babel-core/lib/babel/transformation/modules/_default.js

Turn ES6 code into readable vanilla ES5 with source maps

"use strict";

module.exports = DefaultFormatter;

var messages = require("../../messages");
var extend   = require("lodash/object/extend");
var object   = require("../../helpers/object");
var util     = require("../../util");
var t        = require("../../types");

function DefaultFormatter(file) {
  this.scope = file.scope;
  this.file  = file;
  this.ids   = object();

  this.hasNonDefaultExports = false;

  this.hasLocalExports = false;
  this.hasLocalImports = false;

  this.localImportOccurences = object();
  this.localExports = object();
  this.localImports = object();

  this.getLocalExports();
  this.getLocalImports();

  this.remapAssignments();
}

DefaultFormatter.prototype.doDefaultExportInterop = function (node) {
  return node.default && !this.noInteropRequireExport && !this.hasNonDefaultExports;
};

DefaultFormatter.prototype.bumpImportOccurences = function (node) {
  var source = node.source.value;
  var occurs = this.localImportOccurences;
  occurs[source] = occurs[source] || 0;
  occurs[source] += node.specifiers.length;
};

var exportsVisitor = {
  enter: function (node, parent, scope, formatter) {
    var declar = node && node.declaration;
    if (t.isExportDeclaration(node)) {
      formatter.hasLocalImports = true;

      if (declar && t.isStatement(declar)) {
        extend(formatter.localExports, t.getBindingIdentifiers(declar));
      }

      if (!node.default) {
        formatter.hasNonDefaultExports = true;
      }

      if (node.source) {
        formatter.bumpImportOccurences(node);
      }
    }
  }
};

DefaultFormatter.prototype.getLocalExports = function () {
  this.file.scope.traverse(this.file.ast, exportsVisitor, this);
};

var importsVisitor = {
  enter: function (node, parent, scope, formatter) {
    if (t.isImportDeclaration(node)) {
      formatter.hasLocalImports = true;
      extend(formatter.localImports, t.getBindingIdentifiers(node));
      formatter.bumpImportOccurences(node);
    }
  }
};

DefaultFormatter.prototype.getLocalImports = function () {
  this.file.scope.traverse(this.file.ast, importsVisitor, this);
};

var remapVisitor = {
  enter: function (node, parent, scope, formatter) {
    if (t.isUpdateExpression(node) && formatter.isLocalReference(node.argument, scope)) {
      this.skip();

      // expand to long file assignment expression
      var assign = t.assignmentExpression(node.operator[0] + "=", node.argument, t.literal(1));

      // remap this assignment expression
      var remapped = formatter.remapExportAssignment(assign);

      // we don't need to change the result
      if (t.isExpressionStatement(parent) || node.prefix) {
        return remapped;
      }

      var nodes = [];
      nodes.push(remapped);

      var operator;
      if (node.operator === "--") {
        operator = "+";
      } else { // "++"
        operator = "-";
      }
      nodes.push(t.binaryExpression(operator, node.argument, t.literal(1)));

      return t.sequenceExpression(nodes);
    }

    if (t.isAssignmentExpression(node) && formatter.isLocalReference(node.left, scope)) {
      this.skip();
      return formatter.remapExportAssignment(node);
    }
  }
};

DefaultFormatter.prototype.remapAssignments = function () {
  if (this.hasLocalImports) {
    this.file.scope.traverse(this.file.ast, remapVisitor, this);
  }
};

DefaultFormatter.prototype.isLocalReference = function (node) {
  var localImports = this.localImports;
  return t.isIdentifier(node) && localImports[node.name] && localImports[node.name] !== node;
};

DefaultFormatter.prototype.remapExportAssignment = function (node) {
  return t.assignmentExpression(
    "=",
    node.left,
    t.assignmentExpression(
      node.operator,
      t.memberExpression(t.identifier("exports"), node.left),
      node.right
    )
  );
};

DefaultFormatter.prototype.isLocalReference = function (node, scope) {
  var localExports = this.localExports;
  var name = node.name;
  return t.isIdentifier(node) && localExports[name] && localExports[name] === scope.getBindingIdentifier(name);
};

