196 lines
6.1 KiB
Python
196 lines
6.1 KiB
Python
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# -*- coding: utf-8 -*-
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"""
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jishaku.repl.walkers
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~~~~~~~~~~~~~~~~~~~~
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AST walkers for code transformation and analysis.
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:copyright: (c) 2019 Devon (Gorialis) R
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:license: MIT, see LICENSE for more details.
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"""
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import ast
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# pylint: disable=no-self-use,invalid-name,missing-docstring
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class KeywordTransformer(ast.NodeTransformer):
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"""
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This transformer:
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- Converts return-with-value into yield & return
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- Converts bare deletes into conditional global pops
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"""
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def visit_FunctionDef(self, node):
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# Do not affect nested function definitions
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return node
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def visit_AsyncFunctionDef(self, node):
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# Do not affect nested async function definitions
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return node
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def visit_ClassDef(self, node):
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# Do not affect nested class definitions
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return node
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def visit_Return(self, node):
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# Do not modify valueless returns
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if node.value is None:
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return node
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# Otherwise, replace the return with a yield & valueless return
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return ast.If(
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test=ast.NameConstant(
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value=True, # if True; aka unconditional, will be optimized out
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lineno=node.lineno,
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col_offset=node.col_offset
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),
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body=[
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# yield the value to be returned
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ast.Expr(
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value=ast.Yield(
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value=node.value,
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lineno=node.lineno,
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col_offset=node.col_offset
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),
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lineno=node.lineno,
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col_offset=node.col_offset
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),
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# return valuelessly
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ast.Return(
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value=None,
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lineno=node.lineno,
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col_offset=node.col_offset
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)
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],
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orelse=[],
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lineno=node.lineno,
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col_offset=node.col_offset
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)
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def visit_Delete(self, node):
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"""
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This converter replaces bare deletes with conditional global pops.
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It is roughly equivalent to transforming:
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.. code:: python
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del foobar
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into:
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.. code:: python
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if 'foobar' in globals():
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globals().pop('foobar')
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else:
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del foobar
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This thus makes deletions in retain mode work more-or-less as intended.
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"""
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return ast.If(
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test=ast.NameConstant(
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value=True, # if True; aka unconditional, will be optimized out
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lineno=node.lineno,
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col_offset=node.col_offset
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),
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body=[
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ast.If(
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# if 'x' in globals():
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test=ast.Compare(
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# 'x'
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left=ast.Str(
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s=target.id,
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lineno=node.lineno,
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col_offset=node.col_offset
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),
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ops=[
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# in
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ast.In(
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lineno=node.lineno,
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col_offset=node.col_offset
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)
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],
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comparators=[
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# globals()
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self.globals_call(node)
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],
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lineno=node.lineno,
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col_offset=node.col_offset
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),
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body=[
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ast.Expr(
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# globals().pop('x')
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value=ast.Call(
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# globals().pop
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func=ast.Attribute(
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value=self.globals_call(node),
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attr='pop',
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ctx=ast.Load(),
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lineno=node.lineno,
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col_offset=node.col_offset
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),
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args=[
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# 'x'
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ast.Str(
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s=target.id,
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lineno=node.lineno,
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col_offset=node.col_offset
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)
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],
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keywords=[],
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lineno=node.lineno,
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col_offset=node.col_offset
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),
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lineno=node.lineno,
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col_offset=node.col_offset
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)
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],
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# else:
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orelse=[
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# del x
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ast.Delete(
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targets=[target],
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lineno=node.lineno,
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col_offset=node.col_offset
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)
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],
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lineno=node.lineno,
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col_offset=node.col_offset
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)
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if isinstance(target, ast.Name) else
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ast.Delete(
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targets=[target],
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lineno=node.lineno,
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col_offset=node.col_offset
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)
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# for each target to be deleted, e.g. `del {x}, {y}, {z}`
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for target in node.targets
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],
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orelse=[],
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lineno=node.lineno,
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col_offset=node.col_offset
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)
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def globals_call(self, node):
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"""
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Creates an AST node that calls globals().
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"""
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return ast.Call(
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func=ast.Name(
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id='globals',
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ctx=ast.Load(),
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lineno=node.lineno,
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col_offset=node.col_offset
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),
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args=[],
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keywords=[],
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lineno=node.lineno,
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col_offset=node.col_offset
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)
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