Add Checkout Files to file browser contextual menu

Allows checking out the state of a file from any commit to the working directory.

PBGitHistoryController.m

@@ -266,6 +266,15 @@
 	}
 }
 
+- (void) checkoutFiles:(id)sender
+{
+	NSMutableArray *files = [NSMutableArray array];
+	for (NSString *filePath in [sender representedObject])
+		[files addObject:[filePath stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]];
+
+	[repository checkoutFiles:files fromRefish:realCommit];
+}
+
 
 - (NSMenu *)contextMenuForTreeView
 {
@@ -286,7 +295,10 @@
 	BOOL multiple = [filePaths count] != 1;
 	NSMenuItem *historyItem = [[NSMenuItem alloc] initWithTitle:multiple? @"Show history of files" : @"Show history of file"
 														 action:@selector(showCommitsFromTree:)
-												 keyEquivalent:@""];
+												  keyEquivalent:@""];
+	NSMenuItem *checkoutItem = [[NSMenuItem alloc] initWithTitle:multiple ? @"Checkout files" : @"Checkout file"
+														  action:@selector(checkoutFiles:)
+												   keyEquivalent:@""];
 	NSMenuItem *finderItem = [[NSMenuItem alloc] initWithTitle:@"Show in Finder"
 														action:@selector(showInFinderAction:)
 												 keyEquivalent:@""];
@@ -294,7 +306,7 @@
 														   action:@selector(openFilesAction:)
 													keyEquivalent:@""];
 
-	NSArray *menuItems = [NSArray arrayWithObjects:historyItem, finderItem, openFilesItem, nil];
+	NSArray *menuItems = [NSArray arrayWithObjects:historyItem, checkoutItem, finderItem, openFilesItem, nil];
 	for (NSMenuItem *item in menuItems) {
 		[item setTarget:self];
 		[item setRepresentedObject:filePaths];

PBGitRepository.h

@@ -30,6 +30,7 @@ extern NSString* PBGitRepositoryErrorDomain;
 }
 
 - (BOOL) checkoutRefish:(id <PBGitRefish>)ref;
+- (BOOL) checkoutFiles:(NSArray *)files fromRefish:(id <PBGitRefish>)ref;
 - (BOOL) createBranch:(NSString *)branchName atRefish:(id <PBGitRefish>)ref;
 - (BOOL) createTag:(NSString *)tagName message:(NSString *)message atRefish:(id <PBGitRefish>)commitSHA;
 

PBGitRepository.m

@@ -450,6 +450,30 @@ NSString* PBGitRepositoryErrorDomain = @"GitXErrorDomain";
 	return YES;
 }
 
+- (BOOL) checkoutFiles:(NSArray *)files fromRefish:(id <PBGitRefish>)ref
+{
+	if (!files || ([files count] == 0))
+		return NO;
+
+	NSString *refName = nil;
+	if ([ref refishType] == kGitXBranchType)
+		refName = [ref shortName];
+	else
+		refName = [ref refishName];
+
+	int retValue = 1;
+	NSMutableArray *arguments = [NSMutableArray arrayWithObjects:@"checkout", refName, @"--", nil];
+	[arguments addObjectsFromArray:files];
+	NSString *output = [self outputInWorkdirForArguments:arguments retValue:&retValue];
+	if (retValue) {
+		NSString *message = [NSString stringWithFormat:@"There was an error checking out the file(s) from the %@ '%@'.\n\nPerhaps your working directory is not clean?", [ref refishType], [ref shortName]];
+		[self.windowController showErrorSheetTitle:@"Checkout failed!" message:message arguments:arguments output:output];
+		return NO;
+	}
+
+	return YES;
+}
+
 - (BOOL) createBranch:(NSString *)branchName atRefish:(id <PBGitRefish>)ref
 {
 	if (!branchName || !ref)