DefaultFormatter.prototype.getModuleName = function () {
  var opts = this.file.opts;
  var filenameRelative = opts.filenameRelative;
  var moduleName = "";

  if (opts.moduleRoot) {
    moduleName = opts.moduleRoot + "/";
  }

  if (!opts.filenameRelative) {
    return moduleName + opts.filename.replace(/^\//, "");
  }

  if (opts.sourceRoot) {
    // remove sourceRoot from filename
    var sourceRootRegEx = new RegExp("^" + opts.sourceRoot + "\/?");
    filenameRelative = filenameRelative.replace(sourceRootRegEx, "");
  }

  if (!opts.keepModuleIdExtensions) {
    // remove extension
    filenameRelative = filenameRelative.replace(/\.(\w*?)$/, "");
  }

  moduleName += filenameRelative;

  // normalize path separators
  moduleName = moduleName.replace(/\\/g, "/");

  return moduleName;
};

DefaultFormatter.prototype._pushStatement = function (ref, nodes) {
  if (t.isClass(ref) || t.isFunction(ref)) {
    if (ref.id) {
      nodes.push(t.toStatement(ref));
      ref = ref.id;
    }
  }

  return ref;
};

DefaultFormatter.prototype._hoistExport = function (declar, assign, priority) {
  if (t.isFunctionDeclaration(declar)) {
    assign._blockHoist = priority || 2;
  }

  return assign;
};

DefaultFormatter.prototype.getExternalReference = function (node, nodes) {
  var ids = this.ids;
  var id = node.source.value;

  if (ids[id]) {
    return ids[id];
  } else {
    return this.ids[id] = this._getExternalReference(node, nodes);
  }
};

DefaultFormatter.prototype.checkExportIdentifier = function (node) {
  if (t.isIdentifier(node, { name: "__esModule" })) {
    throw this.file.errorWithNode(node, messages.get("modulesIllegalExportName", node.name));
  }
};

DefaultFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
  if (node.source) {
    var ref = this.getExternalReference(node, nodes);

    if (t.isExportBatchSpecifier(specifier)) {
      // export * from "foo";
      nodes.push(this.buildExportsWildcard(ref, node));
    } else {
      if (t.isSpecifierDefault(specifier) && !this.noInteropRequireExport) {
        // importing a default so we need to normalize it
        ref = t.callExpression(this.file.addHelper("interop-require"), [ref]);
      } else {
        ref = t.memberExpression(ref, t.getSpecifierId(specifier));
      }

      // export { foo } from "test";
      nodes.push(this.buildExportsAssignment(
        t.getSpecifierName(specifier),
        ref,
        node
      ));
    }
  } else {
    // export { foo };
    nodes.push(this.buildExportsAssignment(t.getSpecifierName(specifier), specifier.id, node));
  }
};

DefaultFormatter.prototype.buildExportsWildcard = function (objectIdentifier) {
  return t.expressionStatement(t.callExpression(this.file.addHelper("defaults"), [
    t.identifier("exports"),
    t.callExpression(this.file.addHelper("interop-require-wildcard"), [objectIdentifier])
  ]));
};

DefaultFormatter.prototype.buildExportsAssignment = function (id, init) {
  this.checkExportIdentifier(id);
  return util.template("exports-assign", {
    VALUE: init,
    KEY:   id
  }, true);
};

DefaultFormatter.prototype.exportDeclaration = function (node, nodes) {
  var declar = node.declaration;

  var id = declar.id;

  if (node.default) {
    id = t.identifier("default");
  }

  var assign;

  if (t.isVariableDeclaration(declar)) {
    for (var i = 0; i < declar.declarations.length; i++) {
      var decl = declar.declarations[i];

      decl.init = this.buildExportsAssignment(decl.id, decl.init, node).expression;

      var newDeclar = t.variableDeclaration(declar.kind, [decl]);
      if (i === 0) t.inherits(newDeclar, declar);
      nodes.push(newDeclar);
    }
  } else {
    var ref = declar;

    if (t.isFunctionDeclaration(declar) || t.isClassDeclaration(declar)) {
      ref = declar.id;
      nodes.push(declar);
    }

    assign = this.buildExportsAssignment(id, ref, node);

    nodes.push(assign);

    this._hoistExport(declar, assign);
  }
};