func CompareDepth()

in starlark/value.go [1269:1330]

• 54 lines of code
• 18 McCabe index (conditional complexity)

func CompareDepth(op syntax.Token, x, y Value, depth int) (bool, error) {
	if depth < 1 {
		return false, fmt.Errorf("comparison exceeded maximum recursion depth")
	}
	if sameType(x, y) {
		if xcomp, ok := x.(Comparable); ok {
			return xcomp.CompareSameType(op, y, depth)
		}

		// use identity comparison
		switch op {
		case syntax.EQL:
			return x == y, nil
		case syntax.NEQ:
			return x != y, nil
		}
		return false, fmt.Errorf("%s %s %s not implemented", x.Type(), op, y.Type())
	}

	// different types

	// int/float ordered comparisons
	switch x := x.(type) {
	case Int:
		if y, ok := y.(Float); ok {
			var cmp int
			if y != y {
				cmp = -1 // y is NaN
			} else if !math.IsInf(float64(y), 0) {
				cmp = x.rational().Cmp(y.rational()) // y is finite
			} else if y > 0 {
				cmp = -1 // y is +Inf
			} else {
				cmp = +1 // y is -Inf
			}
			return threeway(op, cmp), nil
		}
	case Float:
		if y, ok := y.(Int); ok {
			var cmp int
			if x != x {
				cmp = +1 // x is NaN
			} else if !math.IsInf(float64(x), 0) {
				cmp = x.rational().Cmp(y.rational()) // x is finite
			} else if x > 0 {
				cmp = +1 // x is +Inf
			} else {
				cmp = -1 // x is -Inf
			}
			return threeway(op, cmp), nil
		}
	}

	// All other values of different types compare unequal.
	switch op {
	case syntax.EQL:
		return false, nil
	case syntax.NEQ:
		return true, nil
	}
	return false, fmt.Errorf("%s %s %s not implemented", x.Type(), op, y.Type())
}