pep440.js

module.exports = {

  version: ($) =>
    seq(
      optional("v"),
      optional(field("epoch", $.epoch)),
      field("release", $.release),
      optional(field("pre_release", $.pre_release)),
      optional(field("post_release", $.post_release)),
      optional(field("dev_release", $.dev_release)),
      optional(field("local_version", $.local_version)),
    ),

  epoch: ($) => seq($._number, "!"),

  release: ($) => seq($._number, repeat(seq(".", $._number))),

  pre_release: ($) =>
    seq(
      optional($._separator),
      field("label", $.pre_release_label),
      optional($._separator),
      optional(field("number", optional($._number))), // Number is optional in regex
    ),

  post_release: ($) =>
    choice(
      seq("-", field("number1", $._number)),
      seq(
        optional($._separator),
        field("label", $.post_release_label),
        optional($._separator),
        optional(field("number2", optional($._number))), // Number is optional in regex
      ),
    ),

  dev_release: ($) =>
    seq(
      optional($._separator),
      field("label", $.dev_release_label),
      optional($._separator),
      optional(field("number", optional($._number))), // Number is optional in regex
    ),

  local_version: ($) => seq("+", field("identifier", $.local_version_identifier)),

  local_version_identifier: ($) => seq($.alphanumeric, repeat(seq($._local_separator, $.alphanumeric))),

  // --- Token Definitions ---
  _number: () => /\d+/,

  alphanumeric: () => /[a-z0-9]+/,

  _separator: () => /[-_\.]/,
  _local_separator: ($) => /[-_\.]/, // Separator for local version can be the same

  pre_release_label: ($) =>
    choice(
      caseInsensitive("a"),
      caseInsensitive("b"),
      caseInsensitive("c"),
      caseInsensitive("rc"),
      caseInsensitive("alpha"),
      caseInsensitive("beta"),
      caseInsensitive("pre"),
      caseInsensitive("preview"),
    ),

  post_release_label: ($) => choice(caseInsensitive("post"), caseInsensitive("rev"), caseInsensitive("r")),

  dev_release_label: ($) => caseInsensitive("dev"),
};

function caseInsensitive(keyword) {
  return new RegExp(keyword, "i");
}