Code coverage report for 6to5/transformers/classes.js

Statements: 100% (80 / 80)      Branches: 100% (41 / 41)      Functions: 100% (12 / 12)      Lines: 100% (77 / 77)      Ignored: none     

All files » 6to5/transformers/ » classes.js
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var traverse = require("../traverse");
var util     = require("../util");
var b        = require("ast-types").builders;
var _        = require("lodash");
 
exports.ClassDeclaration = function (node) {
  return b.variableDeclaration("var", [
    b.variableDeclarator(node.id, buildClass(node))
  ]);
};
 
exports.ClassExpression = function (node) {
  return buildClass(node);
};
 
var getMemberExpressionObject = function (node) {
  while (node.type === "MemberExpression") {
    node = node.object;
  }
  return node;
};
 
var buildClass = function (node) {
  var superName = node.superClass;
  var className = node.id;
 
  var superClassReference = node.superClass;
 
  if (superName && superName.type === "MemberExpression") {
    superClassReference = getMemberExpressionObject(superName);
  }
 
  var container = util.template("class", {
    CLASS_NAME: className
  });
 
  var block     = container.callee.body;
  var body      = block.body;
 
  var returnStatement = body.pop();
 
  if (superName) {
    body.push(util.template("inherits", {
      SUPER_NAME: superName,
      CLASS_NAME: className
    }, true));
 
    container.arguments.push(superClassReference);
    container.callee.params.push(superClassReference);
  }
 
  buildClassBody(body, className, superName, node);
 
  body.push(returnStatement);
 
  return container;
};
 
var buildClassBody = function (body, className, superName, node) {
  var mutatorMap = {};
 
  var classBody = node.body.body;
  _.each(classBody, function (node) {
    var methodName = node.key.name;
    var method     = node.value;
 
    replaceInstanceSuperReferences(superName, method);
 
    if (methodName === "constructor") {
      if (node.kind === "") {
        addConstructor(body[0], method);
      } else {
        throw util.errorWithNode(node, "unknown kind for constructor method");
      }
    } else {
      if (node.kind === "") {
        addInstanceMethod(body, className, methodName, method);
      } else {
        util.pushMutatorMap(mutatorMap, methodName, node.kind, node);
      }
    }
  });
 
  if (!_.isEmpty(mutatorMap)) {
    var protoId = util.template("prototype-identifier", {
      CLASS_NAME: className
    });
 
    body.push(util.buildDefineProperties(mutatorMap, protoId));
  }
};
 
var superIdentifier = function (superName, node, parent) {
  if (parent.property === node) return;
 
  node.name = superName.name || superName.value;
 
  // super(); -> ClassName.call(this);
  if (parent.type === "CallExpression" && parent.callee === node) {
    node.name += ".call";
    parent.arguments.unshift(b.thisExpression());
  }
};
 
var replaceInstanceSuperReferences = function (superName, method) {
  superName = superName || b.literal("Function");
 
  traverse(method, function (node, parent) {
    if (node.type === "Identifier" && node.name === "super") {
      superIdentifier(superName, node, parent);
    } else if (node.type === "MemberExpression") {
      // no accessing of super properties
 
      if (isAccessingSuperProperties(parent, node)) {
        throw util.errorWithNode(node, "cannot access super properties");
      } else {
        return;
      }
    } else if (node.type === "CallExpression") {
      var callee = node.callee;
      if (callee.type !== "MemberExpression") return;
      if (callee.object.name !== "super") return;
 
      callee.property.name = "prototype." + callee.property.name + ".call";
      node.arguments.unshift(b.thisExpression());
    } else {
      return;
    }
  });
};
 
var isAccessingSuperProperties = function (parent, node) {
  var obj = node.object;
  return obj.type === "Identifier" && obj.name === "super" &&
         parent.object === node;
};
 
var addConstructor = function (construct, method) {
  construct.defaults = method.defaults;
  construct.params   = method.params;
  construct.body     = method.body;
};
 
var addInstanceMethod = function (body, className, methodName, method) {
  body.push(util.template("class-method", {
    METHOD_NAME: methodName,
    CLASS_NAME: className,
    FUNCTION: method
  }, true));
};