refactor: new jumpToPattern function that can be used for motions

motions/jumpToHeading.ts

@@ -1,17 +1,16 @@
 import { MotionFn } from "./utils/defineObsidianVimMotion";
+import { jumpToPattern } from "./utils/getNthInstanceOfPattern";
 
-const HEADING_REGEX = /^#+ /;
+const HEADING_REGEX = /^#+ /gm;
 
 export const jumpToNextHeading: MotionFn = (cm, oldPosition, { repeat }) => {
-  const { line, ch } = oldPosition;
-  const noteContent = cm.getValue();
-  const nextContentLines = noteContent.split("\n").slice(line + 1);
-  const nextHeadingIdx =
-    getNthHeadingIndex(nextContentLines, repeat) + line + 1;
-  if (nextHeadingIdx === -1) {
-    return { line, ch };
-  }
-  return { line: nextHeadingIdx, ch: 0 };
+  return jumpToPattern({
+    cm,
+    oldPosition,
+    repeat,
+    regex: HEADING_REGEX,
+    direction: "next",
+  });
 };
 
 export const jumpToPreviousHeading: MotionFn = (
@@ -19,34 +18,11 @@ export const jumpToPreviousHeading: MotionFn = (
   oldPosition,
   { repeat }
 ) => {
-  const { line, ch } = oldPosition;
-  const noteContent = cm.getValue();
-  const isAlreadyOnHeading = cm.getLine(line).startsWith("#");
-  const lastIdxToConsider = isAlreadyOnHeading ? line - 1 : line;
-  const previousContentLines = noteContent
-    .split("\n")
-    .slice(0, lastIdxToConsider + 1)
-    .reverse();
-  const previousHeadingIdx = getNthHeadingIndex(previousContentLines, repeat);
-  if (previousHeadingIdx === -1) {
-    return { line, ch };
-  }
-  return { line: lastIdxToConsider - previousHeadingIdx, ch: 0 };
+  return jumpToPattern({
+    cm,
+    oldPosition,
+    repeat,
+    regex: HEADING_REGEX,
+    direction: "previous",
+  });
 };
-
-function getNthHeadingIndex(contentLines: string[], n: number): number {
-  let numHeadingsFound = 0;
-  let currHeadingIndex = -1;
-  for (let i = 0; i < contentLines.length; i++) {
-    const headingRegex = /^#+ /;
-    if (!headingRegex.test(contentLines[i])) {
-      continue;
-    }
-    currHeadingIndex = i;
-    numHeadingsFound++;
-    if (numHeadingsFound === n) {
-      return currHeadingIndex;
-    }
-  }
-  return currHeadingIndex;
-}

motions/jumpToLink.ts

@@ -1,39 +1,24 @@
 import { MotionFn } from "./utils/defineObsidianVimMotion";
-import {
-  getNthNextInstanceOfPattern,
-  getNthPreviousInstanceOfPattern,
-} from "./utils/getNthInstanceOfPattern";
+import { jumpToPattern } from "./utils/getNthInstanceOfPattern";
 
 const LINK_REGEX = /\[\[[^\]\]]+?\]\]/g;
 
 export const jumpToNextLink: MotionFn = (cm, oldPosition, { repeat }) => {
-  const content = cm.getValue();
-  const cursorOffset = cm.indexFromPos(oldPosition);
-  const nextLinkIdx = getNthNextInstanceOfPattern({
-    content,
+  return jumpToPattern({
+    cm,
+    oldPosition,
+    repeat,
     regex: LINK_REGEX,
-    startingIdx: cursorOffset,
-    n: repeat,
+    direction: "next",
   });
-  if (nextLinkIdx === undefined) {
-    return oldPosition;
-  }
-  const newPosition = cm.posFromIndex(nextLinkIdx + 2);
-  return newPosition;
 };
 
 export const jumpToPreviousLink: MotionFn = (cm, oldPosition, { repeat }) => {
-  const content = cm.getValue();
-  const cursorOffset = cm.indexFromPos(oldPosition);
-  const previousLinkIdx = getNthPreviousInstanceOfPattern({
-    content,
+  return jumpToPattern({
+    cm,
+    oldPosition,
+    repeat,
     regex: LINK_REGEX,
-    startingIdx: cursorOffset,
-    n: repeat,
+    direction: "previous",
   });
-  if (previousLinkIdx === undefined) {
-    return oldPosition;
-  }
-  const newPosition = cm.posFromIndex(previousLinkIdx + 2);
-  return newPosition;
 };

motions/utils/defineObsidianVimMotion.ts

@@ -7,8 +7,12 @@ export type MotionFn = (
   motionArgs: { repeat: number }
 ) => EditorPosition;
 
