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//! Module that defines public event handlers for [`Engine`].
use crate::func::SendSync;
use crate::{Dynamic, Engine, EvalContext, Position, RhaiResultOf, VarDefInfo};
#[cfg(feature = "no_std")]
use std::prelude::v1::*;
impl Engine {
/// Provide a callback that will be invoked before each variable access.
///
/// # WARNING - Unstable API
///
/// This API is volatile and may change in the future.
///
/// # Callback Function Signature
///
/// `Fn(name: &str, index: usize, context: EvalContext) -> Result<Option<Dynamic>, Box<EvalAltResult>>`
///
/// where:
/// * `name`: name of the variable.
/// * `index`: an offset from the bottom of the current [`Scope`][crate::Scope] that the
/// variable is supposed to reside. Offsets start from 1, with 1 meaning the last variable in
/// the current [`Scope`][crate::Scope]. Essentially the correct variable is at position
/// `scope.len() - index`. If `index` is zero, then there is no pre-calculated offset position
/// and a search through the current [`Scope`][crate::Scope] must be performed.
/// * `context`: the current [evaluation context][`EvalContext`].
///
/// ## Return value
///
/// * `Ok(None)`: continue with normal variable access.
/// * `Ok(Some(Dynamic))`: the variable's value.
///
/// ## Raising errors
///
/// Return `Err(...)` if there is an error.
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// use rhai::Engine;
///
/// let mut engine = Engine::new();
///
/// // Register a variable resolver.
/// engine.on_var(|name, _, _| {
/// match name {
/// "MYSTIC_NUMBER" => Ok(Some(42_i64.into())),
/// _ => Ok(None)
/// }
/// });
///
/// engine.eval::<i64>("MYSTIC_NUMBER")?;
///
/// # Ok(())
/// # }
/// ```
#[deprecated = "This API is NOT deprecated, but it is considered volatile and may change in the future."]
#[inline(always)]
pub fn on_var(
&mut self,
callback: impl Fn(&str, usize, EvalContext) -> RhaiResultOf<Option<Dynamic>>
+ SendSync
+ 'static,
) -> &mut Self {
self.resolve_var = Some(Box::new(callback));
self
}
/// Provide a callback that will be invoked before the definition of each variable .
///
/// # WARNING - Unstable API
///
/// This API is volatile and may change in the future.
///
/// # Callback Function Signature
///
/// `Fn(is_runtime: bool, info: VarInfo, context: EvalContext) -> Result<bool, Box<EvalAltResult>>`
///
/// where:
/// * `is_runtime`: `true` if the variable definition event happens during runtime, `false` if during compilation.
/// * `info`: information on the variable.
/// * `context`: the current [evaluation context][`EvalContext`].
///
/// ## Return value
///
/// * `Ok(true)`: continue with normal variable definition.
/// * `Ok(false)`: deny the variable definition with an [runtime error][crate::EvalAltResult::ErrorRuntime].
///
/// ## Raising errors
///
/// Return `Err(...)` if there is an error.
///
/// # Example
///
/// ```should_panic
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// use rhai::Engine;
///
/// let mut engine = Engine::new();
///
/// // Register a variable definition filter.
/// engine.on_def_var(|_, info, _| {
/// // Disallow defining MYSTIC_NUMBER as a constant
/// if info.name() == "MYSTIC_NUMBER" && info.is_const() {
/// Ok(false)
/// } else {
/// Ok(true)
/// }
/// });
///
/// // The following runs fine:
/// engine.eval::<i64>("let MYSTIC_NUMBER = 42;")?;
///
/// // The following will cause an error:
/// engine.eval::<i64>("const MYSTIC_NUMBER = 42;")?;
///
/// # Ok(())
/// # }
/// ```
#[deprecated = "This API is NOT deprecated, but it is considered volatile and may change in the future."]
#[inline(always)]
pub fn on_def_var(
&mut self,
callback: impl Fn(bool, VarDefInfo, EvalContext) -> RhaiResultOf<bool> + SendSync + 'static,
) -> &mut Self {
self.def_var_filter = Some(Box::new(callback));
self
}
/// _(internals)_ Register a callback that will be invoked during parsing to remap certain tokens.
/// Exported under the `internals` feature only.
///
/// # WARNING - Unstable API
///
/// This API is volatile and may change in the future.
///
/// # Callback Function Signature
///
/// `Fn(token: Token, pos: Position, state: &TokenizeState) -> Token`
///
/// where:
/// * [`token`][crate::tokenizer::Token]: current token parsed
/// * [`pos`][`Position`]: location of the token
/// * [`state`][crate::tokenizer::TokenizeState]: current state of the tokenizer
///
/// ## Raising errors
///
/// It is possible to raise a parsing error by returning
/// [`Token::LexError`][crate::tokenizer::Token::LexError] as the mapped token.
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// use rhai::{Engine, Token};
///
/// let mut engine = Engine::new();
///
/// // Register a token mapper.
