Project 3 - Switch Statement

[PauloV1]

Grupo

• Joana D'arc
• Juliana Silva
• Leandro Luiz
• Paulo Vitor
• Thiago Henrique

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Summary

Introduce full syntactic support for switch statements, including AST integration, parser validation rules, and comprehensive test coverage.

This PR implements the switch construct end-to-end at the parsing level, enforcing structural constraints such as mandatory default, at least one case, and valid literal conditions. It also includes extensive tests covering valid scenarios, nesting, and failure cases to ensure parser robustness.

Additionally, it introduces minor developer tooling improvements to simplify local execution of the project.

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Changes Made

AST (ast.rs)

• Add the Statement::Switch variant
• Represent the switch with:
  • a target expression
  • a list of cases (Literal, Vec<Statement>)
  • a mandatory default block

Parser (statements.rs)

• Add parsing support for switch statements
• Supported syntax:
  • switch_stmt = "switch" expr "{" case+ default "}" ;
  • case = "case" literal ":" stmt+ ;
  • default = "default" ":" stmt+ ;
• Constraints enforced:
  • At least one case
  • Exactly one mandatory default
  • Each case/default block contains ≥1 statement
• Support integer (Int) and boolean (Bool) literals in case conditions

Type Checker & Interpreter

• Add todo!() stubs for Statement::Switch to satisfy exhaustive matching
• Keep the project compiling while semantic analysis and evaluation are implemented later

Tooling & Environment

• Add scripts/minic wrapper for easier execution
• Add .envrc for automatic environment setup via direnv
• Enable local usage of the minic command as documented in the README

Tests (parser.rs)

The following tests validate parsing correctness, structure, nesting, and error handling:

• Valid parsing scenarios:

  • test_switch_statement
  • test_switch_multiple_cases
  • test_switch_multiple_statements
  • test_switch_multiple_cases_and_statements
  • test_switch_boolean_cases
  • test_switch_whitespace

• Structural integration:

  • test_switch_in_function
  • test_switch_in_if
  • test_switch_in_while

• Error handling:

  • test_switch_multiple_defaults_err
  • test_switch_no_default_err
  • test_switch_no_cases_err
  • test_switch_non_expression_err

• Invalid case definitions:

  • test_switch_invalid_case_literal

• Invalid syntax detection:

  • test_switch_invalid_syntax

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Next Steps (out of scope for this PR)

• Add type checking support for the switch statement
• Add interpreter support for the switch statement