forked from babel/babel
/
index.ts
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/
index.ts
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import type { NodePath } from "@babel/traverse";
import nameFunction from "@babel/helper-function-name";
import template from "@babel/template";
import {
blockStatement,
callExpression,
functionExpression,
isAssignmentPattern,
isFunctionDeclaration,
isRestElement,
returnStatement,
} from "@babel/types";
import type * as t from "@babel/types";
type ExpressionWrapperBuilder<ExtraBody extends t.Node[]> = (
replacements?: Parameters<ReturnType<typeof template.expression>>[0],
) => t.CallExpression & {
callee: t.FunctionExpression & {
body: {
body: [
t.VariableDeclaration & {
declarations: [
{ init: t.FunctionExpression | t.ArrowFunctionExpression },
];
},
...ExtraBody,
];
};
};
};
const buildAnonymousExpressionWrapper = template.expression(`
(function () {
var REF = FUNCTION;
return function NAME(PARAMS) {
return REF.apply(this, arguments);
};
})()
`) as ExpressionWrapperBuilder<
[t.ReturnStatement & { argument: t.FunctionExpression }]
>;
const buildNamedExpressionWrapper = template.expression(`
(function () {
var REF = FUNCTION;
function NAME(PARAMS) {
return REF.apply(this, arguments);
}
return NAME;
})()
`) as ExpressionWrapperBuilder<
[t.FunctionDeclaration, t.ReturnStatement & { argument: t.Identifier }]
>;
const buildDeclarationWrapper = template.statements(`
function NAME(PARAMS) { return REF.apply(this, arguments); }
function REF() {
REF = FUNCTION;
return REF.apply(this, arguments);
}
`);
function classOrObjectMethod(
path: NodePath<t.ClassMethod | t.ClassPrivateMethod | t.ObjectMethod>,
callId: t.Expression,
) {
const node = path.node;
const body = node.body;
const container = functionExpression(
null,
[],
blockStatement(body.body),
true,
);
body.body = [
returnStatement(callExpression(callExpression(callId, [container]), [])),
];
// Regardless of whether or not the wrapped function is a an async method
// or generator the outer function should not be
node.async = false;
node.generator = false;
// Unwrap the wrapper IIFE's environment so super and this and such still work.
(
path.get("body.body.0.argument.callee.arguments.0") as NodePath
).unwrapFunctionEnvironment();
}
function plainFunction(
path: NodePath<Exclude<t.Function, t.Method>>,
callId: t.Expression,
noNewArrows: boolean,
ignoreFunctionLength: boolean,
) {
let functionId = null;
let node;
if (path.isArrowFunctionExpression()) {
if (process.env.BABEL_8_BREAKING) {
path = path.arrowFunctionToExpression({ noNewArrows });
} else {
// arrowFunctionToExpression returns undefined in @babel/traverse < 7.18.10
path = path.arrowFunctionToExpression({ noNewArrows }) ?? path;
}
node = path.node as t.FunctionDeclaration | t.FunctionExpression;
} else {
node = path.node as t.FunctionDeclaration | t.FunctionExpression;
}
const isDeclaration = isFunctionDeclaration(node);
functionId = node.id;
node.id = null;
node.type = "FunctionExpression";
const built = callExpression(callId, [
node as Exclude<typeof node, t.FunctionDeclaration>,
]);
const params: t.Identifier[] = [];
for (const param of node.params) {
if (isAssignmentPattern(param) || isRestElement(param)) {
break;
}
params.push(path.scope.generateUidIdentifier("x"));
}
const wrapperArgs = {
NAME: functionId || null,
REF: path.scope.generateUidIdentifier(functionId ? functionId.name : "ref"),
FUNCTION: built,
PARAMS: params,
};
if (isDeclaration) {
const container = buildDeclarationWrapper(wrapperArgs);
path.replaceWith(container[0]);
path.insertAfter(container[1]);
} else {
let container;
if (functionId) {
container = buildNamedExpressionWrapper(wrapperArgs);
} else {
container = buildAnonymousExpressionWrapper(wrapperArgs);
const returnFn = container.callee.body.body[1].argument;
nameFunction({
node: returnFn,
parent: path.parent,
scope: path.scope,
});
functionId = returnFn.id;
}
if (functionId || (!ignoreFunctionLength && params.length)) {
path.replaceWith(container);
} else {
// we can omit this wrapper as the conditions it protects for do not apply
path.replaceWith(built);
}
}
}
export default function wrapFunction(
path: NodePath<t.Function>,
callId: t.Expression,
// TODO(Babel 8): Consider defaulting to false for spec compliancy
noNewArrows: boolean = true,
ignoreFunctionLength: boolean = false,
) {
if (path.isMethod()) {
classOrObjectMethod(path, callId);
} else {
plainFunction(
path as NodePath<Exclude<t.Function, t.Method>>,
callId,
noNewArrows,
ignoreFunctionLength,
);
}
}