publish codemirrot helix package flow

packages/codemirror-helix/src/motions.ts

@@ -0,0 +1,180 @@
+import type { EditorState } from "@codemirror/state";
+
+export type CharClass = "space" | "word" | "punct";
+
+export function charAt(state: EditorState, i: number): string {
+  return i >= 0 && i < state.doc.length ? state.doc.sliceString(i, i + 1) : "";
+}
+
+export function classOf(ch: string): CharClass {
+  if (ch === "" || /\s/.test(ch)) return "space";
+  if (/[\p{L}\p{N}_]/u.test(ch)) return "word";
+  return "punct";
+}
+
+// For WORD (big) motions only whitespace separates tokens.
+function bigClassOf(ch: string): CharClass {
+  return ch === "" || /\s/.test(ch) ? "space" : "word";
+}
+
+function classAt(state: EditorState, i: number, big: boolean): CharClass {
+  const ch = charAt(state, i);
+  return big ? bigClassOf(ch) : classOf(ch);
+}
+
+/** Helix `w`/`W`: move to the start of the next word. */
+export function nextWordStart(state: EditorState, pos: number, big: boolean): number {
+  const len = state.doc.length;
+  let i = pos;
+  if (i >= len) return len;
+  if (classAt(state, i, big) === "space") {
+    while (i < len && classAt(state, i, big) === "space") i++;
+  } else {
+    const cls = classAt(state, i, big);
+    while (i < len && classAt(state, i, big) === cls) i++;
+    while (i < len && classAt(state, i, big) === "space") i++;
+  }
+  return i;
+}
+
+/** Helix `b`/`B`: move to the start of the previous word. */
+export function prevWordStart(state: EditorState, pos: number, big: boolean): number {
+  let i = pos;
+  if (i <= 0) return 0;
+  i--;
+  while (i > 0 && classAt(state, i, big) === "space") i--;
+  const cls = classAt(state, i, big);
+  while (i > 0 && classAt(state, i - 1, big) === cls) i--;
+  return i;
+}
+
+/** Helix `e`/`E`: move to the end of the next word. */
+export function nextWordEnd(state: EditorState, pos: number, big: boolean): number {
+  const len = state.doc.length;
+  let i = pos + 1;
+  while (i < len && classAt(state, i, big) === "space") i++;
+  const cls = classAt(state, i, big);
+  while (i < len && classAt(state, i, big) === cls) i++;
+  return Math.min(i, len);
+}
+
+export function firstNonBlank(state: EditorState, line: number): number {
+  const l = state.doc.line(line);
+  return l.from + (l.text.match(/^\s*/)?.[0].length ?? 0);
+}
+
+/** f/t/F/T: find `target` from `pos`. Returns null if not found on the line. */
+export function findCharOnLine(
+  state: EditorState,
+  pos: number,
+  target: string,
+  kind: "f" | "t" | "F" | "T",
+): number | null {
+  const line = state.doc.lineAt(pos);
+  const forward = kind === "f" || kind === "t";
+  const till = kind === "t" || kind === "T";
+
+  if (forward) {
+    let i = pos + 1;
+    // `t` should skip an adjacent target so repeated presses advance.
+    if (till && charAt(state, i) === target) i++;
+    for (; i <= line.to; i++) {
+      if (charAt(state, i) === target) return till ? i - 1 : i;
+    }
+  } else {
+    let i = pos - 1;
+    if (till && charAt(state, i) === target) i--;
+    for (; i >= line.from; i--) {
+      if (charAt(state, i) === target) return till ? i + 1 : i;
+    }
+  }
+  return null;
+}
+
+const PAIRS: Record<string, { open: string; close: string }> = {
+  "(": { open: "(", close: ")" },
+  ")": { open: "(", close: ")" },
+  "[": { open: "[", close: "]" },
+  "]": { open: "[", close: "]" },
+  "{": { open: "{", close: "}" },
+  "}": { open: "{", close: "}" },
+  "<": { open: "<", close: ">" },
+  ">": { open: "<", close: ">" },
+};
+
+export function pairFor(ch: string): { open: string; close: string } | null {
+  return PAIRS[ch] ?? null;
+}
+
+/** Scan forward for the close that matches an open at/after `pos` (nesting-aware). */
+export function findClose(state: EditorState, from: number, open: string, close: string): number | null {
+  const len = state.doc.length;
+  let depth = 0;
+  for (let i = from; i < len; i++) {
+    const ch = charAt(state, i);
+    if (ch === open) depth++;
+    else if (ch === close) {
+      depth--;
+      if (depth === 0) return i;
+    }
+  }
+  return null;
+}
+
+/** Scan backward for the open that matches a close at/before `pos` (nesting-aware). */
+export function findOpen(state: EditorState, from: number, open: string, close: string): number | null {
+  let depth = 0;
+  for (let i = from; i >= 0; i--) {
+    const ch = charAt(state, i);
+    if (ch === close) depth++;
+    else if (ch === open) {
+      depth--;
+      if (depth === 0) return i;
+    }
+  }
+  return null;
+}
+
+/** `mm`: position of the bracket matching the one at/under `pos`, or null. */
+export function matchingBracket(state: EditorState, pos: number): number | null {
+  for (const probe of [pos, pos - 1]) {
+    const ch = charAt(state, probe);
+    const pair = pairFor(ch);
+    if (!pair) continue;
+    if (ch === pair.open) return findClose2(state, probe, pair.open, pair.close);
+    return findOpen2(state, probe, pair.open, pair.close);
+  }
+  return null;
+}
+
+function findClose2(state: EditorState, openPos: number, open: string, close: string): number | null {
+  const len = state.doc.length;
+  let depth = 0;
+  for (let i = openPos; i < len; i++) {
+    const ch = charAt(state, i);
+    if (ch === open) depth++;
+    else if (ch === close && --depth === 0) return i;
+  }
+  return null;
+}
+
+function findOpen2(state: EditorState, closePos: number, open: string, close: string): number | null {
+  let depth = 0;
+  for (let i = closePos; i >= 0; i--) {
+    const ch = charAt(state, i);
+    if (ch === close) depth++;
+    else if (ch === open && --depth === 0) return i;
+  }
+  return null;
+}
+
+/** Paragraph bounds (blank-line delimited) containing `pos`. */
+export function paragraphAt(state: EditorState, pos: number): { from: number; to: number } {
+  const { doc } = state;
+  let startLine = doc.lineAt(pos).number;
+  let endLine = startLine;
+  const blank = (n: number) => doc.line(n).text.trim() === "";
+  while (startLine > 1 && !blank(startLine - 1)) startLine--;
+  while (endLine < doc.lines && !blank(endLine + 1)) endLine++;
+  return { from: doc.line(startLine).from, to: doc.line(endLine).to };
+}