From 72b8c35be4293bd21de123854491c658c53af100 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sat, 4 Dec 2021 04:31:41 +0100
Subject: Adding upstream version 0.17.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 gitlint-core/gitlint/cache.py | 53 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 gitlint-core/gitlint/cache.py

(limited to 'gitlint-core/gitlint/cache.py')

diff --git a/gitlint-core/gitlint/cache.py b/gitlint-core/gitlint/cache.py
new file mode 100644
index 0000000..1b6558f
--- /dev/null
+++ b/gitlint-core/gitlint/cache.py
@@ -0,0 +1,53 @@
+class PropertyCache:
+    """ Mixin class providing a simple cache. """
+
+    def __init__(self):
+        self._cache = {}
+
+    def _try_cache(self, cache_key, cache_populate_func):
+        """ Tries to get a value from the cache identified by `cache_key`.
+            If no value is found in the cache, do a function call to `cache_populate_func` to populate the cache
+            and then return the value from the cache. """
+        if cache_key not in self._cache:
+            cache_populate_func()
+        return self._cache[cache_key]
+
+
+def cache(original_func=None, cachekey=None):  # pylint: disable=unused-argument
+    """ Cache decorator. Caches function return values.
+        Requires the parent class to extend and initialize PropertyCache.
+        Usage:
+            # Use function name as cache key
+            @cache
+            def myfunc(args):
+                ...
+
+            # Specify cache key
+            @cache(cachekey="foobar")
+            def myfunc(args):
+                ...
+    """
+
+    # Decorators with optional arguments are a bit convoluted in python, see some of the links below for details.
+
+    def cache_decorator(func):
+        # Use 'nonlocal' keyword to access parent function variable:
+        # https://stackoverflow.com/a/14678445/381010
+        nonlocal cachekey
+        if not cachekey:
+            cachekey = func.__name__
+
+        def wrapped(*args):
+            def cache_func_result():
+                # Call decorated function and store its result in the cache
+                args[0]._cache[cachekey] = func(*args)
+            return args[0]._try_cache(cachekey, cache_func_result)
+
+        return wrapped
+
+    # To support optional kwargs for decorators, we need to check if a function is passed as first argument or not.
+    # https://stackoverflow.com/a/24617244/381010
+    if original_func:
+        return cache_decorator(original_func)
+
+    return cache_decorator
-- 
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