Wrap the basic file merging mechanisms

Author: tiennou

ObjectiveGit/GTMerge.h

@@ -0,0 +1,72 @@
+//
+//  GTMerge.h
+//  ObjectiveGitFramework
+//
+//  Created by Etienne on 26/10/2018.
+//  Copyright © 2018 GitHub, Inc. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+#import "git2/merge.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+/// Represents the result of a merge
+@interface GTMergeResult : NSObject
+
+/// Was the merge automerable ?
+@property (readonly,getter=isAutomergeable) BOOL automergeable;
+
+/// The path of the resulting merged file, nil in case of conflicts
+@property (readonly) NSString * _Nullable path;
+
+/// The resulting mode of the merged file
+@property (readonly) unsigned int mode;
+
+/// The contents of the resulting merged file
+@property (readonly) NSData *data;
+
+/// Initialize the merge result from a libgit2 struct.
+/// Ownership of the memory will be transferred to the receiver.
+- (instancetype)initWithGitMergeFileResult:(git_merge_file_result *)result;
+
+- (instancetype)init NS_UNAVAILABLE;
+
+@end
+
+/// Represents inputs for a tentative merge
+@interface GTMergeFile : NSObject
+
+/// The file data
+@property (readonly) NSData *data;
+
+/// The file path. Can be nil to not merge paths.
+@property (readonly) NSString * _Nullable path;
+
+/// The file mode. Can be 0 to not merge modes.
+@property (readonly) unsigned int mode;
+
+/// Perform a merge between files
+///
+/// ancestorFile - The file to consider the ancestor
+/// ourFile      - The file to consider as our version
+/// theirFile    - The file to consider as the incoming version
+/// options      - The options of the merge. Can be nil.
+/// error        - A pointer to an error object. Can be NULL.
+///
+/// Returns the result of the merge, or nil if an error occurred.
++ (GTMergeResult * _Nullable)performMergeWithAncestor:(const GTMergeFile *)ancestorFile ourFile:(const GTMergeFile *)ourFile theirFile:(const GTMergeFile *)theirFile options:(NSDictionary * _Nullable)options error:(NSError **)error;
+
++ (instancetype)fileWithString:(NSString *)string path:(NSString * _Nullable)path mode:(unsigned int)mode;
+
+/// Initialize an input file for a merge
+- (instancetype)initWithData:(NSData *)data path:(NSString * _Nullable)path mode:(unsigned int)mode NS_DESIGNATED_INITIALIZER;
+
+- (instancetype)init NS_UNAVAILABLE;
+
+/// Inner pointer to a libgit2-compatible git_merge_file_input struct.
+- (git_merge_file_input *)git_merge_file_input __attribute__((objc_returns_inner_pointer));
+
+@end
+
+NS_ASSUME_NONNULL_END

