42 lines
1.3 KiB
TypeScript
42 lines
1.3 KiB
TypeScript
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// We have the lossless transformation of the delta stream.
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// We want to enable transformations from the lossless view,
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// into various possible "lossy" views that combine or exclude some information.
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//
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// We can achieve this via functional expression, encoded as JSON-Logic.
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// Fields in the output can be described as transformations
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import {CollapsedDelta, Lossless, LosslessViewMany, LosslessViewOne} from "./lossless";
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import {DeltaFilter} from "./types";
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type Resolver = (losslessView: LosslessViewMany) => unknown;
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export function firstValueFromCollapsedDelta(delta: CollapsedDelta, key: string): string | undefined {
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const pointers = delta.pointers;
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for (const pointer of pointers || []) {
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const [[k, value]] = Object.entries(pointer);
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if (k === key && typeof value === "string") {
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return value;
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}
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}
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}
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export function firstValueFromLosslessViewOne(ent: LosslessViewOne, key: string): {delta: CollapsedDelta, value: string} | undefined {
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for (const delta of ent.properties[key] || []) {
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const value = firstValueFromCollapsedDelta(delta, key);
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if (value) return {delta, value};
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}
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}
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export class Lossy {
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lossless: Lossless;
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constructor(lossless: Lossless) {
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this.lossless = lossless;
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}
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resolve(fn: Resolver, deltaFilter?: DeltaFilter) {
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return fn(this.lossless.view(deltaFilter));
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}
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}
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