Added invert mode (-i)

README.md

@@ -12,6 +12,7 @@ Usage
 		tag -a | --add <tags> <path>...     Add tags to file
 		tag -r | --remove <tags> <path>...  Remove tags from file
 		tag -s | --set <tags> <path>...     Set tags on file
+          tag -i | --invert <tags> <path>...  Invert tags on file
 		tag -m | --match <tags> <path>...   Display files with matching tags
 		tag -f | --find <tags> <path>...    Find all files with tags, limited to paths if present
 		tag -l | --list <path>...           List the tags on file
@@ -61,6 +62,13 @@ The *set* operation replaces all tags on the specified files with one or more ne
 	tag --set tagname file
 	tag --set tagname1,tagname2,... file1 file2...
 
+### Invert tags on a file
+
+The *invert* operation sets tags which are not present and remove tags which are present on the specified files.
+
+    tag --invert tagname file
+    tag --invert tagname1,tagname2,... file1 file2...
+
 ### Show files matching tags
 
 The *match* operation prints the file names that match the specified tags.  Matched files must have at least *all* of the tags specified. Note that *match* matches only against the files that are provided as parameters (and those that it encounters if you use the --enter or --recursive options). To search for tagged files across your filesystem, see the *find* operation.
@@ -223,7 +231,7 @@ Advanced Usage
 * Wherever a "file" is expected, a list of files may be used instead. These are provided as separate parameters.
 * Note that directories can be tagged as well, so directories may be specified instead of files.
 * The --all, --enter, and --recursive options apply to --add, --remove, --set, --match, and --list, and control whether hidden files are processed and whether directories are entered and/or processed recursively. If a directory is supplied, but neither of --enter or --recursive, then the operation will apply to the directory itself, rather than to its contents.
-* The operation selector --add, --remove, --set, --match, --list, --find, or --usage may be abbreviated as -a, -r, -s, -m, -l, -f, or -u respectively. All of the options have a short version, in fact. See see the synopsis above, or output from help.
+* The operation selector --add, --remove, --set, --invert, --match, --list, --find, or --usage may be abbreviated as -a, -r, -s, -i, -m, -l, -f, or -u respectively. All of the options have a short version, in fact. See see the synopsis above, or output from help.
 * If no operation selector is given, the operation will default to *list*.
 * A *list* operation will default to the current directory if no directory is given.
 * For compatibility with Finder, tags are compared in a case-insensitive manner.

Tag/Tag.h

@@ -34,6 +34,7 @@ typedef NS_ENUM(int, OperationMode) {
     OperationModeSet        = 's',
     OperationModeAdd        = 'a',
     OperationModeRemove     = 'r',
+    OperationModeInvert     = 'i',
     OperationModeMatch      = 'm',
     OperationModeFind       = 'f',
     OperationModeUsage      = 'u',

Tag/Tag.m

@@ -122,6 +122,7 @@ - (void)parseCommandLineArgv:(char * const *)argv argc:(int)argc
         { "set",        required_argument,      0,              OperationModeSet },
         { "add",        required_argument,      0,              OperationModeAdd },
         { "remove",     required_argument,      0,              OperationModeRemove },
+        { "invert",     required_argument,      0,              OperationModeInvert },
         { "match",      required_argument,      0,              OperationModeMatch },
         { "find",       required_argument,      0,              OperationModeFind },
         { "usage",      optional_argument,      0,              OperationModeUsage },
@@ -182,13 +183,14 @@ - (void)parseCommandLineArgv:(char * const *)argv argc:(int)argc
     // Parse Options
     int option_char;
     int option_index;
-    while ((option_char = getopt_long(argc, argv, "s:a:r:m:f:u::lAeRdnNtTgGcp0hv", options, &option_index)) != -1)
+    while ((option_char = getopt_long(argc, argv, "s:a:r:i:m:f:u::lAeRdnNtTgGcp0hv", options, &option_index)) != -1)
     {
         switch (option_char)
         {
             case OperationModeSet:
             case OperationModeAdd:
             case OperationModeRemove:
+            case OperationModeInvert:
             case OperationModeMatch:
             case OperationModeFind:
             case OperationModeUsage:
@@ -369,6 +371,7 @@ - (void)displayHelp
            "    tag -a | --add <tags> <path>...     Add tags to file\n"
            "    tag -r | --remove <tags> <path>...  Remove tags from file\n"
            "    tag -s | --set <tags> <path>...     Set tags on file\n"
+           "    tag -i | --invert <tags> <path>...  Invert tags on file\n"
            "    tag -m | --match <tags> <path>...   Display files with matching tags\n"
            "    tag -f | --find <tags> <path>...    Find all files with tags (-A, -e, -R ignored)\n"
            "    tag -u | --usage <tags> <path>...   Display tags used, with usage counts\n"
@@ -495,6 +498,10 @@ - (void)performOperation
             [self doRemove];
             break;
 
+        case OperationModeInvert:
+            [self doInvert];
+            break;
+
         case OperationModeMatch:
             [self doMatch];
             break;
@@ -806,6 +813,49 @@ - (void)doRemove
 }
 
 
+- (void)doInvert
+{
+    // If there are no tags to invert, we're done
+    if (![self.tags count])
+        return;
+
+    // Only perform invert on specified URLs
+    // (we don't implicitly enumerate the current directory)
+    if ([self.URLs count] == 0)
+        return;
+
+    // Enumerate the provided URLs, adding tags to each
+    // --all, --enter, and --recursive apply
+    [self enumerateURLsWithBlock:^(NSURL *URL) {
+        NSError* error;
+
+        // Get the existing tags
+        NSArray* existingTags;
+        if (![URL getResourceValue:&existingTags forKey:NSURLTagNamesKey error:&error])
+            [self reportFatalError:error onURL:URL];
+
+        NSMutableSet* curTags = [self tagSetFromTagArray:existingTags];
+
+        // Calculate tags to be removed
+        NSMutableSet* tagsToRemove = [curTags mutableCopy];
+        [tagsToRemove intersectSet:self.tags];
+
+        // Calculate tags to be added
+        NSMutableSet* tagsToAdd = [self.tags mutableCopy];
+        [tagsToAdd minusSet:tagsToRemove];
+
+        // Remove tags to be removed
+        [curTags minusSet:tagsToRemove];
+        // Add tags to be added
+        [curTags unionSet:tagsToAdd];
+
+        // Set all the new tags onto the item
+        if (![URL setResourceValue:[self tagArrayFromTagSet:curTags] forKey:NSURLTagNamesKey error:&error])
+            [self reportFatalError:error onURL:URL];
+    }];
+}
+
+
 - (void)doMatch
 {
     BOOL matchAny = [self wildcardInTagSet:self.tags];