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Iterate algorithm, base it on new js-sdk string lib

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This commit is contained in:
Michael Telatynski 2021-06-14 21:28:32 +01:00
parent 4af2675e23
commit 8fd72fcf79
2 changed files with 98 additions and 100 deletions
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77
src/utils/stringOrderField.ts
View file

@ -14,6 +14,8 @@ See the License for the specific language governing permissions and
limitations under the License.
*/
import { alphabetPad, baseToString, stringToBase } from "matrix-js-sdk/src/utils";
import { reorder } from "./arrays";
export const ALPHABET_START = 0x20;
@ -23,23 +25,6 @@ export const ALPHABET = new Array(1 + ALPHABET_END - ALPHABET_START)
.map((_, i) => String.fromCharCode(ALPHABET_START + i))
.join("");
export const baseToString = (base: bigint, alphabet = ALPHABET): string => {
const len = BigInt(alphabet.length);
if (base < len) return alphabet[Number(base)];
return baseToString(base / len, alphabet) + alphabet[Number(base % len)];
};
export const stringToBase = (str: string, alphabet = ALPHABET): bigint => {
let result = BigInt(0);
const len = BigInt(alphabet.length);
for (let i = str.length - 1, j = BigInt(0); i >= 0; i--, j++) {
result += BigInt(str.charCodeAt(i) - alphabet.charCodeAt(0)) * (len ** j);
}
return result;
};
const pad = (str: string, length: number, alphabet = ALPHABET): string => str.padEnd(length, alphabet[0]);
export const midPointsBetweenStrings = (
a: string,
b: string,
@ -47,26 +32,28 @@ export const midPointsBetweenStrings = (
maxLen: number,
alphabet = ALPHABET,
): string[] => {
const n = Math.min(maxLen, Math.max(a.length, b.length));
const aPadded = pad(a, n, alphabet);
const bPadded = pad(b, n, alphabet);
const aBase = stringToBase(aPadded, alphabet);
const bBase = stringToBase(bPadded, alphabet);
if (bBase - aBase - BigInt(1) < count) {
if (n < maxLen) {
const padN = Math.min(Math.max(a.length, b.length), maxLen);
const padA = alphabetPad(a, padN, alphabet);
const padB = alphabetPad(b, padN, alphabet);
const baseA = stringToBase(padA, alphabet);
const baseB = stringToBase(padB, alphabet);
if (baseB - baseA - BigInt(1) < count) {
if (padN < maxLen) {
// this recurses once at most due to the new limit of n+1
return midPointsBetweenStrings(
pad(aPadded, n + 1, alphabet),
pad(bPadded, n + 1, alphabet),
alphabetPad(padA, padN + 1, alphabet),
alphabetPad(padB, padN + 1, alphabet),
count,
n + 1,
padN + 1,
alphabet,
);
}
return [];
}
const step = (bBase - aBase) / BigInt(count + 1);
const start = BigInt(aBase + step);
const step = (baseB - baseA) / BigInt(count + 1);
const start = BigInt(baseA + step);
return Array(count).fill(undefined).map((_, i) => baseToString(start + (BigInt(i) * step), alphabet));
};
@ -95,6 +82,7 @@ export const reorderLexicographically = (
// apply the fundamental order update to the zipped array
const newOrder = reorder(ordersWithIndices, fromIndex, toIndex);
// check if we have to fill undefined orders to complete placement
const orderToLeftUndefined = newOrder[toIndex - 1]?.order === undefined;
let leftBoundIdx = toIndex;
@ -105,14 +93,19 @@ export const reorderLexicographically = (
? stringToBase(newOrder[toIndex + 1].order)
: BigInt(Number.MAX_VALUE);
// check how far left we would have to mutate to fit in that direction
for (let i = toIndex - 1, j = 1; i >= 0; i--, j++) {
if (newOrder[i]?.order !== undefined && nextBase - stringToBase(newOrder[i].order) > j) break;
leftBoundIdx = i;
}
// verify the left move would be sufficient
const firstOrderBase = newOrder[0].order === undefined ? undefined : stringToBase(newOrder[0].order);
const bigToIndex = BigInt(toIndex);
if (leftBoundIdx === 0 &&
newOrder[0].order !== undefined &&
nextBase - stringToBase(newOrder[0].order) < toIndex
firstOrderBase !== undefined &&
nextBase - firstOrderBase <= bigToIndex &&
firstOrderBase <= bigToIndex
) {
canMoveLeft = false;
}
@ -124,11 +117,13 @@ export const reorderLexicographically = (
? stringToBase(newOrder[toIndex - 1]?.order)
: BigInt(Number.MIN_VALUE);
// check how far right we would have to mutate to fit in that direction
