Attribute Macro spec

#[spec]

Generates a lexer spec struct.

This macro generates the type of struct described in the crate documentation. The syntax is as follows.

use ilex::rule::Keyword;
use ilex::Lexeme;

/// My cool spec.
#[ilex::spec]
struct MySpec {
  #[named("...")]
  #[rule(/* ... */)]
  dollar: Lexeme<Keyword> = "$",
}

The type of each field must be a Lexeme with a Rule type as its parameter. There are two special attributes that can follow.

• #[named] makes the rule into a named rule. This name can be used by diagnostics, and corresponds to calling Spec::named_rule().

• #[rule] is the value to use to construct the rule, which must be Into<R>, where R is the type inside Lexeme (so, above, the rule value must be Into<Keyword>). By default, this value is the name of the rule, to make the common case of declaring a keyword as simple as writing nullptr: Lexeme<Keyword>, assuming Rust itself doesn’t already use that keyword.

Note that order matters for the fields: when breaking a tie between two potential tokens of the same length, the first one in the struct will win. In practice, this means you should put keywords before identifiers.

Additionally, the following functions will be defined for the MySpec type.

impl MySpec {
  /// Gets the global instance of this spec.
  pub fn get() -> &'static Self {
    // ...
  }

  /// Gets the actual compiled spec.
  pub fn spec(&self) -> &Spec {
    // ...
  }
}