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/
decorators.ts
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/
decorators.ts
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// TODO(Babel 8): Remove this file
import { types as t, template } from "@babel/core";
import type { File } from "@babel/core";
import type { NodePath } from "@babel/traverse";
import ReplaceSupers from "@babel/helper-replace-supers";
import nameFunction from "@babel/helper-function-name";
type Decorable = Extract<t.Node, { decorators?: t.Decorator[] | null }>;
export function hasOwnDecorators(node: t.Node) {
// @ts-expect-error(flow->ts) TODO: maybe we could add t.isDecoratable to make ts happy
return !!(node.decorators && node.decorators.length);
}
export function hasDecorators(node: t.Class) {
return hasOwnDecorators(node) || node.body.body.some(hasOwnDecorators);
}
function prop(key: string, value?: t.Expression) {
if (!value) return null;
return t.objectProperty(t.identifier(key), value);
}
function method(key: string, body: t.Statement[]) {
return t.objectMethod(
"method",
t.identifier(key),
[],
t.blockStatement(body),
);
}
function takeDecorators(node: Decorable) {
let result: t.ArrayExpression | undefined;
if (node.decorators && node.decorators.length > 0) {
result = t.arrayExpression(
node.decorators.map(decorator => decorator.expression),
);
}
node.decorators = undefined;
return result;
}
type AcceptedElement = Exclude<ClassElement, t.TSIndexSignature>;
type SupportedElement = Exclude<
AcceptedElement,
| t.ClassPrivateMethod
| t.ClassPrivateProperty
| t.ClassAccessorProperty
| t.StaticBlock
>;
function getKey(node: SupportedElement) {
if (node.computed) {
return node.key;
} else if (t.isIdentifier(node.key)) {
return t.stringLiteral(node.key.name);
} else {
return t.stringLiteral(
String(
// A non-identifier non-computed key
(node.key as t.StringLiteral | t.NumericLiteral | t.BigIntLiteral)
.value,
),
);
}
}
function extractElementDescriptor(
file: File,
classRef: t.Identifier,
superRef: t.Identifier,
path: NodePath<AcceptedElement>,
) {
const isMethod = path.isClassMethod();
if (path.isPrivate()) {
throw path.buildCodeFrameError(
`Private ${
isMethod ? "methods" : "fields"
} in decorated classes are not supported yet.`,
);
}
if (path.node.type === "ClassAccessorProperty") {
throw path.buildCodeFrameError(
`Accessor properties are not supported in 2018-09 decorator transform, please specify { "version": "2021-12" } instead.`,
);
}
if (path.node.type === "StaticBlock") {
throw path.buildCodeFrameError(
`Static blocks are not supported in 2018-09 decorator transform, please specify { "version": "2021-12" } instead.`,
);
}
const { node, scope } = path as NodePath<SupportedElement>;
if (!path.isTSDeclareMethod()) {
new ReplaceSupers({
methodPath: path as NodePath<
Exclude<SupportedElement, t.TSDeclareMethod>
>,
objectRef: classRef,
superRef,
file,
refToPreserve: classRef,
}).replace();
}
const properties: t.ObjectExpression["properties"] = [
prop("kind", t.stringLiteral(t.isClassMethod(node) ? node.kind : "field")),
prop("decorators", takeDecorators(node as Decorable)),
prop("static", node.static && t.booleanLiteral(true)),
prop("key", getKey(node)),
].filter(Boolean);
if (t.isClassMethod(node)) {
const id = node.computed
? null
: (node.key as
| t.Identifier
| t.StringLiteral
| t.NumericLiteral
| t.BigIntLiteral);
const transformed = t.toExpression(node);
properties.push(
prop(
"value",
nameFunction({ node: transformed, id, scope }) || transformed,
),
);
} else if (t.isClassProperty(node) && node.value) {
properties.push(
method("value", template.statements.ast`return ${node.value}`),
);
} else {
properties.push(prop("value", scope.buildUndefinedNode()));
}
path.remove();
return t.objectExpression(properties);
}
function addDecorateHelper(file: File) {
return file.addHelper("decorate");
}
type ClassElement = t.Class["body"]["body"][number];
type ClassElementPath = NodePath<ClassElement>;
export function buildDecoratedClass(
ref: t.Identifier,
path: NodePath<t.Class>,
elements: ClassElementPath[],
file: File,
) {
const { node, scope } = path;
const initializeId = scope.generateUidIdentifier("initialize");
const isDeclaration = node.id && path.isDeclaration();
const isStrict = path.isInStrictMode();
const { superClass } = node;
node.type = "ClassDeclaration";
if (!node.id) node.id = t.cloneNode(ref);
let superId: t.Identifier;
if (superClass) {
superId = scope.generateUidIdentifierBasedOnNode(node.superClass, "super");
node.superClass = superId;
}
const classDecorators = takeDecorators(node);
const definitions = t.arrayExpression(
elements
.filter(
element =>
// @ts-expect-error Ignore TypeScript's abstract methods (see #10514)
!element.node.abstract && element.node.type !== "TSIndexSignature",
)
.map(path =>
extractElementDescriptor(
file,
node.id,
superId,
// @ts-expect-error TS can not exclude TSIndexSignature
path,
),
),
);
const wrapperCall = template.expression.ast`
${addDecorateHelper(file)}(
${classDecorators || t.nullLiteral()},
function (${initializeId}, ${superClass ? t.cloneNode(superId) : null}) {
${node}
return { F: ${t.cloneNode(node.id)}, d: ${definitions} };
},
${superClass}
)
` as t.CallExpression & { arguments: [unknown, t.FunctionExpression] };
if (!isStrict) {
wrapperCall.arguments[1].body.directives.push(
t.directive(t.directiveLiteral("use strict")),
);
}
let replacement: t.Node = wrapperCall;
let classPathDesc = "arguments.1.body.body.0";
if (isDeclaration) {
replacement = template.statement.ast`let ${ref} = ${wrapperCall}`;
classPathDesc = "declarations.0.init." + classPathDesc;
}
return {
instanceNodes: [template.statement.ast`${t.cloneNode(initializeId)}(this)`],
wrapClass(path: NodePath<t.Class>) {
path.replaceWith(replacement);
return path.get(classPathDesc) as NodePath;
},
};
}