24 lines
1.0 KiB
TypeScript
24 lines
1.0 KiB
TypeScript
import { largestNesting } from './nesting.ts'
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export type JsonValue = JsonValue[] | boolean | null | number | string | { [key: string]: JsonValue }
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export function isJsonValue(value: unknown): value is JsonValue {
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const pending: { depth: number; item: unknown }[] = [{ depth: 0, item: value }]
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while (pending.length > 0) {
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const entry = pending.pop()
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if (entry === undefined) continue
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const { depth, item } = entry
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if (depth > largestNesting) return false
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if (item === null || typeof item === 'boolean' || typeof item === 'string') continue
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if (typeof item === 'number') {
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if (!Number.isFinite(item)) return false
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continue
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}
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// A hole is not a JSON value, and Array.prototype methods skip holes — spreading materialises them.
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if (Array.isArray(item)) for (const child of [...item]) pending.push({ depth: depth + 1, item: child })
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else if (typeof item === 'object') for (const child of Object.values(item)) pending.push({ depth: depth + 1, item: child })
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else return false
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}
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return true
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}
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