file/FileBasedConfig.java

@@ -5,7 +5,7 @@
  * Copyright (C) 2009, JetBrains s.r.o.
  * Copyright (C) 2008-2009, Robin Rosenberg <robin.rosenberg@dewire.com>
  * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
- * Copyright (C) 2008, Thad Hughes <thadh@thad.corp.google.com> and others
+ * Copyright (C) 2008, 2023 Thad Hughes <thadh@thad.corp.google.com> and others
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Distribution License v. 1.0 which is available at
@@ -22,7 +22,6 @@
 import java.io.File;
 import java.io.IOException;
 import java.text.MessageFormat;
-import java.util.List;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 import org.eclipse.jgit.errors.ConfigInvalidException;
@@ -107,17 +106,6 @@ boolean exists() {
 		return exists.get();
 	}
 
-	@Override
-	public void setStringList(String section, String subsection, String name,
-			List<String> values) {
-		super.setStringList(section, subsection, name, values);
-	}
-
-	@Override
-	public void unsetSection(String section, String subsection) {
-		super.unsetSection(section, subsection);
-	}
-
 	/**
 	 * {@inheritDoc}
 	 * <p>

org.eclipse.jgit/src/org/eclipse/jgit/storage/file/UserConfigFile.java

@@ -82,6 +82,14 @@ public void unsetSection(String section, String subsection) {
 		}
 	}
 
+	@Override
+	public boolean removeSection(String section, String subsection) {
+		if (exists() || !parent.exists()) {
+			return super.removeSection(section, subsection);
+		}
+		return parent.removeSection(section, subsection);
+	}
+
 	@Override
 	public boolean isOutdated() {
 		return super.isOutdated() || parent.isOutdated();