for (let i = toIndex + 1, j = 1; i < newOrder.length; i++, j++) {
if (newOrder[i]?.order === undefined || stringToBase(newOrder[i].order) - prevBase > j) break; // TODO verify
if (newOrder[i]?.order === undefined || stringToBase(newOrder[i].order) - prevBase > j) break;
rightBoundIdx = i;
}
// verify the right move would be sufficient
if (rightBoundIdx === newOrder.length - 1 &&
(newOrder[rightBoundIdx]
? stringToBase(newOrder[rightBoundIdx].order)
@ -138,27 +133,23 @@ export const reorderLexicographically = (
}
}
// pick the cheaper direction
const leftDiff = canMoveLeft ? toIndex - leftBoundIdx : Number.MAX_SAFE_INTEGER;
const rightDiff = canMoveRight ? rightBoundIdx - toIndex : Number.MAX_SAFE_INTEGER;
if (orderToLeftUndefined || leftDiff < rightDiff) {
rightBoundIdx = toIndex;
} else {
leftBoundIdx = toIndex;
}
const prevOrder = newOrder[leftBoundIdx - 1]?.order
?? String.fromCharCode(ALPHABET_START).repeat(5);
const prevOrder = newOrder[leftBoundIdx - 1]?.order ?? "";
const nextOrder = newOrder[rightBoundIdx + 1]?.order
?? String.fromCharCode(ALPHABET_END).repeat(prevOrder.length);
?? String.fromCharCode(ALPHABET_END).repeat(prevOrder.length || 1);
const changes = midPointsBetweenStrings(prevOrder, nextOrder, 1 + rightBoundIdx - leftBoundIdx, maxLen);
console.log("@@ test", { canMoveLeft, canMoveRight, prevOrder, nextOrder, changes, leftBoundIdx, rightBoundIdx, orders, fromIndex, toIndex, newOrder, orderToLeftUndefined, leftDiff, rightDiff });
return changes.map((order, i) => {
const index = newOrder[leftBoundIdx + i].index;
return { index, order };
});
return changes.map((order, i) => ({
index: newOrder[leftBoundIdx + i].index,
order,
}));
};

119
test/utils/stringOrderField-test.ts
View file

@ -15,13 +15,12 @@ limitations under the License.
*/
import { sortBy } from "lodash";
import { stringToBase, baseToString, averageBetweenStrings } from "matrix-js-sdk/src/utils";
import {
ALPHABET,
baseToString,
midPointsBetweenStrings,
reorderLexicographically,
stringToBase,
} from "../../src/utils/stringOrderField";
const moveLexicographicallyTest = (
@ -39,7 +38,6 @@ const moveLexicographicallyTest = (
});
const newOrders = sortBy(zipped, i => i[1]);
console.log("@@ moveLexicographicallyTest", {orders, zipped, newOrders, fromIndex, toIndex, ops});
expect(newOrders[toIndex][0]).toBe(fromIndex);
expect(ops).toHaveLength(expectedChanges);
};
@ -47,35 +45,51 @@ const moveLexicographicallyTest = (
describe("stringOrderField", () => {
it("stringToBase", () => {
expect(Number(stringToBase(""))).toBe(0);
expect(Number(stringToBase("a"))).toBe(65);
expect(Number(stringToBase("aa"))).toBe(6240);
expect(Number(stringToBase("cat"))).toBe(610934);
expect(Number(stringToBase("doggo"))).toBe(5607022724);
expect(Number(stringToBase(" "))).toEqual(0);
expect(Number(stringToBase("a", "abcdefghijklmnopqrstuvwxyz"))).toEqual(0);
expect(Number(stringToBase("a"))).toEqual(65);
expect(Number(stringToBase("c", "abcdefghijklmnopqrstuvwxyz"))).toEqual(2);
expect(Number(stringToBase("ab"))).toEqual(6241);
expect(Number(stringToBase("cb", "abcdefghijklmnopqrstuvwxyz"))).toEqual(53);
expect(Number(stringToBase("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"))).toEqual(4.511596985796182e+78);
expect(Number(stringToBase("~".repeat(50)))).toEqual(7.694497527671333e+98);
// expect(typeof stringToBase("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA")).toEqual("bigint");
expect(Number(stringToBase(" "))).toBe(1);
expect(Number(stringToBase("a"))).toBe(66);
expect(Number(stringToBase(" !"))).toBe(97);
expect(Number(stringToBase("aa"))).toBe(6336);
expect(Number(stringToBase("cat"))).toBe(620055);
expect(Number(stringToBase("doggo"))).toBe(5689339845);
expect(Number(stringToBase("a", "abcdefghijklmnopqrstuvwxyz"))).toEqual(1);
expect(Number(stringToBase("a"))).toEqual(66);
expect(Number(stringToBase("c", "abcdefghijklmnopqrstuvwxyz"))).toEqual(3);
expect(Number(stringToBase("ab"))).toEqual(6337);
expect(Number(stringToBase("cb", "abcdefghijklmnopqrstuvwxyz"))).toEqual(80);
expect(Number(stringToBase("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"))).toEqual(4.648312045971824e+78);
