text: import {plugin} from 'postcss';
  
  import transform from './lib/transform';
  
  export default plugin('postcss-calc', (opts) => {
    const options = Object.assign({
      precision: 5,
      preserve: false,
      warnWhenCannotResolve: false,
      mediaQueries: false,
      selectors: false
    }, opts);
  
    return (css, result) => {
      css.walk(node => {
        const { type } = node;
        if (type === 'decl') transform(node, "value", options, result);
        if (type === 'atrule' && options.mediaQueries) transform(node, "params", options, result);
        if (type === 'rule' && options.selectors) transform(node, "selector", options, result);
      });
    };
  });
  