comparison env/lib/python3.7/site-packages/jinja2/optimizer.py @ 5:9b1c78e6ba9c draft default tip

"planemo upload commit 6c0a8142489327ece472c84e558c47da711a9142"
author shellac
date Mon, 01 Jun 2020 08:59:25 -0400
parents 79f47841a781
children
comparison
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4:79f47841a781 5:9b1c78e6ba9c
1 # -*- coding: utf-8 -*-
2 """The optimizer tries to constant fold expressions and modify the AST
3 in place so that it should be faster to evaluate.
4
5 Because the AST does not contain all the scoping information and the
6 compiler has to find that out, we cannot do all the optimizations we
7 want. For example, loop unrolling doesn't work because unrolled loops
8 would have a different scope. The solution would be a second syntax tree
9 that stored the scoping rules.
10 """
11 from . import nodes
12 from .visitor import NodeTransformer
13
14
15 def optimize(node, environment):
16 """The context hint can be used to perform an static optimization
17 based on the context given."""
18 optimizer = Optimizer(environment)
19 return optimizer.visit(node)
20
21
22 class Optimizer(NodeTransformer):
23 def __init__(self, environment):
24 self.environment = environment
25
26 def generic_visit(self, node, *args, **kwargs):
27 node = super(Optimizer, self).generic_visit(node, *args, **kwargs)
28
29 # Do constant folding. Some other nodes besides Expr have
30 # as_const, but folding them causes errors later on.
31 if isinstance(node, nodes.Expr):
32 try:
33 return nodes.Const.from_untrusted(
34 node.as_const(args[0] if args else None),
35 lineno=node.lineno,
36 environment=self.environment,
37 )
38 except nodes.Impossible:
39 pass
40
41 return node