herocode/rhaj
Archived
13
0
Fork 0
Code Issues 1 Pull Requests Actions Packages Projects Releases Wiki Activity

reorganize module

Browse Source
This commit is contained in:
Timur Gordon
2025-04-04 08:28:07 +02:00
parent 1ea37e2e7f
commit 939b6b4e57
375 changed files with 7580 additions and 191 deletions
Download Patch File Download Diff File Expand all files Collapse all files

110
_archive/rhai_engine/rhaibook/rust/context.md Normal file
View File

@@ -0,0 +1,110 @@
`NativeCallContext`
===================
{{#include ../links.md}}
If the _first_ parameter of a function is of type `rhai::NativeCallContext`, then it is treated
specially by the [`Engine`].
`NativeCallContext` is a type that encapsulates the current _call context_ of a Rust function call
and exposes the following.
| Method | Return type | Description |
| ------------------------- | :----------------------------------------------------: | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `engine()` | [`&Engine`][`Engine`] | the current [`Engine`], with all configurations and settings.<br/>This is sometimes useful for calling a script-defined function within the same evaluation context using [`Engine::call_fn`][`call_fn`], or calling a [function pointer]. |
| `fn_name()` | `&str` | name of the function called (useful when the same Rust function is mapped to multiple Rhai-callable function names) |
| `source()` | `Option<&str>` | reference to the current source, if any |
| `position()` | `Position` | position of the function call |
| `call_level()` | `usize` | the current nesting level of function calls |
| `tag()` | [`&Dynamic`][`Dynamic`] | reference to the _custom state_ that is persistent during the current run |
| `iter_imports()` | `impl Iterator<Item = (&str,`[`&Module`][`Module`]`)>` | iterator of the current stack of [modules] imported via `import` statements, in reverse order (i.e. later [modules] come first) |
| `global_runtime_state()` | [`&GlobalRuntimeState`][`GlobalRuntimeState`] | reference to the current [global runtime state][`GlobalRuntimeState`] (including the stack of [modules] imported via `import` statements); requires the [`internals`] feature |
| `iter_namespaces()` | `impl Iterator<Item =`[`&Module`][`Module`]`>` | iterator of the [namespaces][function namespaces] (as [modules]) containing all script-defined [functions], in reverse order (i.e. later [modules] come first) |
| `namespaces()` | [`&[&Module]`][`Module`] | reference to the [namespaces][function namespaces] (as [modules]) containing all script-defined [functions]; requires the [`internals`] feature |
| `call_fn(...)` | `Result<T, Box<EvalAltResult>>` | call a function with the supplied arguments, casting the result into the required type |
| `call_native_fn(...)` | `Result<T, Box<EvalAltResult>>` | call a registered native Rust function with the supplied arguments, casting the result into the required type |
| `call_fn_raw(...)` | `Result<`[`Dynamic`]`, Box<EvalAltResult>>` | call a function with the supplied arguments; this is an advanced method |
| `call_native_fn_raw(...)` | `Result<`[`Dynamic`]`, Box<EvalAltResult>>` | call a registered native Rust function with the supplied arguments; this is an advanced method |
Example Implementations
-----------------------
~~~admonish example "Example &ndash; Implement Safety Checks"
The native call context is useful for protecting a function from malicious scripts.
```rust
use rhai::{Array, NativeCallContext, EvalAltResult, Position};
// This function builds an array of arbitrary size, but is protected against attacks
// by first checking with the allowed limit set into the 'Engine'.
pub fn new_array(context: NativeCallContext, size: i64) -> Result<Array, Box<EvalAltResult>>
{
let array = Array::new();
if size <= 0 {
return array;
}
let size = size as usize;
let max_size = context.engine().max_array_size();
// Make sure the function does not generate a data structure larger than
// the allowed limit for the Engine!
if max_size > 0 && size > max_size {
return Err(EvalAltResult::ErrorDataTooLarge(
"Size to grow".to_string(),
max_size, size,
context.position(),
).into());
}
for x in 0..size {
array.push(x.into());
}
OK(array)
}
```
~~~
~~~admonish example "Example &ndash; Call a Function Within a Function"
The _native call context_ can be used to call a [function] within the current evaluation
via `call_fn` (or more commonly `call_native_fn`).
```rust
use rhai::{Engine, NativeCallContext};
let mut engine = Engine::new();
// A function expecting a callback in form of a function pointer.
engine.register_fn("super_call", |context: NativeCallContext, value: i64| {
// Call a function within the current evaluation!
// 'call_native_fn' ensures that only registered native Rust functions
// are called, so a scripted function named 'double' cannot hijack
// the process.
// To also include scripted functions, use 'call_fn' instead.
context.call_native_fn::<i64>("double", (value,))
// ^^^^^^^^ arguments passed in tuple
});
```
~~~
~~~admonish example "Example &ndash; Implement a Callback"
The _native call context_ can be used to call a [function pointer] or [closure] that has been passed
as a parameter to the function (via `FnPtr::call_within_context`), thereby implementing a _callback_.
```rust
use rhai::{Dynamic, FnPtr, NativeCallContext, EvalAltResult};
pub fn greet(context: NativeCallContext, callback: FnPtr) -> Result<String, Box<EvalAltResult>>
{
// Call the callback closure with the current evaluation context!
let name = callback.call_within_context(&context, ())?;
Ok(format!("hello, {}!", name))
}
```
~~~