cpython/Lib/test/test_compiler_codegen.py

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from test.support.bytecode_helper import CodegenTestCase
# Tests for the code-generation stage of the compiler.
# Examine the un-optimized code generated from the AST.
class IsolatedCodeGenTests(CodegenTestCase):
def codegen_test(self, snippet, expected_insts):
import ast
a = ast.parse(snippet, "my_file.py", "exec");
insts = self.generate_code(a)
self.assertInstructionsMatch(insts, expected_insts)
def test_if_expression(self):
snippet = "42 if True else 24"
false_lbl = self.Label()
expected = [
('RESUME', 0, 0),
('LOAD_CONST', 0, 1),
('TO_BOOL', 0, 1),
('POP_JUMP_IF_FALSE', false_lbl := self.Label(), 1),
('LOAD_CONST', 1, 1),
('JUMP', exit_lbl := self.Label()),
false_lbl,
('LOAD_CONST', 2, 1),
exit_lbl,
('POP_TOP', None),
('LOAD_CONST', 3),
('RETURN_VALUE', None),
]
self.codegen_test(snippet, expected)
def test_for_loop(self):
snippet = "for x in l:\n\tprint(x)"
false_lbl = self.Label()
expected = [
('RESUME', 0, 0),
('LOAD_NAME', 0, 1),
('GET_ITER', None, 1),
loop_lbl := self.Label(),
('FOR_ITER', exit_lbl := self.Label(), 1),
('STORE_NAME', 1, 1),
('LOAD_NAME', 2, 2),
('PUSH_NULL', None, 2),
('LOAD_NAME', 1, 2),
('CALL', 1, 2),
('POP_TOP', None),
('JUMP', loop_lbl),
exit_lbl,
('END_FOR', None),
('LOAD_CONST', 0),
('RETURN_VALUE', None),
]
self.codegen_test(snippet, expected)