Implement ours/theirs content conflict resolution

Git has different conflict resolution strategies:

* There is a tree merge strategy "ours" which just ignores any changes
  from theirs ("-s ours"). JGit also has the mirror strategy "theirs"
  ignoring any changes from "ours". (This doesn't exist in C git.)
  Adapt StashApplyCommand and CherrypickCommand to be able to use those
  tree merge strategies.
* For the resolve/recursive tree merge strategies, there are content
  conflict resolution strategies "ours" and "theirs", which resolve
  any conflict hunks by taking the "ours" or "theirs" hunk. In C git
  those correspond to "-Xours" or -Xtheirs". Implement that in
  MergeAlgorithm, and add API to set and pass through such a strategy
  for resolving content conflicts.
* The "ours/theirs" content conflict resolution strategies also apply
  for binary files. Handle these cases in ResolveMerger.

Note that the content conflict resolution strategies ("-X ours/theirs")
do _not_ apply to modify/delete or delete/modify conflicts. Such
conflicts are always reported as conflicts by C git. They do apply,
however, if one side completely clears a file's content.

Bug: 501111
Change-Id: I2c9c170c61c440a2ab9c387991e7a0c3ab960e07
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

2 files changed, 21 insertions, 2 deletions

diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Merge.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Merge.java
index fdc449e063..ca4877fb34 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Merge.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Merge.java
@@ -24,6 +24,7 @@ import org.eclipse.jgit.lib.AnyObjectId;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Ref;
+import org.eclipse.jgit.merge.ContentMergeStrategy;
 import org.eclipse.jgit.merge.MergeStrategy;
 import org.eclipse.jgit.merge.ResolveMerger.MergeFailureReason;
 import org.eclipse.jgit.pgm.internal.CLIText;
@@ -69,6 +70,20 @@ class Merge extends TextBuiltin {
 	@Option(name = "-m", usage = "usage_message")
 	private String message;
 
+	private ContentMergeStrategy contentStrategy = null;
+
+	@Option(name = "--strategy-option", aliases = { "-X" },
+			metaVar = "metaVar_extraArgument", usage = "usage_extraArgument")
+	void extraArg(String name) {
+		if (ContentMergeStrategy.OURS.name().equalsIgnoreCase(name)) {
+			contentStrategy = ContentMergeStrategy.OURS;
+		} else if (ContentMergeStrategy.THEIRS.name().equalsIgnoreCase(name)) {
+			contentStrategy = ContentMergeStrategy.THEIRS;
+		} else {
+			throw die(MessageFormat.format(CLIText.get().unknownExtraArgument, name));
+		}
+	}
+
 	/** {@inheritDoc} */
 	@Override
 	protected void run() {
@@ -96,8 +111,11 @@ class Merge extends TextBuiltin {
 			Ref oldHead = getOldHead();
 			MergeResult result;
 			try (Git git = new Git(db)) {
-				MergeCommand mergeCmd = git.merge().setStrategy(mergeStrategy)
-						.setSquash(squash).setFastForward(ff)
+				MergeCommand mergeCmd = git.merge()
+						.setStrategy(mergeStrategy)
+						.setContentMergeStrategy(contentStrategy)
+						.setSquash(squash)
+						.setFastForward(ff)
 						.setCommit(!noCommit);
 				if (srcRef != null) {
 					mergeCmd.include(srcRef);
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/internal/CLIText.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/internal/CLIText.java
index 991b3ba58a..8e49a76a33 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/internal/CLIText.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/internal/CLIText.java
@@ -284,6 +284,7 @@ public class CLIText extends TranslationBundle {
 	/***/ public String tooManyRefsGiven;
 	/***/ public String treeIsRequired;
 	/***/ public char[] unknownIoErrorStdout;
+	/***/ public String unknownExtraArgument;
 	/***/ public String unknownMergeStrategy;
 	/***/ public String unknownSubcommand;
 	/***/ public String unmergedPaths;