Merge pull request #116 from takker99/cached-lines

✨ 同じscrapbox.Page.linesの再生成コストをなくす関数を追加

Author: takker99

browser/dom/getCachedLines.ts

@@ -0,0 +1,22 @@
+import { Line, Scrapbox } from "../../deps/scrapbox.ts";
+declare const scrapbox: Scrapbox;
+
+let isLatestData = false;
+let lines: typeof scrapbox.Page.lines = null;
+
+scrapbox.addListener("lines:changed", () => isLatestData = false);
+scrapbox.addListener("layout:changed", () => isLatestData = false);
+
+/** scrapbox.Page.linesをcacheして取得する
+ *
+ * scrapbox.Page.linesの生成には時間がかかるので、実際に必要になるまで呼び出さないようにする
+ *
+ * @return `scrapbox.Page.lines`と同じ。常に最新のものが返される
+ */
+export const getCachedLines = (): readonly Line[] | null => {
+  if (!isLatestData) {
+    lines = scrapbox.Page.lines;
+    isLatestData = true;
+  }
+  return lines;
+};

browser/dom/node.ts

@@ -3,6 +3,7 @@
 /// <reference lib="dom" />
 import { isNone, isNumber, isString } from "../../is.ts";
 import { ensureArray } from "../../ensure.ts";
+import { getCachedLines } from "./getCachedLines.ts";
 import type { Line, Scrapbox } from "../../deps/scrapbox.ts";
 import { lines } from "./dom.ts";
 import * as Text from "../../text.ts";
@@ -83,9 +84,10 @@ export const isLineDOM = (dom: unknown): dom is HTMLDivElement =>
 
 export const getLineCount = (): number => getLines().length;
 
-export const getLines = (): Line[] => {
-  ensureArray(scrapbox.Page.lines, "scrapbox.Page.lines");
-  return scrapbox.Page.lines;
+export const getLines = (): readonly Line[] => {
+  const lines = getCachedLines();
+  ensureArray<Line>(lines, "scrapbox.Page.lines");
+  return lines;
 };
 
 export const getText = <T extends HTMLElement>(

text.ts

@@ -1,5 +1,6 @@
 import { isString } from "./is.ts";
 
+/** インデント数を数える */
 export const getIndentCount = (text: string): number =>
   text.match(/^(\s*)/)?.[1]?.length ?? 0;
 
@@ -8,10 +9,10 @@ export const getIndentCount = (text: string): number =>
  * @param index 指定したい行の行番号
  * @param lines 行のリスト
  */
-export function getIndentLineCount(
+export const getIndentLineCount = (
   index: number,
-  lines: string[] | { text: string }[],
-): number {
+  lines: readonly string[] | readonly { text: string }[],
+): number => {
   const base = getIndentCount(getText(index, lines));
   let count = 0;
   while (
@@ -21,9 +22,12 @@ export function getIndentLineCount(
     count++;
   }
   return count;
-}
+};
 
-function getText(index: number, lines: string[] | { text: string }[]) {
+const getText = (
+  index: number,
+  lines: readonly string[] | readonly { text: string }[],
+) => {
   const line = lines[index];
   return isString(line) ? line : line.text;
-}
+};