src/doc/reference/src/identifiers.md

   1 # Identifiers
   2
   3 > **<sup>Lexer:<sup>**\
   4 > IDENTIFIER_OR_KEYWORD :\
   5 > &nbsp;&nbsp; &nbsp;&nbsp; XID_start XID_continue<sup>\*</sup>\
   6 > &nbsp;&nbsp; | `_` XID_continue<sup>+</sup>
   7 >
   8 > RAW_IDENTIFIER : `r#` IDENTIFIER_OR_KEYWORD <sub>*Except `crate`, `self`, `super`, `Self`*</sub>
   9 >
  10 > NON_KEYWORD_IDENTIFIER : IDENTIFIER_OR_KEYWORD <sub>*Except a [strict] or [reserved] keyword*</sub>
  11 >
  12 > IDENTIFIER :\
  13 > NON_KEYWORD_IDENTIFIER | RAW_IDENTIFIER
  14
  15 An identifier is any nonempty Unicode string of the following form:
  16
  17 Either
  18
  19 * The first character has property [`XID_start`].
  20 * The remaining characters have property [`XID_continue`].
  21
  22 Or
  23
  24 * The first character is `_`.
  25 * The identifier is more than one character. `_` alone is not an identifier.
  26 * The remaining characters have property [`XID_continue`].
  27
  28 > **Note**: [`XID_start`] and [`XID_continue`] as character properties cover the
  29 > character ranges used to form the more familiar C and Java language-family
  30 > identifiers.
  31
  32 A raw identifier is like a normal identifier, but prefixed by `r#`. (Note that
  33 the `r#` prefix is not included as part of the actual identifier.)
  34 Unlike a normal identifier, a raw identifier may be any strict or reserved
  35 keyword except the ones listed above for `RAW_IDENTIFIER`.
  36
  37 [strict]: keywords.md#strict-keywords
  38 [reserved]: keywords.md#reserved-keywords
  39 [`XID_start`]:  http://unicode.org/cldr/utility/list-unicodeset.jsp?a=%5B%3AXID_Start%3A%5D&abb=on&g=&i=
  40 [`XID_continue`]: http://unicode.org/cldr/utility/list-unicodeset.jsp?a=%5B%3AXID_Continue%3A%5D&abb=on&g=&i=