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config.rs
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config.rs
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// EndBASIC
// Copyright 2020 Julio Merino
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy
// of the License at:
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations
// under the License.
//! Configuration file parser using an EndBASIC interpreter.
//!
//! This example sets up a minimal EndBASIC interpreter and uses it to parse what could be a
//! configuration file. Because the interpreter is configured without any commands or functions,
//! the scripted code cannot call back into Rust land, so the script's execution is guaranteed to
//! not have side-effects.
use endbasic_core::exec::{Machine, StopReason};
use futures_lite::future::block_on;
/// Sample configuration file to parse.
const INPUT: &str = r#"
foo_value = 123
enable_bar = (foo_value > 122)
'enable_baz = "this is commented out"
"#;
fn main() {
// Create an empty machine.
let mut machine = Machine::default();
// Execute the sample script. All this script can do is modify the state of the machine itself.
// In other words: the script can set variables in the machine's environment, but that's it.
loop {
match block_on(machine.exec(&mut INPUT.as_bytes())).expect("Execution error") {
StopReason::Eof => break,
StopReason::Exited(i) => println!("Script explicitly exited with code {}", i),
StopReason::Break => (), // Ignore signals.
}
}
// Now that our script has run, inspect the variables it set on the machine.
match machine.get_var_as_int("foo_value") {
Ok(i) => println!("foo_value is {}", i),
Err(e) => println!("Input did not contain foo_value: {}", e),
}
match machine.get_var_as_bool("enable_bar") {
Ok(b) => println!("enable_bar is {}", b),
Err(e) => println!("Input did not contain enable_bar: {}", e),
}
match machine.get_var_as_string("enable_baz") {
Ok(b) => println!("enable_bar is {}", b),
Err(e) => println!("enable_baz is not set: {}", e),
}
}