140 lines
3.8 KiB
Rust
140 lines
3.8 KiB
Rust
//! Implementation of the Event Handler With State Pattern - Main Style
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#[cfg(feature = "no_function")]
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pub fn main() {
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panic!("This example does not run under 'no_function'.")
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}
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#[cfg(not(feature = "no_function"))]
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pub fn main() {
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use rhai::{CallFnOptions, Dynamic, Engine, Scope, AST};
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use std::io::{stdin, stdout, Write};
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const SCRIPT_FILE: &str = "event_handler_main/script.rhai";
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#[derive(Debug)]
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struct Handler {
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pub engine: Engine,
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pub scope: Scope<'static>,
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pub ast: AST,
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}
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fn print_scope(scope: &Scope) {
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for (i, (name, constant, value)) in scope.iter_raw().enumerate() {
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#[cfg(not(feature = "no_closure"))]
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let value_is_shared = if value.is_shared() { " (shared)" } else { "" };
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#[cfg(feature = "no_closure")]
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let value_is_shared = "";
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println!(
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"[{}] {}{}{} = {:?}",
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i + 1,
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if constant { "const " } else { "" },
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name,
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value_is_shared,
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*value.read_lock::<Dynamic>().unwrap(),
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)
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}
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println!();
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}
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println!("Events Handler Example - Main Style");
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println!("===================================");
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let mut input = String::new();
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// Read script file
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print!("Script file [{SCRIPT_FILE}]: ");
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stdout().flush().expect("flush stdout");
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input.clear();
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stdin().read_line(&mut input).expect("read input");
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let path = match input.trim() {
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"" => SCRIPT_FILE,
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path => path,
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};
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// Create Engine
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let engine = Engine::new();
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// Create a custom 'Scope' to hold state
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let mut scope = Scope::new();
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// Add any system-provided state into the custom 'Scope'.
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// Constants can be used to optimize the script.
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scope.push_constant("MY_CONSTANT", 42_i64);
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// Compile the handler script.
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println!("> Loading script file: {path}");
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let ast = match engine.compile_file_with_scope(&scope, path.into()) {
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Ok(ast) => ast,
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Err(err) => {
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eprintln!("! Error: {}", err);
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println!("Cannot continue. Bye!");
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return;
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}
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};
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println!("> Script file loaded.");
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println!();
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println!("quit = exit program");
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println!("scope = print scope");
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println!("event arg = run function with argument");
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println!();
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// Run the 'init' function to initialize the state, retaining variables.
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let options = CallFnOptions::new().eval_ast(false).rewind_scope(false);
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let result = engine.call_fn_with_options::<()>(options, &mut scope, &ast, "init", ());
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if let Err(err) = result {
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eprintln!("! {err}")
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}
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// Create handler instance
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let mut handler = Handler { engine, scope, ast };
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// Events loop
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loop {
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print!("event> ");
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stdout().flush().expect("flush stdout");
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// Read event
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input.clear();
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stdin().read_line(&mut input).expect("read input");
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let mut fields = input.trim().splitn(2, ' ');
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let event = fields.next().expect("event").trim();
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let arg = fields.next().unwrap_or("").to_string();
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// Process event
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match event {
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"quit" => break,
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"scope" => {
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print_scope(&handler.scope);
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continue;
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}
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// Map all other events to function calls
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_ => {
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let engine = &handler.engine;
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let scope = &mut handler.scope;
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let ast = &handler.ast;
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let result = engine.call_fn::<()>(scope, ast, event, (arg,));
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if let Err(err) = result {
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eprintln!("! {err}")
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}
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}
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}
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}
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println!("Bye!");
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}
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