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//! Module that defines the public evaluation API of [`Engine`].
use crate::eval::{Caches, GlobalRuntimeState};
use crate::func::native::locked_write;
use crate::parser::ParseState;
use crate::types::dynamic::Variant;
use crate::types::StringsInterner;
use crate::{
Dynamic, Engine, OptimizationLevel, Position, RhaiResult, RhaiResultOf, Scope, AST, ERR,
};
#[cfg(feature = "no_std")]
use std::prelude::v1::*;
use std::{
any::{type_name, TypeId},
mem,
};
impl Engine {
/// Evaluate a string as a script, returning the result value or an error.
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// use rhai::Engine;
///
/// let engine = Engine::new();
///
/// assert_eq!(engine.eval::<i64>("40 + 2")?, 42);
/// # Ok(())
/// # }
/// ```
#[inline(always)]
pub fn eval<T: Variant + Clone>(&self, script: &str) -> RhaiResultOf<T> {
self.eval_with_scope(&mut Scope::new(), script)
}
/// Evaluate a string as a script with own scope, returning the result value or an error.
///
/// ## Constants Propagation
///
/// If not [`OptimizationLevel::None`][crate::OptimizationLevel::None], constants defined within
/// the scope are propagated throughout the script _including_ functions.
///
/// This allows functions to be optimized based on dynamic global constants.
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// use rhai::{Engine, Scope};
///
/// let engine = Engine::new();
///
/// // Create initialized scope
/// let mut scope = Scope::new();
/// scope.push("x", 40_i64);
///
/// assert_eq!(engine.eval_with_scope::<i64>(&mut scope, "x += 2; x")?, 42);
/// assert_eq!(engine.eval_with_scope::<i64>(&mut scope, "x += 2; x")?, 44);
///
/// // The variable in the scope is modified
/// assert_eq!(scope.get_value::<i64>("x").expect("variable x should exist"), 44);
/// # Ok(())
/// # }
/// ```
#[inline]
pub fn eval_with_scope<T: Variant + Clone>(
&self,
scope: &mut Scope,
script: &str,
) -> RhaiResultOf<T> {
let ast = self.compile_with_scope_and_optimization_level(
Some(scope),
[script],
self.optimization_level,
)?;
self.eval_ast_with_scope(scope, &ast)
}
/// Evaluate a string containing an expression, returning the result value or an error.
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// use rhai::Engine;
///
/// let engine = Engine::new();
///
/// assert_eq!(engine.eval_expression::<i64>("40 + 2")?, 42);
/// # Ok(())
/// # }
/// ```
#[inline(always)]
pub fn eval_expression<T: Variant + Clone>(&self, script: &str) -> RhaiResultOf<T> {
self.eval_expression_with_scope(&mut Scope::new(), script)
}
/// Evaluate a string containing an expression with own scope, returning the result value or an error.
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// use rhai::{Engine, Scope};
///
/// let engine = Engine::new();
///
/// // Create initialized scope
/// let mut scope = Scope::new();
/// scope.push("x", 40_i64);
///
/// assert_eq!(engine.eval_expression_with_scope::<i64>(&mut scope, "x + 2")?, 42);
/// # Ok(())
/// # }
/// ```
#[inline]
pub fn eval_expression_with_scope<T: Variant + Clone>(
&self,
scope: &mut Scope,
script: &str,
) -> RhaiResultOf<T> {
let scripts = [script];
let ast = {
let mut interner;
let mut guard;
let interned_strings = if let Some(ref interner) = self.interned_strings {
guard = locked_write(interner);
&mut *guard
} else {
interner = StringsInterner::new();
&mut interner
};
let (stream, tc) = self.lex_raw(&scripts, self.token_mapper.as_deref());
let state = &mut ParseState::new(Some(scope), interned_strings, tc);
// No need to optimize a lone expression
self.parse_global_expr(
stream.peekable(),
state,
|_| {},
#[cfg(not(feature = "no_optimize"))]
OptimizationLevel::None,
#[cfg(feature = "no_optimize")]
<_>::default(),
)?
