boa_engine 0.21.1

//! This module contains the [`TryFromJs`] trait, and conversions to basic Rust types.

use crate::{Context, JsBigInt, JsNativeError, JsObject, JsResult, JsString, JsValue, js_error};
use boa_string::StaticJsStrings;
use num_bigint::BigInt;
use num_traits::AsPrimitive;

mod collections;
mod tuples;

/// This trait adds a fallible and efficient conversions from a [`JsValue`] to Rust types.
pub trait TryFromJs: Sized {
    /// This function tries to convert a JavaScript value into `Self`.
    fn try_from_js(value: &JsValue, context: &mut Context) -> JsResult<Self>;
}

impl JsValue {
    /// This function is the inverse of [`TryFromJs`]. It tries to convert a [`JsValue`] to a given
    /// Rust type.
    pub fn try_js_into<T>(&self, context: &mut Context) -> JsResult<T>
    where
        T: TryFromJs,
    {
        T::try_from_js(self, context)
    }
}

impl TryFromJs for bool {
    fn try_from_js(value: &JsValue, _context: &mut Context) -> JsResult<Self> {
        if let Some(b) = value.as_boolean() {
            Ok(b)
        } else {
            Err(JsNativeError::typ()
                .with_message("cannot convert value to a boolean")
                .into())
        }
    }
}

impl TryFromJs for () {
    fn try_from_js(_value: &JsValue, _context: &mut Context) -> JsResult<Self> {
        Ok(())
    }
}

impl TryFromJs for String {
    fn try_from_js(value: &JsValue, _context: &mut Context) -> JsResult<Self> {
        if let Some(s) = value.as_string() {
            s.to_std_string().map_err(|e| {
                JsNativeError::typ()
                    .with_message(format!("could not convert JsString to Rust string: {e}"))
                    .into()
            })
        } else {
            Err(JsNativeError::typ()
                .with_message("cannot convert value to a String")
                .into())
        }
    }
}

impl TryFromJs for JsString {
    fn try_from_js(value: &JsValue, _context: &mut Context) -> JsResult<Self> {
        if let Some(s) = value.as_string() {
            Ok(s.clone())
        } else {
            Err(JsNativeError::typ()
                .with_message("cannot convert value to a JsString")
                .into())
        }
    }
}

impl<T> TryFromJs for Option<T>
where
    T: TryFromJs,
{
    fn try_from_js(value: &JsValue, context: &mut Context) -> JsResult<Self> {
        if value.is_undefined() {
            Ok(None)
        } else {
            Ok(Some(T::try_from_js(value, context)?))
        }
    }
}

impl<T> TryFromJs for Vec<T>
where
    T: TryFromJs,
{
    fn try_from_js(value: &JsValue, context: &mut Context) -> JsResult<Self> {
        let Some(object) = &value.as_object() else {
            return Err(JsNativeError::typ()
                .with_message("cannot convert value to a Vec")
                .into());
        };

        let length = object.get(StaticJsStrings::LENGTH, context)?;
        // If there's no length, return an error.
        if length.is_null_or_undefined() {
            return Err(js_error!(TypeError: "Not an array"));
        }
        let length = length.to_length(context)?;

        let length = match usize::try_from(length) {
            Ok(length) => length,
            Err(e) => {
                return Err(JsNativeError::typ()
                    .with_message(format!("could not convert length to usize: {e}"))
                    .into());
            }
        };
        let mut vec = Vec::with_capacity(length);
        for i in 0..length {
            let value = object.get(i, context)?;
            vec.push(T::try_from_js(&value, context)?);
        }

        Ok(vec)
    }
}

impl TryFromJs for JsObject {
    fn try_from_js(value: &JsValue, _context: &mut Context) -> JsResult<Self> {
        if let Some(o) = value.as_object() {
            Ok(o.clone())
        } else {
            Err(JsNativeError::typ()
                .with_message("cannot convert value to a Object")
                .into())
        }
    }
}

impl TryFromJs for JsBigInt {
    fn try_from_js(value: &JsValue, _context: &mut Context) -> JsResult<Self> {
        if let Some(b) = value.as_bigint() {
            Ok(b.clone())
        } else {
            Err(JsNativeError::typ()
                .with_message("cannot convert value to a BigInt")
                .into())
        }
    }
}

