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>
137 lines
3.6 KiB
Python
137 lines
3.6 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, TokenType
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from parser import Parser, ParseError, NumberNode, BinOpNode, UnaryOpNode
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def parse(expr):
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"""Helper: tokenize and parse in one step."""
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return Parser(tokenize(expr)).parse()
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# ---------- Basic parsing ----------
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def test_parse_number():
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ast = parse("42")
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assert isinstance(ast, NumberNode)
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assert ast.value == 42.0
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def test_parse_decimal():
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ast = parse("3.14")
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assert isinstance(ast, NumberNode)
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assert ast.value == 3.14
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def test_parse_addition():
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ast = parse("3 + 4")
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assert isinstance(ast, BinOpNode)
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assert ast.op == TokenType.PLUS
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assert isinstance(ast.left, NumberNode)
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assert isinstance(ast.right, NumberNode)
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# ---------- Precedence ----------
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def test_multiply_before_add():
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"""3 + 4 * 2 should parse as 3 + (4 * 2)."""
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ast = parse("3 + 4 * 2")
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assert ast.op == TokenType.PLUS
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assert isinstance(ast.right, BinOpNode)
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assert ast.right.op == TokenType.MULTIPLY
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def test_power_before_multiply():
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"""2 * 3 ^ 4 should parse as 2 * (3 ^ 4)."""
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ast = parse("2 * 3 ^ 4")
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assert ast.op == TokenType.MULTIPLY
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assert isinstance(ast.right, BinOpNode)
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assert ast.right.op == TokenType.POWER
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def test_parentheses_override_precedence():
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"""(3 + 4) * 2 should parse as (3 + 4) * 2."""
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ast = parse("(3 + 4) * 2")
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assert ast.op == TokenType.MULTIPLY
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assert isinstance(ast.left, BinOpNode)
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assert ast.left.op == TokenType.PLUS
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# ---------- Associativity ----------
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def test_left_associative_subtraction():
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"""10 - 3 - 2 should parse as (10 - 3) - 2."""
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ast = parse("10 - 3 - 2")
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assert ast.op == TokenType.MINUS
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assert isinstance(ast.left, BinOpNode)
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assert ast.left.op == TokenType.MINUS
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assert isinstance(ast.right, NumberNode)
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def test_power_right_associative():
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"""2 ^ 3 ^ 4 should parse as 2 ^ (3 ^ 4)."""
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ast = parse("2 ^ 3 ^ 4")
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assert ast.op == TokenType.POWER
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assert isinstance(ast.left, NumberNode)
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assert isinstance(ast.right, BinOpNode)
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assert ast.right.op == TokenType.POWER
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# ---------- Unary minus ----------
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def test_unary_minus():
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ast = parse("-3")
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assert isinstance(ast, UnaryOpNode)
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assert ast.operand.value == 3.0
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def test_double_negation():
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ast = parse("--3")
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assert isinstance(ast, UnaryOpNode)
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assert isinstance(ast.operand, UnaryOpNode)
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assert ast.operand.operand.value == 3.0
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def test_unary_minus_precedence():
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"""-3^2 should parse as -(3^2), not (-3)^2."""
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ast = parse("-3 ^ 2")
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assert isinstance(ast, UnaryOpNode)
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assert isinstance(ast.operand, BinOpNode)
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assert ast.operand.op == TokenType.POWER
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def test_unary_minus_in_expression():
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"""2 * -3 should parse as 2 * (-(3))."""
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ast = parse("2 * -3")
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assert ast.op == TokenType.MULTIPLY
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assert isinstance(ast.right, UnaryOpNode)
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# ---------- Nested parentheses ----------
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def test_nested_parens():
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ast = parse("((3))")
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assert isinstance(ast, NumberNode)
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assert ast.value == 3.0
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def test_complex_nesting():
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"""((2 + 3) * (7 - 2))"""
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ast = parse("((2 + 3) * (7 - 2))")
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assert isinstance(ast, BinOpNode)
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assert ast.op == TokenType.MULTIPLY
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# ---------- Errors ----------
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def test_missing_rparen():
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with pytest.raises(ParseError):
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parse("(3 + 4")
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def test_empty_expression():
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with pytest.raises(ParseError):
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parse("")
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def test_trailing_operator():
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with pytest.raises(ParseError):
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parse("3 +")
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def test_empty_parens():
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with pytest.raises(ParseError):
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parse("()")
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