Add caching functionality, and have Tex and Text both use it for saved svg strings

manimlib/utils/cache.py

@@ -0,0 +1,33 @@
+import appdirs
+import os
+from diskcache import Cache
+from contextlib import contextmanager
+
+
+CACHE_SIZE = 1e9  # 1 Gig
+
+
+def get_cached_value(key, value_func, message=""):
+    cache_dir = appdirs.user_cache_dir("manim")
+    cache = Cache(cache_dir, size_limit=CACHE_SIZE)
+
+    value = cache.get(key)
+    if value is None:
+        with display_during_execution(message):
+            value = value_func()
+        cache.set(key, value)
+    return value
+
+
+@contextmanager
+def display_during_execution(message: str):
+    # Merge into a single line
+    to_print = message.replace("\n", " ")
+    max_characters = os.get_terminal_size().columns - 1
+    if len(to_print) > max_characters:
+        to_print = to_print[:max_characters - 3] + "..."
+    try:
+        print(to_print, end="\r")
+        yield
+    finally:
+        print(" " * len(to_print), end="\r")