boa-cat 0.6.0

Tree-walking ECMAScript interpreter built on ecma-syntax-cat. v0.6.0 adds `await` evaluator dispatch + async function call wrapping (async track chunk 3 of 5-7): `await Resolved(v)` -> `v`, `await Rejected(v)` -> throw `v`, `await Pending` -> TypeError (no continuation in the synchronous tree-walking model), `await non_promise` -> pass through. Calling an async function (`FunctionDef::is_async()` flag, threaded from `Function::is_async()` / `ArrowFunction::is_async()`) wraps the body's normal completion in a `Resolved` promise and its throw completion in a `Rejected` promise.
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//! Completion records: the spec's abrupt-completion mechanism, lifted into
//! a sum type the interpreter can return from statement evaluation.

use crate::value::Value;

/// The result of evaluating a statement.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum Completion {
    /// Normal completion with an optional value (the result of an
    /// `Expression` statement, the body of a block, etc.).
    Normal(Value),
    /// `return value;`
    Return(Value),
    /// `throw value;`
    Throw(Value),
    /// `break;` (labeled break deferred to v0.2).
    Break,
    /// `continue;` (labeled continue deferred to v0.2).
    Continue,
}

impl Completion {
    /// Whether this completion is abrupt (anything other than `Normal`).
    #[must_use]
    pub fn is_abrupt(&self) -> bool {
        !matches!(self, Self::Normal(_))
    }
}