- init

src/engine/refs.ts

@@ -0,0 +1,69 @@
+/**
+ * Reference helpers: A1 <-> (col,row) conversion and range expansion.
+ *
+ * All coordinates the engine uses internally are 0-based. The A1 notation
+ * exposed to the user is 1-based for rows and letter-based for columns
+ * (A=0, B=1, ..., Z=25, AA=26, ...).
+ */
+
+const CELL_RE = /^\$?([A-Za-z]{1,3})\$?([0-9]{1,7})$/;
+
+/** "A" -> 0, "B" -> 1, "Z" -> 25, "AA" -> 26 ... */
+export function colToNumber(letters: string): number {
+  let n = 0;
+  const up = letters.toUpperCase();
+  for (let i = 0; i < up.length; i++) {
+    n = n * 26 + (up.charCodeAt(i) - 64); // 'A' -> 1
+  }
+  return n - 1;
+}
+
+/** 0 -> "A", 25 -> "Z", 26 -> "AA" ... */
+export function numberToCol(n: number): string {
+  let s = '';
+  let x = n + 1;
+  while (x > 0) {
+    const rem = (x - 1) % 26;
+    s = String.fromCharCode(65 + rem) + s;
+    x = Math.floor((x - 1) / 26);
+  }
+  return s;
+}
+
+/** True if `text` looks like a bare cell reference (e.g. "A1", "$B$2", "aa10"). */
+export function looksLikeCell(text: string): boolean {
+  return CELL_RE.test(text);
+}
+
+/** Parse "A1" -> { col: 0, row: 0 }. Throws for malformed input. */
+export function parseA1(text: string): { col: number; row: number } {
+  const m = CELL_RE.exec(text);
+  if (!m) throw new Error(`Bad cell reference: ${text}`);
+  return { col: colToNumber(m[1]), row: Number(m[2]) - 1 };
+}
+
+/** Build "A1" from 0-based coordinates. */
+export function toA1(col: number, row: number): string {
+  return `${numberToCol(col)}${row + 1}`;
+}
+
+/**
+ * Expand a rectangular range (given by two corners, any order) into the list of
+ * cell coordinates it covers, row-major.
+ */
+export function expandRange(
+  a: { col: number; row: number },
+  b: { col: number; row: number },
+): Array<{ col: number; row: number }> {
+  const c0 = Math.min(a.col, b.col);
+  const c1 = Math.max(a.col, b.col);
+  const r0 = Math.min(a.row, b.row);
+  const r1 = Math.max(a.row, b.row);
+  const out: Array<{ col: number; row: number }> = [];
+  for (let r = r0; r <= r1; r++) {
+    for (let c = c0; c <= c1; c++) {
+      out.push({ col: c, row: r });
+    }
+  }
+  return out;
+}