Bug 1363811 - Allow to combine two DependsFunctions with "&". r=cmanchester+432261

Similar to how they can be combined with "|", we now allow using "&".
As for "|", it would have been better if it were "and", but it's not
possible to override "and" in python ; __and__ is for "&".

python/mozbuild/mozbuild/configure/__init__.py

@@ -46,6 +46,7 @@ class SandboxDependsFunction(object):
     '''Sandbox-visible representation of @depends functions.'''
     def __init__(self, unsandboxed):
         self._or = unsandboxed.__or__
+        self._and = unsandboxed.__and__
 
     def __call__(self, *arg, **kwargs):
         raise ConfigureError('The `%s` function may not be called'
@@ -57,6 +58,12 @@ class SandboxDependsFunction(object):
                                  'with another @depends function.')
         return self._or(other).sandboxed
 
+    def __and__(self, other):
+        if not isinstance(other, SandboxDependsFunction):
+            raise ConfigureError('Can only do binary arithmetic operations '
+                                 'with another @depends function.')
+        return self._and(other).sandboxed
+
     def __nonzero__(self):
         raise ConfigureError(
             'Cannot do boolean operations on @depends functions.')
@@ -135,6 +142,23 @@ class DependsFunction(object):
                 return i
         return i
 
+    def __and__(self, other):
+        if isinstance(other, SandboxDependsFunction):
+            other = self.sandbox._depends.get(other)
+        assert isinstance(other, DependsFunction)
+        assert self.sandbox is other.sandbox
+        return CombinedDependsFunction(self.sandbox, self.and_impl,
+                                       (self, other))
+
+    @staticmethod
+    def and_impl(iterable):
+        # Applies "and" to all the items of iterable.
+        # e.g. if iterable contains a, b and c, returns `a and b and c`.
+        for i in iterable:
+            if not i:
+                return i
+        return i
+
 
 class CombinedDependsFunction(DependsFunction):
     def __init__(self, sandbox, func, dependencies):

python/mozbuild/mozbuild/test/configure/test_configure.py

@@ -1287,7 +1287,7 @@ class TestConfigure(unittest.TestCase):
         ''' + moz_configure):
             self.get_config(['--enable-when'])
 
-    def test_depends_or(self):
+    def test_depends_binary_ops(self):
         with self.moz_configure('''
             option('--foo', nargs=1, help='foo')
             @depends('--foo')
@@ -1304,8 +1304,10 @@ class TestConfigure(unittest.TestCase):
             def baz(value):
                 return value
 
-            set_config('FOOBAR', foo | bar)
-            set_config('FOOBARBAZ', foo | bar | baz)
+            set_config('FOOorBAR', foo | bar)
+            set_config('FOOorBARorBAZ', foo | bar | baz)
+            set_config('FOOandBAR', foo & bar)
+            set_config('FOOandBARandBAZ', foo & bar & baz)
         '''):
             for foo_opt, foo_value in (
                 ('',  0),
@@ -1322,8 +1324,10 @@ class TestConfigure(unittest.TestCase):
                         config = self.get_config(
                             [x for x in (foo_opt, bar_opt, baz_opt) if x])
                         self.assertEqual(config, {
-                            'FOOBAR': foo_value or bar_value,
-                            'FOOBARBAZ': foo_value or bar_value or baz_value,
+                            'FOOorBAR': foo_value or bar_value,
+                            'FOOorBARorBAZ': foo_value or bar_value or baz_value,
+                            'FOOandBAR': foo_value and bar_value,
+                            'FOOandBARandBAZ': foo_value and bar_value and baz_value,
                         })