eslint-plugin-ember/lib/rules/use-brace-expansion.js

Eslint plugin for Ember.js apps

'use strict';

const utils = require('../utils/utils');
const ember = require('../utils/ember');

//------------------------------------------------------------------------------
// General rule - Use brace expansion
//------------------------------------------------------------------------------

module.exports = {
  meta: {
    docs: {
      description: 'Enforces usage of brace expansion',
      category: 'Stylistic Issues',
      recommended: true,
      url: 'https://github.com/ember-cli/eslint-plugin-ember/tree/master/docs/rules/use-brace-expansion.md'
    },
    fixable: null, // or "code" or "whitespace"
  },

  create(context) {
    const message = 'Use brace expansion';

    function report(node) {
      context.report(node, message);
    }

    return {
      CallExpression(node) {
        if (!ember.isComputedProp(node)) return;

        const matchesBraces = x => !!x.match(/[{}]/g);
        const hasBraces = arr => arr.some(matchesBraces);
        const beforeBraces = arr => arr.slice(0, arr.indexOf(arr.find(matchesBraces)));
        const arrayDeepEqual = (a, b) =>
          a.length === b.length && a.reduce((acc, e, i) => acc && e === b[i], true);

        const problem = node.arguments
          .filter(arg => utils.isLiteral(arg) && typeof arg.value === 'string' && arg.value.indexOf('.') >= 0)
          .map(e => e.value.split('.'))
          .find((prop, i, props) => props.filter((e) => {
            const propHasBraces = hasBraces(prop);
            const eHasBraces = hasBraces(e);

            if (propHasBraces && eHasBraces) {
              return arrayDeepEqual(beforeBraces(e), beforeBraces(prop));
            } else if (!propHasBraces && !eHasBraces) {
              return prop[0] === e[0];
            }

            const withBraces = propHasBraces ? prop : e;
            const withoutBraces = propHasBraces ? e : prop;
            const shareable = beforeBraces(withBraces);
            return arrayDeepEqual(shareable, withoutBraces.slice(0, shareable.length));
          }).length > 1);

        if (problem) {
          report(node);
        }
      },
    };
  }
};