| // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| part of dart.core; |
| |
| /// Opaque name used by mirrors, invocations and [Function.apply]. |
| abstract class Symbol { |
| /** The symbol corresponding to the name of the unary minus operator. */ |
| static const Symbol unaryMinus = const Symbol("unary-"); |
| |
| /** |
| * The empty symbol. |
| * |
| * The empty symbol is the name of libraries with no library declaration, |
| * and the base-name of the unnamed constructor. |
| */ |
| static const Symbol empty = const Symbol(""); |
| |
| /** |
| * Constructs a new [Symbol] representing the provided name. |
| * |
| * The name must be a valid public Dart member name, |
| * public constructor name, or library name, optionally qualified. |
| * |
| * A qualified name is a valid name preceded by a public identifier name |
| * and a '`.`', e.g., `foo.bar.baz=` is a qualified version of `baz=`. |
| * That means that the content of the [name] String must be either |
| * |
| * * a valid public Dart identifier |
| * (that is, an identifier not starting with "`_`"), |
| * * such an identifier followed by "=" (a setter name), |
| * * the name of a declarable operator |
| * (one of "`+`", "`-`", "`*`", "`/`", "`%`", "`~/`", "`&`", "`|`", |
| * "`^`", "`~`", "`<<`", "`>>`", "`<`", "`<=`", "`>`", "`>=`", "`==`", |
| * "`[]`", "`[]=`", or "`unary-`"), |
| * * any of the above preceded by any number of qualifiers, |
| * where a qualifier is a non-private identifier followed by '`.`', |
| * * or the empty string (the default name of a library with no library |
| * name declaration). |
| * |
| * Symbol instances created from the same [name] are equal, |
| * but not necessarily identical, but symbols created as compile-time |
| * constants are canonicalized, as all other constant object creations. |
| * |
| * ```dart |
| * assert(new Symbol("foo") == new Symbol("foo")); |
| * assert(identical(const Symbol("foo"), const Symbol("foo"))); |
| * ``` |
| * |
| * If [name] is a single identifier that does not start with an underscore, |
| * or it is a qualified identifier, |
| * or it is an operator name different from `unary-`, |
| * then the result of `const Symbol(name)` is the same instance that |
| * the symbol literal created by prefixing `#` to the content of [name] |
| * would evaluate to. |
| * |
| * ```dart |
| * assert(new Symbol("foo") == #foo); |
| * assert(new Symbol("[]=") == #[]=]); |
| * assert(new Symbol("foo.bar") == #foo.bar); |
| * assert(identical(const Symbol("foo"), #foo)); |
| * assert(identical(const Symbol("[]="), #[]=])); |
| * assert(identical(const Symbol("foo.bar"), #foo.bar)); |
| * ``` |
| * |
| * This constructor cannot create a [Symbol] instance that is equal to |
| * a private symbol literal like `#_foo`. |
| * ```dart |
| * const Symbol("_foo") // Invalid |
| * `` |
| * |
| * The following text is non-normative: |
| * |
| * Creating non-const Symbol instances may result in larger output. If |
| * possible, use `MirrorsUsed` from "dart:mirrors" to specify which names |
| * might be passed to this constructor. |
| */ |
| const factory Symbol(String name) = internal.Symbol; |
| |
| /** |
| * Returns a hash code compatible with [operator==]. |
| * |
| * Equal symbols have the same hash code. |
| */ |
| int get hashCode; |
| |
| /** |
| * Symbols are equal to other symbols that correspond to the same member name. |
| * |
| * Qualified member names, like `#foo.bar` are equal only if they have the |
| * same identifiers before the same final member name. |
| */ |
| bool operator ==(other); |
| } |