Refresh the implementation of Symbols to catch up with what the
specification now mandates:
* The global Symbol() function manufactures new Symbol values,
optionally with a string description attached.
* Invoking Symbol() as a constructor will now throw.
* ToString() over Symbol values still throws, and
Object.prototype.toString() stringifies like before.
* A Symbol value is wrapped in a Symbol object either implicitly if
it is the receiver, or explicitly done via Object(symbolValue) or
(new Object(symbolValue).)
* The Symbol.prototype.toString() method no longer throws on Symbol
wrapper objects (nor Symbol values.) Ditto for Symbol.prototype.valueOf().
* Symbol.prototype.toString() stringifies as "Symbol("<description>"),
valueOf() returns the wrapper's Symbol value.
* ToPrimitive() over Symbol wrapper objects now throws.
Overall, this provides a stricter separation between Symbol values and
wrapper objects than before, and the explicit fetching out of the
description (nee name) via the "name" property is no longer supported
(by the spec nor the implementation.)
Adjusted existing Symbol test files to fit current, adding some extra
tests for new/changed behavior.
LOG=N
R=arv@chromium.org, rossberg@chromium.org, arv, rossberg
BUG=v8:3053
Review URL: https://codereview.chromium.org/118553003
Patch from Sigbjorn Finne <sigbjornf@opera.com>.
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19490 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
(qua last week's TC39)
Specifically:
- Install Symbol constructor function on the global object.
- Adjust code generation for typeof.
- Remove IsSymbol built-in, IS_SYMBOL macro now defined using typeof.
- Remove hack that allowed symbols as constructor results, and some other special cases.
- Remove symbol_delegate and GetDelegate function.
- Extend ToBoolean stub to handle symbols.
- Extend ToNumber to return NaN on symbols.
- Poison symbol's toString function, and thereby ToString on symbols.
R=mstarzinger@chromium.org
BUG=v8:2158
Review URL: https://codereview.chromium.org/12957004
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14051 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
- Add --harmony-symbols flag.
- Add Symbol constructor; allow symbols as (unreplaced) return value from constructors.
- Introduce %CreateSymbol and %_IsSymbol natives and respective instructions.
- Extend 'typeof' code generation to handle symbols.
- Extend CompareIC with a UNIQUE_NAMES state that (uniformly) handles internalized strings and symbols.
- Property lookup delegates to SymbolDelegate object for symbols, which only carries the toString method.
- Extend Object.prototype.toString to recognise symbols.
Per the current draft spec, symbols are actually pseudo objects that are frozen with a null prototype and only one property (toString). For simplicity, we do not treat them as proper objects for now, although typeof will return "object". Only property access works as if they were (frozen) objects (via the internal delegate object).
(Baseline CL: https://codereview.chromium.org/12223071/)
R=mstarzinger@chromium.org
BUG=v8:2158
Review URL: https://codereview.chromium.org/12296026
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13786 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
