ASTQuery

Use css-like selectors for walking over AST-tree

Example

``javascript
var ast = esprima.parse('function test(){ var a, b = 0; a = 1; a += 2; b++; b--; };test();');
var astQuery = new ASTQuery(ast, 'es5');
astQuery.on({
print: function(node, message) {
console.log('node type is ' + node.type + ' | ' + message)
}

, ':: FunctionDeclaration': function(node) {
this.print(node, '1| ');
}

, ':: VariableDeclarator': function(node) {
this.print(node, '2| ' + node.id.name);
}

, ':: AssignmentExpression[operator="="]': function(node) {
this.print(node, '3| ' + node.left.name + "|" + node.operator);
}

// TODO::
// , ':: UpdateExpression[operator="++"]': function(node) {
// this.print(node, '4| ' + node.argument.name + "|" + node.operator);
// }

// TODO::
// , ':: :other': function(node) {
// console.log(' untouched node type is ' + node.type);
// }
}, {prefix: '::'});

astQuery.apply();

// console output is:
// > node type is FunctionDeclaration | 1|
// > node type is VariableDeclarator | 2| a
// > node type is VariableDeclarator | 2| b
// > node type is AssignmentExpression | 3| a|=

`

TODO

1. ':other' pseudo-class
1. complex selector's support ('tag>tag')
1. classes support with API to adding class description
1. es6 'query' string template tag (astQuery.queryVariableDeclarator:${function(node){ return node.id.name == 'a' }}`)
1. 'removeListener'