Add DiffMerge tool support

Changes come from original PR #481 made by @akantsevoi. Fixes #59.

Author: lucasderraugh

GitUp/Application/Base.lproj/MainMenu.xib

@@ -356,6 +356,7 @@ You must close and reopen any opened repositories in GitUp after changing this s
                                                         <menuItem title="Kaleidoscope" id="EDr-i6-aAh"/>
                                                         <menuItem title="Beyond Compare" id="cip-D6-GZD"/>
                                                         <menuItem title="P4Merge" id="RNS-uQ-WHF"/>
+                                                        <menuItem title="DiffMerge" id="yH0-Kd-hsv"/>
                                                         <menuItem isSeparatorItem="YES" id="XvM-0Z-bmM"/>
                                                         <menuItem title="Git Tool" id="iEl-zc-obP"/>
                                                     </items>
@@ -392,6 +393,7 @@ You must close and reopen any opened repositories in GitUp after changing this s
                                                         <menuItem title="Kaleidoscope" id="pqO-7b-B5J"/>
                                                         <menuItem title="Beyond Compare" id="AaP-5A-YVD"/>
                                                         <menuItem title="P4Merge" id="Uq1-pA-HzR"/>
+                                                        <menuItem title="DiffMerge" id="AXz-pD-fZY"/>
                                                         <menuItem isSeparatorItem="YES" id="opM-b3-5YC"/>
                                                         <menuItem title="Git Tool" id="yyO-2T-uYr"/>
                                                     </items>

GitUpKit/Utilities/GIViewController+Utilities.h

@@ -22,6 +22,7 @@ extern NSString* const GIViewControllerTool_Kaleidoscope;
 extern NSString* const GIViewControllerTool_BeyondCompare;
 extern NSString* const GIViewControllerTool_P4Merge;
 extern NSString* const GIViewControllerTool_GitTool;
+extern NSString* const GIViewControllerTool_DiffMerge;
 
 extern NSString* const GIViewController_DiffTool;
 extern NSString* const GIViewController_MergeTool;

GitUpKit/Utilities/GIViewController+Utilities.m

@@ -30,12 +30,14 @@
 #define kKSDiffPath @"/usr/local/bin/ksdiff"
 #define kBComparePath @"/usr/local/bin/bcompare"
 #define kP4MergePath @"/Applications/p4merge.app/Contents/Resources/launchp4merge"
+#define kDiffMergePath @"/Applications/DiffMerge.app/Contents/Resources/diffmerge.sh"
 
 NSString* const GIViewControllerTool_FileMerge = @"FileMerge";
 NSString* const GIViewControllerTool_Kaleidoscope = @"Kaleidoscope";
 NSString* const GIViewControllerTool_BeyondCompare = @"Beyond Compare";
 NSString* const GIViewControllerTool_P4Merge = @"P4Merge";
 NSString* const GIViewControllerTool_GitTool = @"Git Tool";
+NSString* const GIViewControllerTool_DiffMerge = @"DiffMerge";
 
 NSString* const GIViewController_DiffTool = @"GIViewController_DiffTool";
 NSString* const GIViewController_MergeTool = @"GIViewController_MergeTool";
@@ -395,6 +397,14 @@ - (void)_runDiffGitToolForFile:(NSString*)file withOldPath:(NSString*)oldPath ne
   }
 }
 
+- (void)_runDiffMergeToolWithArguments:(NSArray*)arguments {
+  if (([[NSFileManager defaultManager] isExecutableFileAtPath:kDiffMergePath])) {
+    [self _runTaskWithPath:kDiffMergePath arguments:arguments variables:nil waitUntilExit:NO reportErrors:NO];  // launch diff merge
+  } else {
+    [self presentAlertWithType:kGIAlertType_Stop title:NSLocalizedString(@"DiffMerge is not available!", nil) message:NSLocalizedString(@"P4Merge app doesn't appear to be installed.", nil)];
+  }
+}
+
 // http://git-scm.com/docs/git-mergetool
 - (void)_runMergeGitToolForFile:(NSString*)file withOldPath:(NSString*)oldPath newPath:(NSString*)newPath basePath:(NSString*)basePath {
   NSString* tool = [[self.repository readConfigOptionForVariable:@"merge.tool" error:NULL] value];
@@ -455,6 +465,8 @@ - (void)viewDeltasInDiffTool:(NSArray*)deltas {
       [self _runP4MergeWithArguments:@[ @"-nl", oldTitle, @"-nr", newTitle, oldPath, newPath ]];
     } else if ([identifier isEqualToString:GIViewControllerTool_GitTool]) {
       [self _runDiffGitToolForFile:delta.canonicalPath withOldPath:oldPath newPath:newPath];
+    } else if ([identifier isEqualToString:GIViewControllerTool_DiffMerge]) {
+      [self _runDiffMergeToolWithArguments:@[ [NSString stringWithFormat:@"-t1=%@", oldTitle], [NSString stringWithFormat:@"-t2=%@", newTitle], oldPath, newPath ]];
     } else {
       XLOG_DEBUG_UNREACHABLE();
     }
@@ -571,6 +583,15 @@ - (void)resolveConflictInMergeTool:(GCIndexConflict*)conflict {
     [self _runP4MergeWithArguments:arguments];
   } else if ([identifier isEqualToString:GIViewControllerTool_GitTool]) {
     [self _runMergeGitToolForFile:mergePath withOldPath:ourPath newPath:theirPath basePath:ancestorPath];
+  } else if ([identifier isEqualToString:GIViewControllerTool_DiffMerge]) {
+    [arguments addObject:[NSString stringWithFormat:@"-r=%@", mergePath]];
+    [arguments addObject:[NSString stringWithFormat:@"-t1=%@", ourTitle]];
+    [arguments addObject:[NSString stringWithFormat:@"-t2=%@", ancestorTitle]];
+    [arguments addObject:[NSString stringWithFormat:@"-t3=%@", theirTitle]];
+    [arguments addObject:ourPath];
+    [arguments addObject:ancestorPath];
+    [arguments addObject:theirPath];
+    [self _runDiffMergeToolWithArguments:arguments];
   } else {
     XLOG_DEBUG_UNREACHABLE();
   }
@@ -840,6 +861,8 @@ - (void)launchDiffToolWithCommit:(GCCommit*)commit otherCommit:(GCCommit*)otherC
     [self _runBeyondCompareWithArguments:@[ [NSString stringWithFormat:@"-title1=%@", oldTitle], [NSString stringWithFormat:@"-title2=%@", newTitle], oldPath, newPath ]];
   } else if ([identifier isEqualToString:GIViewControllerTool_P4Merge] || [identifier isEqualToString:GIViewControllerTool_GitTool]) {
     ;  // Handled above
+  } else if ([identifier isEqualToString:GIViewControllerTool_DiffMerge]) {
+    [self _runDiffMergeToolWithArguments:@[ [NSString stringWithFormat:@"-t1=%@", oldTitle], [NSString stringWithFormat:@"-t2=%@", newTitle], oldPath, newPath ]];
   } else {
     XLOG_DEBUG_UNREACHABLE();
   }