初始化

src/components/canvas-spreadsheet/formula/evaluator.ts

@@ -0,0 +1,191 @@
+export type CellValueReader = (viewRow: number, col: number) => unknown;
+
+export type FormulaResult = number | 'DIV_ZERO' | null;
+
+class DivZeroError extends Error {
+  constructor() {
+    super('Division by zero');
+    this.name = 'DivZeroError';
+  }
+}
+
+export function colLettersToIndex(letters: string): number {
+  let n = 0;
+  for (const ch of letters.toUpperCase()) {
+    n = n * 26 + (ch.charCodeAt(0) - 64);
+  }
+  return n - 1;
+}
+
+export function colIndexToLetters(index: number): string {
+  let n = index + 1;
+  let result = '';
+  while (n > 0) {
+    n -= 1;
+    result = String.fromCharCode(65 + (n % 26)) + result;
+    n = Math.floor(n / 26);
+  }
+  return result;
+}
+
+function toNumber(value: unknown): number {
+  if (value == null || value === '') return 0;
+  const n = Number(value);
+  return Number.isFinite(n) ? n : Number.NaN;
+}
+
+function tokenize(expr: string): string[] {
+  const tokens: string[] = [];
+  let i = 0;
+  while (i < expr.length) {
+    const ch = expr[i]!;
+    if (ch === ' ' || ch === '\t') {
+      i += 1;
+      continue;
+    }
+    if ('+-*/()'.includes(ch)) {
+      tokens.push(ch);
+      i += 1;
+      continue;
+    }
+    if (/[0-9.]/.test(ch)) {
+      let num = ch;
+      i += 1;
+      while (i < expr.length && /[0-9.]/.test(expr[i]!)) {
+        num += expr[i];
+        i += 1;
+      }
+      tokens.push(num);
+      continue;
+    }
+    if (/[A-Za-z]/.test(ch)) {
+      let ref = ch;
+      i += 1;
+      while (i < expr.length && /[A-Za-z0-9]/.test(expr[i]!)) {
+        ref += expr[i];
+        i += 1;
+      }
+      tokens.push(ref);
+      continue;
+    }
+    throw new Error(`Unexpected character: ${ch}`);
+  }
+  return tokens;
+}
+
+function parseFactor(
+  tokens: string[],
+  pos: { i: number },
+  readCell: CellValueReader,
+  viewRow: number,
+): number {
+  const token = tokens[pos.i];
+  if (token === undefined) throw new Error('Unexpected end');
+
+  if (token === '(') {
+    pos.i += 1;
+    const value = parseExpression(tokens, pos, readCell, viewRow);
+    if (tokens[pos.i] !== ')') throw new Error('Missing )');
+    pos.i += 1;
+    return value;
+  }
+
+  if (token === '+') {
+    pos.i += 1;
+    return parseFactor(tokens, pos, readCell, viewRow);
+  }
+
+  if (token === '-') {
+    pos.i += 1;
+    return -parseFactor(tokens, pos, readCell, viewRow);
+  }
+
+  if (/^[0-9]+(\.[0-9]+)?$/.test(token)) {
+    pos.i += 1;
+    return Number(token);
+  }
+
+  const match = /^([A-Za-z]+)(\d+)$/.exec(token);
+  if (match) {
+    pos.i += 1;
+    const col = colLettersToIndex(match[1]!);
+    return toNumber(readCell(viewRow, col));
+  }
+
+  throw new Error(`Invalid token: ${token}`);
+}
+
+function parseTerm(
+  tokens: string[],
+  pos: { i: number },
+  readCell: CellValueReader,
+  viewRow: number,
+): number {
+  let value = parseFactor(tokens, pos, readCell, viewRow);
+  while (pos.i < tokens.length) {
+    const op = tokens[pos.i];
+    if (op === '*' || op === '/') {
+      pos.i += 1;
+      const rhs = parseFactor(tokens, pos, readCell, viewRow);
+      if (op === '/') {
+        if (rhs === 0) throw new DivZeroError();
+        value /= rhs;
+      } else {
+        value *= rhs;
+      }
+    } else {
+      break;
+    }
+  }
+  return value;
+}
+
+function parseExpression(
+  tokens: string[],
+  pos: { i: number },
+  readCell: CellValueReader,
+  viewRow: number,
+): number {
+  let value = parseTerm(tokens, pos, readCell, viewRow);
+  while (pos.i < tokens.length) {
+    const op = tokens[pos.i];
+    if (op === '+' || op === '-') {
+      pos.i += 1;
+      const rhs = parseTerm(tokens, pos, readCell, viewRow);
+      value = op === '+' ? value + rhs : value - rhs;
+    } else {
+      break;
+    }
+  }
+  return value;
+}
+
+export function evaluateFormula(
+  formula: string,
+  viewRow: number,
+  readCell: CellValueReader,
+): FormulaResult {
+  if (!formula?.trim()) return null;
+  let expr = formula.trim();
+  if (expr.startsWith('=')) expr = expr.slice(1);
+  if (!expr) return null;
+
+  try {
+    const tokens = tokenize(expr);
+    const pos = { i: 0 };
+    const result = parseExpression(tokens, pos, readCell, viewRow);
+    if (pos.i < tokens.length) throw new Error('Trailing tokens');
+    if (!Number.isFinite(result)) return null;
+    return result;
+  } catch (err) {
+    if (err instanceof DivZeroError) return 'DIV_ZERO';
+    return null;
+  }
+}
+
+export function formatFormulaResult(value: FormulaResult): string {
+  if (value === 'DIV_ZERO') return '-';
+  if (value == null || Number.isNaN(value)) return '#ERROR';
+  if (Number.isInteger(value)) return String(value);
+  return String(Math.round(value * 100) / 100);
+}