ObjectiveGit/GTMerge.m

@@ -0,0 +1,128 @@
+//
+//  GTMergeFile.m
+//  ObjectiveGitFramework
+//
+//  Created by Etienne on 26/10/2018.
+//  Copyright © 2018 GitHub, Inc. All rights reserved.
+//
+
+#import "GTMerge.h"
+#import "NSError+Git.h"
+
+@interface GTMergeResult ()
+
+@property (assign) git_merge_file_result result;
+
+@end
+
+@implementation GTMergeResult
+
+- (instancetype)initWithGitMergeFileResult:(git_merge_file_result *)result {
+	self = [super init];
+	if (!self) return nil;
+
+	memcpy(&_result, result, sizeof(_result));
+
+	return self;
+}
+
+- (void)dealloc {
+	git_merge_file_result_free(&_result);
+}
+
+- (BOOL)isAutomergeable {
+	return !!_result.automergeable;
+}
+
+- (NSString *)path {
+	return [NSString stringWithUTF8String:_result.path];
+}
+
+- (unsigned int)mode {
+	return _result.mode;
+}
+
+- (NSData *)data {
+	return [[NSData alloc] initWithBytesNoCopy:(void *)_result.ptr length:_result.len freeWhenDone:NO];
+}
+
+@end
+
+@interface GTMergeFile ()
+
+@property (copy) NSData *data;
+@property (copy) NSString *path;
+@property (assign) unsigned int mode;
+@property (assign) git_merge_file_input file;
+
+@end
+
+@implementation GTMergeFile
+
++ (instancetype)fileWithString:(NSString *)string path:(NSString * _Nullable)path mode:(unsigned int)mode {
+	NSData *stringData = [string dataUsingEncoding:NSUTF8StringEncoding];
+
+	NSAssert(stringData != nil, @"String couldn't be converted to UTF-8");
+
+	return [[self alloc] initWithData:stringData path:path mode:mode];
+}
+
+- (instancetype)initWithData:(NSData *)data path:(NSString *)path mode:(unsigned int)mode {
+	self = [super init];
+	if (!self) return nil;
+
+	_data = data;
+	_path = path;
+	_mode = mode;
+
+	git_merge_file_init_input(&_file, GIT_MERGE_FILE_INPUT_VERSION);
+
+	_file.ptr = self.data.bytes;
+	_file.size = self.data.length;
+	_file.path = [self.path UTF8String];
+	_file.mode = self.mode;
+
+	return self;
+}
+
+- (git_merge_file_input *)git_merge_file_input {
+	return &_file;
+}
+
++ (BOOL)handleMergeFileOptions:(git_merge_file_options *)opts optionsDict:(NSDictionary *)dict error:(NSError **)error {
+	NSParameterAssert(opts);
+
+	int gitError = git_merge_file_init_options(opts, GIT_MERGE_FILE_OPTIONS_VERSION);
+	if (gitError != 0) {
+		if (error) *error = [NSError git_errorFor:gitError description:@"Invalid option initialization"];
+		return NO;
+	}
+
+	if (dict.count != 0) {
+		if (error) *error = [NSError git_errorFor:-1 description:@"No options handled"];
+		return NO;
+	}
+	return YES;
+}
+
++ (GTMergeResult *)performMergeWithAncestor:(const GTMergeFile *)ancestorFile ourFile:(const GTMergeFile *)ourFile theirFile:(const GTMergeFile *)theirFile options:(NSDictionary *)options error:(NSError **)error {
+	NSParameterAssert(ourFile);
+	NSParameterAssert(theirFile);
+	NSParameterAssert(ancestorFile);
+
+	git_merge_file_result gitResult;
+	git_merge_file_options opts;
+
+	BOOL success = [GTMergeFile handleMergeFileOptions:&opts optionsDict:options error:error];
+	if (!success) return nil;
+
+	int gitError = git_merge_file(&gitResult, ancestorFile.git_merge_file_input, ourFile.git_merge_file_input, theirFile.git_merge_file_input, &opts);
+	if (gitError != 0) {
+		if (error) *error = [NSError git_errorFor:gitError description:@"Merge file failed"];
+		return nil;
+	}
+
+	return [[GTMergeResult alloc] initWithGitMergeFileResult:&gitResult];
+}
+
+@end

ObjectiveGit/ObjectiveGit.h

@@ -72,6 +72,7 @@ FOUNDATION_EXPORT const unsigned char ObjectiveGitVersionString[];
 #import <ObjectiveGit/GTFetchHeadEntry.h>
 #import <ObjectiveGit/GTNote.h>
 #import <ObjectiveGit/GTCheckoutOptions.h>
+#import <ObjectiveGit/GTMerge.h>
 
