micropython/ports/webassembly/objjsproxy.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2023-2024 Damien P. George
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <stdio.h>
#include <stdlib.h>

#include "emscripten.h"
#include "py/objmodule.h"
#include "py/runtime.h"
#include "proxy_c.h"

// *FORMAT-OFF*
EM_JS(bool, lookup_attr, (int jsref, const char *str, uint32_t * out), {
    const base = proxy_js_ref[jsref];
    const attr = UTF8ToString(str);
    if (attr in base) {
        let value = base[attr];
        if (typeof value == "function") {
            if (base !== globalThis) {
                value = value.bind(base);
            }
        }
        proxy_convert_js_to_mp_obj_jsside(value, out);
        return true;
    } else {
        return false;
    }
});
// *FORMAT-ON*

EM_JS(void, store_attr, (int jsref, const char *attr_ptr, uint32_t * value_ref), {
    const attr = UTF8ToString(attr_ptr);
    const value = proxy_convert_mp_to_js_obj_jsside(value_ref);
    proxy_js_ref[jsref][attr] = value;
});

EM_JS(void, call0, (int f_ref, uint32_t * out), {
    // Because of JavaScript "this" semantics, we must extract the target function
    // to a variable before calling it, so "this" is bound to the correct value.
    //
    // In detail:
    // In JavaScript, proxy_js_ref[f_ref] acts like a function call
    // proxy_js_ref.at(f_ref), and "this" will be bound to proxy_js_ref if
    // there is a chain of calls, such as proxy_js_ref.at(f_ref)().
    // But proxy_js_ref is not "this" in the context of the call, so we
    // must extract the function to an independent variable and then call
    // that variable, so that "this" is correct (it will be "undefined").

    const f = proxy_js_ref[f_ref];
    const ret = f();
    proxy_convert_js_to_mp_obj_jsside(ret, out);
});

EM_JS(int, call1, (int f_ref, uint32_t * a0, uint32_t * out), {
    const a0_js = proxy_convert_mp_to_js_obj_jsside(a0);
    const f = proxy_js_ref[f_ref];
    const ret = f(a0_js);
    proxy_convert_js_to_mp_obj_jsside(ret, out);
});

EM_JS(int, call2, (int f_ref, uint32_t * a0, uint32_t * a1, uint32_t * out), {
    const a0_js = proxy_convert_mp_to_js_obj_jsside(a0);
    const a1_js = proxy_convert_mp_to_js_obj_jsside(a1);
    const f = proxy_js_ref[f_ref];
    const ret = f(a0_js, a1_js);
    proxy_convert_js_to_mp_obj_jsside(ret, out);
});

EM_JS(int, calln, (int f_ref, uint32_t n_args, uint32_t * value, uint32_t * out), {
    const f = proxy_js_ref[f_ref];
    const a = [];
    for (let i = 0; i < n_args; ++i) {
        const v = proxy_convert_mp_to_js_obj_jsside(value + i * 3 * 4);
        a.push(v);
    }
    const ret = f(... a);
    proxy_convert_js_to_mp_obj_jsside(ret, out);
});

EM_JS(void, call0_kwarg, (int f_ref, uint32_t n_kw, uint32_t * key, uint32_t * value, uint32_t * out), {
    const f = proxy_js_ref[f_ref];
    const a = {};
    for (let i = 0; i < n_kw; ++i) {
        const k = UTF8ToString(getValue(key + i * 4, "i32"));
        const v = proxy_convert_mp_to_js_obj_jsside(value + i * 3 * 4);
        a[k] = v;
    }
    const ret = f(a);
    proxy_convert_js_to_mp_obj_jsside(ret, out);
});

EM_JS(void, call1_kwarg, (int f_ref, uint32_t * arg0, uint32_t n_kw, uint32_t * key, uint32_t * value, uint32_t * out), {
    const f = proxy_js_ref[f_ref];
    const a0 = proxy_convert_mp_to_js_obj_jsside(arg0);
    const a = {};
    for (let i = 0; i < n_kw; ++i) {
        const k = UTF8ToString(getValue(key + i * 4, "i32"));
        const v = proxy_convert_mp_to_js_obj_jsside(value + i * 3 * 4);
        a[k] = v;
    }
    const ret = f(a0, a);
    proxy_convert_js_to_mp_obj_jsside(ret, out);
});

