quickjs/examples/point.c

/*
 * QuickJS: Example of C module with a class
 *
 * Copyright (c) 2019 Fabrice Bellard
 *
 * 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 "../quickjs.h"
#include <math.h>

#define countof(x) (sizeof(x) / sizeof((x)[0]))

/* Point Class */

typedef struct {
    int x;
    int y;
} JSPointData;

static JSClassID js_point_class_id;

static void js_point_finalizer(JSRuntime *rt, JSValue val)
{
    JSPointData *s = JS_GetOpaque(val, js_point_class_id);
    /* Note: 's' can be NULL in case JS_SetOpaque() was not called */
    js_free_rt(rt, s);
}

static JSValue js_point_ctor(JSContext *ctx,
                             JSValueConst new_target,
                             int argc, JSValueConst *argv)
{
    JSPointData *s;
    JSValue obj = JS_UNDEFINED;
    JSValue proto;

    s = js_mallocz(ctx, sizeof(*s));
    if (!s)
        return JS_EXCEPTION;
    if (JS_ToInt32(ctx, &s->x, argv[0]))
        goto fail;
    if (JS_ToInt32(ctx, &s->y, argv[1]))
        goto fail;
    /* using new_target to get the prototype is necessary when the
       class is extended. */
    proto = JS_GetPropertyStr(ctx, new_target, "prototype");
    if (JS_IsException(proto))
        goto fail;
    obj = JS_NewObjectProtoClass(ctx, proto, js_point_class_id);
    JS_FreeValue(ctx, proto);
    if (JS_IsException(obj))
        goto fail;
    JS_SetOpaque(obj, s);
    return obj;
 fail:
    js_free(ctx, s);
    JS_FreeValue(ctx, obj);
    return JS_EXCEPTION;
}

static JSValue js_point_get_xy(JSContext *ctx, JSValueConst this_val, int magic)
{
    JSPointData *s = JS_GetOpaque2(ctx, this_val, js_point_class_id);
    if (!s)
        return JS_EXCEPTION;
    if (magic == 0)
        return JS_NewInt32(ctx, s->x);
    else
        return JS_NewInt32(ctx, s->y);
}

static JSValue js_point_set_xy(JSContext *ctx, JSValueConst this_val, JSValue val, int magic)
{
    JSPointData *s = JS_GetOpaque2(ctx, this_val, js_point_class_id);
    int v;
    if (!s)
        return JS_EXCEPTION;
    if (JS_ToInt32(ctx, &v, val))
        return JS_EXCEPTION;
    if (magic == 0)
        s->x = v;
    else
        s->y = v;
    return JS_UNDEFINED;
}

static JSValue js_point_norm(JSContext *ctx, JSValueConst this_val,
                             int argc, JSValueConst *argv)
{
    JSPointData *s = JS_GetOpaque2(ctx, this_val, js_point_class_id);
    if (!s)
        return JS_EXCEPTION;
    return JS_NewFloat64(ctx, sqrt((double)s->x * s->x + (double)s->y * s->y));
}

static JSClassDef js_point_class = {
    "Point",
    .finalizer = js_point_finalizer,
};

static const JSCFunctionListEntry js_point_proto_funcs[] = {
    JS_CGETSET_MAGIC_DEF("x", js_point_get_xy, js_point_set_xy, 0),
    JS_CGETSET_MAGIC_DEF("y", js_point_get_xy, js_point_set_xy, 1),
    JS_CFUNC_DEF("norm", 0, js_point_norm),
};

static int js_point_init(JSContext *ctx, JSModuleDef *m)
{
    JSValue point_proto, point_class;
    JSRuntime *rt = JS_GetRuntime(ctx);

    /* create the Point class */
    JS_NewClassID(rt, &js_point_class_id);
    JS_NewClass(rt, js_point_class_id, &js_point_class);

    point_proto = JS_NewObject(ctx);
    JS_SetPropertyFunctionList(ctx, point_proto, js_point_proto_funcs, countof(js_point_proto_funcs));

    point_class = JS_NewCFunction2(ctx, js_point_ctor, "Point", 2, JS_CFUNC_constructor, 0);
    /* set proto.constructor and ctor.prototype */
    JS_SetConstructor(ctx, point_class, point_proto);
    JS_SetClassProto(ctx, js_point_class_id, point_proto);

    JS_SetModuleExport(ctx, m, "Point", point_class);
    return 0;
}

JSModuleDef *js_init_module(JSContext *ctx, const char *module_name)
{
    JSModuleDef *m;
    m = JS_NewCModule(ctx, module_name, js_point_init);
    if (!m)
        return NULL;
    JS_AddModuleExport(ctx, m, "Point");
    return m;
}