duktape-1.5.2/src-separate/duk_bi_proxy.c

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/*
 *  Proxy built-in (ES6)
 */
 
#include "duk_internal.h"
 
#if defined(DUK_USE_ES6_PROXY)
DUK_INTERNAL duk_ret_t duk_bi_proxy_constructor(duk_context *ctx) {
    duk_hobject *h_target;
    duk_hobject *h_handler;
 
    if (!duk_is_constructor_call(ctx)) {
        return DUK_RET_TYPE_ERROR;
    }
 
    /* Reject a proxy object as the target because it would need
     * special handler in property lookups.  (ES6 has no such restriction)
     */
    h_target = duk_require_hobject_or_lfunc_coerce(ctx, 0);
    DUK_ASSERT(h_target != NULL);
    if (DUK_HOBJECT_HAS_EXOTIC_PROXYOBJ(h_target)) {
        return DUK_RET_TYPE_ERROR;
    }
 
    /* Reject a proxy object as the handler because it would cause
     * potentially unbounded recursion.  (ES6 has no such restriction)
     */
    h_handler = duk_require_hobject_or_lfunc_coerce(ctx, 1);
    DUK_ASSERT(h_handler != NULL);
    if (DUK_HOBJECT_HAS_EXOTIC_PROXYOBJ(h_handler)) {
        return DUK_RET_TYPE_ERROR;
    }
 
    /* XXX: the returned value is exotic in ES6, but we use a
     * simple object here with no prototype.  Without a prototype,
     * [[DefaultValue]] coercion fails which is abit confusing.
     * No callable check/handling in the current Proxy subset.
     */
    (void) duk_push_object_helper_proto(ctx,
                                        DUK_HOBJECT_FLAG_EXTENSIBLE |
                                        DUK_HOBJECT_FLAG_EXOTIC_PROXYOBJ |
                                        DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_OBJECT),
                                        NULL);
    DUK_ASSERT_TOP(ctx, 3);
 
    /* Make _Target and _Handler non-configurable and non-writable.
     * They can still be forcibly changed by C code (both user and
     * Duktape internal), but not by Ecmascript code.
     */
 
    /* Proxy target */
    duk_dup(ctx, 0);
    duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_INT_TARGET, DUK_PROPDESC_FLAGS_NONE);
 
    /* Proxy handler */
    duk_dup(ctx, 1);
    duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_INT_HANDLER, DUK_PROPDESC_FLAGS_NONE);
 
    return 1;  /* replacement handler */
}
#else  /* DUK_USE_ES6_PROXY */
DUK_INTERNAL duk_ret_t duk_bi_proxy_constructor(duk_context *ctx) {
    DUK_UNREF(ctx);
    return DUK_RET_UNSUPPORTED_ERROR;
}
#endif  /* DUK_USE_ES6_PROXY */