1 files changed, 80 insertions, 0 deletions
diff --git a/third_party/python/taskcluster_taskgraph/taskgraph/util/templates.py b/third_party/python/taskcluster_taskgraph/taskgraph/util/templates.py
new file mode 100644
index 0000000000..23cd5f8d68
--- /dev/null
+++ b/third_party/python/taskcluster_taskgraph/taskgraph/util/templates.py
@@ -0,0 +1,80 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import copy
+
+
+def merge_to(source, dest):
+    """
+    Merge dict and arrays (override scalar values)
+
+    Keys from source override keys from dest, and elements from lists in source
+    are appended to lists in dest.
+
+    :param dict source: to copy from
+    :param dict dest: to copy to (modified in place)
+    """
+
+    for key, value in source.items():
+        # Override mismatching or empty types
+        if type(value) != type(dest.get(key)):  # noqa
+            dest[key] = source[key]
+            continue
+
+        # Merge dict
+        if isinstance(value, dict):
+            merge_to(value, dest[key])
+            continue
+
+        if isinstance(value, list):
+            dest[key] = dest[key] + source[key]
+            continue
+
+        dest[key] = source[key]
+
+    return dest
+
+
+def merge(*objects):
+    """
+    Merge the given objects, using the semantics described for merge_to, with
+    objects later in the list taking precedence.  From an inheritance
+    perspective, "parents" should be listed before "children".
+
+    Returns the result without modifying any arguments.
+    """
+    if len(objects) == 1:
+        return copy.deepcopy(objects[0])
+    return merge_to(objects[-1], merge(*objects[:-1]))
+
+
+def deep_get(dict_, field):
+    container, subfield = dict_, field
+    while "." in subfield:
+        f, subfield = subfield.split(".", 1)
+        if f not in container:
+            return None
+
+        container = container[f]
+
+    return container.get(subfield)
+
+
+def substitute(item, **subs):
+    if isinstance(item, list):
+        for i in range(len(item)):
+            item[i] = substitute(item[i], **subs)
+    elif isinstance(item, dict):
+        new_dict = {}
+        for k, v in item.items():
+            k = k.format(**subs)
+            new_dict[k] = substitute(v, **subs)
+        item = new_dict
+    elif isinstance(item, str):
+        item = item.format(**subs)
+    else:
+        item = item
+
+    return item