generator function for sbn compiler

generator.js

function generator (svg_ast) {

  // create attributes string out of attr object
  // { "width": 100, "height": 100 } becomes 'width="100" height="100"'
  function createAttrString (attr) {
    return Object.keys(attr).map(function (key){
      return key + '="' + attr[key] + '"'
    }).join(' ')
  }

  // top node is always <svg>. Create attributes string for svg tag
  var svg_attr = createAttrString(svg_ast.attr)

  // for each elements in the body of svg_ast, generate svg tag
  var elements = svg_ast.body.map(function (node) {
    return '<' + node.tag + ' ' + createAttrString(node.attr) + '></' + node.tag + '>'
  }).join('\n\t')

  // wrap with open and close svg tag to complete SVG code
  return '<svg '+ svg_attr +'>\n' + elements + '\n</svg>'
}