Files
babel/src/babel/transformation/transformers/es6/classes.js

583 lines
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JavaScript

import memoiseDecorators from "../../helpers/memoise-decorators";
import ReplaceSupers from "../../helpers/replace-supers";
import * as nameMethod from "../../helpers/name-method";
import * as defineMap from "../../helpers/define-map";
import * as messages from "../../../messages";
import * as util from "../../../util";
import traverse from "../../../traversal";
import each from "lodash/collection/each";
import has from "lodash/object/has";
import * as t from "../../../types";
const PROPERTY_COLLISION_METHOD_NAME = "__initializeProperties";
export function ClassDeclaration(node, parent, scope, file) {
return t.variableDeclaration("let", [
t.variableDeclarator(node.id, t.toExpression(node))
]);
}
export function ClassExpression(node, parent, scope, file) {
return new ClassTransformer(this, file).run();
}
var collectPropertyReferencesVisitor = {
Identifier: {
enter(node, parent, scope, state) {
if (this.parentPath.isClassProperty({ key: node })) {
return;
}
if (this.isReferenced() && scope.getBinding(node.name) === state.scope.getBinding(node.name)) {
state.references[node.name] = true;
}
}
}
};
var constructorVisitor = {
ThisExpression: {
enter(node, parent, scope, ref) {
return ref;
}
},
Function: {
enter(node) {
if (!node.shadow) {
this.skip();
}
}
}
};
var verifyConstructorVisitor = {
MethodDefinition: {
enter() {
this.skip();
}
},
Property: {
enter(node) {
if (node.method) this.skip();
}
},
CallExpression: {
exit(node, parent, scope, state) {
if (this.get("callee").isSuper()) {
state.hasBareSuper = true;
state.bareSuper = this;
if (!state.hasSuper) {
throw this.errorWithNode("super call is only allowed in derived constructor");
}
}
}
},
FunctionDeclaration: {
enter() {
this.skip();
}
},
FunctionExpression: {
enter() {
this.skip();
}
},
ThisExpression: {
enter(node, parent, scope, state) {
if (state.hasSuper && !state.hasBareSuper) {
throw this.errorWithNode("'this' is not allowed before super()");
}
}
}
};
class ClassTransformer {
/**
* Description
*/
constructor(path: TraversalPath, file: File) {
this.parent = path.parent;
this.scope = path.scope;
this.node = path.node;
this.path = path;
this.file = file;
this.hasInstanceDescriptors = false;
this.hasStaticDescriptors = false;
this.instanceMutatorMap = {};
this.staticMutatorMap = {};
this.instancePropBody = [];
this.instancePropRefs = {};
this.staticPropBody = [];
this.body = [];
this.hasConstructor = false;
this.hasDecorators = false;
this.className = this.node.id;
this.classRef = this.node.id || this.scope.generateUidIdentifier("class");
this.superName = this.node.superClass || t.identifier("Function");
this.hasSuper = !!this.node.superClass;
this.isLoose = file.isLoose("es6.classes");
}
/**
* Description
*
* @returns {Array}
*/
run() {
var superName = this.superName;
var className = this.className;
var classBody = this.node.body.body;
var classRef = this.classRef;
var file = this.file;
//
var body = this.body;
//
var constructorBody = this.constructorBody = t.blockStatement([]);
var constructor;
if (this.className) {
constructor = t.functionDeclaration(this.className, [], constructorBody);
body.push(constructor);
} else {
constructor = t.functionExpression(null, [], constructorBody);
}
this.constructor = constructor;
//
var closureParams = [];
var closureArgs = [];
//
if (this.hasSuper) {
closureArgs.push(superName);
superName = this.scope.generateUidBasedOnNode(superName);
closureParams.push(superName);
this.superName = superName;
body.push(t.expressionStatement(t.callExpression(file.addHelper("inherits"), [classRef, superName])));
}
//
var decorators = this.node.decorators;
if (decorators) {
// create a class reference to use later on
this.classRef = this.scope.generateUidIdentifier(classRef);
// this is so super calls and the decorators have access to the raw function
body.push(t.variableDeclaration("var", [
t.variableDeclarator(this.classRef, classRef)
]));
}
//
this.buildBody();
// make sure this class isn't directly called
constructorBody.body.unshift(t.expressionStatement(t.callExpression(file.addHelper("class-call-check"), [
t.thisExpression(),
this.classRef
])));
//
if (decorators) {
// reverse the decorators so we execute them in the right order
decorators = decorators.reverse();
for (var i = 0; i < decorators.length; i++) {
