Remove empty iterator from TreeWalk

Its confusing that a new TreeWalk() needs to have reset() invoked
on it before addTree().  This is a historical accident caused by
how TreeWalk was abused within ObjectWalk.

Drop the initial empty tree from the TreeWalk and thus remove a
number of pointless reset() operations from unit tests and some of
the internal JGit code.

Existing application code which is still calling reset() will simply
be incurring a few unnecessary field assignments, but they should
consider cleaning up their code in the future.

Change-Id: I434e94ffa43491019e7dff52ca420a4d2245f48b
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

10 files changed, 5 insertions, 19 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheBuilderIteratorTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheBuilderIteratorTest.java
index a09f8e86c4..10dcd2af86 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheBuilderIteratorTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheBuilderIteratorTest.java
@@ -71,7 +71,6 @@ public class DirCacheBuilderIteratorTest extends RepositoryTestCase {
 		final int expIdx = 2;
 		final DirCacheBuilder b = dc.builder();
 		final TreeWalk tw = new TreeWalk(db);
-		tw.reset();
 		tw.addTree(new DirCacheBuildIterator(b));
 		tw.setRecursive(true);
 		tw.setFilter(PathFilterGroup.createFromStrings(Collections
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheCGitCompatabilityTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheCGitCompatabilityTest.java
index a7e2bc823b..00b94b38cf 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheCGitCompatabilityTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheCGitCompatabilityTest.java
@@ -90,7 +90,6 @@ public class DirCacheCGitCompatabilityTest extends LocalDiskRepositoryTestCase {
 		{
 			final Iterator<CGitIndexRecord> rItr = ls.values().iterator();
 			final TreeWalk tw = new TreeWalk(db);
-			tw.reset();
 			tw.setRecursive(true);
 			tw.addTree(new DirCacheIterator(dc));
 			while (rItr.hasNext()) {
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheIteratorTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheIteratorTest.java
index 24e3c34ddf..9390e29819 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheIteratorTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheIteratorTest.java
@@ -64,7 +64,6 @@ public class DirCacheIteratorTest extends RepositoryTestCase {
 		assertEquals(0, dc.getEntryCount());
 
 		final TreeWalk tw = new TreeWalk(db);
-		tw.reset();
 		tw.addTree(new DirCacheIterator(dc));
 		assertFalse(tw.next());
 	}
@@ -112,7 +111,6 @@ public class DirCacheIteratorTest extends RepositoryTestCase {
 
 		final DirCacheIterator i = new DirCacheIterator(dc);
 		final TreeWalk tw = new TreeWalk(db);
-		tw.reset();
 		tw.addTree(i);
 		int pathIdx = 0;
 		while (tw.next()) {
@@ -149,7 +147,6 @@ public class DirCacheIteratorTest extends RepositoryTestCase {
 
 		final DirCacheIterator i = new DirCacheIterator(dc);
 		final TreeWalk tw = new TreeWalk(db);
-		tw.reset();
 		tw.addTree(i);
 		tw.setRecursive(false);
 		int pathIdx = 0;
@@ -189,7 +186,6 @@ public class DirCacheIteratorTest extends RepositoryTestCase {
 
 		final DirCacheIterator i = new DirCacheIterator(dc);
 		final TreeWalk tw = new TreeWalk(db);
-		tw.reset();
 		tw.addTree(i);
 		tw.setRecursive(true);
 		int pathIdx = 0;
@@ -223,7 +219,6 @@ public class DirCacheIteratorTest extends RepositoryTestCase {
 		b.finish();
 
 		final TreeWalk tw = new TreeWalk(db);
-		tw.reset();
 		tw.addTree(new DirCacheIterator(dc));
 		tw.setRecursive(true);
 		int pathIdx = 0;
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/ignore/IgnoreNodeTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/ignore/IgnoreNodeTest.java
index f5b6bfb640..867e0603d9 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/ignore/IgnoreNodeTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/ignore/IgnoreNodeTest.java
@@ -158,7 +158,6 @@ public class IgnoreNodeTest extends RepositoryTestCase {
 
 	private void beginWalk() throws CorruptObjectException {
 		walk = new TreeWalk(db);
-		walk.reset();
 		walk.addTree(new FileTreeIterator(db));
 	}
 
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/RacyGitTests.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/RacyGitTests.java
index 5e04f32f82..bf86ef4585 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/RacyGitTests.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/RacyGitTests.java
@@ -77,7 +77,6 @@ public class RacyGitTests extends RepositoryTestCase {
 		FileTreeIteratorWithTimeControl fileIt = new FileTreeIteratorWithTimeControl(
 				db, modTimes);
 		NameConflictTreeWalk tw = new NameConflictTreeWalk(db);
-		tw.reset();
 		tw.addTree(fileIt);
 		tw.setRecursive(true);
 		FileTreeIterator t;
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/ReadTreeTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/ReadTreeTest.java
index b4732e2dc1..2bf81e16f1 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/ReadTreeTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/ReadTreeTest.java
@@ -685,7 +685,6 @@ public abstract class ReadTreeTest extends RepositoryTestCase {
 	public void assertWorkDir(HashMap<String, String> i)
 			throws CorruptObjectException, IOException {
 		TreeWalk walk = new TreeWalk(db);
-		walk.reset();
 		walk.setRecursive(true);
 		walk.addTree(new FileTreeIterator(db));
 		String expectedValue;
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/NameConflictTreeWalkTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/NameConflictTreeWalkTest.java
index 7e3dea6714..12ed780b8f 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/NameConflictTreeWalkTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/NameConflictTreeWalkTest.java
@@ -82,7 +82,6 @@ public class NameConflictTreeWalkTest extends RepositoryTestCase {
 		}
 
 		final TreeWalk tw = new TreeWalk(db);
-		tw.reset();
 		tw.addTree(new DirCacheIterator(tree0));
 		tw.addTree(new DirCacheIterator(tree1));
 