EM_JS(void, js_reflect_construct, (int f_ref, uint32_t n_args, uint32_t * args, uint32_t * out), {
    const f = proxy_js_ref[f_ref];
    const as = [];
    for (let i = 0; i < n_args; ++i) {
        as.push(proxy_convert_mp_to_js_obj_jsside(args + i * 4));
    }
    const ret = Reflect.construct(f, as);
    proxy_convert_js_to_mp_obj_jsside(ret, out);
});

EM_JS(int, js_get_len, (int f_ref), {
    return proxy_js_ref[f_ref].length;
});

EM_JS(void, js_subscr_int, (int f_ref, int idx, uint32_t * out), {
    const f = proxy_js_ref[f_ref];
    const ret = f[idx];
    proxy_convert_js_to_mp_obj_jsside(ret, out);
});

EM_JS(void, js_subscr_load, (int f_ref, uint32_t * index_ref, uint32_t * out), {
    const target = proxy_js_ref[f_ref];
    const index = python_index_semantics(target, proxy_convert_mp_to_js_obj_jsside(index_ref));
    const ret = target[index];
    proxy_convert_js_to_mp_obj_jsside(ret, out);
});

EM_JS(void, js_subscr_store, (int f_ref, uint32_t * idx, uint32_t * value), {
    const f = proxy_js_ref[f_ref];
    f[proxy_convert_mp_to_js_obj_jsside(idx)] = proxy_convert_mp_to_js_obj_jsside(value);
});

static void jsproxy_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
    mp_obj_jsproxy_t *self = MP_OBJ_TO_PTR(self_in);
    mp_printf(print, "<JsProxy %d>", self->ref);
}

static mp_obj_t jsproxy_call(mp_obj_t self_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
    mp_obj_jsproxy_t *self = MP_OBJ_TO_PTR(self_in);

    if (n_kw == 0) {
        mp_arg_check_num(n_args, n_kw, 0, MP_OBJ_FUN_ARGS_MAX, false);
    } else {
        mp_arg_check_num(n_args, n_kw, 0, 1, true);
        uint32_t key[n_kw];
        uint32_t value[PVN * n_kw];
        for (int i = 0; i < n_kw; ++i) {
            key[i] = (uintptr_t)mp_obj_str_get_str(args[n_args + i * 2]);
            proxy_convert_mp_to_js_obj_cside(args[n_args + i * 2 + 1], &value[i * PVN]);
        }
        uint32_t out[3];
        if (n_args == 0) {
            call0_kwarg(self->ref, n_kw, key, value, out);
        } else {
            // n_args == 1
            uint32_t arg0[PVN];
            proxy_convert_mp_to_js_obj_cside(args[0], arg0);
            call1_kwarg(self->ref, arg0, n_kw, key, value, out);
        }
        return proxy_convert_js_to_mp_obj_cside(out);
    }

    if (n_args == 0) {
        uint32_t out[3];
        call0(self->ref, out);
        return proxy_convert_js_to_mp_obj_cside(out);
    } else if (n_args == 1) {
        uint32_t arg0[PVN];
        uint32_t out[PVN];
        proxy_convert_mp_to_js_obj_cside(args[0], arg0);
        call1(self->ref, arg0, out);
        return proxy_convert_js_to_mp_obj_cside(out);
    } else if (n_args == 2) {
        uint32_t arg0[PVN];
        proxy_convert_mp_to_js_obj_cside(args[0], arg0);
        uint32_t arg1[PVN];
        proxy_convert_mp_to_js_obj_cside(args[1], arg1);
        uint32_t out[3];
        call2(self->ref, arg0, arg1, out);
        return proxy_convert_js_to_mp_obj_cside(out);
    } else {
        uint32_t value[PVN * n_args];
        for (int i = 0; i < n_args; ++i) {
            proxy_convert_mp_to_js_obj_cside(args[i], &value[i * PVN]);
        }
        uint32_t out[3];
        calln(self->ref, n_args, value, out);
        return proxy_convert_js_to_mp_obj_cside(out);
    }
}

static mp_obj_t jsproxy_reflect_construct(size_t n_args, const mp_obj_t *args) {
    int arg0 = mp_obj_jsproxy_get_ref(args[0]);
    n_args -= 1;
    args += 1;
    uint32_t args_conv[n_args];
    for (unsigned int i = 0; i < n_args; ++i) {
        proxy_convert_mp_to_js_obj_cside(args[i], &args_conv[i * PVN]);
    }
    uint32_t out[3];
    js_reflect_construct(arg0, n_args, args_conv, out);
    return proxy_convert_js_to_mp_obj_cside(out);
}
static MP_DEFINE_CONST_FUN_OBJ_VAR(jsproxy_reflect_construct_obj, 1, jsproxy_reflect_construct);