 #import <ObjectiveGit/GTObjectDatabase.h>
 #import <ObjectiveGit/GTOdbObject.h>

ObjectiveGitFramework.xcodeproj/project.pbxproj

@@ -91,6 +91,12 @@
 		4D1C40D8182C006D00BE2960 /* GTBlobSpec.m in Sources */ = {isa = PBXBuildFile; fileRef = 4D1C40D7182C006D00BE2960 /* GTBlobSpec.m */; };
 		4D79C0EE17DF9F4D00997DE4 /* GTCredential.h in Headers */ = {isa = PBXBuildFile; fileRef = 4D79C0EC17DF9F4D00997DE4 /* GTCredential.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		4D79C0EF17DF9F4D00997DE4 /* GTCredential.m in Sources */ = {isa = PBXBuildFile; fileRef = 4D79C0ED17DF9F4D00997DE4 /* GTCredential.m */; };
+		4D7BA1BA2183C4C9003CD3CE /* GTMerge.h in Headers */ = {isa = PBXBuildFile; fileRef = 4D7BA1B82183C4C9003CD3CE /* GTMerge.h */; settings = {ATTRIBUTES = (Public, ); }; };
+		4D7BA1BB2183C4C9003CD3CE /* GTMerge.h in Headers */ = {isa = PBXBuildFile; fileRef = 4D7BA1B82183C4C9003CD3CE /* GTMerge.h */; settings = {ATTRIBUTES = (Public, ); }; };
+		4D7BA1BC2183C4C9003CD3CE /* GTMerge.m in Sources */ = {isa = PBXBuildFile; fileRef = 4D7BA1B92183C4C9003CD3CE /* GTMerge.m */; };
+		4D7BA1BD2183C4C9003CD3CE /* GTMerge.m in Sources */ = {isa = PBXBuildFile; fileRef = 4D7BA1B92183C4C9003CD3CE /* GTMerge.m */; };
+		4D7BA1C02183DD55003CD3CE /* GTMergeSpec.m in Sources */ = {isa = PBXBuildFile; fileRef = 4D7BA1BF2183DD55003CD3CE /* GTMergeSpec.m */; };
+		4D7BA1C12183DD55003CD3CE /* GTMergeSpec.m in Sources */ = {isa = PBXBuildFile; fileRef = 4D7BA1BF2183DD55003CD3CE /* GTMergeSpec.m */; };
 		4D9BCD24206D84AD003CD3CE /* libgit2.a in Frameworks */ = {isa = PBXBuildFile; fileRef = 4D9BCD23206D84AD003CD3CE /* libgit2.a */; };
 		4D9BCD25206D84B2003CD3CE /* libgit2.a in Frameworks */ = {isa = PBXBuildFile; fileRef = 4D9BCD23206D84AD003CD3CE /* libgit2.a */; };
 		4DBA4A3217DA73CE006CD5F5 /* GTRemoteSpec.m in Sources */ = {isa = PBXBuildFile; fileRef = 4DBA4A3117DA73CE006CD5F5 /* GTRemoteSpec.m */; };
@@ -492,6 +498,9 @@
 		4D79C0EC17DF9F4D00997DE4 /* GTCredential.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = GTCredential.h; sourceTree = "<group>"; };
 		4D79C0ED17DF9F4D00997DE4 /* GTCredential.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GTCredential.m; sourceTree = "<group>"; };
 		4D79C0F617DFAA7100997DE4 /* GTCredential+Private.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "GTCredential+Private.h"; sourceTree = "<group>"; };
+		4D7BA1B82183C4C9003CD3CE /* GTMerge.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GTMerge.h; sourceTree = "<group>"; };
+		4D7BA1B92183C4C9003CD3CE /* GTMerge.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = GTMerge.m; sourceTree = "<group>"; };
+		4D7BA1BF2183DD55003CD3CE /* GTMergeSpec.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = GTMergeSpec.m; sourceTree = "<group>"; };
 		4D9BCD23206D84AD003CD3CE /* libgit2.a */ = {isa = PBXFileReference; lastKnownFileType = archive.ar; name = libgit2.a; path = External/build/lib/libgit2.a; sourceTree = "<group>"; };
 		4DBA4A3117DA73CE006CD5F5 /* GTRemoteSpec.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GTRemoteSpec.m; sourceTree = "<group>"; };
 		4DC55AE31AD859AD0032563C /* GTCheckoutOptions.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = GTCheckoutOptions.h; sourceTree = "<group>"; };
@@ -837,6 +846,7 @@
 				D0751CD818BE520400134314 /* GTFilterListSpec.m */,
 				886E623618AECD86000611A0 /* GTFilterSpec.m */,
 				8832811E173D8816006D7DCF /* GTIndexSpec.m */,
+				4D7BA1BF2183DD55003CD3CE /* GTMergeSpec.m */,
 				F9D1D4221CEB79D1009E5855 /* GTNoteSpec.m */,
 				88948AC81779243600809CDA /* GTObjectDatabaseSpec.m */,
 				88F05AA816011FFD00B7AD1D /* GTObjectSpec.m */,
@@ -977,6 +987,8 @@
 				6EEB51A0199D62B9001D72C0 /* GTFetchHeadEntry.m */,
 				4DC55AE31AD859AD0032563C /* GTCheckoutOptions.h */,
 				4DC55AE41AD859AD0032563C /* GTCheckoutOptions.m */,
+				4D7BA1B82183C4C9003CD3CE /* GTMerge.h */,
+				4D7BA1B92183C4C9003CD3CE /* GTMerge.m */,
 			);
 			path = ObjectiveGit;
 			sourceTree = "<group>";
@@ -1096,6 +1108,7 @@
 				88F6D9FB1320467500CC0BA8 /* GTObject.h in Headers */,
 				AA046112134F4D2000DF526B /* GTOdbObject.h in Headers */,
 				D0A0129519F99EF8007F1914 /* NSDate+GTTimeAdditions.h in Headers */,
+				4D7BA1BA2183C4C9003CD3CE /* GTMerge.h in Headers */,
 				4DFFB15B183AA8D600D1565E /* GTRepository+RemoteOperations.h in Headers */,
 				BDB2B1301386F34300C88D55 /* GTObjectDatabase.h in Headers */,
 				88F6D9FC1320467800CC0BA8 /* GTSignature.h in Headers */,
@@ -1174,6 +1187,7 @@
 				D01B6F2F19F82F8700D411BC /* GTObject.h in Headers */,
 				4DC55AE61AD859AD0032563C /* GTCheckoutOptions.h in Headers */,
 				D01B6F4B19F82F8700D411BC /* GTConfiguration.h in Headers */,
+				4D7BA1BB2183C4C9003CD3CE /* GTMerge.h in Headers */,
 				D01B6F6719F82FA600D411BC /* GTFetchHeadEntry.h in Headers */,
 				D01B6F5F19F82FA600D411BC /* GTFilter.h in Headers */,
 				D01B6F5319F82FA600D411BC /* GTBlameHunk.h in Headers */,
@@ -1459,6 +1473,7 @@
 				D040AF70177B9779001AD9EB /* GTOIDSpec.m in Sources */,
 				D040AF78177B9A9E001AD9EB /* GTSignatureSpec.m in Sources */,
 				4DBA4A3217DA73CE006CD5F5 /* GTRemoteSpec.m in Sources */,
+				4D7BA1C02183DD55003CD3CE /* GTMergeSpec.m in Sources */,
 				4D123240178E009E0048F785 /* GTRepositoryCommittingSpec.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -1518,6 +1533,7 @@
 				8821547F17147B3600D76B76 /* GTOID.m in Sources */,
 				D03B57A418BFFF07007124F4 /* GTDiffPatch.m in Sources */,
 				D03B07F71965DAB0009E5624 /* NSData+Git.m in Sources */,
+				4D7BA1BC2183C4C9003CD3CE /* GTMerge.m in Sources */,
 				20F43DE618A2F668007D3621 /* GTRepository+Blame.m in Sources */,
 				5BE6128A1745EE3400266D8C /* GTTreeBuilder.m in Sources */,
 				D09C2E381755F16200065E36 /* GTSubmodule.m in Sources */,
@@ -1580,6 +1596,7 @@
 				D01B6F5E19F82FA600D411BC /* GTCredential.m in Sources */,
 				D01B6F6219F82FA600D411BC /* GTFilterSource.m in Sources */,
 				D01B6F1C19F82F7B00D411BC /* NSDate+GTTimeAdditions.m in Sources */,
+				4D7BA1BD2183C4C9003CD3CE /* GTMerge.m in Sources */,
 				D01B6F1619F82F7B00D411BC /* NSData+Git.m in Sources */,
 				D01B6F1E19F82F7B00D411BC /* NSArray+StringArray.m in Sources */,
 				D01B6F5819F82FA600D411BC /* GTReflogEntry.m in Sources */,
@@ -1629,6 +1646,7 @@
 				F8D007A01B4FA03B009A8DAF /* GTRepository+StatusSpec.m in Sources */,
 				F8D007961B4FA03B009A8DAF /* GTRemotePushSpec.m in Sources */,
 				F8D007A51B4FA03B009A8DAF /* GTDiffDeltaSpec.m in Sources */,
+				4D7BA1C12183DD55003CD3CE /* GTMergeSpec.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

