@graffy/common/cjs/ops/step.js

Common libraries that used by various Graffy modules.

"use strict";

exports.__esModule = true;
exports.keyStep = keyStep;
exports.keyBefore = keyBefore;
exports.keyAfter = keyAfter;

function keyStep(key) {
  if (key === '') return {
    key: key,
    step: 1
  };
  if (key === "\uFFFF") return {
    key: key,
    step: -1
  };
  var l = key.length - 1;

  switch (key.charCodeAt(l)) {
    case 0:
      return {
        key: key.substr(0, l),
        step: 1
      };

    case 0xffff:
      return {
        key: key.substr(0, l - 1) + String.fromCharCode(key.charCodeAt(l - 1) + 1),
        step: -1
      };

    default:
      return {
        key: key,
        step: 0
      };
  }
}

function keyBefore(key) {
  if (key === '' || key === "\uFFFF" || key === '\0' || key === "\0\uFFFF") {
    return key;
  }

  var l = key.length - 1;
  return key.charCodeAt(l) === 0 ? key.substr(0, l) : key.substr(0, l) + String.fromCharCode(key.charCodeAt(l) - 1) + "\uFFFF";
}

function keyAfter(key) {
  if (key === '' || key === "\uFFFF" || key === '\0' || key === "\0\uFFFF") {
    return key;
  }

  var l = key.length - 1;
  return key.charCodeAt(l) === 0xffff ? key.substr(0, l - 1) + String.fromCharCode(key.charCodeAt(l - 1) + 1) : key + '\0';
}