[feature] implement a visitor & filter helper

[ichiriac]

implement a visitor helper in order to handle AST transversal :

const ast = parser.parse('...some code...');

// visiting child nodes :
ast.visit(function(node) {
  // do something
});

// filtering a list of nodes
const nodes = ast.filter(function(node) {
  return node.kind === 'something';
});

NOTE : this is implemented on each node, can be used on program node as in the example, or on any other node

[cedw032]

Is anything happening with this? I'm trying to get a complete traversable AST but from the types and documentation, I cannot tell how basic traversing is supposed to be achieved. I am very interested in using this package but am having trouble getting started. Any help would be appreciated.

Does anyone have a demo of basic tree traversal? I can only see as deep as the class declaration. Also, the AST seems to print nicely but is showing no children of my class, and no errors...

[ichiriac]

Hi @cedw032, glad to see your interest for this library.

If you want to see some usage you can check this other project, but it may seem hard to read : https://github.com/glayzzle/php-reflection

You have the documentation here : https://php-parser.glayzzle.com/readme and the structure of nodes is documented here : https://php-parser.glayzzle.com/api/ast.js

The main idea of the visitor is to recursivelly scan each property node, and to launch the visit callback when you find a kind property on an entity.

Here a pseudo example :

function visit(node, parent, cb) {
  cb(node.kind, node, parent);
  for(var k in node) {
    var child = node[k];
    if (typeof child.type === 'string') {
     cb(child.kind, child, node);
    } else if (Array.isArray(child) ... ) {
       ....
    } else if (typeof child === 'object) { 
       ....
    }
  }
}

And the filter is something similar with filtering callback and returns an array of nodes