ObjectiveGitTests/GTMergeSpec.m

@@ -0,0 +1,51 @@
+//
+//  GTMerge.h
+//  ObjectiveGitFramework
+//
+//  Created by Etienne on 26/10/2018.
+//  Copyright © 2018 GitHub, Inc. All rights reserved.
+//
+
+
+@import ObjectiveGit;
+@import Nimble;
+@import Quick;
+
+#import "QuickSpec+GTFixtures.h"
+
+QuickSpecBegin(GTMergeSpec)
+
+__block GTRepository *repository;
+__block GTIndex *index;
+
+beforeEach(^{
+	repository = self.testAppFixtureRepository;
+
+	index = [repository indexWithError:NULL];
+	expect(index).notTo(beNil());
+
+	BOOL success = [index refresh:NULL];
+	expect(@(success)).to(beTruthy());
+});
+
+fdescribe(@"+performMergeWithAncestor:ourFile:theirFile:options:error:", ^{
+	it(@"can merge strings", ^{
+		GTMergeFile *ourFile = [GTMergeFile fileWithString:@"A test string\n" path:nil mode:0];
+		GTMergeFile *theirFile = [GTMergeFile fileWithString:@"A better test string\n" path:nil mode:0];
+		GTMergeFile *ancestorFile = [GTMergeFile fileWithString:@"A basic string\n" path:nil mode:0];
+
+		NSError *error = nil;
+		GTMergeResult *result = [GTMergeFile performMergeWithAncestor:ancestorFile ourFile:ourFile theirFile:theirFile options:nil error:&error];
+		expect(result).notTo(beNil());
+		expect(error).to(beNil());
+
+		NSString *mergedString = [[NSString alloc] initWithData:result.data encoding:NSUTF8StringEncoding];
+		expect(mergedString).to(equal(@"<<<<<<< file.txt\nA test string\n=======\nA better test string\n>>>>>>> file.txt\n"));
+	});
+});
+
+afterEach(^{
+	[self tearDown];
+});
+
+QuickSpecEnd