-// Reference: @replit/codemirror-vim/src/vim.js
-type VimApi = {
+/**
+ * Partial representation of the CodeMirror Vim API that we use to define motions, commands, etc.
+ *
+ * Reference: https://github.com/replit/codemirror-vim/blob/master/src/vim.js
+ */
+export type VimApi = {
   defineMotion: (name: string, fn: MotionFn) => void;
   mapCommand: (
     keys: string,

motions/utils/getNthInstanceOfPattern.ts

@@ -1,9 +1,38 @@
+import { Editor as CodeMirrorEditor } from "codemirror";
+import { EditorPosition } from "obsidian";
 import { shim as matchAllShim } from "string.prototype.matchall";
 matchAllShim();
 
+export function jumpToPattern({
+  cm,
+  oldPosition,
+  repeat,
+  regex,
+  direction,
+}: {
+  cm: CodeMirrorEditor;
+  oldPosition: EditorPosition;
+  repeat: number;
+  regex: RegExp;
+  direction: "next" | "previous";
+}): EditorPosition {
+  const content = cm.getValue();
+  const startingIdx = cm.indexFromPos(oldPosition);
+  const jumpFn =
+    direction === "next"
+      ? getNthNextInstanceOfPattern
+      : getNthPreviousInstanceOfPattern;
+  const matchIdx = jumpFn({ content, regex, startingIdx, n: repeat });
+  if (matchIdx === undefined) {
+    return oldPosition;
+  }
+  const newPosition = cm.posFromIndex(matchIdx);
+  return newPosition;
+}
+
 /**
- * Returns the index of the first instance of a pattern in a string after a given starting index.
- * If the pattern is not found, returns the starting index.
+ * Returns the index of (up to) the n-th instance of a pattern in a string after a given starting
+ * index. If the pattern is not found at all, returns undefined.
  */
 export function getNthNextInstanceOfPattern({
   content,
@@ -16,24 +45,19 @@ export function getNthNextInstanceOfPattern({
   startingIdx: number;
   n: number;
 }): number {
+  const globalRegex = makeGlobalRegex(regex);
+  globalRegex.lastIndex = startingIdx + 1;
+  let currMatch;
   let numMatchesFound = 0;
-  let currMatchIdx = startingIdx;
-  const globalRegex = addGlobalFlagIfNeeded(regex);
-  while (currMatchIdx < content.length - 1 && numMatchesFound < n) {
-    const contentToSearch = content.substring(currMatchIdx + 1);
-    const substringMatchIdx = contentToSearch.search(globalRegex);
-    if (substringMatchIdx === -1) {
-      return currMatchIdx;
-    }
-    currMatchIdx = currMatchIdx + substringMatchIdx + 1;
+  while (numMatchesFound < n && (currMatch = globalRegex.exec(content)) != null) {
     numMatchesFound++;
   }
-  return currMatchIdx;
+  return currMatch?.index;
 }
 
 /**
- * Returns the index of the last found instance of a pattern in a string before a given starting
- * index. If the pattern is not found, returns undefined.
+ * Returns the index of (up to) the nth-last instance of a pattern in a string before a given
+ * starting index. If the pattern is not found at all, returns undefined.
  */
 export function getNthPreviousInstanceOfPattern({
   content,
@@ -46,7 +70,7 @@ export function getNthPreviousInstanceOfPattern({
   startingIdx: number;
   n: number;
 }): number | undefined {
-  const globalRegex = addGlobalFlagIfNeeded(regex);
+  const globalRegex = makeGlobalRegex(regex);
   const contentToSearch = content.substring(0, startingIdx);
   const previousMatches = [...contentToSearch.matchAll(globalRegex)];
   if (previousMatches.length < n) {
@@ -55,8 +79,9 @@ export function getNthPreviousInstanceOfPattern({
   return previousMatches[previousMatches.length - n].index;
 }
 
-function addGlobalFlagIfNeeded(regex: RegExp): RegExp {
-  return regex.global ? regex : new RegExp(regex.source, getGlobalFlags(regex));
+function makeGlobalRegex(regex: RegExp): RegExp {
+  const globalFlags = getGlobalFlags(regex);
+  return new RegExp(regex.source, globalFlags);
 }
 
 function getGlobalFlags(regex: RegExp): string {