54 lines
1.7 KiB
TypeScript
54 lines
1.7 KiB
TypeScript
const DANGEROUS_KEYS = new Set(["__proto__", "constructor", "prototype"]);
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const MAX_DEPTH = 50;
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export function isPlainObject(value: unknown): value is Record<string, unknown> {
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return (
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typeof value === "object" &&
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value !== null &&
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!Array.isArray(value) &&
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Object.prototype.toString.call(value) === "[object Object]"
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);
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}
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/**
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* Deep merges two objects, with override values taking precedence.
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* - Objects are recursively merged
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* - Arrays are replaced (not concatenated)
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* - undefined values in override do not overwrite base values
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*
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* @example
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* deepMerge({ a: 1, b: { c: 2, d: 3 } }, { b: { c: 10 }, e: 5 })
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* // => { a: 1, b: { c: 10, d: 3 }, e: 5 }
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*/
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export function deepMerge<T extends Record<string, unknown>>(base: T, override: Partial<T>, depth?: number): T;
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export function deepMerge<T extends Record<string, unknown>>(base: T | undefined, override: T | undefined, depth?: number): T | undefined;
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export function deepMerge<T extends Record<string, unknown>>(
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base: T | undefined,
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override: T | undefined,
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depth = 0
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): T | undefined {
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if (!base && !override) return undefined;
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if (!base) return override;
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if (!override) return base;
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if (depth > MAX_DEPTH) return override ?? base;
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const result = { ...base } as Record<string, unknown>;
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for (const key of Object.keys(override)) {
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if (DANGEROUS_KEYS.has(key)) continue;
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const baseValue = base[key];
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const overrideValue = override[key];
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if (overrideValue === undefined) continue;
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if (isPlainObject(baseValue) && isPlainObject(overrideValue)) {
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result[key] = deepMerge(baseValue, overrideValue, depth + 1);
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} else {
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result[key] = overrideValue;
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}
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}
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return result as T;
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}
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