Crate rhai

Rhai - embedded scripting for Rust

Rhai is a tiny, simple and very fast embedded scripting language for Rust that gives you a safe and easy way to add scripting to your applications. It provides a familiar syntax based on JavaScript and Rust and a simple Rust interface. Here is a quick example.

First, the contents of my_script.rhai:

// Brute force factorial function
fn factorial(x) {
    if x == 1 { return 1; }
    x * factorial(x - 1)
}

// Calling an external function 'compute'
compute(factorial(10))

And the Rust part:

use rhai::{Engine, EvalAltResult, RegisterFn};

fn main() -> Result<(), Box<EvalAltResult>>
{
    // Define external function
    fn compute_something(x: i64) -> bool {
        (x % 40) == 0
    }

    // Create scripting engine
    let mut engine = Engine::new();

    // Register external function as 'compute'
    engine.register_fn("compute", compute_something);

    assert_eq!(
        // Evaluate the script, expects a 'bool' return
        engine.eval_file::<bool>("my_script.rhai".into())?,
        true
    );

    Ok(())
}

Documentation

See The Rhai Book for details on the Rhai script engine and language.

Modules

de	Deserialization support for serde.
module_resolvers	Module containing all built-in module resolvers available to Rhai.
packages	Module containing all built-in packages available to Rhai, plus facilities to define custom packages.
ser	Serialization support for serde.

Macros

def_package

Macro that makes it easy to define a package (which is basically a shared module) and register functions into it.

Structs

AST	Compiled AST (abstract syntax tree) of a Rhai script.
CustomExpr	[INTERNALS] A type wrapping a custom syntax definition. Exported under the internals feature only.
Dynamic	Dynamic type containing any value.
Engine	Rhai main scripting engine.
EvalContext	Context of a script evaluation process.
EvalState	[INTERNALS] A type that holds all the current states of the Engine. Exported under the internals feature only.
Expression	An expression sub-tree in an AST.
FloatWrapper	[INTERNALS] A type wrapping a floating-point number. Exported under the internals feature only.
FnPtr	A general function pointer, which may carry additional (i.e. curried) argument values to be passed onto a function during a call.
ImmutableString	The system immutable string type.
Limits	[INTERNALS] A type containing all the limits imposed by the Engine. Exported under the internals feature only.
Module	An imported module, which may contain variables, sub-modules, external Rust functions, and script-defined functions.
ModuleRef	[INTERNALS] A chain of module names to qualify a variable or function call. Exported under the internals feature only.
ParseError	Error when parsing a script.
Position	A location (line number + character position) in the input script.
Scope	Type containing information about the current scope. Useful for keeping state between Engine evaluation runs.
ScriptFnDef	[INTERNALS] A type containing information on a scripted function. Exported under the internals feature only.
TokenizeState	[INTERNALS] State of the tokenizer. Exported under the internals feature only.

Enums

EvalAltResult	Evaluation result.
Expr	[INTERNALS] An expression sub-tree. Exported under the internals feature only.
FnAccess	A type representing the access mode of a scripted function.
LexError	[INTERNALS] Error encountered when tokenizing the script text. Exported under the internals feature only.
OptimizationLevel	Level of optimization performed.
ParseErrorType	Type of error encountered when parsing a script.
ReturnType	[INTERNALS] A type encapsulating the mode of a return/throw statement. Exported under the internals feature only.
Stmt	[INTERNALS] A Rhai statement. Exported under the internals feature only.
Token	[INTERNALS] A Rhai language token. Exported under the internals feature only.

Traits

Func	Trait to create a Rust anonymous function from a script.
InputStream	[INTERNALS] Trait that encapsulates a peekable character input stream. Exported under the internals feature only.
ModuleResolver	Trait that encapsulates a module resolution service.
RegisterFn	Trait to register custom functions with the Engine.
RegisterResultFn	Trait to register fallible custom functions returning Result<Dynamic, Box<EvalAltResult>> with the Engine.

Functions

calc_fn_hash	Calculate a u64 hash key from a module-qualified function name and parameter types.
get_next_token	[INTERNALS] Get the next token from the InputStream. Exported under the internals feature only.
parse_string_literal	[INTERNALS] Parse a string literal wrapped by enclosing_char. Exported under the internals feature only.

Type Definitions

Array	Variable-sized array of Dynamic values.
FLOAT	The system floating-point type.
INT	The system integer type.
Imports	[INTERNALS] A stack of imported modules. Exported under the internals feature only.
IteratorFn	A standard function that gets an iterator from a type.
Map	Hash map of Dynamic values with ImmutableString keys.
StaticVec	[INTERNALS] Alias to smallvec::SmallVec<[T; 4]>, which is a specialized Vec backed by a small, fixed-size array when there are <= 4 items stored. Exported under the internals feature only.