165 lines
4.7 KiB
Python
165 lines
4.7 KiB
Python
"""Tests for calc.parser — asserts on AST structure, not evaluation."""
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import unittest
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from calc.lexer import tokenize
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from calc.parser import parse, ParseError, Num, BinOp, Unary
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def p(src: str):
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return parse(tokenize(src))
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class TestPrecedence(unittest.TestCase):
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"""D1 — * and / bind tighter than + and -."""
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def test_add_then_mul(self):
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# 1+2*3 → BinOp('+', Num(1), BinOp('*', Num(2), Num(3)))
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self.assertEqual(
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p("1+2*3"),
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BinOp("+", Num(1), BinOp("*", Num(2), Num(3))),
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)
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def test_mul_then_add(self):
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# 2*3+1 → BinOp('+', BinOp('*', Num(2), Num(3)), Num(1))
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self.assertEqual(
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p("2*3+1"),
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BinOp("+", BinOp("*", Num(2), Num(3)), Num(1)),
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)
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def test_sub_then_div(self):
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# 10-6/3 → BinOp('-', Num(10), BinOp('/', Num(6), Num(3)))
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self.assertEqual(
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p("10-6/3"),
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BinOp("-", Num(10), BinOp("/", Num(6), Num(3))),
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)
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def test_mul_and_div_same_precedence_left(self):
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# 4*3/2 → BinOp('/', BinOp('*', Num(4), Num(3)), Num(2))
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self.assertEqual(
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p("4*3/2"),
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BinOp("/", BinOp("*", Num(4), Num(3)), Num(2)),
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)
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class TestAssociativity(unittest.TestCase):
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"""D2 — same-precedence operators associate left."""
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def test_sub_left_assoc(self):
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# 8-3-2 → BinOp('-', BinOp('-', Num(8), Num(3)), Num(2))
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self.assertEqual(
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p("8-3-2"),
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BinOp("-", BinOp("-", Num(8), Num(3)), Num(2)),
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)
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def test_div_left_assoc(self):
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# 8/4/2 → BinOp('/', BinOp('/', Num(8), Num(4)), Num(2))
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self.assertEqual(
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p("8/4/2"),
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BinOp("/", BinOp("/", Num(8), Num(4)), Num(2)),
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)
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def test_add_left_assoc(self):
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# 1+2+3 → BinOp('+', BinOp('+', Num(1), Num(2)), Num(3))
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self.assertEqual(
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p("1+2+3"),
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BinOp("+", BinOp("+", Num(1), Num(2)), Num(3)),
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)
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def test_mul_left_assoc(self):
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# 2*3*4 → BinOp('*', BinOp('*', Num(2), Num(3)), Num(4))
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self.assertEqual(
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p("2*3*4"),
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BinOp("*", BinOp("*", Num(2), Num(3)), Num(4)),
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)
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class TestParentheses(unittest.TestCase):
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"""D3 — parens override precedence."""
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def test_parens_force_add_under_mul(self):
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# (1+2)*3 → BinOp('*', BinOp('+', Num(1), Num(2)), Num(3))
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self.assertEqual(
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p("(1+2)*3"),
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BinOp("*", BinOp("+", Num(1), Num(2)), Num(3)),
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)
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def test_nested_parens(self):
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# ((2+3)) → BinOp('+', Num(2), Num(3))
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self.assertEqual(p("((2+3))"), BinOp("+", Num(2), Num(3)))
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def test_parens_right_side(self):
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# 3*(1+2) → BinOp('*', Num(3), BinOp('+', Num(1), Num(2)))
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self.assertEqual(
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p("3*(1+2)"),
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BinOp("*", Num(3), BinOp("+", Num(1), Num(2))),
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)
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class TestUnaryMinus(unittest.TestCase):
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"""D4 — leading and nested unary minus."""
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def test_leading_unary(self):
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# -5 → Unary('-', Num(5))
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self.assertEqual(p("-5"), Unary("-", Num(5)))
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def test_unary_in_parens(self):
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# -(1+2) → Unary('-', BinOp('+', Num(1), Num(2)))
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self.assertEqual(
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p("-(1+2)"),
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Unary("-", BinOp("+", Num(1), Num(2))),
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)
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def test_unary_right_operand(self):
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# 3 * -2 → BinOp('*', Num(3), Unary('-', Num(2)))
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self.assertEqual(
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p("3 * -2"),
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BinOp("*", Num(3), Unary("-", Num(2))),
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)
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def test_double_unary(self):
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# --5 → Unary('-', Unary('-', Num(5)))
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self.assertEqual(p("--5"), Unary("-", Unary("-", Num(5))))
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def test_unary_in_addition(self):
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# 1 + -2 → BinOp('+', Num(1), Unary('-', Num(2)))
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self.assertEqual(
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p("1 + -2"),
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BinOp("+", Num(1), Unary("-", Num(2))),
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)
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class TestErrors(unittest.TestCase):
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"""D5 — malformed input raises ParseError."""
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def test_trailing_operator(self):
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with self.assertRaises(ParseError):
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p("1 +")
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def test_unclosed_paren(self):
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with self.assertRaises(ParseError):
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p("(1")
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def test_two_numbers_no_op(self):
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with self.assertRaises(ParseError):
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p("1 2")
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def test_close_before_open(self):
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with self.assertRaises(ParseError):
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p(")(")
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def test_empty_string(self):
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with self.assertRaises(ParseError):
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p("")
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def test_only_operator(self):
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with self.assertRaises(ParseError):
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p("*")
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def test_mismatched_parens_extra_close(self):
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with self.assertRaises(ParseError):
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p("(1+2))")
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if __name__ == "__main__":
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unittest.main()
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