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//! Module that defines the public evaluation API of [`Engine`].
use crate::eval::{Caches, GlobalRuntimeState};
use crate::parser::ParseState;
use crate::types::dynamic::Variant;
use crate::{
Dynamic, Engine, OptimizationLevel, Position, RhaiResult, RhaiResultOf, Scope, AST, ERR,
};
use std::any::type_name;
#[cfg(feature = "no_std")]
use std::prelude::v1::*;
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(
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 (stream, tokenizer_control) =
self.lex_raw(&scripts, self.token_mapper.as_ref().map(<_>::as_ref));
let mut state = ParseState::new(self, scope, Default::default(), tokenizer_control);
// No need to optimize a lone expression
let ast = self.parse_global_expr(
&mut stream.peekable(),
&mut state,
#[cfg(not(feature = "no_optimize"))]
OptimizationLevel::None,
#[cfg(feature = "no_optimize")]
OptimizationLevel::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 result = self.eval_ast_with_scope_raw(scope, global, ast, 0)?;
#[cfg(feature = "debugging")]
if self.debugger.is_some() {
global.debugger.status = crate::eval::DebuggerStatus::Terminate;
let lib = &[
#[cfg(not(feature = "no_function"))]
ast.as_ref(),
];
let node = &crate::ast::Stmt::Noop(Position::NONE);
self.run_debugger(scope, global, lib, &mut None, node, 0)?;
}
let typ = self.map_type_name(result.type_name());
result.try_cast::<T>().ok_or_else(|| {
let t = self.map_type_name(type_name::<T>()).into();
ERR::ErrorMismatchOutputType(t, typ.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<'a>(
&self,
scope: &mut Scope,
global: &mut GlobalRuntimeState,
ast: &'a AST,
level: usize,
) -> RhaiResult {
let mut caches = Caches::new();
global.source = ast.source_raw().clone();
#[cfg(not(feature = "no_module"))]
let orig_embedded_module_resolver = std::mem::replace(
&mut global.embedded_module_resolver,
ast.resolver().cloned(),
);
let statements = ast.statements();
if statements.is_empty() {
return Ok(Dynamic::UNIT);
}
let mut _lib = &[
#[cfg(not(feature = "no_function"))]
ast.as_ref(),
][..];
#[cfg(not(feature = "no_function"))]
if !ast.has_functions() {
_lib = &[];
}
let result =
self.eval_global_statements(scope, global, &mut caches, statements, _lib, level);
#[cfg(not(feature = "no_module"))]
{
global.embedded_module_resolver = orig_embedded_module_resolver;
}
result
}
/// _(internals)_ Evaluate a list of statements with no `this` pointer.
/// Exported under the `internals` feature only.
///
/// This is commonly used to evaluate a list of statements in an [`AST`] or a script function body.
///
/// # WARNING - Low Level API
///
/// This function is very low level.
#[cfg(feature = "internals")]
#[inline(always)]
pub fn eval_statements_raw(
&self,
scope: &mut Scope,
global: &mut GlobalRuntimeState,
caches: &mut Caches,
statements: &[crate::ast::Stmt],
lib: &[&crate::Module],
level: usize,
) -> RhaiResult {
self.eval_global_statements(scope, global, caches, statements, lib, level)
}
}
/// 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)
}