1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/js/public/PropertyKey.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,95 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
1.5 + * vim: set ts=8 sts=4 et sw=4 tw=99:
1.6 + * This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +/* JS::PropertyKey implementation. */
1.11 +
1.12 +#ifndef js_PropertyKey_h
1.13 +#define js_PropertyKey_h
1.14 +
1.15 +#include "js/TypeDecls.h"
1.16 +#include "js/Value.h"
1.17 +
1.18 +namespace JS {
1.19 +
1.20 +class PropertyKey;
1.21 +
1.22 +namespace detail {
1.23 +
1.24 +extern JS_PUBLIC_API(bool)
1.25 +ToPropertyKeySlow(JSContext *cx, HandleValue v, PropertyKey *key);
1.26 +
1.27 +} // namespace detail
1.28 +
1.29 +/*
1.30 + * A PropertyKey is a key used to access some property on an object. It is a
1.31 + * natural way to represent a property accessed using a JavaScript value.
1.32 + *
1.33 + * PropertyKey can represent indexes, named properties, and ES6 symbols. The
1.34 + * latter aren't implemented in SpiderMonkey yet, but PropertyKey carves out
1.35 + * space for them.
1.36 + */
1.37 +class PropertyKey
1.38 +{
1.39 + Value v;
1.40 + friend JS_PUBLIC_API(bool) detail::ToPropertyKeySlow(JSContext *cx, HandleValue v, PropertyKey *key);
1.41 +
1.42 + public:
1.43 + explicit PropertyKey(uint32_t index) : v(PrivateUint32Value(index)) {}
1.44 +
1.45 + /*
1.46 + * An index is a string property name whose characters exactly spell out an
1.47 + * unsigned 32-bit integer in decimal: "0", "1", "2", ...., "4294967294",
1.48 + * "4294967295".
1.49 + */
1.50 + bool isIndex(uint32_t *index) {
1.51 + // The implementation here assumes that private uint32_t are stored
1.52 + // using the int32_t representation. This is purely an implementation
1.53 + // detail: embedders must not rely upon this!
1.54 + if (!v.isInt32())
1.55 + return false;
1.56 + *index = v.toPrivateUint32();
1.57 + return true;
1.58 + }
1.59 +
1.60 + /*
1.61 + * A name is a string property name which is *not* an index. Note that by
1.62 + * the ECMAScript language grammar, any dotted property access |obj.prop|
1.63 + * will access a named property.
1.64 + */
1.65 + bool isName(JSString **str) {
1.66 + uint32_t dummy;
1.67 + if (isIndex(&dummy))
1.68 + return false;
1.69 + *str = v.toString();
1.70 + return true;
1.71 + }
1.72 +
1.73 + /*
1.74 + * A symbol is a property name that's a Symbol, a particular kind of object
1.75 + * in ES6. It is the only kind of property name that's not a string.
1.76 + *
1.77 + * SpiderMonkey doesn't yet implement symbols, but we're carving out API
1.78 + * space for them in advance.
1.79 + */
1.80 + bool isSymbol() {
1.81 + return false;
1.82 + }
1.83 +};
1.84 +
1.85 +inline bool
1.86 +ToPropertyKey(JSContext *cx, HandleValue v, PropertyKey *key)
1.87 +{
1.88 + if (v.isInt32() && v.toInt32() >= 0) {
1.89 + *key = PropertyKey(uint32_t(v.toInt32()));
1.90 + return true;
1.91 + }
1.92 +
1.93 + return detail::ToPropertyKeySlow(cx, v, key);
1.94 +}
1.95 +
1.96 +} // namespace JS
1.97 +
1.98 +#endif /* js_PropertyKey_h */
