REPL Support - Group 5

[JohnnySpider]

Documentation

Group Members

• João Pedro Daher Aranha - 190109742
• João Ubirajara - 211055399
• Kauan Henrique - 221017050
• Paulo Filho - 200025937
• Ramon Oliveira de Azevedo - 242039630

Summary

This pull request implements Read-Eval-Print Loop (REPL) and Command Line Interface (CLI) to the R-Python language.

• The command to generate an executable for RPython is cargo run --release and the generated executable is in r-python-REPL/target/release
• To run a r-python program via cli, the command is cargo run -- --exec path_to_r-python_file or ./r-python --exec path_to_r-python_file. The cli outputs by default the environment before and after execution, since the 'print' statement was not yet available.
• REPL is initialized via ./r-python and expects ';' as end character to every line provided to the program. This decision was used so that REPL supports multiline statements like 'IfThenElse'.
• cargo run -- -h or ./r-python -h shows all available options to run.
• The REPL is integrated to type_checker via check_exp and check_stmt functions

Functions

• main.rs function can invoke repl() or cli() depending on the arguments provided.

pub fn repl( env: Option<Environment<EnvValue>>,env_type: Option<Environment<Type>>) -> io::Result<()>

pub fn cli(file_path: &String) -> io::Result<()>

REPL functions

fn repl_parse_expression(input: &str,current_env: &Environment<EnvValue>,current_env_type: &Environment<Type>) -> Result<String, String>

fn repl_parse_statements(input: &str, mut current_env: Environment<EnvValue>, mut current_env_type: Environment<Type>) -> Result<(Environment<EnvValue>, Environment<Type>), String>

Each function takes an input string, along with two environments: one for variable names and values (Environment<EnvValue>) and one for variable types (Environment<Type>). Since only assignments modify the environment, only the second function arguments are mutable.

The repl_parse_statement returns a tuple (Environment <EnvValue>, Environment<Type>), which is verified in tests.

Features

Inline rpython via CLI

Usage: cargo run -- -c "10+10" or ./rpython -c "10+10"

Executes file and loads environment in REPL

Usage: cargo run -- --exec path_to_rpython_file -i or ./rpython --exec path_to_rpython_file -i

Supports internal commands in REPL preceded by !:

• !exit: Terminates the REPL session.
• !reset: Resets the execution environment.
• !clear: Clears the screen.
• !help: Displays available commands.

Tests

• The functionalitites where tested through 18 tests in repl.rs, which integrates both interpreter and type checker verifications.
• The language enforces that a variable’s type is fixed after its first assignment. For example, the statement a=10 followed by a=True will result in a type mismatch error.

Other fixes

• Updated tests: test_propagation_parsing_statements() and check_assignment_error1() have been modified to ensure that types are handled by the type checker (inference), rather than by the parser.