expect(Number(stringToBase("~".repeat(50)))).toEqual(7.776353884348688e+98);
expect(Number(stringToBase(" "))).toEqual(7820126496);
expect(Number(stringToBase(" "))).toEqual(96);
expect(Number(stringToBase(" !"))).toEqual(97);
expect(Number(stringToBase("S:J\\~"))).toEqual(4258975590);
expect(Number(stringToBase("!'Tu:}"))).toEqual(16173443434);
});
it("baseToString", () => {
expect(baseToString(BigInt(10))).toBe(ALPHABET[10]);
expect(baseToString(BigInt(10), "abcdefghijklmnopqrstuvwxyz")).toEqual("k");
expect(baseToString(BigInt(6241))).toEqual("ab");
expect(baseToString(BigInt(53), "abcdefghijklmnopqrstuvwxyz")).toEqual("cb");
expect(baseToString(BigInt(1234))).toBe(",~");
expect(baseToString(BigInt(10))).toBe(ALPHABET[9]);
expect(baseToString(BigInt(10), "abcdefghijklmnopqrstuvwxyz")).toEqual("j");
expect(baseToString(BigInt(6241))).toEqual("`a");
expect(baseToString(BigInt(53), "abcdefghijklmnopqrstuvwxyz")).toEqual("ba");
expect(baseToString(BigInt(1234))).toBe("+}");
expect(baseToString(BigInt(0))).toBe(""); // TODO
expect(baseToString(BigInt(1))).toBe(" ");
expect(baseToString(BigInt(95))).toBe("~");
expect(baseToString(BigInt(96))).toBe(" ");
expect(baseToString(BigInt(97))).toBe(" !");
expect(baseToString(BigInt(98))).toBe(' "');
expect(baseToString(BigInt(1))).toBe(" ");
});
it("midPointsBetweenStrings", () => {
expect(averageBetweenStrings("!!", "##")).toBe('""');
const midpoints = ["a", ...midPointsBetweenStrings("a", "e", 3, 1), "e"].sort();
expect(midpoints[0]).toBe("a");
expect(midpoints[4]).toBe("e");
expect(midPointsBetweenStrings("a", "e", 0, 1)).toStrictEqual([]);
expect(midPointsBetweenStrings("a", "e", 4, 1)).toStrictEqual([]);
expect(midPointsBetweenStrings(" ", "!'Tu:}", 1, 50)).toStrictEqual([" S:J\\~"]);
expect(averageBetweenStrings(" ", "!!")).toBe(" P");
expect(averageBetweenStrings("! ", "!!")).toBe("! ");
});
it("moveLexicographically left", () => {
@ -221,7 +235,7 @@ describe("stringOrderField", () => {
);
});
it.skip("test moving left into no left space", () => {
it("test moving left into no left space", () => {
moveLexicographicallyTest(
["11", "12", "13", "14", "19"],
3,
@ -229,41 +243,11 @@ describe("stringOrderField", () => {
2,
2,
);
});
it("test moving right into no right space", () => {
moveLexicographicallyTest(
["15", "16", "17", "18", "19"],
1,
3,
3,
2,
);
});
it("test moving right into no left space", () => {
moveLexicographicallyTest(
["11", "12", "13", "14", "15", "16", undefined],
1,
3,
3,
);
});
it("test moving left into no right space", () => {
moveLexicographicallyTest(
["15", "16", "17", "18", "19"],
4,
3,
4,
2,
);
});
it("test moving left into no left space", () => {
moveLexicographicallyTest(
[
ALPHABET.charAt(0),
// Target
ALPHABET.charAt(1),
ALPHABET.charAt(2),
ALPHABET.charAt(3),
@ -278,6 +262,14 @@ describe("stringOrderField", () => {
});
it("test moving right into no right space", () => {
moveLexicographicallyTest(
["15", "16", "17", "18", "19"],
1,
3,
3,
2,
);
moveLexicographicallyTest(
[
ALPHABET.charAt(ALPHABET.length - 5),
@ -294,6 +286,13 @@ describe("stringOrderField", () => {
});
it("test moving right into no left space", () => {
moveLexicographicallyTest(
["11", "12", "13", "14", "15", "16", undefined],
1,
3,
3,
);
moveLexicographicallyTest(
["0", "1", "2", "3", "4", "5"],
1,
@ -304,6 +303,14 @@ describe("stringOrderField", () => {
});
it("test moving left into no right space", () => {
moveLexicographicallyTest(
["15", "16", "17", "18", "19"],
4,
3,
4,
2,
);
moveLexicographicallyTest(
[
ALPHABET.charAt(ALPHABET.length - 5),
@ -329,11 +336,11 @@ describe("stringOrderField", () => {
it("rolls over sanely", () => {
const maxSpaceValue = "~".repeat(50);
const fiftyFirstChar = "!" + " ".repeat(50);
const fiftyFirstChar = " ".repeat(51);
expect(next(maxSpaceValue)).toBe(fiftyFirstChar);
expect(prev(fiftyFirstChar)).toBe(maxSpaceValue);
expect(stringToBase(ALPHABET[0])).toEqual(BigInt(0));
expect(stringToBase(ALPHABET[1])).toEqual(BigInt(1));
expect(Number(stringToBase(ALPHABET[0]))).toEqual(1);
expect(Number(stringToBase(ALPHABET[1]))).toEqual(2);
expect(ALPHABET[ALPHABET.length - 1]).toBe("~");
expect(ALPHABET[0]).toBe(" ");
});