/// # #[allow(deprecated)]
/// engine.on_parse_token(|token, _, _| {
/// match token {
/// // Convert all integer literals to strings
/// Token::IntegerConstant(n) => Token::StringConstant(Box::new(n.to_string().into())),
/// // Convert 'begin' .. 'end' to '{' .. '}'
/// Token::Identifier(s) if &*s == "begin" => Token::LeftBrace,
/// Token::Identifier(s) if &*s == "end" => Token::RightBrace,
/// // Pass through all other tokens unchanged
/// _ => token
/// }
/// });
///
/// assert_eq!(engine.eval::<String>("42")?, "42");
/// assert_eq!(engine.eval::<bool>("true")?, true);
/// assert_eq!(engine.eval::<String>("let x = 42; begin let x = 0; end; x")?, "42");
///
/// # Ok(())
/// # }
/// ```
#[deprecated = "This API is NOT deprecated, but it is considered volatile and may change in the future."]
#[cfg(feature = "internals")]
#[inline(always)]
pub fn on_parse_token(
&mut self,
callback: impl Fn(
crate::tokenizer::Token,
Position,
&crate::tokenizer::TokenizeState,
) -> crate::tokenizer::Token
+ SendSync
+ 'static,
) -> &mut Self {
self.token_mapper = Some(Box::new(callback));
self
}
/// Register a callback for script evaluation progress.
///
/// Not available under `unchecked`.
///
/// # Callback Function Signature
///
/// `Fn(counter: u64) -> Option<Dynamic>`
///
/// ## Return value
///
/// * `None`: continue running the script.
/// * `Some(Dynamic)`: terminate the script with the specified exception value.
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// # use std::sync::RwLock;
/// # use std::sync::Arc;
/// use rhai::Engine;
///
/// let result = Arc::new(RwLock::new(0_u64));
/// let logger = result.clone();
///
/// let mut engine = Engine::new();
///
/// engine.on_progress(move |ops| {
/// if ops > 1000 {
/// Some("Over 1,000 operations!".into())
/// } else if ops % 123 == 0 {
/// *logger.write().unwrap() = ops;
/// None
/// } else {
/// None
/// }
/// });
///
/// engine.run("for x in 0..5000 { print(x); }")
/// .expect_err("should error");
///
/// assert_eq!(*result.read().unwrap(), 984);
///
/// # Ok(())
/// # }
/// ```
#[cfg(not(feature = "unchecked"))]
#[inline(always)]
pub fn on_progress(
&mut self,
callback: impl Fn(u64) -> Option<Dynamic> + SendSync + 'static,
) -> &mut Self {
self.progress = Some(Box::new(callback));
self
}
/// Override default action of `print` (print to stdout using [`println!`])
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// # use std::sync::RwLock;
/// # use std::sync::Arc;
/// use rhai::Engine;
///
/// let result = Arc::new(RwLock::new(String::new()));
///
/// let mut engine = Engine::new();
///
/// // Override action of 'print' function
/// let logger = result.clone();
/// engine.on_print(move |s| logger.write().unwrap().push_str(s));
///
/// engine.run("print(40 + 2);")?;
///
/// assert_eq!(*result.read().unwrap(), "42");
/// # Ok(())
/// # }
/// ```
#[inline(always)]
pub fn on_print(&mut self, callback: impl Fn(&str) + SendSync + 'static) -> &mut Self {
self.print = Some(Box::new(callback));
self
}
/// Override default action of `debug` (print to stdout using [`println!`])
///
/// # Callback Function Signature
///
/// The callback function signature passed takes the following form:
///
/// `Fn(text: &str, source: Option<&str>, pos: Position)`
///
/// where:
/// * `text`: the text to display
/// * `source`: current source, if any
/// * [`pos`][`Position`]: location of the `debug` call
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// # use std::sync::RwLock;
/// # use std::sync::Arc;
/// use rhai::Engine;
///
/// let result = Arc::new(RwLock::new(String::new()));
///
/// let mut engine = Engine::new();
///
/// // Override action of 'print' function
/// let logger = result.clone();
/// engine.on_debug(move |s, src, pos| logger.write().unwrap().push_str(
/// &format!("{} @ {:?} > {}", src.unwrap_or("unknown"), pos, s)
/// ));
///
/// let mut ast = engine.compile(r#"let x = "hello"; debug(x);"#)?;
/// ast.set_source("world");
/// engine.run_ast(&ast)?;
///
/// #[cfg(not(feature = "no_position"))]
/// assert_eq!(*result.read().unwrap(), r#"world @ 1:18 > "hello""#);
/// #[cfg(feature = "no_position")]
/// assert_eq!(*result.read().unwrap(), r#"world @ none > "hello""#);
/// # Ok(())
/// # }
/// ```
#[inline(always)]
pub fn on_debug(
&mut self,
callback: impl Fn(&str, Option<&str>, Position) + SendSync + 'static,
) -> &mut Self {
self.debug = Some(Box::new(callback));
self
}
/// _(debugging)_ Register a callback for debugging.
/// Exported under the `debugging` feature only.
///
/// # WARNING - Unstable API
///
/// This API is volatile and may change in the future.
#[deprecated = "This API is NOT deprecated, but it is considered volatile and may change in the future."]
#[cfg(feature = "debugging")]
#[inline(always)]
pub fn register_debugger(
&mut self,
init: impl Fn(&Self, crate::debugger::Debugger) -> crate::debugger::Debugger
+ SendSync
+ 'static,
callback: impl Fn(
EvalContext,
crate::eval::DebuggerEvent,
crate::ast::ASTNode,
Option<&str>,
Position,
) -> RhaiResultOf<crate::eval::DebuggerCommand>
+ SendSync
+ 'static,
) -> &mut Self {
self.debugger_interface = Some((Box::new(init), Box::new(callback)));
self
}
}