dynamodb-toolbox
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Lightweight and type-safe query builder for DynamoDB and TypeScript.
15 lines (14 loc) • 1.48 kB
TypeScript
/**
* Given a union of possible attribute keys & filtered attribute paths, returns the possible attribute keys.
*
* @example MatchKey<"foo" | "bar" | "baz", ".foo.prop" | `['bar']`> => "foo" | "bar"
*/
export type MatchKeys<KEYS extends string, PATHS extends string, KEY_PREFIX extends string = '.'> = KEYS extends infer KEY ? KEY extends string ? PATHS extends `['${KEY}']${string}` | `${KEY_PREFIX}${KEY}${string}` ? KEY : never : never : never;
/**
* Given a tuple of elements & filtered attribute paths, returns the possible element indexes.
*
* @example MatchIndexes<[unknown, unknown], "[0].foo.prop" | `[1]['bar']`> => 0 | 1
*/
export type MatchIndexes<ELEMENTS extends unknown[], PATHS extends string, MATCHING_INDEXES extends number = never> = ELEMENTS extends [...infer ELEMENTS_INIT, unknown] ? MatchIndexes<ELEMENTS_INIT, PATHS, MATCHING_INDEXES | (PATHS extends `[${ELEMENTS_INIT['length']}]${string}` ? ELEMENTS_INIT['length'] : never)> : MATCHING_INDEXES;
export type ChildPaths<KEY extends string, PATHS extends string, KEY_PREFIX extends string = '.'> = `${KEY_PREFIX}${KEY}` extends PATHS ? undefined : `['${KEY}']` extends PATHS ? undefined : PATHS extends `['${KEY}']${infer CHILD_PATHS}` | `${KEY_PREFIX}${KEY}${infer CHILD_PATHS}` ? CHILD_PATHS : never;
export type ElementPaths<PATHS extends string, INDEX extends number = number> = PATHS extends `[${INDEX}]` ? undefined : PATHS extends `[${INDEX}]${infer ELEMENT_PATHS}` ? ELEMENT_PATHS : never;