Basic file merging

ObjectiveGit/GTIndex.h

@@ -33,6 +33,7 @@
 @class GTIndexEntry;
 @class GTRepository;
 @class GTTree;
+@class GTMergeResult;
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -234,6 +235,23 @@ NS_ASSUME_NONNULL_BEGIN
 - (GTIndexEntry * _Nullable)entryWithName:(NSString *)name error:(NSError **)error __deprecated_msg("use entryWithPath:error: instead.");
 
 
+@end
+
+@interface GTIndex (FileMerging)
+
+/// Gets the result of a merge with the given file entries
+///
+/// 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
+/// options  - The merge options to use. Can be nil.
+/// error    - The error if one occurred. Can be NULL.
+///
+/// Returns The results of the merge or nil on error
+- (GTMergeResult * _Nullable)resultOfMergingAncestorEntry:(GTIndexEntry *)ancestor ourEntry:(GTIndexEntry *)ours theirEntry:(GTIndexEntry *)theirs options:(NSDictionary * _Nullable)options error:(NSError * _Nullable __autoreleasing *)error;
+
 @end
 
 NS_ASSUME_NONNULL_END

ObjectiveGit/GTIndex.m

@@ -39,8 +39,10 @@
 #import "GTBlob.h"
 #import "NSArray+StringArray.h"
 #import "NSError+Git.h"
+#import "GTMerge+Private.h"
 
 #import "git2/errors.h"
+#import "git2/merge.h"
 
 // The block synonymous with libgit2's `git_index_matched_path_cb` callback.
 typedef BOOL (^GTIndexPathspecMatchedBlock)(NSString *matchedPathspec, NSString *path, BOOL *stop);
@@ -406,4 +408,29 @@ - (GTIndexEntry *)entryWithName:(NSString *)name {
 - (GTIndexEntry *)entryWithName:(NSString *)name error:(NSError **)error {
     return [self entryWithPath:name error:error];
 }
+
+@end
+
+@implementation GTIndex (FileMerging)
+
+- (GTMergeResult *)resultOfMergingAncestorEntry:(GTIndexEntry *)ancestorEntry ourEntry:(GTIndexEntry *)ourEntry theirEntry:(GTIndexEntry *)theirEntry options:(NSDictionary *)options error:(NSError * _Nullable __autoreleasing *)error {
+	NSParameterAssert(ourEntry);
+	NSParameterAssert(theirEntry);
+	NSParameterAssert(ancestorEntry);
+
+	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_from_index(&gitResult, self.repository.git_repository, ancestorEntry.git_index_entry, ourEntry.git_index_entry, theirEntry.git_index_entry, &opts);
+	if (gitError != 0) {
+		if (error) *error = [NSError git_errorFor:gitError description:@"Merging entries failed"];
+		return nil;
+	}
+
+	return [[GTMergeResult alloc] initWithGitMergeFileResult:&gitResult];
+}
+
 @end

ObjectiveGit/GTMerge+Private.h

@@ -0,0 +1,15 @@
+//
+//  GTMerge+Private.h
+//  ObjectiveGitFramework
+//
+//  Created by Etienne on 27/10/2018.
+//  Copyright © 2018 GitHub, Inc. All rights reserved.
+//
+
+#import "GTMerge.h"
+
+@interface GTMergeFile (Private)
+
++ (BOOL)handleMergeFileOptions:(git_merge_file_options *)opts optionsDict:(NSDictionary *)dict error:(NSError **)error;
+
+@end

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:(GTMergeFile *)ancestorFile ourFile:(GTMergeFile *)ourFile theirFile:(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 +1,150 @@
+//
+//  GTMergeFile.m
+//  ObjectiveGitFramework
+//
+//  Created by Etienne on 26/10/2018.
+//  Copyright © 2018 GitHub, Inc. All rights reserved.
+//
+
+#import "GTMerge.h"
+#import "GTOID.h"
+#import "GTObjectDatabase.h"
+#import "GTOdbObject.h"
+#import "GTRepository.h"
+#import "GTIndex.h"
+#import "GTIndexEntry.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 (_result.path ? [NSString stringWithUTF8String:_result.path] : nil);
+}
+
+- (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)fileWithIndexEntry:(GTIndexEntry *)entry error:(NSError **)error {
+	NSParameterAssert(entry);
+
+	const git_index_entry *git_entry = entry.git_index_entry;
+	GTOID *ancestorOID = [[GTOID alloc] initWithGitOid:&git_entry->id];
+	GTRepository *repository = entry.index.repository;
+	GTObjectDatabase *database = [repository objectDatabaseWithError:error];
+	NSData *contents = [[database objectWithOID:ancestorOID error:error] data];
+	if (contents == nil) {
+		return nil;
+	}
+
+	return [[self alloc] initWithData:contents path:entry.path mode:git_entry->mode];
+}
+
+- (instancetype)initWithData:(NSData *)data path:(NSString *)path mode:(unsigned int)mode {
+	NSParameterAssert(data);
+	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:(GTMergeFile *)ancestorFile ourFile:(GTMergeFile *)ourFile theirFile:(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