89 lines
2.3 KiB
Rust
89 lines
2.3 KiB
Rust
use rhai::{Engine, EvalAltResult, Scope, AST};
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use std::{
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io::{stdin, stdout, Write},
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iter,
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};
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fn print_error(input: &str, err: EvalAltResult) {
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fn padding(pad: &str, len: usize) -> String {
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iter::repeat(pad).take(len).collect::<String>()
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}
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let lines: Vec<_> = input.split("\n").collect();
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// Print error
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match err.position() {
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p if p.is_eof() => {
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// EOF
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let last = lines[lines.len() - 2];
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println!("{}", last);
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println!("{}^ {}", padding(" ", last.len() - 1), err);
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}
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p if p.is_none() => {
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// No position
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println!("{}", err);
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}
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p => {
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// Specific position
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let pos_text = format!(
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" (line {}, position {})",
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p.line().unwrap(),
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p.position().unwrap()
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);
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println!("{}", lines[p.line().unwrap() - 1]);
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println!(
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"{}^ {}",
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padding(" ", p.position().unwrap() - 1),
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err.to_string().replace(&pos_text, "")
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);
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}
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}
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}
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fn main() {
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let mut engine = Engine::new();
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let mut scope = Scope::new();
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let mut input = String::new();
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let mut ast: Option<AST> = None;
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loop {
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print!("rhai> ");
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stdout().flush().expect("couldn't flush stdout");
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input.clear();
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if let Err(err) = stdin().read_line(&mut input) {
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println!("input error: {}", err);
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}
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// Implement standard commands
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match input.as_str().trim() {
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"exit" | "quit" => break, // quit
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"ast" => {
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// print the last AST
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match &ast {
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Some(ast) => println!("{:#?}", ast),
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None => println!("()"),
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}
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continue;
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}
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_ => (),
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}
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if let Err(err) = engine
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.compile(&input)
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.map_err(EvalAltResult::ErrorParsing)
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.and_then(|r| {
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ast = Some(r);
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engine.consume_ast_with_scope(&mut scope, true, ast.as_ref().unwrap())
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})
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{
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println!("");
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print_error(&input, err);
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println!("");
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}
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}
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}
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