burrito

    0.2.12 • Public • Published

    burrito

    Burrito makes it easy to do crazy stuff with the javascript AST.

    This is super useful if you want to roll your own stack traces or build a code coverage tool.

    build status

    node.wrap("burrito")

    examples

    microwave

    examples/microwave.js

    var burrito = require('burrito');
     
    var res = burrito.microwave('Math.sin(2)', function (node) {
        if (node.name === 'num') node.wrap('Math.PI / %s');
    });
     
    console.log(res); // sin(pi / 2) == 1

    output:

    1
    

    wrap

    examples/wrap.js

    var burrito = require('burrito');
     
    var src = burrito('f() && g(h())\nfoo()', function (node) {
        if (node.name === 'call') node.wrap('qqq(%s)');
    });
     
    console.log(src);

    output:

    qqq(f()) && qqq(g(qqq(h())));
    
    qqq(foo());
    

    methods

    var burrito = require('burrito');
    

    burrito(code, cb)

    Given some source code and a function trace, walk the ast by expression.

    The cb gets called with a node object described below.

    If code is an Array then it is assumbed to be an AST which you can generate yourself with burrito.parse(). The AST must be annotated, so make sure to burrito.parse(src, false, true).

    burrito.microwave(code, context={}, cb)

    Like burrito() except the result is run using vm.runInNewContext(res, context).

    node object

    node.name

    Name is a string that contains the type of the expression as named by uglify.

    node.wrap(s)

    Wrap the current expression in s.

    If s is a string, "%s" will be replaced with the stringified current expression.

    If s is a function, it is called with the stringified current expression and should return a new stringified expression.

    If the node.name === "binary", you get the subterms "%a" and "%b" to play with too. These subterms are applied if s is a function too: s(expr, a, b).

    Protip: to insert multiple statements you can use javascript's lesser-known block syntax that it gets from C:

    if (node.name === 'stat') node.wrap('{ foo(); %s }')

    node.node

    raw ast data generated by uglify

    node.value

    node.node.slice(1) to skip the annotations

    node.start

    The start location of the expression, like this:

    { type: 'name',
      value: 'b',
      line: 0,
      col: 3,
      pos: 3,
      nlb: false,
      comments_before: [] }

    node.end

    The end location of the expression, formatted the same as node.start.

    node.state

    The state of the traversal using traverse.

    node.source()

    Returns a stringified version of the expression.

    node.parent()

    Returns the parent node or null if the node is the root element.

    node.label()

    Return the label of the present node or null if there is no label.

    Labels are returned for "call", "var", "defun", and "function" nodes.

    Returns an array for "var" nodes since var statements can contain multiple labels in assignment.

    install

    With npm you can just:

    npm install burrito
    

    in the browser

    Burrito works in browser with browserify.

    It has been tested against:

    • Internet Explorer 5.5, 6.0, 7.0, 8.0, 9.0
    • Firefox 3.5
    • Chrome 6.0
    • Opera 10.6
    • Safari 5.0

    kudos

    Heavily inspired by (and previously mostly lifted outright from) isaacs's nifty tmp/instrument.js thingy from uglify-js.

    Keywords

    none

    Install

    npm i burrito

    DownloadsWeekly Downloads

    11,917

    Version

    0.2.12

    License

    BSD

    Last publish

    Collaborators

    • substack