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![Accessing the AST
a = 26
b = 0
print(a + b)
example.py
In [1]: import ast
In [2]: source =
open('example.py').read()
In [3]: tree = ast.parse(source)](https://image.slidesharecdn.com/suhasastpycon2016-160925142741/75/Hacking-the-Python-AST-15-2048.jpg)
![Accessing the AST
a = 26
b = 0
print(a + b)
example.py
Module(body=[
Expr(value=Str(s='Docstring')),
Assign(
targets=[Name(
id='a',
ctx=Store())],
value=Num(n=26)),
Assign(
targets=[Name(
id='b',
ctx=Store())],
value=Num(n=0)),
Expr(value=Call(
func=Name(
id='print',
ctx=Load()),
args=[BinOp(
left=Name(
id='a',
ctx=Load()),
op=Add(),
right=Name(
id='b',
ctx=Load()))],
keywords=[]))])](https://image.slidesharecdn.com/suhasastpycon2016-160925142741/75/Hacking-the-Python-AST-16-2048.jpg)
![Having a little fun, now
In [3]: tree = ast.parse('x = 5')
In [4]:
print(astunparse.dump(tree))
Module(body=[Assign(
targets=[Name(
id='x',
ctx=Store())],
value=Num(n=5))])
In [5]: tree.body[0].targets[0].id
Out[5]: 'x'
In [6]: astunparse.unparse(tree)
x = 5
In [7]:
tree.body[0].targets[0].id = 'y'
In [8]:
print(astunparse.unparse(tree))
y = 5](https://image.slidesharecdn.com/suhasastpycon2016-160925142741/75/Hacking-the-Python-AST-17-2048.jpg)
![Inside Python [OSCON 2012]](https://cdn.slidesharecdn.com/ss_thumbnails/insidepythonpresentation-120724001527-phpapp02-thumbnail.jpg?width=640&height=640&fit=bounds)
Hacking the Python AST
- 1.
- 2.
- 3. A primer on compiling computer languages Front end Middleend Back end C JAVA ARM x86 IR IR
- 4.
- 5. A primer on compiling computer languages Front end Middleend Back end C JAVA ARM x86 IR IR
- 6.
- 7. Grammars S –> AB A–> aA | ε B –> b | bB S AB S –> AB aAB A –> aA aaAB A –> aA aaaAB A –> aA aaaεB A –> ε aaab B –> b A parse of aaab Does aaab belong to this Grammar?
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- 15. Accessing the AST a = 26 b= 0 print(a + b) example.py In [1]: import ast In [2]: source = open('example.py').read() In [3]: tree = ast.parse(source)
- 16. Accessing the AST a = 26 b= 0 print(a + b) example.py Module(body=[ Expr(value=Str(s='Docstring')), Assign( targets=[Name( id='a', ctx=Store())], value=Num(n=26)), Assign( targets=[Name( id='b', ctx=Store())], value=Num(n=0)), Expr(value=Call( func=Name( id='print', ctx=Load()), args=[BinOp( left=Name( id='a', ctx=Load()), op=Add(), right=Name( id='b', ctx=Load()))], keywords=[]))])
- 17. Having a little fun, now In [3]: tree= ast.parse('x = 5') In [4]: print(astunparse.dump(tree)) Module(body=[Assign( targets=[Name( id='x', ctx=Store())], value=Num(n=5))]) In [5]: tree.body[0].targets[0].id Out[5]: 'x' In [6]: astunparse.unparse(tree) x = 5 In [7]: tree.body[0].targets[0].id = 'y' In [8]: print(astunparse.unparse(tree)) y = 5
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- 20. @jargnar github.com/jargnar Hacking is amindset, not a skill. suhas.org