impl TryFromJs for BigInt {
    fn try_from_js(value: &JsValue, _context: &mut Context) -> JsResult<Self> {
        if let Some(b) = value.as_bigint() {
            Ok(b.as_inner().clone())
        } else {
            Err(JsNativeError::typ()
                .with_message("cannot convert value to a BigInt")
                .into())
        }
    }
}

impl TryFromJs for JsValue {
    fn try_from_js(value: &JsValue, _context: &mut Context) -> JsResult<Self> {
        Ok(value.clone())
    }
}

impl TryFromJs for f64 {
    fn try_from_js(value: &JsValue, _context: &mut Context) -> JsResult<Self> {
        if let Some(i) = value.0.as_integer32() {
            Ok(f64::from(i))
        } else if let Some(f) = value.0.as_float64() {
            Ok(f)
        } else {
            Err(JsNativeError::typ()
                .with_message("cannot convert value to a f64")
                .into())
        }
    }
}

fn from_f64<T>(v: f64) -> Option<T>
where
    T: AsPrimitive<f64>,
    f64: AsPrimitive<T>,
{
    if <f64 as AsPrimitive<T>>::as_(v).as_().to_bits() == v.to_bits() {
        return Some(v.as_());
    }
    None
}

macro_rules! impl_try_from_js_integer {
    ( $( $type: ty ),* ) => {
        $(
            impl TryFromJs for $type {
                fn try_from_js(value: &JsValue, _context: &mut Context) -> JsResult<Self> {
                    if let Some(i) = value.as_i32() {
                        i.try_into().map_err(|e| {
                            JsNativeError::typ()
                                .with_message(format!(
                                    concat!("cannot convert value to a ", stringify!($type), ": {}"),
                                    e)
                                )
                                .into()
                        })
                    } else if let Some(f) = value.as_number() {
                        from_f64(f).ok_or_else(|| {
                            JsNativeError::typ()
                                .with_message(concat!("cannot convert value to a ", stringify!($type)))
                                .into()
                        })
                    } else {
                        Err(JsNativeError::typ()
                            .with_message(concat!("cannot convert value to a ", stringify!($type)))
                            .into())
                    }
                }
            }
        )*
    }
}

impl_try_from_js_integer!(i8, u8, i16, u16, i32, u32, i64, u64, usize, i128, u128);

#[test]
fn integer_floating_js_value_to_integer() {
    let context = &mut Context::default();

    assert_eq!(i8::try_from_js(&JsValue::from(4.0), context), Ok(4));
    assert_eq!(u8::try_from_js(&JsValue::from(4.0), context), Ok(4));
    assert_eq!(i16::try_from_js(&JsValue::from(4.0), context), Ok(4));
    assert_eq!(u16::try_from_js(&JsValue::from(4.0), context), Ok(4));
    assert_eq!(i32::try_from_js(&JsValue::from(4.0), context), Ok(4));
    assert_eq!(u32::try_from_js(&JsValue::from(4.0), context), Ok(4));
    assert_eq!(i64::try_from_js(&JsValue::from(4.0), context), Ok(4));
    assert_eq!(u64::try_from_js(&JsValue::from(4.0), context), Ok(4));

    // Floating with fractional part
    let result = i32::try_from_js(&JsValue::from(4.000_000_000_000_001), context);
    assert!(result.is_err());

    // NaN
    let result = i32::try_from_js(&JsValue::nan(), context);
    assert!(result.is_err());

    // +Infinity
    let result = i32::try_from_js(&JsValue::positive_infinity(), context);
    assert!(result.is_err());

    // -Infinity
    let result = i32::try_from_js(&JsValue::negative_infinity(), context);
    assert!(result.is_err());
}

#[test]
fn value_into_vec() {
    use boa_engine::{TestAction, run_test_actions};
    use indoc::indoc;

    #[derive(Debug, PartialEq, Eq, boa_macros::TryFromJs)]
    struct TestStruct {
        inner: bool,
        my_int: i16,
        my_vec: Vec<String>,
    }

    run_test_actions([
        TestAction::assert_with_op(
            indoc! {r#"
            let value = {
                inner: true,
                my_int: 11,
                my_vec: ["a", "b", "c"]
            };
            value
        "#},
            |value, context| {
                let value = TestStruct::try_from_js(&value, context);

                match value {
                    Ok(value) => {
                        value
                            == TestStruct {
                                inner: true,
                                my_int: 11,
                                my_vec: vec!["a".to_string(), "b".to_string(), "c".to_string()],
                            }
                    }
                    _ => false,
                }
            },
        ),
        TestAction::assert_with_op(
            indoc!(
                r#"
            let wrong = {
                inner: false,
                my_int: 22,
                my_vec: [{}, "e", "f"]
            };
            wrong"#
            ),
            |value, context| {
                let Err(value) = TestStruct::try_from_js(&value, context) else {
                    return false;
                };
                assert!(value.to_string().contains("TypeError"));
                true
            },
        ),
    ]);
}

