Add rel complement (set diff) arg to eups diff

This commit adds a new argument to eups list: -C or  --diff. This
argument calculates the relative complement (aka, set difference) of
declared version products with respect to currently setup products.

All dependent products associated with the named product will be used as
a reference, relative to the list of setup products managed by EUPS.

python/eups/app.py

@@ -18,7 +18,7 @@
 from .utils import cmp_or_key
 
 def printProducts(ostrm, productName=None, versionName=None, eupsenv=None,
-                  tags=None, setup=False, tablefile=False, directory=False,
+                  tags=None, setup=False, tablefile=False, difference=False, directory=False,
                   dependencies=False, showVersion=False, showName=False, showTagsGlob="*",
                   depth=None, productDir=None, topological=False, checkCycles=False, raw=False):
     """
@@ -32,6 +32,8 @@ def printProducts(ostrm, productName=None, versionName=None, eupsenv=None,
     @param setup           restrict the listing to products that are currently
                               setup (or print actually setup versions with dependencies)
     @param tablefile       include the path to each product's table file
+    @param difference      Print the relative complement (set difference) of declared version
+                              products to setup products
     @param directory       include each product's installation directory
     @param dependencies    print the product's dependencies
     @param showVersion     Only print the product{'s,s'} version[s] (e.g. eups list -V -s afw)
@@ -97,7 +99,25 @@ def printProducts(ostrm, productName=None, versionName=None, eupsenv=None,
 
             raise ProductNotFound(productName, versionName, msg="Unable to find product %s" % msg)
 
+    if difference:
+        if versionName:
+            raise EupsException("--diff does not make sense with a version")
+        if dependencies:
+            raise EupsException("--diff does not make sense with --dependencies")
+        setupProducts = set(eupsenv.getSetupProducts())
+        dependentProductList = eupsenv.getDependentProducts(productList[0])
+        dependentProducts = {x[0] for x in dependentProductList}
+        productList = list(setupProducts - dependentProducts)
+        if not productList:
+            return 0
+
     productList.sort(key=lambda p: (p.name, p.version))
+
+    if difference:
+        # Insert the main product name at the front of the list, to be printed first
+        productNameIndex = [i for i, p in enumerate(productList) if p.name == productName][0]
+        productList.insert(0, productList.pop(productList.index(productList[productNameIndex])))
+
     if dependencies:
         _msgs = {}               # maintain list of printed dependencies
         recursionDepth, indent = 0, ""
@@ -249,7 +269,7 @@ def includeProduct(recursionDepth):
                     info += "|"
                 info += name + "|" + version
             else:
-                if productName and not utils.isGlob(productName):
+                if productName and not utils.isGlob(productName) and not difference:
                     info += "   "
                 else:
                     info += "%-21s " % (name)

python/eups/cmd.py

@@ -455,6 +455,8 @@ def addOptions(self):
         # these are specific to this command
         self.clo.add_option("-c", "--current", dest="currentTag", action="store_true", default=False,
                             help="same as --postTag=current")
+        self.clo.add_option("-C", "--diff", dest="difference", action="store_true", default=False,
+                            help="Print the relative complement (set difference) of declared version products with respect to currently setup products")
         self.clo.add_option("-D", "--dependencies", dest="depends", action="store_true", default=False,
                             help="Print product's dependencies (must specify version if ambiguous). With --setup print the versions of dependent products that are actually setup.")
         self.clo.add_option("--depth", dest="depth", action="store",
@@ -506,8 +508,9 @@ def execute(self):
             n = eups.printProducts(sys.stdout, product, version,
                                    self.createEups(self.opts, versionName=version, quiet=1),
                                    tags=self.opts.tag,
-                                   setup=self.opts.setup,
+                                   setup=self.opts.setup or self.opts.difference,
                                    tablefile=self.opts.tablefile,
+                                   difference=self.opts.difference,
                                    directory=self.opts.printdir,
                                    dependencies=self.opts.depends,
                                    showVersion=self.opts.version, showName=self.opts.showName,