parcel-bundler/lib/visitors/dependencies.js

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'use strict';

const types = require('babel-types');
const template = require('babel-template');

const requireTemplate = template('require("_bundle_loader")');
const argTemplate = template('require.resolve(MODULE)');

module.exports = {
  ImportDeclaration(node, asset) {
    asset.isES6Module = true;
    addDependency(asset, node.source);
  },

  ExportNamedDeclaration(node, asset) {
    asset.isES6Module = true;
    if (node.source) {
      addDependency(asset, node.source);
    }
  },

  ExportAllDeclaration(node, asset) {
    asset.isES6Module = true;
    addDependency(asset, node.source);
  },

  ExportDefaultDeclaration(node, asset) {
    asset.isES6Module = true;
  },

  CallExpression(node, asset) {
    let callee = node.callee,
        args = node.arguments;


    let isRequire = types.isIdentifier(callee) && callee.name === 'require' && args.length === 1 && types.isStringLiteral(args[0]);

    if (isRequire) {
      addDependency(asset, args[0]);
    }

    let isDynamicImport = callee.type === 'Import' && args.length === 1 && types.isStringLiteral(args[0]);

    if (isDynamicImport) {
      asset.addDependency('_bundle_loader');
      addDependency(asset, args[0], { dynamic: true });

      node.callee = requireTemplate().expression;
      node.arguments[0] = argTemplate({ MODULE: args[0] }).expression;
      asset.isAstDirty = true;
    }
  }
};

function addDependency(asset, node, opts = {}) {
  opts.loc = node.loc && node.loc.start;
  asset.addDependency(node.value, opts);
}