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
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164

use std::ptr;

use log::debug;

use crate::sys::napi_value;
use crate::sys::napi_env;
use crate::sys::napi_callback_info;
use crate::sys::napi_ref;
use crate::val::JsEnv;
use crate::val::JsExports;
use crate::val::JsCallback;
use crate::NjError;
use crate::IntoJs;
use crate::PropertiesBuilder;

pub struct JSObjectWrapper<T> {
    wrapper: napi_ref,
    inner: T,
}

impl<T> JSObjectWrapper<T> {
    pub fn mut_inner(&mut self) -> &mut T {
        &mut self.inner
    }

    pub fn inner(&self) -> &T {
        &self.inner
    }
}

impl<T> JSObjectWrapper<T>
where
    T: JSClass,
{
    /// wrap myself in the JS instance
    /// and saved the reference
    fn wrap(self, js_env: &JsEnv, js_cb: JsCallback) -> Result<napi_value, NjError> {
        let boxed_self = Box::new(self);
        let raw_ptr = Box::into_raw(boxed_self); // rust no longer manages this struct

        let wrap = js_env.wrap(js_cb.this(), raw_ptr as *mut u8, T::js_finalize)?;

        unsafe {
            // save the wrap reference in wrapper container
            let rust_ref: &mut Self = &mut *raw_ptr;
            rust_ref.wrapper = wrap;
        }

        // Finally, remove the reference in response to finalize callback
        // See footnote on `napi_wrap` documentation: https://nodejs.org/api/n-api.html#n_api_napi_wrap
        //
        // "Caution: The optional returned reference (if obtained) should be deleted via napi_delete_reference
        // ONLY in response to the finalize callback invocation. If it is deleted before then,
        // then the finalize callback may never be invoked. Therefore, when obtaining a reference a
        // finalize callback is also required in order to enable correct disposal of the reference."
        js_env.delete_reference(wrap)?;

        Ok(js_cb.this_owned())
    }
}

pub trait JSClass: Sized {
    const CLASS_NAME: &'static str;

    // create rust object from argument
    fn create_from_js(
        js_env: &JsEnv,
        cb: napi_callback_info,
    ) -> Result<(Self, JsCallback), NjError>;

    fn set_constructor(constructor: napi_ref);

    fn get_constructor() -> napi_ref;

    /// new instance
    fn new_instance(js_env: &JsEnv, js_args: Vec<napi_value>) -> Result<napi_value, NjError> {
        debug!("new instance with args: {:#?}", js_args);
        let constructor = js_env.get_reference_value(Self::get_constructor())?;
        js_env.new_instance(constructor, js_args)
    }

    /// given instance, return my object
    fn unwrap_mut(js_env: &JsEnv, instance: napi_value) -> Result<&'static mut Self, NjError> {
        Ok(js_env
            .unwrap_mut::<JSObjectWrapper<Self>>(instance)?
            .mut_inner())
    }

    fn unwrap(js_env: &JsEnv, instance: napi_value) -> Result<&'static Self, NjError> {
        Ok(js_env.unwrap::<JSObjectWrapper<Self>>(instance)?.inner())
    }

    fn properties() -> PropertiesBuilder {
        vec![].into()
    }

    /// define class and properties under exports
    fn js_init(js_exports: &mut JsExports) -> Result<(), NjError> {
        let js_constructor =
            js_exports
                .env()
                .define_class(Self::CLASS_NAME, Self::js_new, Self::properties())?;

        // save the constructor reference, we need this later in order to instantiate
        let js_ref = js_exports.env().create_reference(js_constructor, 1)?;
        Self::set_constructor(js_ref);

        js_exports.set_name_property(Self::CLASS_NAME, js_constructor)?;
        Ok(())
    }

    /// call when Javascript class constructor is called
    /// For example:  new Car(...)
    extern "C" fn js_new(env: napi_env, info: napi_callback_info) -> napi_value {
        let js_env = JsEnv::new(env);

        let result: Result<napi_value, NjError> = (|| {
            debug!(
                "Class constructor called: {:#?}",
                std::any::type_name::<Self>()
            );

            let target = js_env.get_new_target(info)?;

            if target.is_null() {
                Err(NjError::NoPlainConstructor)
            } else {
                debug!("invoked as constructor");

                let (rust_obj, js_cb) = Self::create_from_js(&js_env, info)?;
                let my_obj = JSObjectWrapper {
                    inner: rust_obj,
                    wrapper: ptr::null_mut(),
                };

                my_obj.wrap(&js_env, js_cb)
            }
        })();

        result.to_js(&js_env)
    }

    /*
    /// convert my self as JS object
    fn as_js_instance(self,js_env: &JsEnv,js_args: Vec<napi_value>) -> napi_value {

        let new_instance = Self::new_instance(js_env,args);

        // unwrap the actual inner
    }
    */

    extern "C" fn js_finalize(
        _env: napi_env,
        finalize_data: *mut ::std::os::raw::c_void,
        _finalize_hint: *mut ::std::os::raw::c_void,
    ) {
        debug!("my object finalize");
        unsafe {
            let ptr: *mut JSObjectWrapper<Self> = finalize_data as *mut JSObjectWrapper<Self>;
            Box::from_raw(ptr);
        }
    }
}