};
self.eval_ast_with_scope(scope, &ast)
}
/// Evaluate an [`AST`], returning the result value or an error.
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// use rhai::Engine;
///
/// let engine = Engine::new();
///
/// // Compile a script to an AST and store it for later evaluation
/// let ast = engine.compile("40 + 2")?;
///
/// // Evaluate it
/// assert_eq!(engine.eval_ast::<i64>(&ast)?, 42);
/// # Ok(())
/// # }
/// ```
#[inline(always)]
pub fn eval_ast<T: Variant + Clone>(&self, ast: &AST) -> RhaiResultOf<T> {
self.eval_ast_with_scope(&mut Scope::new(), ast)
}
/// Evaluate an [`AST`] with own scope, returning the result value or an error.
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// use rhai::{Engine, Scope};
///
/// let engine = Engine::new();
///
/// // Create initialized scope
/// let mut scope = Scope::new();
/// scope.push("x", 40_i64);
///
/// // Compile a script to an AST and store it for later evaluation
/// let ast = engine.compile("x += 2; x")?;
///
/// // Evaluate it
/// assert_eq!(engine.eval_ast_with_scope::<i64>(&mut scope, &ast)?, 42);
/// assert_eq!(engine.eval_ast_with_scope::<i64>(&mut scope, &ast)?, 44);
///
/// // The variable in the scope is modified
/// assert_eq!(scope.get_value::<i64>("x").expect("variable x should exist"), 44);
/// # Ok(())
/// # }
/// ```
#[inline]
pub fn eval_ast_with_scope<T: Variant + Clone>(
&self,
scope: &mut Scope,
ast: &AST,
) -> RhaiResultOf<T> {
let global = &mut GlobalRuntimeState::new(self);
let caches = &mut Caches::new();
let result = self.eval_ast_with_scope_raw(global, caches, scope, ast)?;
// Bail out early if the return type needs no cast
if TypeId::of::<T>() == TypeId::of::<Dynamic>() {
return Ok(reify! { result => T });
}
result.try_cast_raw::<T>().map_err(|v| {
let typename = match type_name::<T>() {
typ if typ.contains("::") => self.map_type_name(typ),
typ => typ,
};
ERR::ErrorMismatchOutputType(
typename.into(),
self.map_type_name(v.type_name()).into(),
Position::NONE,
)
.into()
})
}
/// Evaluate an [`AST`] with own scope, returning the result value or an error.
#[inline]
pub(crate) fn eval_ast_with_scope_raw(
&self,
global: &mut GlobalRuntimeState,
caches: &mut Caches,
scope: &mut Scope,
ast: &AST,
) -> RhaiResult {
let orig_source = mem::replace(&mut global.source, ast.source_raw().cloned());
#[cfg(not(feature = "no_function"))]
let orig_lib_len = global.lib.len();
#[cfg(not(feature = "no_function"))]
global.lib.push(ast.shared_lib().clone());
#[cfg(not(feature = "no_module"))]
let orig_embedded_module_resolver = mem::replace(
&mut global.embedded_module_resolver,
ast.resolver().cloned(),
);
defer! { global => move |g| {
#[cfg(not(feature = "no_module"))]
{
g.embedded_module_resolver = orig_embedded_module_resolver;
}
#[cfg(not(feature = "no_function"))]
g.lib.truncate(orig_lib_len);
g.source = orig_source;
}}
let r = self.eval_global_statements(global, caches, scope, ast.statements(), true)?;
#[cfg(feature = "debugging")]
if self.is_debugger_registered() {
global.debugger_mut().status = crate::eval::DebuggerStatus::Terminate;
let node = &crate::ast::Stmt::Noop(Position::NONE);
self.run_debugger(global, caches, scope, None, node)?;
}
Ok(r)
}
}
/// Evaluate a string as a script, returning the result value or an error.
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// let result: i64 = rhai::eval("40 + 2")?;
///
/// assert_eq!(result, 42);
/// # Ok(())
/// # }
/// ```
#[inline(always)]
pub fn eval<T: Variant + Clone>(script: &str) -> RhaiResultOf<T> {
Engine::new().eval(script)
}