diff --git a/libconlang/examples/interpret.rs b/libconlang/examples/interpret.rs index e34a464..5c2f732 100644 --- a/libconlang/examples/interpret.rs +++ b/libconlang/examples/interpret.rs @@ -1,5 +1,10 @@ //! This example grabs input from stdin or a file, lexes it, parses it, and interprets it -use conlang::{interpreter::Interpreter, lexer::Lexer, parser::Parser}; +use conlang::{ + ast::{expression::Expr, Start}, + interpreter::Interpreter, + lexer::Lexer, + parser::Parser, +}; use std::{ error::Error, io::{stdin, stdout, IsTerminal, Write}, @@ -28,27 +33,48 @@ impl Config { } } +macro_rules! prompt { + ($($t:tt)*) => {{ + let mut out = stdout().lock(); + out.write_all(b"\x1b[36m")?; + write!(out, $($t)*)?; + out.write_all(b"\x1b[0m")?; + out.flush() + }}; +} + fn take_stdin() -> Result<(), Box> { - const PROMPT: &str = "> "; + const CONLANG: &str = "cl>"; + const MOREPLS: &str = " ?>"; if stdin().is_terminal() { let mut interpreter = Interpreter::new(); let mut buf = String::new(); - print!("{PROMPT}"); - stdout().flush()?; + prompt!("{CONLANG} ")?; while let Ok(len) = stdin().read_line(&mut buf) { - match len { - 0 => { + let code = Program::parse(&buf); + match (len, code) { + // Exit the loop + (0, _) => { println!(); break; } - 1 => { - let _ = run(&buf, &mut interpreter).map_err(|e| eprintln!("{e}")); - print!("\n{PROMPT}"); + // If the code is OK, run it and print any errors + (_, Ok(code)) => { + let _ = code.run(&mut interpreter).map_err(|e| eprintln!("{e}")); buf.clear(); } - _ => print!(". "), + // If the user types two newlines, print syntax errors + (1, Err(e)) => { + eprintln!("{e}"); + buf.clear(); + } + // Otherwise, ask for more input + _ => { + prompt!("{MOREPLS} ")?; + continue; + } } - stdout().flush()?; + prompt!("{CONLANG} ")?; } } else { run_file(&std::io::read_to_string(stdin())?, None)? @@ -66,16 +92,28 @@ fn run_file(file: &str, path: Option<&Path>) -> Result<(), Box> { Ok(()) } -fn run(input: &str, interpreter: &mut Interpreter) -> Result<(), Box> { - // If it parses successfully as a program, run the program - let ast = Parser::from(Lexer::new(input)).parse(); - if let Ok(ast) = ast { - interpreter.interpret(&ast)?; - return Ok(()); - } - let ast = Parser::from(Lexer::new(input)).parse_expr()?; - for value in interpreter.eval(&ast)? { - println!("{value}"); - } - Ok(()) +enum Program { + Program(Start), + Expr(Expr), +} + +impl Program { + fn parse(input: &str) -> conlang::parser::error::PResult { + let ast = Parser::from(Lexer::new(input)).parse(); + if let Ok(ast) = ast { + return Ok(Self::Program(ast)); + } + Ok(Self::Expr(Parser::from(Lexer::new(input)).parse_expr()?)) + } + fn run(&self, interpreter: &mut Interpreter) -> conlang::interpreter::error::IResult<()> { + match self { + Program::Program(start) => interpreter.interpret(start), + Program::Expr(expr) => { + for value in interpreter.eval(expr)? { + println!("{value}") + } + Ok(()) + } + } + } }