static mp_obj_t jsproxy_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
    mp_obj_jsproxy_t *self = MP_OBJ_TO_PTR(self_in);
    if (value == MP_OBJ_SENTINEL) {
        // Load subscript.
        uint32_t idx[PVN], out[PVN];
        proxy_convert_mp_to_js_obj_cside(index, idx);
        js_subscr_load(self->ref, idx, out);
        return proxy_convert_js_to_mp_obj_cside(out);
    } else if (value == MP_OBJ_NULL) {
        // Delete subscript.
        return MP_OBJ_NULL; // not supported
    } else {
        // Store subscript.
        uint32_t idx[PVN], val[PVN];
        proxy_convert_mp_to_js_obj_cside(index, idx);
        proxy_convert_mp_to_js_obj_cside(value, val);
        js_subscr_store(self->ref, idx, val);
        return mp_const_none;
    }
}

void mp_obj_jsproxy_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
    mp_obj_jsproxy_t *self = MP_OBJ_TO_PTR(self_in);
    if (dest[0] == MP_OBJ_NULL) {
        // Load attribute.
        uint32_t out[PVN];
        if (lookup_attr(self->ref, qstr_str(attr), out)) {
            dest[0] = proxy_convert_js_to_mp_obj_cside(out);
        } else if (attr == MP_QSTR_new) {
            // Special case to handle construction of JS objects.
            // JS objects don't have a ".new" attribute, doing "Obj.new" is a Pyodide idiom for "new Obj".
            // It translates to the JavaScript "Reflect.construct(Obj, Array(...args))".
            dest[0] = MP_OBJ_FROM_PTR(&jsproxy_reflect_construct_obj);
            dest[1] = self_in;
        }
    } else if (dest[1] == MP_OBJ_NULL) {
        // Delete attribute.
    } else {
        // Store attribute.
        uint32_t value[PVN];
        proxy_convert_mp_to_js_obj_cside(dest[1], value);
        store_attr(self->ref, qstr_str(attr), value);
        dest[0] = MP_OBJ_NULL;
    }
}

/******************************************************************************/
// jsproxy iterator

typedef struct _jsproxy_it_t {
    mp_obj_base_t base;
    mp_fun_1_t iternext;
    int ref;
    uint16_t cur;
    uint16_t len;
} jsproxy_it_t;

static mp_obj_t jsproxy_it_iternext(mp_obj_t self_in) {
    jsproxy_it_t *self = MP_OBJ_TO_PTR(self_in);
    if (self->cur < self->len) {
        uint32_t out[3];
        js_subscr_int(self->ref, self->cur, out);
        self->cur += 1;
        return proxy_convert_js_to_mp_obj_cside(out);
    } else {
        return MP_OBJ_STOP_ITERATION;
    }
}

static mp_obj_t jsproxy_getiter(mp_obj_t o_in, mp_obj_iter_buf_t *iter_buf) {
    assert(sizeof(jsproxy_it_t) <= sizeof(mp_obj_iter_buf_t));
    jsproxy_it_t *o = (jsproxy_it_t *)iter_buf;
    o->base.type = &mp_type_polymorph_iter;
    o->iternext = jsproxy_it_iternext;
    o->ref = mp_obj_jsproxy_get_ref(o_in);
    o->cur = 0;
    o->len = js_get_len(o->ref);
    return MP_OBJ_FROM_PTR(o);
}

/******************************************************************************/

MP_DEFINE_CONST_OBJ_TYPE(
    mp_type_jsproxy,
    MP_QSTR_JsProxy,
    MP_TYPE_FLAG_ITER_IS_GETITER,
    print, jsproxy_print,
    call, jsproxy_call,
    attr, mp_obj_jsproxy_attr,
    subscr, jsproxy_subscr,
    iter, jsproxy_getiter
    );

mp_obj_t mp_obj_new_jsproxy(int ref) {
    mp_obj_jsproxy_t *o = mp_obj_malloc(mp_obj_jsproxy_t, &mp_type_jsproxy);
    o->ref = ref;
    return MP_OBJ_FROM_PTR(o);
}