var decorator = decorators[i];
var decoratorNode = util.template("class-decorator", {
DECORATOR: decorator.expression,
CLASS_REF: classRef
}, true);
decoratorNode.expression._ignoreModulesRemap = true;
body.push(decoratorNode);
}
}
if (this.className) {
// named class with only a constructor
if (body.length === 1) return t.toExpression(body[0]);
} else {
// infer class name if this is a nameless class expression
constructor = nameMethod.bare(constructor, this.parent, this.scope) || constructor;
body.unshift(t.variableDeclaration("var", [
t.variableDeclarator(classRef, constructor)
]));
t.inheritsComments(body[0], this.node);
}
body = body.concat(this.staticPropBody);
//
body.push(t.returnStatement(classRef));
return t.callExpression(
t.functionExpression(null, closureParams, t.blockStatement(body)),
closureArgs
);
}
/**
* Description
*/
pushToMap(node, enumerable, kind = "value") {
var mutatorMap;
if (node.static) {
this.hasStaticDescriptors = true;
mutatorMap = this.staticMutatorMap;
} else {
this.hasInstanceDescriptors = true;
mutatorMap = this.instanceMutatorMap;
}
var map = defineMap.push(mutatorMap, node, kind, this.file);
if (enumerable) {
map.enumerable = t.literal(true)
}
if (map.decorators) {
this.hasDecorators = true;
}
}
/**
* Description
*/
buildBody() {
var constructorBody = this.constructorBody;
var constructor = this.constructor;
var className = this.className;
var superName = this.superName;
var classBody = this.node.body.body;
var body = this.body;
var classBodyPaths = this.path.get("body").get("body");
for (var i = 0; i < classBody.length; i++) {
var node = classBody[i];
var path = classBodyPaths[i];
if (node.decorators) {
memoiseDecorators(node.decorators, this.scope);
}
if (t.isMethodDefinition(node)) {
var isConstructor = node.kind === "constructor";
if (isConstructor) this.verifyConstructor(path);
var replaceSupers = new ReplaceSupers({
methodPath: path,
methodNode: node,
objectRef: this.classRef,
superRef: this.superName,
isStatic: node.static,
isLoose: this.isLoose,
scope: this.scope,
file: this.file
}, true);
replaceSupers.replace();
if (isConstructor) {
this.pushConstructor(node, path);
} else {
this.pushMethod(node, path);
}
} else if (t.isClassProperty(node)) {
this.pushProperty(node);
}
}
// we have no constructor, but we're a derived class
if (!this.hasConstructor && this.hasSuper) {
var helperName = "class-super-constructor-call";
if (this.isLoose) helperName += "-loose";
constructorBody.body.push(util.template(helperName, {
CLASS_NAME: this.classRef,
SUPER_NAME: this.superName
}, true));
}
//
this.placePropertyInitializers();
//
if (this.userConstructor) {
constructorBody.body = constructorBody.body.concat(this.userConstructor.body.body);
t.inherits(this.constructor, this.userConstructor);
t.inherits(this.constructorBody, this.userConstructor.body);
}
var instanceProps;
var staticProps;
var classHelper = "create-class";
if (this.hasDecorators) classHelper = "create-decorated-class";
if (this.hasInstanceDescriptors) {
instanceProps = defineMap.toClassObject(this.instanceMutatorMap);
}
if (this.hasStaticDescriptors) {
staticProps = defineMap.toClassObject(this.staticMutatorMap);
}
if (instanceProps || staticProps) {
if (instanceProps) instanceProps = defineMap.toComputedObjectFromClass(instanceProps);
if (staticProps) staticProps = defineMap.toComputedObjectFromClass(staticProps);
var nullNode = t.literal(null);
// (Constructor, instanceDescriptors, staticDescriptors, instanceInitializers, staticInitializers)
var args = [this.classRef, nullNode, nullNode, nullNode, nullNode];
if (instanceProps) args[1] = instanceProps;
if (staticProps) args[2] = staticProps;
if (this.instanceInitializersId) {
args[3] = this.instanceInitializersId;
body.unshift(this.buildObjectAssignment(this.instanceInitializersId));
}
if (this.staticInitializersId) {
args[4] = this.staticInitializersId;
body.unshift(this.buildObjectAssignment(this.staticInitializersId));
}
var lastNonNullIndex = 0;
for (var i = 0; i < args.length; i++) {
if (args[i] !== nullNode) lastNonNullIndex = i;
}
args = args.slice(0, lastNonNullIndex + 1);
body.push(t.expressionStatement(
t.callExpression(this.file.addHelper(classHelper), args)
));
}
}
buildObjectAssignment(id) {
return t.variableDeclaration("var", [
t.variableDeclarator(id, t.objectExpression([]))
]);
}
/**
* Description
*/
placePropertyInitializers() {
var body = this.instancePropBody;
