/
index.ts
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/
index.ts
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import * as whitespace from "./whitespace";
import * as parens from "./parentheses";
import {
FLIPPED_ALIAS_KEYS,
isCallExpression,
isExpressionStatement,
isMemberExpression,
isNewExpression,
} from "@babel/types";
import type * as t from "@babel/types";
export type NodeHandlers<R> = {
[K in string]?: (
node: K extends t.Node["type"] ? Extract<t.Node, { type: K }> : t.Node,
// todo:
// node: K extends keyof typeof t
// ? Extract<typeof t[K], { type: "string" }>
// : t.Node,
parent: t.Node,
stack: t.Node[],
) => R;
};
function expandAliases<R>(obj: NodeHandlers<R>) {
const newObj: NodeHandlers<R> = {};
function add(
type: string,
func: (node: t.Node, parent: t.Node, stack: t.Node[]) => R,
) {
const fn = newObj[type];
newObj[type] = fn
? function (node, parent, stack) {
const result = fn(node, parent, stack);
return result == null ? func(node, parent, stack) : result;
}
: func;
}
for (const type of Object.keys(obj)) {
const aliases = FLIPPED_ALIAS_KEYS[type];
if (aliases) {
for (const alias of aliases) {
add(alias, obj[type]);
}
} else {
add(type, obj[type]);
}
}
return newObj;
}
// Rather than using `t.is` on each object property, we pre-expand any type aliases
// into concrete types so that the 'find' call below can be as fast as possible.
const expandedParens = expandAliases(parens);
const expandedWhitespaceNodes = expandAliases(whitespace.nodes);
//const expandedWhitespaceList = expandAliases(whitespace.list);
function find<R>(
obj: NodeHandlers<R>,
node: t.Node,
parent: t.Node,
printStack?: t.Node[],
): R | null {
const fn = obj[node.type];
return fn ? fn(node, parent, printStack) : null;
}
function isOrHasCallExpression(node: t.Node): boolean {
if (isCallExpression(node)) {
return true;
}
return isMemberExpression(node) && isOrHasCallExpression(node.object);
}
export function needsWhitespace(
node: t.Node,
parent: t.Node,
type: number,
): boolean {
if (!node) return false;
if (isExpressionStatement(node)) {
node = node.expression;
}
const flag = find(expandedWhitespaceNodes, node, parent);
if (typeof flag === "number") {
return (flag & type) !== 0;
}
// A bug that existed before, commenting out it will cause the test to fail.
// const items = find(expandedWhitespaceList, node, parent);
// if (items) {
// for (let i = 0; i < items.length; i++) {
// if (needsWhitespace(items[i], node, type)) {
// return true;
// }
// }
// }
return false;
}
export function needsWhitespaceBefore(node: t.Node, parent: t.Node) {
return needsWhitespace(node, parent, 1);
}
export function needsWhitespaceAfter(node: t.Node, parent: t.Node) {
return needsWhitespace(node, parent, 2);
}
export function needsParens(
node: t.Node,
parent: t.Node,
printStack?: t.Node[],
) {
if (!parent) return false;
if (isNewExpression(parent) && parent.callee === node) {
if (isOrHasCallExpression(node)) return true;
}
return find(expandedParens, node, parent, printStack);
}