duktape

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Author	SHA1	Message	Date
Sami Vaarala	5ed6bb980b	Add initial, minimal ES6 Symbol support * Strings with 0xFF byte prefix are considered special symbols: they have typeof "symbol" but still mostly behave as strings (e.g. allow ToString) so that existing code dealing with internal keys, especially inside Duktape, can work with fewer changes. * Strings with 0x80 byte prefix are global symbols, e.g. Symbol.for('foo') creates the byte representatio: 0x80 "foo" * Strings with 0x81 byte prefix are unique symbols; the 0x81 byte is followed by the Symbol description, and an internal string component ensuring uniqueness is separated by a 0xFF byte (which can never appear anywhere in an extended UTF-8 string). The unique suffix is up to Duktape internals, currently two 32-bit counters are used. For example: 0x81 "mySymbol" 0xFF "0-17". * Well-known symbols use the 0x81 prefix but lack a unique suffix, so their format is 0x81 <description> 0xFF. * ES6 distinguishes between an undefined symbol description and an empty string symbol description. This distinction is not currently visible via Ecmascript bindings but may be visible in the future. Append an extra 0xFF to the unique suffix when the description is undefined, i.e. 0x81 0xFF <unique suffix> 0xFF.	8 years ago

Author

SHA1

Message

Date

Sami Vaarala

5ed6bb980b

Add initial, minimal ES6 Symbol support

* Strings with 0xFF byte prefix are considered special symbols: they have
  typeof "symbol" but still mostly behave as strings (e.g. allow ToString)
  so that existing code dealing with internal keys, especially inside
  Duktape, can work with fewer changes.

* Strings with 0x80 byte prefix are global symbols, e.g. Symbol.for('foo')
  creates the byte representatio: 0x80 "foo"

* Strings with 0x81 byte prefix are unique symbols; the 0x81 byte is followed
  by the Symbol description, and an internal string component ensuring
  uniqueness is separated by a 0xFF byte (which can never appear anywhere in
  an extended UTF-8 string).  The unique suffix is up to Duktape internals,
  currently two 32-bit counters are used.  For example:
  0x81 "mySymbol" 0xFF "0-17".

* Well-known symbols use the 0x81 prefix but lack a unique suffix, so their
  format is 0x81 <description> 0xFF.

* ES6 distinguishes between an undefined symbol description and an empty
  string symbol description.  This distinction is not currently visible via
  Ecmascript bindings but may be visible in the future.  Append an extra
  0xFF to the unique suffix when the description is undefined, i.e.
  0x81 0xFF <unique suffix> 0xFF.

8 years ago

1 Commits (f64a50944e05607a65685b865a88e2c2480c3182)