gonzales-ast

This is library to help navigate CSS AST produced by the Gonzales CSS parser

Installation

$ npm install gonzales-ast

Why

Gonzales eats CSS and spits AST. It also eats AST and spits CSS.

But it doesn't have an API for AST-to-AST manipulations.

Tell me more

Additionally, this library makes the Gonzales' APIs a little more sensible (in the author's opinion).

E.g. the srcToCSSP() method is available as parse().

Currently this library offers:

• renamed APIs
• a method traverse() to walk the AST and visit each node

Renamed APIs

Simple usage:

var gonzo = require('gonzales-ast');
var ast = gonzo.parse('a {margin: 0}'); // formerly `srcToCSSP()`
var css_string = gonzo.toCSS(ast); // formerly `csspToSrc()`

There's also toTree() (formerly csspToTree()) that shows a formatted view of the AST.

gonzo.toTree(ast);

Returns the string:

['stylesheet', 
  ['ruleset', 
    ['selector', 
      ['simpleselector', 
        ['ident', 'a'], 
        ['s', ' ']]], 
    ['block', 
      ['declaration', 
        ['property', 
          ['ident', 'margin']], 
        ['value', 
          ['s', ' '], 
          ['number', '0']]]]]]

AST visitors

When traversing the AST you can provide any number of "visitors" that take a node and look at it, and maybe do something with it.

Like:

var newast = gonzo.traverse(ast, [
  visitor1,
  visitor2,
  {
    test: function(name, nodes) {
      return true;
    },
    process: function(node) {
      return node;
    }
  }
]);

Each visitor must provide a process() method which returns a node or false (which removes the node from the tree)

A visitor may provide an optional test() method which is a lightweight way to see whether or not the process() method should be called. test()methods return boolean.

See the examples directory for an examples of visitors that add, remove and change nodes.

UI

To admire the AST that Gonzales produces, check this out.

Other stuffs

• https://github.com/css/gonzales - Gonzales itself
• https://github.com/tonyganch/gonzales-pe - Fork of Gonzales that also supports preprocessors
• https://github.com/csscomb/csscomb.js/ - Formatter on top of -pe. No AST-to-AST, only AST-to-string
• https://github.com/ai/postcss/ - Another parser, source maps and more fun. Simpler AST.
• https://github.com/visionmedia/rework - like above