#[test]
fn value_into_tuple() {
    use boa_engine::{TestAction, run_test_actions};
    use indoc::indoc;

    run_test_actions([
        TestAction::assert_with_op(indoc! {r#" [42, "hello", true] "#}, |value, context| {
            type TestType = (i32, String, bool);
            TestType::try_from_js(&value, context).unwrap() == (42, "hello".to_string(), true)
        }),
        TestAction::assert_with_op(indoc! {r#" [42, "hello", true] "#}, |value, context| {
            type TestType = (i32, String, Option<bool>, Option<u8>);
            TestType::try_from_js(&value, context).unwrap()
                == (42, "hello".to_string(), Some(true), None)
        }),
        TestAction::assert_with_op(indoc! {r#" [] "#}, |value, context| {
            type TestType = (
                Option<bool>,
                Option<bool>,
                Option<bool>,
                Option<bool>,
                Option<bool>,
                Option<bool>,
                Option<bool>,
                Option<bool>,
                Option<bool>,
                Option<bool>,
            );
            TestType::try_from_js(&value, context).unwrap()
                == (None, None, None, None, None, None, None, None, None, None)
        }),
        TestAction::assert_with_op(indoc!(r#"[42, "hello", {}]"#), |value, context| {
            type TestType = (i32, String, bool);
            let Err(value) = TestType::try_from_js(&value, context) else {
                return false;
            };
            assert!(value.to_string().contains("TypeError"));
            true
        }),
        TestAction::assert_with_op(indoc!(r#"[42, "hello"]"#), |value, context| {
            type TestType = (i32, String, bool);
            let Err(value) = TestType::try_from_js(&value, context) else {
                return false;
            };
            assert!(value.to_string().contains("TypeError"));
            true
        }),
    ]);
}

#[test]
fn value_into_map() {
    use boa_engine::{TestAction, run_test_actions};
    use indoc::indoc;

    run_test_actions([
        TestAction::assert_with_op(indoc! {r#" ({ a: 1, b: 2, c: 3 }) "#}, |value, context| {
            let value = std::collections::BTreeMap::<String, i32>::try_from_js(&value, context);

            match value {
                Ok(value) => {
                    value
                        == vec![
                            ("a".to_string(), 1),
                            ("b".to_string(), 2),
                            ("c".to_string(), 3),
                        ]
                        .into_iter()
                        .collect::<std::collections::BTreeMap<String, i32>>()
                }
                _ => false,
            }
        }),
        TestAction::assert_with_op(indoc! {r#" ({ a: 1, b: 2, c: 3 }) "#}, |value, context| {
            let value = std::collections::HashMap::<String, i32>::try_from_js(&value, context);

            match value {
                Ok(value) => {
                    value
                        == std::collections::HashMap::from_iter(
                            vec![
                                ("a".to_string(), 1),
                                ("b".to_string(), 2),
                                ("c".to_string(), 3),
                            ]
                            .into_iter()
                            .collect::<std::collections::BTreeMap<String, i32>>(),
                        )
                }
                _ => false,
            }
        }),
    ]);
}

#[test]
fn js_map_into_rust_map() -> JsResult<()> {
    use boa_engine::Source;
    use std::collections::{BTreeMap, HashMap};

    let js_code = "new Map([['a', 1], ['b', 3], ['aboba', 42024]])";
    let mut context = Context::default();

    let js_value = context.eval(Source::from_bytes(js_code))?;

    let hash_map = HashMap::<String, i32>::try_from_js(&js_value, &mut context)?;
    let btree_map = BTreeMap::<String, i32>::try_from_js(&js_value, &mut context)?;

    let expect = [("a".into(), 1), ("aboba".into(), 42024), ("b".into(), 3)];

    let expected_hash_map: HashMap<String, _> = expect.iter().cloned().collect();
    assert_eq!(expected_hash_map, hash_map);

    let expected_btree_map: BTreeMap<String, _> = expect.iter().cloned().collect();
    assert_eq!(expected_btree_map, btree_map);
    Ok(())
}