babel-core/lib/babel/transformation/transformers/es6/template-literals.js

Turn ES6 code into readable vanilla ES5 with source maps

"use strict";

var t = require("../../../types");

var buildBinaryExpression = function (left, right) {
  return t.binaryExpression("+", left, right);
};

exports.check = function (node) {
  return t.isTemplateLiteral(node) || t.isTaggedTemplateExpression(node);
};

exports.TaggedTemplateExpression = function (node, parent, scope, file) {
  var args = [];
  var quasi = node.quasi;

  var strings = [];
  var raw = [];

  for (var i = 0; i < quasi.quasis.length; i++) {
    var elem = quasi.quasis[i];
    strings.push(t.literal(elem.value.cooked));
    raw.push(t.literal(elem.value.raw));
  }

  strings = t.arrayExpression(strings);
  raw = t.arrayExpression(raw);

  var templateName = "tagged-template-literal";
  if (file.isLoose("es6.templateLiterals")) templateName += "-loose";
  args.push(t.callExpression(file.addHelper(templateName), [strings, raw]));

  args = args.concat(quasi.expressions);

  return t.callExpression(node.tag, args);
};

exports.TemplateLiteral = function (node) {
  var nodes = [];
  var i;

  for (i = 0; i < node.quasis.length; i++) {
    var elem = node.quasis[i];

    nodes.push(t.literal(elem.value.cooked));

    var expr = node.expressions.shift();
    if (expr) nodes.push(expr);
  }

  if (nodes.length > 1) {
    // remove redundant '' at the end of the expression
    var last = nodes[nodes.length - 1];
    if (t.isLiteral(last, { value: "" })) nodes.pop();

    var root = buildBinaryExpression(nodes.shift(), nodes.shift());

    for (i = 0; i < nodes.length; i++) {
      root = buildBinaryExpression(root, nodes[i]);
    }

    return root;
  } else {
    return nodes[0];
  }
};