Crate rhai

Rhai - embedded scripting for Rust

Rhai is a tiny, simple and 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 scripting engine and language.

Modules

module_resolvers	Re-export module resolvers.
packages	Module containing all built-in packages available to Rhai, plus facilities to define custom packages.
plugin	Module defining macros for developing plugins.
serde	(SERDE) Serialization and deserialization support for serde. Exported under the serde feature.

Macros

combine_with_exported_module	Macro to combine a plugin module into an existing module.
def_package	Macro that makes it easy to define a package (which is basically a shared module) and register functions into it.
exported_module	Macro to generate a Rhai Module from a plugin module defined via #[export_module].
register_exported_fn	Macro to register a plugin function (defined via #[export_fn]) into an Engine.
set_exported_fn	Macro to register a plugin function into a Rhai Module.
set_exported_global_fn	Macro to register a plugin function into a Rhai Module and expose it globally.

Structs

AST	Compiled AST (abstract syntax tree) of a Rhai script.
BinaryExpr	(INTERNALS) A binary expression. Exported under the internals feature only.
CustomExpr	(INTERNALS) 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.
FnCallExpr	(INTERNALS) A function call. 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.
Ident	(INTERNALS) An identifier containing a string name and a position. Exported under the internals feature only.
IdentX	(INTERNALS) An identifier containing an immutable string name and a position. Exported under the internals feature only.
ImmutableString	The system immutable string type.
Imports	(INTERNALS) A stack of imported modules. Exported under the internals feature only.
Limits	(INTERNALS) A type containing all the limits imposed by the Engine. Exported under the internals feature only.
Module	A module which may contain variables, sub-modules, external Rust functions, and/or script-defined functions.
NamespaceRef	(INTERNALS) A chain of module names to namespace-qualify a variable or function call. Exported under the internals feature only.
NativeCallContext	Context of a native Rust function call.
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 function.
FnNamespace	A type representing the namespace of a 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 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 closure 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_native_fn_hash	(INTERNALS) Calculate a u64 hash key from a namespace-qualified function name and parameter types. Exported under the internals feature only.
calc_script_fn_hash	(INTERNALS) Calculate a u64 hash key from a namespace-qualified function name and the number of parameters, but no parameter types. Exported under the internals feature only.
get_next_token	(INTERNALS) Get the next token from the stream. 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. It is defined as f64.
INT	The system integer type. It is defined as i64.
Map	Hash map of Dynamic values with ImmutableString keys.
Shared	Immutable reference-counted container.
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.

Attribute Macros

export_fn	Attribute, when put on a Rust function, turns it into a plugin function.
export_module	Attribute, when put on a Rust module, turns it into a plugin module.