1 files changed, 56 insertions, 0 deletions
diff --git a/packages/Python/lldbsuite/support/optional_with.py b/packages/Python/lldbsuite/support/optional_with.py
new file mode 100644
index 000000000000..41342288bc6a
--- /dev/null
+++ b/packages/Python/lldbsuite/support/optional_with.py
@@ -0,0 +1,56 @@
+# ====================================================================
+# Provides a with-style resource handler for optionally-None resources
+# ====================================================================
+
+class optional_with(object):
+    # pylint: disable=too-few-public-methods
+    # This is a wrapper - it is not meant to provide any extra methods.
+    """Provides a wrapper for objects supporting "with", allowing None.
+
+    This lets a user use the "with object" syntax for resource usage
+    (e.g. locks) even when the wrapped with object is None.
+
+    e.g.
+
+    wrapped_lock = optional_with(thread.Lock())
+    with wrapped_lock:
+        # Do something while the lock is obtained.
+        pass
+
+    might_be_none = None
+    wrapped_none = optional_with(might_be_none)
+    with wrapped_none:
+        # This code here still works.
+        pass
+
+    This prevents having to write code like this when
+    a lock is optional:
+
+    if lock:
+        lock.acquire()
+
+    try:
+        code_fragment_always_run()
+    finally:
+        if lock:
+            lock.release()
+
+    And I'd posit it is safer, as it becomes impossible to
+    forget the try/finally using optional_with(), since
+    the with syntax can be used.
+    """
+    def __init__(self, wrapped_object):
+        self.wrapped_object = wrapped_object
+
+    def __enter__(self):
+        if self.wrapped_object is not None:
+            return self.wrapped_object.__enter__()
+        else:
+            return self
+
+    def __exit__(self, the_type, value, traceback):
+        if self.wrapped_object is not None:
+            return self.wrapped_object.__exit__(the_type, value, traceback)
+        else:
+            # Don't suppress any exceptions
+            return False