eslint-plugin-ft-flow/dist/rules/requireCompoundTypeAlias.js.flow

Flowtype linting rules for ESLint by flow-typed

const schema = [
  {
    enum: ['always', 'never'],
    type: 'string',
  },
  {
    additionalProperties: false,
    properties: {
      allowNull: {
        type: 'boolean',
      },
    },
    type: 'object',
  },
];

const create = (context) => {
  const always = (context.options[0] || 'always') === 'always';

  const allowNull = !(context.options[1] && context.options[1].allowNull === false);

  if (always) {
    return {
      IntersectionTypeAnnotation(node) {
        if (
          allowNull
          && node.types.length === 2
          && (
            node.types[0].type === 'NullLiteralTypeAnnotation'
            || node.types[1].type === 'NullLiteralTypeAnnotation'
          )
        ) {
          return;
        }

        if (node.parent.type !== 'TypeAlias') {
          context.report({
            message: 'All intersection types must be declared with named type alias.',
            node,
          });
        }
      },
      UnionTypeAnnotation(node) {
        if (
          allowNull
          && node.types.length === 2
          && (
            node.types[0].type === 'NullLiteralTypeAnnotation'
            || node.types[1].type === 'NullLiteralTypeAnnotation'
          )
        ) {
          return;
        }

        if (node.parent.type !== 'TypeAlias') {
          context.report({
            message: 'All union types must be declared with named type alias.',
            node,
          });
        }
      },
    };
  }

  return {};
};

export default {
  create,
  meta: {
    schema,
  },
};