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https://github.com/vercel-labs/scriptc.git
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Chris Tate
3f51c72ae8
- Construct Sets from live collection iterators while preserving order and reference identity. - Reject checked key conversions that would copy existing references. - Avoid repeated compiler traversal and cache-validation reads.
57 lines
2.2 KiB
TypeScript
57 lines
2.2 KiB
TypeScript
const key = { id: 1 };
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const value = { count: 2 };
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const records = new Map<typeof key, typeof value>([[key, value]]);
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const keys = new Set(records.keys());
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const values = new Set(records.values());
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console.log("record identity", keys.has(key), values.has(value));
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for (const item of values) item.count++;
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console.log("record mutation", value.count);
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const array = [1, 2];
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const arrays = new Set<number[]>([array]);
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const arrayCopy = new Set(arrays.values());
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console.log("array identity", arrayCopy.has(array));
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for (const item of arrayCopy) item.push(3);
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console.log("array mutation", array.join(","));
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class Box {
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count: number;
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constructor(count: number) { this.count = count; }
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}
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const box = new Box(4);
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const boxes = new Map<string, Box>([["first", box], ["second", box]]);
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const copiedBoxes = new Set(boxes.values());
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console.log("class identity", copiedBoxes.size, copiedBoxes.has(box));
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for (const item of copiedBoxes) item.count++;
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console.log("class mutation", box.count);
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const inner = new Map<string, number>([["x", 7]]);
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const holder = { inner };
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const outer = new Set<typeof holder>([holder]);
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const nested = new Set(outer.keys());
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console.log("nested identity", nested.has(holder));
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for (const item of nested) item.inner.set("y", 8);
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console.log("nested mutation", inner.get("y"));
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const mixed = new Set<number[] | typeof key>([array, key]);
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const mixedCopy = new Set(mixed.values());
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console.log("union identity", mixedCopy.has(array), mixedCopy.has(key));
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const wider = { id: 2, label: "wide" };
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const overlapping = new Set<typeof key | typeof wider>([key, wider]);
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const overlapCopy = new Set(overlapping.values());
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console.log("overlapping identity", overlapCopy.size, overlapCopy.has(key), overlapCopy.has(wider));
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// Each entries() result is a fresh pair retaining its original members.
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const entries = new Set(records.entries());
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console.log("entry count", entries.size);
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for (const [k, v] of entries) console.log("entry identity", k === key, v === value);
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const pairs = new Set(arrays.entries());
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for (const [a, b] of pairs) console.log("set pair identity", a === array, a === b);
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records.clear();
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arrays.clear();
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boxes.clear();
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outer.clear();
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console.log("retained", keys.has(key), values.has(value), arrayCopy.has(array), copiedBoxes.has(box), nested.has(holder));
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