alexion
4def357d09
Imported as a linear vendor commit so forge rebases do not replay the upstream root tree. git-subtree-dir: third_party/pi git-subtree-split: d981de1229ef899957bbe968bc8dcda02a21f477
51 lines
1.7 KiB
TypeScript
51 lines
1.7 KiB
TypeScript
import type { JsonValue } from "./types.ts";
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/** Return whether a value is finite strict JSON with plain objects and no cycles. */
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export function isJsonValue(value: unknown): value is JsonValue {
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return check(value, new Set<object>(), 0);
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}
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function check(value: unknown, ancestors: Set<object>, depth: number): boolean {
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if (depth > 512) return false;
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if (value === null || typeof value === "string" || typeof value === "boolean") return true;
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if (typeof value === "number") return Number.isFinite(value);
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if (Array.isArray(value)) {
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const keys = Reflect.ownKeys(value);
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if (keys.length !== value.length + 1 || keys.some((key) => typeof key !== "string")) return false;
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if (ancestors.has(value)) return false;
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ancestors.add(value);
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try {
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for (let index = 0; index < value.length; index++) {
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const descriptor = Object.getOwnPropertyDescriptor(value, String(index));
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if (
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descriptor === undefined ||
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!descriptor.enumerable ||
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!("value" in descriptor) ||
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!check(descriptor.value, ancestors, depth + 1)
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) {
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return false;
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}
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}
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return true;
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} finally {
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ancestors.delete(value);
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}
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}
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if (typeof value !== "object" || value === null) return false;
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const prototype = Object.getPrototypeOf(value);
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if (prototype !== Object.prototype && prototype !== null) return false;
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if (Reflect.ownKeys(value).some((key) => typeof key !== "string")) return false;
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if (ancestors.has(value)) return false;
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ancestors.add(value);
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try {
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for (const descriptor of Object.values(Object.getOwnPropertyDescriptors(value))) {
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if (!descriptor.enumerable || !("value" in descriptor) || !check(descriptor.value, ancestors, depth + 1)) {
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return false;
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}
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}
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return true;
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} finally {
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ancestors.delete(value);
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}
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}
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