Function matchPermutation

src/compute-engine/boxed-expression/match.ts:495–630

* * Try all needed permutations of the operands of a pattern expression, against the operands of a * match target. Assumes that *expr* and *pattern* have the same operator. * * For patterns containing sequence wildcards (__) with anchor elements (non-wildcards), * uses anchor-based matching: an

(
  expr: Expression,
  pattern: Expression,
  substitution: BoxedSubstitution,
  options: PatternMatchOptions
)

    if (result !== null) return result;
  }

  if (operator === 'Square') {
    // Power(x, 2) -> Square(x)
    const result = matchVariation('Power', [expr, 2]);
    if (result !== null) return result;
  }

  if (operator === 'Exp') {
    // Power(E, x) -> Exp(x): a subject `e^z` (canonicalized to
    // `Power(E, z)`) matches an `Exp` pattern as `Exp(z)`
    if (isFunction(expr, 'Power') && isSymbol(expr.op1, 'ExponentialE')) {
      const result = matchVariation('Exp', [expr.op2]);
      if (result !== null) return result;
    }
  }

  if (operator === 'Power' && isFunction(pattern)) {
    // Square(x) -> Power(x, 2)
    if (pattern.op2.re === 2 && pattern.op2.im === 0) {
      const result = matchVariation('Square', [expr]);
      if (result !== null) return result;
    }
    // Exp(x) -> Power(E, x)
    if (isSymbol(pattern.op1, 'ExponentialE')) {
      const result = matchVariation('Exp', [expr]);
      if (result !== null) return result;
    }
    // x -> Power(x, 1)
    {
      const result = matchVariation('Power', [expr, 1]);
      if (result !== null) return result;
    }
  }

  return null;
}

/**
 *
 * Try all needed permutations of the operands of a pattern expression, against the operands of a
 * match target. Assumes that *expr* and *pattern* have the same operator.
 *
 * For patterns containing sequence wildcards (__) with anchor elements (non-wildcards),
 * uses anchor-based matching: anchors match against specific expression elements,
 * and sequence wildcards capture ALL remaining elements.
 *
 * @param expr
 * @param pattern
 * @param substitution
 * @param options
 * @returns
 */
function matchPermutation(
  expr: Expression,
  pattern: Expression,
  substitution: BoxedSubstitution,
  options: PatternMatchOptions
): BoxedSubstitution | null {