neon/types_impl/error.rs
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//! Types and traits representing JavaScript error values.
use std::panic::{catch_unwind, UnwindSafe};
use crate::{
context::{
internal::{ContextInternal, Env},
Context, Cx,
},
handle::{internal::TransparentNoCopyWrapper, Handle},
object::Object,
result::{NeonResult, Throw},
sys::{self, raw},
types::{build, private::ValueInternal, utf8::Utf8, Value},
};
/// The type of JavaScript
/// [`Error`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)
/// objects.
///
/// # Example
///
/// ```
/// # use neon::prelude::*;
/// # fn test(mut cx: FunctionContext) -> JsResult<JsUndefined> {
/// // Create a type error:
/// let err = cx.type_error("expected a number, found a string")?;
///
/// // Add some custom diagnostic properties to the error:
/// err.prop(&mut cx, "expected").set("number")?;
/// err.prop(&mut cx, "found").set("string")?;
///
/// // Throw the error:
/// cx.throw(err)?;
/// # Ok(cx.undefined())
/// # }
/// ```
#[repr(transparent)]
#[derive(Debug)]
pub struct JsError(raw::Local);
unsafe impl TransparentNoCopyWrapper for JsError {
type Inner = raw::Local;
fn into_inner(self) -> Self::Inner {
self.0
}
}
impl ValueInternal for JsError {
fn name() -> &'static str {
"Error"
}
fn is_typeof<Other: Value>(cx: &mut Cx, other: &Other) -> bool {
unsafe { sys::tag::is_error(cx.env().to_raw(), other.to_local()) }
}
fn to_local(&self) -> raw::Local {
self.0
}
unsafe fn from_local(_env: Env, h: raw::Local) -> Self {
JsError(h)
}
}
impl Value for JsError {}
impl Object for JsError {}
impl JsError {
/// Creates a direct instance of the [`Error`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error) class.
///
/// **See also:** [`Context::error`]
pub fn error<'a, C: Context<'a>, S: AsRef<str>>(
cx: &mut C,
msg: S,
) -> NeonResult<Handle<'a, JsError>> {
let msg = cx.string(msg.as_ref());
build(cx.env(), |out| unsafe {
sys::error::new_error(cx.env().to_raw(), out, msg.to_local());
true
})
}
/// Creates an instance of the [`TypeError`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/TypeError) class.
///
/// **See also:** [`Context::type_error`]
pub fn type_error<'a, C: Context<'a>, S: AsRef<str>>(
cx: &mut C,
msg: S,
) -> NeonResult<Handle<'a, JsError>> {
let msg = cx.string(msg.as_ref());
build(cx.env(), |out| unsafe {
sys::error::new_type_error(cx.env().to_raw(), out, msg.to_local());
true
})
}
/// Creates an instance of the [`RangeError`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/RangeError) class.
///
/// **See also:** [`Context::range_error`]
pub fn range_error<'a, C: Context<'a>, S: AsRef<str>>(
cx: &mut C,
msg: S,
) -> NeonResult<Handle<'a, JsError>> {
let msg = cx.string(msg.as_ref());
build(cx.env(), |out| unsafe {
sys::error::new_range_error(cx.env().to_raw(), out, msg.to_local());
true
})
}
}
pub(crate) fn convert_panics<T, F: UnwindSafe + FnOnce() -> NeonResult<T>>(
env: Env,
f: F,
) -> NeonResult<T> {
match catch_unwind(f) {
Ok(result) => result,
Err(panic) => {
let msg = if let Some(string) = panic.downcast_ref::<String>() {
format!("internal error in Neon module: {string}")
} else if let Some(str) = panic.downcast_ref::<&str>() {
format!("internal error in Neon module: {str}")
} else {
"internal error in Neon module".to_string()
};
let (data, len) = Utf8::from(&msg[..]).truncate().lower();
unsafe {
sys::error::clear_exception(env.to_raw());
sys::error::throw_error_from_utf8(env.to_raw(), data, len);
Err(Throw::new())
}
}
}
}