01d5532823
Educational calculator teaching FSMs (explicit transition table tokenizer) and DAGs (recursive descent parser with AST evaluation). Includes CLI with REPL, graphviz visualization, and 61 tests. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
121 lines
2.7 KiB
Python
121 lines
2.7 KiB
Python
import sys
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from pathlib import Path
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sys.path.insert(0, str(Path(__file__).parent.parent))
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import pytest
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from tokenizer import tokenize
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from parser import Parser
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from evaluator import evaluate, evaluate_traced, EvalError
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def eval_expr(expr):
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"""Helper: tokenize -> parse -> evaluate in one step."""
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tokens = tokenize(expr)
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ast = Parser(tokens).parse()
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return evaluate(ast)
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# ---------- Basic arithmetic ----------
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def test_addition():
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assert eval_expr("3 + 4") == 7.0
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def test_subtraction():
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assert eval_expr("10 - 3") == 7.0
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def test_multiplication():
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assert eval_expr("3 * 4") == 12.0
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def test_division():
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assert eval_expr("10 / 4") == 2.5
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def test_power():
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assert eval_expr("2 ^ 10") == 1024.0
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# ---------- Precedence ----------
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def test_standard_precedence():
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assert eval_expr("3 + 4 * 2") == 11.0
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def test_parentheses():
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assert eval_expr("(3 + 4) * 2") == 14.0
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def test_power_precedence():
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assert eval_expr("2 * 3 ^ 2") == 18.0
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def test_right_associative_power():
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# 2^(2^3) = 2^8 = 256
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assert eval_expr("2 ^ 2 ^ 3") == 256.0
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# ---------- Unary minus ----------
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def test_negation():
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assert eval_expr("-5") == -5.0
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def test_double_negation():
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assert eval_expr("--5") == 5.0
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def test_negation_with_power():
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# -(3^2) = -9, not (-3)^2 = 9
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assert eval_expr("-3 ^ 2") == -9.0
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def test_negation_in_parens():
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assert eval_expr("(-3) ^ 2") == 9.0
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# ---------- Decimals ----------
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def test_decimal_addition():
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assert eval_expr("0.1 + 0.2") == pytest.approx(0.3)
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def test_leading_dot():
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assert eval_expr(".5 + .5") == 1.0
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# ---------- Edge cases ----------
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def test_nested_parens():
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assert eval_expr("((((3))))") == 3.0
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def test_complex_expression():
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assert eval_expr("(2 + 3) * (7 - 2) / 5 ^ 1") == 5.0
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def test_long_chain():
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assert eval_expr("1 + 2 + 3 + 4 + 5") == 15.0
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def test_mixed_operations():
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assert eval_expr("2 + 3 * 4 - 6 / 2") == 11.0
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# ---------- Division by zero ----------
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def test_division_by_zero():
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with pytest.raises(EvalError):
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eval_expr("1 / 0")
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def test_division_by_zero_in_expression():
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with pytest.raises(EvalError):
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eval_expr("5 + 3 / (2 - 2)")
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# ---------- Traced evaluation ----------
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def test_traced_returns_correct_result():
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tokens = tokenize("3 + 4 * 2")
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ast = Parser(tokens).parse()
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result, steps = evaluate_traced(ast)
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assert result == 11.0
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assert len(steps) > 0
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def test_traced_step_count():
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"""A simple binary op has 3 evaluation events: left, right, combine."""
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tokens = tokenize("3 + 4")
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ast = Parser(tokens).parse()
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result, steps = evaluate_traced(ast)
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assert result == 7.0
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# NumberNode(3), NumberNode(4), BinOp(+)
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assert len(steps) == 3
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