Wrap git_merge_file

ObjectiveGit/GTRepository+Merging.h

@@ -7,6 +7,7 @@
 //
 
 #import "GTRepository.h"
+#import "GTIndexEntry.h"
 #import "git2/merge.h"
 
 NS_ASSUME_NONNULL_BEGIN
@@ -52,6 +53,18 @@ typedef NS_OPTIONS(NSInteger, GTMergeAnalysis) {
 /// will point to an error describing what happened).
 - (BOOL)mergeBranchIntoCurrentBranch:(GTBranch *)fromBranch withError:(NSError **)error;
 
+/// Gets the file content with conflict markers for the given file
+///
+/// The parameters taked are the ones received from `enumerateConflictedFiles`.
+///
+/// ancestor - The ancestor entry
+/// ours     - The index entry of our side
+/// theirs   - The index entry of their side
+/// error    - The error if one occurred. Can be NULL.
+///
+/// Returns The file content annotated with conflict markers or null on error
+- (NSString * _Nullable)contentsOfDiffWithAncestor:(GTIndexEntry *)ancestor ourSide:(GTIndexEntry *)ourSide theirSide:(GTIndexEntry *)theirSide error:(NSError **)error;
+
 /// Analyze which merge to perform.
 ///
 /// analysis   - The resulting analysis.

ObjectiveGit/GTRepository+Merging.m

@@ -17,6 +17,8 @@
 #import "GTTree.h"
 #import "GTIndex.h"
 #import "GTIndexEntry.h"
+#import "GTOdbObject.h"
+#import "GTObjectDatabase.h"
 
 typedef void (^GTRemoteFetchTransferProgressBlock)(const git_transfer_progress *stats, BOOL *stop);
 
@@ -170,6 +172,87 @@ - (BOOL)mergeBranchIntoCurrentBranch:(GTBranch *)branch withError:(NSError **)er
 	return NO;
 }
 
+- (NSString * _Nullable)contentsOfDiffWithAncestor:(GTIndexEntry *)ancestor ourSide:(GTIndexEntry *)ourSide theirSide:(GTIndexEntry *)theirSide error:(NSError **)error {
+
+	GTObjectDatabase *database = [self objectDatabaseWithError:error];
+	if (database == nil) {
+		return nil;
+	}
+
+	// initialize the ancestor's merge file input
+	git_merge_file_input ancestorInput;
+	int gitError = git_merge_file_init_input(&ancestorInput, GIT_MERGE_FILE_INPUT_VERSION);
+	if (gitError != GIT_OK) {
+		if (error != NULL) *error = [NSError git_errorFor:gitError description:@"Failed to create merge file input for ancestor"];
+		return nil;
+	}
+
+	git_oid ancestorId = ancestor.git_index_entry->id;
+	GTOID *ancestorOID = [[GTOID alloc] initWithGitOid:&ancestorId];
+	NSData *ancestorData = [[database objectWithOID:ancestorOID error: error] data];
+	if (ancestorData == nil) {
+		return nil;
+	}
+	ancestorInput.ptr = ancestorData.bytes;
+	ancestorInput.size = ancestorData.length;
+
+
+	// initialize our merge file input
+	git_merge_file_input ourInput;
+	gitError = git_merge_file_init_input(&ourInput, GIT_MERGE_FILE_INPUT_VERSION);
+	if (gitError != GIT_OK) {
+		if (error != NULL) *error = [NSError git_errorFor:gitError description:@"Failed to create merge file input for our side"];
+		return nil;
+	}
+
+	git_oid ourId = ourSide.git_index_entry->id;
+	GTOID *ourOID = [[GTOID alloc] initWithGitOid:&ourId];
+	NSData *ourData = [[database objectWithOID:ourOID error: error] data];
+	if (ourData == nil) {
+		return nil;
+	}
+	ourInput.ptr = ourData.bytes;
+	ourInput.size = ourData.length;
+
+
+	// initialize their merge file input
+	git_merge_file_input theirInput;
+	gitError = git_merge_file_init_input(&theirInput, GIT_MERGE_FILE_INPUT_VERSION);
+	if (gitError != GIT_OK) {
+		if (error != NULL) *error = [NSError git_errorFor:gitError description:@"Failed to create merge file input other side"];
+		return nil;
+	}
+
+	git_oid theirId = theirSide.git_index_entry->id;
+	GTOID *theirOID = [[GTOID alloc] initWithGitOid:&theirId];
+	NSData *theirData = [[database objectWithOID:theirOID error: error] data];
+	if (theirData == nil) {
+		return nil;
+	}
+	theirInput.ptr = theirData.bytes;
+	theirInput.size = theirData.length;
+
+
+	git_merge_file_result result;
+	gitError = git_merge_file(&result, &ancestorInput, &ourInput, &theirInput, nil);
+	if (gitError != GIT_OK) {
+		if (error != NULL) *error = [NSError git_errorFor:gitError description:@"Failed to create merge file"];
+		return nil;
+	}
+
+	char *cString = malloc(result.len * sizeof(char *) + 1);
+	strncpy(cString, result.ptr, result.len);
+	cString[result.len] = '\0';
+
+	NSString *mergedContent = [[NSString alloc] initWithCString:cString encoding:NSUTF8StringEncoding];
+
+	free(cString);
+
+	git_merge_file_result_free(&result);
+
+	return mergedContent;
+}
+
 - (BOOL)annotatedCommit:(git_annotated_commit **)annotatedCommit fromCommit:(GTCommit *)fromCommit error:(NSError **)error {
 	int gitError = git_annotated_commit_lookup(annotatedCommit, self.git_repository, fromCommit.OID.git_oid);
 	if (gitError != GIT_OK) {

