neon/types_impl/
error.rs

1//! Types and traits representing JavaScript error values.
2
3use std::panic::{catch_unwind, UnwindSafe};
4
5use crate::{
6    context::{
7        internal::{ContextInternal, Env},
8        Context, Cx,
9    },
10    handle::{internal::TransparentNoCopyWrapper, Handle},
11    object::Object,
12    result::{NeonResult, Throw},
13    sys::{self, raw},
14    types::{build, private::ValueInternal, utf8::Utf8, Value},
15};
16
17/// The type of JavaScript
18/// [`Error`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)
19/// objects.
20///
21/// # Example
22///
23/// ```
24/// # use neon::prelude::*;
25/// # fn test(mut cx: FunctionContext) -> JsResult<JsUndefined> {
26/// // Create a type error:
27/// let err = cx.type_error("expected a number, found a string")?;
28///
29/// // Add some custom diagnostic properties to the error:
30/// err.prop(&mut cx, "expected").set("number")?;
31/// err.prop(&mut cx, "found").set("string")?;
32///
33/// // Throw the error:
34/// cx.throw(err)?;
35/// # Ok(cx.undefined())
36/// # }
37/// ```
38#[repr(transparent)]
39#[derive(Debug)]
40pub struct JsError(raw::Local);
41
42unsafe impl TransparentNoCopyWrapper for JsError {
43    type Inner = raw::Local;
44
45    fn into_inner(self) -> Self::Inner {
46        self.0
47    }
48}
49
50impl ValueInternal for JsError {
51    fn name() -> &'static str {
52        "Error"
53    }
54
55    fn is_typeof<Other: Value>(cx: &mut Cx, other: &Other) -> bool {
56        unsafe { sys::tag::is_error(cx.env().to_raw(), other.to_local()) }
57    }
58
59    fn to_local(&self) -> raw::Local {
60        self.0
61    }
62
63    unsafe fn from_local(_env: Env, h: raw::Local) -> Self {
64        JsError(h)
65    }
66}
67
68impl Value for JsError {}
69
70impl Object for JsError {}
71
72impl JsError {
73    /// Creates a direct instance of the [`Error`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error) class.
74    ///
75    /// **See also:** [`Context::error`]
76    pub fn error<'a, C: Context<'a>, S: AsRef<str>>(
77        cx: &mut C,
78        msg: S,
79    ) -> NeonResult<Handle<'a, JsError>> {
80        let msg = cx.string(msg.as_ref());
81        build(cx.env(), |out| unsafe {
82            sys::error::new_error(cx.env().to_raw(), out, msg.to_local());
83            true
84        })
85    }
86
87    /// Creates an instance of the [`TypeError`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/TypeError) class.
88    ///
89    /// **See also:** [`Context::type_error`]
90    pub fn type_error<'a, C: Context<'a>, S: AsRef<str>>(
91        cx: &mut C,
92        msg: S,
93    ) -> NeonResult<Handle<'a, JsError>> {
94        let msg = cx.string(msg.as_ref());
95        build(cx.env(), |out| unsafe {
96            sys::error::new_type_error(cx.env().to_raw(), out, msg.to_local());
97            true
98        })
99    }
100
101    /// Creates an instance of the [`RangeError`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/RangeError) class.
102    ///
103    /// **See also:** [`Context::range_error`]
104    pub fn range_error<'a, C: Context<'a>, S: AsRef<str>>(
105        cx: &mut C,
106        msg: S,
107    ) -> NeonResult<Handle<'a, JsError>> {
108        let msg = cx.string(msg.as_ref());
109        build(cx.env(), |out| unsafe {
110            sys::error::new_range_error(cx.env().to_raw(), out, msg.to_local());
111            true
112        })
113    }
114}
115
116pub(crate) fn convert_panics<T, F: UnwindSafe + FnOnce() -> NeonResult<T>>(
117    env: Env,
118    f: F,
119) -> NeonResult<T> {
120    match catch_unwind(f) {
121        Ok(result) => result,
122        Err(panic) => {
123            let msg = if let Some(string) = panic.downcast_ref::<String>() {
124                format!("internal error in Neon module: {string}")
125            } else if let Some(str) = panic.downcast_ref::<&str>() {
126                format!("internal error in Neon module: {str}")
127            } else {
128                "internal error in Neon module".to_string()
129            };
130            let (data, len) = Utf8::from(&msg[..]).truncate().lower();
131            unsafe {
132                sys::error::clear_exception(env.to_raw());
133                sys::error::throw_error_from_utf8(env.to_raw(), data, len);
134                Err(Throw::new())
135            }
136        }
137    }
138}
neon/types_impl/error.rs

neon/types_impl/
error.rs