if (!body.length) return;
if (this.hasPropertyCollision()) {
var call = t.expressionStatement(t.callExpression(
t.memberExpression(t.thisExpression(), t.identifier(PROPERTY_COLLISION_METHOD_NAME)),
[]
));
this.pushMethod(t.methodDefinition(
t.identifier(PROPERTY_COLLISION_METHOD_NAME),
t.functionExpression(null, [], t.blockStatement(body))
), null, true);
if (this.hasSuper) {
this.bareSuper.insertAfter(call);
} else {
this.constructorBody.body.unshift(call);
}
} else {
if (this.hasSuper) {
if (this.hasConstructor) {
this.bareSuper.insertAfter(body);
} else {
this.constructorBody.body = this.constructorBody.body.concat(body);
}
} else {
this.constructorBody.body = body.concat(this.constructorBody.body);
}
}
}
/**
* Description
*/
hasPropertyCollision(): boolean {
if (this.userConstructorPath) {
for (var name in this.instancePropRefs) {
if (this.userConstructorPath.scope.hasOwnBinding(name)) {
return true;
}
}
}
return false;
}
/**
* Description
*/
verifyConstructor(path: TraversalPath) {
var state = {
hasBareSuper: false,
bareSuper: null,
hasSuper: this.hasSuper,
file: this.file
};
path.get("value").traverse(verifyConstructorVisitor, state);
this.bareSuper = state.bareSuper;
if (!state.hasBareSuper && this.hasSuper) {
throw path.errorWithNode("Derived constructor must call super()");
}
}
/**
* Push a method to its respective mutatorMap.
*/
pushMethod(node: { type: "MethodDefinition" }, path?: TraversalPath, allowedIllegal?) {
if (!allowedIllegal && t.isLiteral(t.toComputedKey(node), { value: PROPERTY_COLLISION_METHOD_NAME })) {
throw this.file.errorWithNode(node, messages.get("illegalMethodName", PROPERTY_COLLISION_METHOD_NAME));
}
if (node.kind === "method") {
nameMethod.property(node, this.file, path ? path.get("value").scope : this.scope);
if (this.isLoose && !node.decorators) {
// use assignments instead of define properties for loose classes
var classRef = this.classRef;
if (!node.static) classRef = t.memberExpression(classRef, t.identifier("prototype"));
var methodName = t.memberExpression(classRef, node.key, node.computed);
var expr = t.expressionStatement(t.assignmentExpression("=", methodName, node.value));
t.inheritsComments(expr, node);
this.body.push(expr);
return;
}
}
this.pushToMap(node);
}
/**
* Description
*/
pushProperty(node: { type: "ClassProperty" }) {
var key;
this.scope.traverse(node, collectPropertyReferencesVisitor, {
references: this.instancePropRefs,
scope: this.scope
});
if (node.decorators) {
var body = [];
if (node.value) {
body.push(t.returnStatement(node.value));
node.value = t.functionExpression(null, [], t.blockStatement(body));
} else {
node.value = t.literal(null);
}
this.pushToMap(node, true, "initializer");
var initializers;
var body;
var target;
if (node.static) {
initializers = this.staticInitializersId = this.staticInitializersId || this.scope.generateUidIdentifier("staticInitializers");
body = this.staticPropBody;
target = this.classRef;
} else {
initializers = this.instanceInitializersId = this.instanceInitializersId || this.scope.generateUidIdentifier("instanceInitializers");
body = this.instancePropBody;
target = t.thisExpression();
}
body.push(t.expressionStatement(
t.callExpression(this.file.addHelper("define-decorated-property-descriptor"), [
target,
t.literal(node.key.name),
initializers
])
));
} else {
if (!node.value && !node.decorators) return;
if (node.static) {
// can just be added to the static map
this.pushToMap(node, true);
} else if (node.value) {
// add this to the instancePropBody which will be added after the super call in a derived constructor
// or at the start of a constructor for a non-derived constructor
this.instancePropBody.push(t.expressionStatement(
t.assignmentExpression("=", t.memberExpression(t.thisExpression(), node.key), node.value)
));
}
}
}
/**
* Replace the constructor body of our class.
*/
pushConstructor(method: { type: "MethodDefinition" }, path: TraversalPath) {
// https://github.com/babel/babel/issues/1077
var fnPath = path.get("value");
if (fnPath.scope.hasOwnBinding(this.classRef.name)) {
fnPath.scope.rename(this.classRef.name);
}
var construct = this.constructor;
var fn = method.value;
this.userConstructorPath = fnPath;
this.userConstructor = fn;
this.hasConstructor = true;
t.inheritsComments(construct, method);
construct._ignoreUserWhitespace = true;
construct.params = fn.params;
t.inherits(construct.body, fn.body);
}
}