boa_engine 0.17.0

Boa is a Javascript lexer, parser and compiler written in Rust. Currently, it has support for some of the language.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49

//! An implementation of a `CompletionRecord` for Boa's VM.

use boa_gc::{custom_trace, Finalize, Trace};

use crate::{JsError, JsResult, JsValue};

/// An implementation of the ECMAScript's `CompletionRecord` [specification] for
/// Boa's VM output Completion and Result.
///
/// [specification]: https://tc39.es/ecma262/#sec-completion-record-specification-type
#[derive(Debug, Clone, Finalize)]
pub(crate) enum CompletionRecord {
    Normal(JsValue),
    Return(JsValue),
    Throw(JsError),
}

// SAFETY: this matches all possible variants and traces
// their inner contents, which makes this safe.
unsafe impl Trace for CompletionRecord {
    custom_trace!(this, {
        match this {
            Self::Normal(v) => mark(v),
            Self::Return(r) => mark(r),
            Self::Throw(th) => mark(th),
        }
    });
}

// ---- `CompletionRecord` methods ----
impl CompletionRecord {
    pub(crate) const fn is_throw_completion(&self) -> bool {
        matches!(self, Self::Throw(_))
    }

    /// This function will consume the current `CompletionRecord` and return a `JsResult<JsValue>`
    // NOTE: rustc bug around evaluating destructors that prevents this from being a const function.
    // Related issue(s):
    //   - https://github.com/rust-lang/rust-clippy/issues/4041
    //   - https://github.com/rust-lang/rust/issues/60964
    //   - https://github.com/rust-lang/rust/issues/73255
    #[allow(clippy::missing_const_for_fn)]
    pub(crate) fn consume(self) -> JsResult<JsValue> {
        match self {
            Self::Throw(error) => Err(error),
            Self::Normal(value) | Self::Return(value) => Ok(value),
        }
    }
}