implementing cache at the level of the leaves

Author: mmatera

mathics/builtin/lists.py

@@ -2906,6 +2906,7 @@ class AppendTo(Builtin):
 
     def apply(self, s, item, evaluation):
         "AppendTo[s_, item_]"
+        evaluation.cache_result = False
         resolved_s = s.evaluate(evaluation)
         if s == resolved_s:
             return evaluation.message("AppendTo", "rvalue", s)
@@ -3008,6 +3009,7 @@ class PrependTo(Builtin):
 
     def apply(self, s, item, evaluation):
         "PrependTo[s_, item_]"
+        evaluation.cache_result = False
         resolved_s = s.evaluate(evaluation)
         if s == resolved_s:
             return evaluation.message("PrependTo", "rvalue", s)

mathics/core/expression.py

@@ -1378,7 +1378,11 @@ def evaluate(self, evaluation) -> typing.Union["Expression", "Symbol"]:
     def evaluate_next(self, evaluation) -> typing.Tuple["Expression", bool]:
         from mathics.builtin.base import BoxConstruct
 
+        up_cache_result = evaluation.cache_result
+        cache_result = up_cache_result
         head = self._head.evaluate(evaluation)
+        cache_result = cache_result and evaluation.cache_result
+        evaluation.cache_result = up_cache_result
         attributes = head.get_attributes(evaluation.definitions)
         leaves = self.get_mutable_leaves()
 
@@ -1389,7 +1393,11 @@ def rest_range(indices):
                 for index in indices:
                     leaf = leaves[index]
                     if leaf.has_form("Evaluate", 1):
+                        up_cache_result = evaluation.cache_result
+                        cache_result = up_cache_result
                         leaves[index] = leaf.evaluate(evaluation)
+                        cache_result = cache_result and evaluation.cache_result
+                        evaluation.cache_result = up_cache_result
 
         def eval_range(indices):
             for index in indices:
@@ -1405,11 +1413,18 @@ def eval_range(indices):
         elif "System`HoldFirst" in attributes:
             rest_range(range(0, min(1, len(leaves))))
             eval_range(range(1, len(leaves)))
+            cache_result = cache_result and evaluation.cache_result
+            evaluation.cache_result = up_cache_result
         elif "System`HoldRest" in attributes:
             eval_range(range(0, min(1, len(leaves))))
+            cache_result = cache_result and evaluation.cache_result
+            evaluation.cache_result = up_cache_result
             rest_range(range(1, len(leaves)))
         else:
             eval_range(range(len(leaves)))
+            cache_result = cache_result and evaluation.cache_result
+            evaluation.cache_result = up_cache_result
+
             # rest_range(range(0, 0))
 
         new = Expression(head)
@@ -1454,6 +1469,7 @@ def flatten_callback(new_leaves, old):
         if "System`Listable" in attributes:
             done, threaded = new.thread(evaluation)
             if done:
+                evaluation.cache_result = cache_result
                 if threaded.sameQ(new):
                     new._timestamp_cache(evaluation)
                     return new, False
@@ -1481,6 +1497,7 @@ def rules():
         for rule in rules():
             result = rule.apply(new, evaluation, fully=False)
             if result is not None:
+                evaluation.cache_result = cache_result
                 if isinstance(result, BoxConstruct):
                     return result, False
                 if result.sameQ(new):
@@ -1504,11 +1521,19 @@ def rules():
 
         new.unformatted = self.unformatted
         new._timestamp_cache(evaluation)
+        evaluation.cache_result = cache_result
         return new, False
 
     def evaluate_leaves(self, evaluation) -> "Expression":
-        leaves = [leaf.evaluate(evaluation) for leaf in self._leaves]
+        up_cache_result = evaluation.cache_result
+        cache_result = up_cache_result
+        leaves = []
+        for leaf in self._leaves:
+            leaves.append(leaf.evaluate(evaluation))
+            cache_result = cache_result and evaluation.cache_result
+            evaluation.cache_result = up_cache_result        
         head = self._head.evaluate_leaves(evaluation)
+        evaluation.cache_result = cache_result and evaluation.cache_result
         return Expression(head, *leaves)
 
     def __str__(self) -> str: