2 files changed, 60 insertions, 0 deletions

diff --git a/meta/lib/oe/license.py b/meta/lib/oe/license.py
index b230d3ef45..7ab66e762f 100644
--- a/meta/lib/oe/license.py
+++ b/meta/lib/oe/license.py
@@ -30,3 +30,33 @@ class LicenseVisitor(ast.NodeVisitor):
             new_elements.append(element)
 
         self.visit(ast.parse(' '.join(new_elements)))
+
+class FlattenVisitor(LicenseVisitor):
+    """Flatten a license tree (parsed from a string) by selecting one of each
+    set of OR options, in the way the user specifies"""
+    def __init__(self, choose_licenses):
+        self.choose_licenses = choose_licenses
+        self.licenses = []
+        LicenseVisitor.__init__(self)
+
+    def visit_Str(self, node):
+        self.licenses.append(node.s)
+
+    def visit_BinOp(self, node):
+        if isinstance(node.op, ast.BitOr):
+            left = FlattenVisitor(self.choose_licenses)
+            left.visit(node.left)
+
+            right = FlattenVisitor(self.choose_licenses)
+            right.visit(node.right)
+
+            selected = self.choose_licenses(left.licenses, right.licenses)
+            self.licenses.extend(selected)
+        else:
+            self.generic_visit(node)
+
+def flattened_licenses(licensestr, choose_licenses):
+    """Given a license string and choose_licenses function, return a flat list of licenses"""
+    flatten = FlattenVisitor(choose_licenses)
+    flatten.visit_string(licensestr)
+    return flatten.licenses
diff --git a/meta/lib/oe/tests/test_license.py b/meta/lib/oe/tests/test_license.py
index cb949fc76f..c388886184 100644
--- a/meta/lib/oe/tests/test_license.py
+++ b/meta/lib/oe/tests/test_license.py
@@ -36,3 +36,33 @@ class TestSingleLicense(unittest.TestCase):
             with self.assertRaises(oe.license.InvalidLicense) as cm:
                 self.parse(license)
             self.assertEqual(cm.exception.license, license)
+
+class TestSimpleCombinations(unittest.TestCase):
+    tests = {
+        "FOO&BAR": ["FOO", "BAR"],
+        "BAZ & MOO": ["BAZ", "MOO"],
+        "ALPHA|BETA": ["ALPHA"],
+        "BAZ&MOO|FOO": ["FOO"],
+        "FOO&BAR|BAZ": ["FOO", "BAR"],
+    }
+    preferred = ["ALPHA", "FOO", "BAR"]
+
+    def test_tests(self):
+        def choose(a, b):
+            if all(lic in self.preferred for lic in b):
+                return b
+            else:
+                return a
+
+        for license, expected in self.tests.items():
+            licenses = oe.license.flattened_licenses(license, choose)
+            self.assertListEqual(licenses, expected)
+
+class TestComplexCombinations(TestSimpleCombinations):
+    tests = {
+        "FOO & (BAR | BAZ)&MOO": ["FOO", "BAR", "MOO"],
+        "(ALPHA|(BETA&THETA)|OMEGA)&DELTA": ["OMEGA", "DELTA"],
+        "((ALPHA|BETA)&FOO)|BAZ": ["BETA", "FOO"],
+        "(GPL-2.0|Proprietary)&BSD-4-clause&MIT": ["GPL-2.0", "BSD-4-clause", "MIT"],
+    }
+    preferred = ["BAR", "OMEGA", "BETA", "GPL-2.0"]