Function exprToStringRecursive

test/utils.ts:44–100

* Special printing utility for printing the *MathJson* representation - of either a boxed or * un-boxed expression. * * If an *Expression*, the **pretty** (prettified) MathJson representation is printed. * * Conveniently - prints on one line if expr. is less than local `MAX_LINE_LENGTH` (e.g. 7

(expr: ExpressionInput, start: number)

  const indent = ' '.repeat(start);

  if (start > 50) return indent + '...';

  if (expr === null) return 'null';
  if (expr instanceof _BoxedExpression) {
    const ce = expr.engine;
    return exprToStringRecursive(
      ce.expr(expr, { form: 'raw' }).toMathJson({ prettify: true }), // The default is 'prettify: true'
      start
    );
  }

  if (Array.isArray(expr)) {
    const elements = expr.map((x) => exprToStringRecursive(x, start + 2));
    const result = `[${elements.join(', ')}]`;
    if (start + result.length < MAX_LINE_LENGTH) return result;
    return `[\n${indent}  ${elements.join(`,\n${indent}  `)}\n${indent}]`;
  }
  if (typeof expr === 'object') {
    const elements = {};

    for (const key of Object.keys(expr)) {
      if (expr[key] instanceof _BoxedExpression) {
        elements[key] = exprToStringRecursive(
          expr[key] as ExpressionInput,
          start + 2
        );
      } else if (expr[key] === null) {
        elements[key] = 'null';
      } else if (expr[key] === undefined) {
        elements[key] = 'undefined';
      } else if (typeof expr[key] === 'object' && 'json' in expr[key]) {
        elements[key] = exprToStringRecursive(expr[key], start + 2);
      } else elements[key] = exprToStringRecursive(expr[key], start + 2);
    }

    const result = `{${Object.keys(expr)
      .map((key) => `${key}: ${elements[key]}`)
      .join('; ')}}`;
    if (start + result.length < MAX_LINE_LENGTH) return result;
    return (
      `{\n` +
      Object.keys(expr)
        .map((key) => `${indent}  ${key}: ${elements[key]}`)
        .join(`;\n${indent}`) +
      '\n' +
      indent +
      '}'
    );
  }
  if (typeof expr === 'string' && start === 0) return expr;
  if (typeof expr === 'string') return `"${expr}"`;

  return JSON.stringify(expr, null, 2);
}

export function exprToString(expr: ExpressionInput | null | undefined): string {
  if (typeof expr === 'number') return expr.toString();
  if (!expr) return '';