Function matchArguments

src/compute-engine/boxed-expression/match.ts:958–1218

* Match a list of patterns against operands of expression, appending wildcards (named) to * *substitution* (along the way). If a successful match, returns the new substitution (or the same * if no named wildcard), or *null* for no match. * * @param expr * @param patterns * @param substitution

(
  expr: Expression,
  patterns: ReadonlyArray<Expression>,
  substitution: BoxedSubstitution,
  options: PatternMatchOptions
)

    if (n > 20 && k > 2 && k < n - 2) {
      // For large n and moderate k, combinations grow fast
      // Approximate: if n > 15 and k > 3, check more carefully
      let approxCount = 1;
      for (let i = 0; i < Math.min(k, n - k); i++) {
        approxCount = (approxCount * (n - i)) / (i + 1);
        if (approxCount > MAX_COMBINATIONS) return [];
      }
    }

    // Generate all combinations of k indices from 0..n-1
    const result: number[][] = [];
    const combo: number[] = [];

    function backtrack(start: number) {
      if (result.length >= MAX_COMBINATIONS) return; // Stop if limit reached
      if (combo.length === k) {
        result.push([...combo]);
        return;
      }
      for (let i = start; i < n; i++) {
        combo.push(i);
        backtrack(i + 1);
        combo.pop();
      }
    }

    backtrack(0);
    return result;
  }
}

/**
 * Match a list of patterns against operands of expression, appending wildcards (named) to
 * *substitution* (along the way). If a successful match, returns the new substitution (or the same
 * if no named wildcard), or *null* for no match.
 *
 * @param expr
 * @param patterns
 * @param substitution
 * @param options
 * @returns
 */
function matchArguments(
  expr: Expression,
  patterns: ReadonlyArray<Expression>,
  substitution: BoxedSubstitution,
  options: PatternMatchOptions
): BoxedSubstitution | null {
  if (patterns.length === 0) {
    if (isFunction(expr) && expr.ops.length === 0) return substitution;
    return null;
  }

  const ce = patterns[0].engine;

  // We're going to consume the ops array, so make a copy
  if (!isFunction(expr)) return null;
  const ops = [...expr.ops];