Merge pull request #68 from piranna/master

Optimizations on INCLUDE statement

1 files changed, 46 insertions, 0 deletions

diff --git a/sqlparse/utils.py b/sqlparse/utils.py
new file mode 100644
index 0000000..fd6651a
--- /dev/null
+++ b/sqlparse/utils.py
@@ -0,0 +1,46 @@
+'''
+Created on 17/05/2012
+
+@author: piranna
+'''
+
+
+def memoize_generator(func):
+    """Memoize decorator for generators
+
+    Store `func` results in a cache according to their arguments as 'memoize'
+    does but instead this works on decorators instead of regular functions.
+    Obviusly, this is only useful if the generator will always return the same
+    values for each specific parameters...
+    """
+    cache = {}
+
+    def wrapped_func(*args, **kwargs):
+        params = (args, kwargs)
+
+        # Look if cached
+        try:
+            cached = cache[params]
+
+        # Not cached, exec and store it
+        except KeyError:
+            # Reset the cache if we have too much cached entries and start over
+            # In the future would be better to use an OrderedDict and drop the
+            # Least Recent Used entries
+            if len(cache) >= 10:
+                cache.clear()
+
+            cached = []
+
+            for item in func(*args, **kwargs):
+                cached.append(item)
+                yield item
+
+            cache[params] = cached
+
+        # Cached, yield its items
+        else:
+            for item in cached:
+                yield item
+
+    return wrapped_func