@@ -113,7 +112,6 @@ public class NameConflictTreeWalkTest extends RepositoryTestCase {
 		}
 
 		final NameConflictTreeWalk tw = new NameConflictTreeWalk(db);
-		tw.reset();
 		tw.addTree(new DirCacheIterator(tree0));
 		tw.addTree(new DirCacheIterator(tree1));
 
@@ -149,7 +147,6 @@ public class NameConflictTreeWalkTest extends RepositoryTestCase {
 		}
 
 		final NameConflictTreeWalk tw = new NameConflictTreeWalk(db);
-		tw.reset();
 		tw.addTree(new DirCacheIterator(tree0));
 		tw.addTree(new DirCacheIterator(tree1));
 
@@ -185,7 +182,6 @@ public class NameConflictTreeWalkTest extends RepositoryTestCase {
 		}
 
 		final NameConflictTreeWalk tw = new NameConflictTreeWalk(db);
-		tw.reset();
 		tw.addTree(new DirCacheIterator(tree0));
 		tw.addTree(new DirCacheIterator(tree1));
 
@@ -222,7 +218,6 @@ public class NameConflictTreeWalkTest extends RepositoryTestCase {
 		}
 
 		final NameConflictTreeWalk tw = new NameConflictTreeWalk(db);
-		tw.reset();
 		tw.addTree(new DirCacheIterator(tree0));
 		tw.addTree(new DirCacheIterator(tree1));
 
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/PostOrderTreeWalkTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/PostOrderTreeWalkTest.java
index 8f813a806b..9152c60fed 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/PostOrderTreeWalkTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/PostOrderTreeWalkTest.java
@@ -98,7 +98,6 @@ public class PostOrderTreeWalkTest extends RepositoryTestCase {
 		}
 
 		final TreeWalk tw = new TreeWalk(db);
-		tw.reset();
 		tw.setPostOrderTraversal(false);
 		tw.addTree(new DirCacheIterator(tree));
 
@@ -127,7 +126,6 @@ public class PostOrderTreeWalkTest extends RepositoryTestCase {
 		}
 
 		final TreeWalk tw = new TreeWalk(db);
-		tw.reset();
 		tw.setPostOrderTraversal(true);
 		tw.addTree(new DirCacheIterator(tree));
 
@@ -162,7 +160,6 @@ public class PostOrderTreeWalkTest extends RepositoryTestCase {
 		}
 
 		final TreeWalk tw = new TreeWalk(db);
-		tw.reset();
 		tw.setPostOrderTraversal(true);
 		tw.addTree(new DirCacheIterator(tree));
 
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/TreeWalkBasicDiffTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/TreeWalkBasicDiffTest.java
index e0957401c5..7c882719f7 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/TreeWalkBasicDiffTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/TreeWalkBasicDiffTest.java
@@ -105,7 +105,7 @@ public class TreeWalkBasicDiffTest extends RepositoryTestCase {
 		inserter.release();
 
 		final TreeWalk tw = new TreeWalk(db);
-		tw.reset(new ObjectId[] { oldTree, newTree });
+		tw.reset(oldTree, newTree);
 		tw.setRecursive(true);
 		tw.setFilter(TreeFilter.ANY_DIFF);
 
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/filter/TreeFilterTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/filter/TreeFilterTest.java
index 12326eade2..4ac82ecad4 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/filter/TreeFilterTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/treewalk/filter/TreeFilterTest.java
@@ -44,11 +44,13 @@
 package org.eclipse.jgit.treewalk.filter;
 
 import org.eclipse.jgit.lib.RepositoryTestCase;
+import org.eclipse.jgit.treewalk.EmptyTreeIterator;
 import org.eclipse.jgit.treewalk.TreeWalk;
 
 public class TreeFilterTest extends RepositoryTestCase {
 	public void testALL_IncludesAnything() throws Exception {
 		final TreeWalk tw = new TreeWalk(db);
+		tw.addTree(new EmptyTreeIterator());
 		assertTrue(TreeFilter.ALL.include(tw));
 	}
 
@@ -62,11 +64,13 @@ public class TreeFilterTest extends RepositoryTestCase {
 
 	public void testNotALL_IncludesNothing() throws Exception {
 		final TreeWalk tw = new TreeWalk(db);
+		tw.addTree(new EmptyTreeIterator());
 		assertFalse(TreeFilter.ALL.negate().include(tw));
 	}
 
 	public void testANY_DIFF_IncludesSingleTreeCase() throws Exception {
 		final TreeWalk tw = new TreeWalk(db);
+		tw.addTree(new EmptyTreeIterator());
 		assertTrue(TreeFilter.ANY_DIFF.include(tw));
 	}