ObjectiveGitTests/GTRepositorySpec.m

@@ -260,6 +260,48 @@
 	});
 });
 
+describe(@"-contentsOfDiffWithAncestor:ourSide:theirSide:error:", ^{
+	it(@"should produce a nice merge conflict description", ^{
+		NSURL *mainURL = [repository.fileURL URLByAppendingPathComponent:@"main.m"];
+		NSData *mainData = [[NSFileManager defaultManager] contentsAtPath:mainURL.path];
+		expect(mainData).notTo(beNil());
+
+		NSString *mainString = [[NSString alloc] initWithData:mainData encoding:NSUTF8StringEncoding];
+		NSData *masterData = [[mainString stringByReplacingOccurrencesOfString:@"return" withString:@"//The meaning of life is 41\n    return"] dataUsingEncoding:NSUTF8StringEncoding];
+		NSData *otherData = [[mainString stringByReplacingOccurrencesOfString:@"return" withString:@"//The meaning of life is 42\n    return"] dataUsingEncoding:NSUTF8StringEncoding];
+
+		expect(@([[NSFileManager defaultManager] createFileAtPath:mainURL.path contents:masterData attributes:nil])).to(beTruthy());
+
+		GTIndex *index = [repository indexWithError:NULL];
+		expect(@([index addFile:mainURL.lastPathComponent error:NULL])).to(beTruthy());
+		GTReference *head = [repository headReferenceWithError:NULL];
+		GTCommit *parent = [repository lookUpObjectByOID:head.targetOID objectType:GTObjectTypeCommit error:NULL];
+		expect(parent).toNot(beNil());
+		GTTree *masterTree = [index writeTree:NULL];
+		expect(masterTree).toNot(beNil());
+
+		GTBranch *otherBranch = [repository lookUpBranchWithName:@"other-branch" type:GTBranchTypeLocal success:NULL error:NULL];
+		expect(otherBranch).toNot(beNil());
+		expect(@([repository checkoutReference:otherBranch.reference options:nil error:NULL])).to(beTruthy());
+
+		expect(@([[NSFileManager defaultManager] createFileAtPath:mainURL.path contents:otherData attributes:nil])).to(beTruthy());
+
+		index = [repository indexWithError:NULL];
+		expect(@([index addFile:mainURL.lastPathComponent error:NULL])).to(beTruthy());
+		GTTree *otherTree = [index writeTree:NULL];
+		expect(otherTree).toNot(beNil());
+
+		GTIndex *conflictIndex = [otherTree merge:masterTree ancestor:parent.tree error:NULL];
+		expect(@([conflictIndex hasConflicts])).to(beTruthy());
+
+		[conflictIndex enumerateConflictedFilesWithError:NULL usingBlock:^(GTIndexEntry * _Nonnull ancestor, GTIndexEntry * _Nonnull ours, GTIndexEntry * _Nonnull theirs, BOOL * _Nonnull stop) {
+
+			NSString *conflictString = [repository contentsOfDiffWithAncestor:ancestor ourSide:ours theirSide:theirs error:NULL];
+			expect(conflictString).to(equal(@"//\n//  main.m\n//  Test\n//\n//  Created by Joe Ricioppo on 9/28/10.\n//  Copyright 2010 __MyCompanyName__. All rights reserved.\n//\n\n#import <Cocoa/Cocoa.h>\n\nint main(int argc, char *argv[])\n{\n<<<<<<< file.txt\n    //The meaning of life is 42\n=======\n    //The meaning of life is 41\n>>>>>>> file.txt\n    return NSApplicationMain(argc,  (const char **) argv);\n}\n123456789\n123456789\n123456789\n123456789!blah!\n"));
+		}];
+	});
+});
+
 describe(@"-mergeBaseBetweenFirstOID:secondOID:error:", ^{
 	it(@"should find the merge base between two branches", ^{
 		NSError *error = nil;