Parser Improvements for Expressions

[lwgray]

Parser Improvements for Expressions

This PR fixes issues with parsing parenthesized expressions and unary operations, while adding comprehensive test coverage for expression evaluation.

Changes

Parser Updates

• Added explicit handling of parenthesized expressions in grammar rules
• Fixed unary minus operation handling
• Simplified primary expression rules
• Improved operator precedence handling

Interpreter Updates

• Added dedicated handling for unary minus operations in evaluate_operation
• Modified operation evaluation to check operator type before accessing operands

New Tests

Added TestExpressionEvaluation class with test cases for:

• Basic parenthesized expressions (e.g., 2 * (3 + 4))
• Nested unary operations (e.g., - -42)
• Complex nested expressions (e.g., (a + b) * (c - d))
• Proper operator precedence

Testing

All tests pass, including new test cases that verify:

• Correct evaluation of basic arithmetic with parentheses
• Proper handling of unary minus operations
• Complex nested expressions with multiple operators
• Operator precedence rules

Notes for Reviewers

Key areas to review:

1. Grammar rule changes in parser.py
2. Unary operation handling in interpreter.py
3. Comprehensive test coverage in test_integration.py