core: simplify contest rank function

packages/hydrooj/src/lib/rank.ts

@@ -1,20 +1,14 @@
 import { Cursor } from 'mongodb';
 import paginate from './paginate';
 
-type G<T> = Promise<[[number, T], () => G<T>] | []>;
-interface ranked {
-    <T>(cursor: Cursor<T>, equ: (a: T, b: T) => boolean, page: number): Promise<[[number, T][], number]>;
-    iterate<T>(cursor: Cursor<T>, equ: (a: T, b: T) => boolean): G<T>;
-    all<T>(cursor: Cursor<T>, equ: (a: T, b: T) => boolean): Promise<[[number, T][], 1]>;
-}
+type ranked = <T>(cursor: Cursor<T>, equ: ((a: T, b: T) => boolean), page?: number) => Promise<[[number, T][], number]>;
 
-const ranked: ranked = async function rankedPage(cursor, equ = (a, b) => a === b, page) {
-    if (!page) return await ranked.all(cursor, equ);
+const ranked: ranked = async (cursor, equ, page) => {
     let last = null;
-    let r = (page - 1) * 100;
-    let count = r;
+    let r = page ? (page - 1) * 100 : 0;
+    let count = page ? r : 0;
     const results = [];
-    const [docs, nPages] = await paginate(cursor, page, 100);
+    const [docs, nPages] = page ? await paginate(cursor, page, 100) : [await cursor.toArray(), 1];
     for (const doc of docs) {
         count++;
         if (!last || !equ(last, doc)) r = count;
@@ -23,34 +17,6 @@ const ranked: ranked = async function rankedPage(cursor, equ = (a, b) => a === b
     }
     return [results, nPages];
 };
-ranked.iterate = async function rankedIterate<T>(cursor: Cursor<T>, equ = (a, b) => a === b) {
-    let last = null;
-    let r = 0;
-    let count = 0;
-    async function getNext(): G<T> {
-        if (!await cursor.hasNext()) return [];
-        const doc = await cursor.next();
-        count++;
-        if (!last || !equ(last, doc)) r = count;
-        last = doc;
-        return [[r, doc], getNext];
-    }
-    return await getNext();
-};
-ranked.all = async function rankedAll(cursor, equ = (a, b) => a === b) {
-    let last = null;
-    let r = 0;
-    let count = 0;
-    const results = [];
-    const docs = await cursor.toArray();
-    for (const doc of docs) {
-        count++;
-        if (!last || !equ(last, doc)) r = count;
-        last = doc;
-        results.push([r, doc]);
-    }
-    return [results, 1];
-};
 
 global.Hydro.lib.rank = ranked;
 export = ranked;

packages/hydrooj/src/model/contest.ts

@@ -189,7 +189,7 @@ const acm = buildContestRule({
         return [rows, udict, nPages];
     },
     async ranked(tdoc, cursor) {
-        return await ranked.all(cursor, (a, b) => a.accept === b.accept && a.time === b.time);
+        return await ranked(cursor, (a, b) => a.accept === b.accept && a.time === b.time);
     },
 });
 
@@ -310,7 +310,7 @@ const oi = buildContestRule({
         return [rows, udict, nPages];
     },
     async ranked(tdoc, cursor) {
-        return await ranked.all(cursor, (a, b) => a.score === b.score);
+        return await ranked(cursor, (a, b) => a.score === b.score);
     },
 });
 
@@ -467,7 +467,7 @@ const homework = buildContestRule({
         return [rows, udict, nPages];
     },
     async ranked(tdoc, cursor) {
-        return await ranked.all(cursor, (a, b) => a.score === b.score);
+        return await ranked(cursor, (a, b) => a.score === b.score);
     },
 });