njk2php.js

#!/usr/bin/env node
'use strict';
// note: meta-template is not published on npm yet, so you will
// need to clone it and run `npm install && npm link` first!
const mt = require('meta-template');

var input = '{% if foo %}{{ foo }}{% else %}no foo!{% endif %}';
var ast = mt.parse.string(input);

// or read from stdin with something like:
// process.stdin.pipe(require('concat-stream')(buffer => {
//   ast = mt.parse.buffer(buffer);
// }));

mt.ast.walk(ast, node => {
  if (node.type === 'TemplateData') {
    // you can do whatever you want with node.value here, e.g.
    // node.value = '(' + node.value + ')';
  }
});

var out = mt.format.php(ast);
console.log(out);