@coffeelint/cli/lib/rules/arrow_spacing.js

Lint your CoffeeScript

(function() {
  var ArrowSpacing;

  module.exports = ArrowSpacing = (function() {
    class ArrowSpacing {
      lintToken(token, tokenApi) {
        var pp;
        // Throw error unless the following happens.

        // We will take a look at the previous token to see
        // 1. That the token is properly spaced
        // 2. Wasn't generated by the CoffeeScript compiler
        // 3. That it is just indentation
        // 4. If the function declaration has no parameters
        // e.g. x(-> 3)
        //      x( -> 3)

        // or a statement is wrapped in parentheses
        // e.g. (-> true)()

        // we will accept either having a space or not having a space there.

        // Also if the -> is the beginning of the file, then simply just return
        pp = tokenApi.peek(-1);
        if (!pp) {
          return;
        }
        // Ignore empty functions
        if (!token.spaced && tokenApi.peek(1)[0] === 'INDENT' && tokenApi.peek(2)[0] === 'OUTDENT') {
          return null;
        // Throw error unless the previous token...
        } else if (!(((token.spaced != null) || (token.newLine != null)) && (((pp.spaced != null) || pp[0] === 'TERMINATOR') || (pp.generated != null) || pp[0] === 'INDENT' || (pp[1] === '(' && (pp.generated == null))))) { //4
          return {token};
        } else {
          return null;
        }
      }

    };

    ArrowSpacing.prototype.rule = {
      type: 'style',
      name: 'arrow_spacing',
      level: 'ignore',
      message: 'Function arrows (-> and =>) must be spaced properly',
      description: `<p>This rule checks to see that there is spacing before and after
the arrow operator that declares a function. This rule is disabled
by default.</p> <p>Note that if arrow_spacing is enabled, and you
pass an empty function as a parameter, arrow_spacing will accept
either a space or no space in-between the arrow operator and the
parenthesis</p>
<pre><code># Both of this will not trigger an error,
# even with arrow_spacing enabled.
x(-> 3)
x( -> 3)

# However, this will trigger an error
x((a,b)-> 3)
</code>
</pre>`
    };

    ArrowSpacing.prototype.tokens = ['->', '=>'];

    return ArrowSpacing;

  }).call(this);

}).call(this);