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-rw-r--r--third_party/python/Jinja2/jinja2/optimizer.py41
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diff --git a/third_party/python/Jinja2/jinja2/optimizer.py b/third_party/python/Jinja2/jinja2/optimizer.py
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+# -*- coding: utf-8 -*-
+"""The optimizer tries to constant fold expressions and modify the AST
+in place so that it should be faster to evaluate.
+
+Because the AST does not contain all the scoping information and the
+compiler has to find that out, we cannot do all the optimizations we
+want. For example, loop unrolling doesn't work because unrolled loops
+would have a different scope. The solution would be a second syntax tree
+that stored the scoping rules.
+"""
+from . import nodes
+from .visitor import NodeTransformer
+
+
+def optimize(node, environment):
+ """The context hint can be used to perform an static optimization
+ based on the context given."""
+ optimizer = Optimizer(environment)
+ return optimizer.visit(node)
+
+
+class Optimizer(NodeTransformer):
+ def __init__(self, environment):
+ self.environment = environment
+
+ def generic_visit(self, node, *args, **kwargs):
+ node = super(Optimizer, self).generic_visit(node, *args, **kwargs)
+
+ # Do constant folding. Some other nodes besides Expr have
+ # as_const, but folding them causes errors later on.
+ if isinstance(node, nodes.Expr):
+ try:
+ return nodes.Const.from_untrusted(
+ node.as_const(args[0] if args else None),
+ lineno=node.lineno,
+ environment=self.environment,
+ )
+ except nodes.Impossible:
+ pass
+
+ return node