cyb70289 commented on a change in pull request #9841:
URL: https://github.com/apache/arrow/pull/9841#discussion_r606046786
##########
File path: cpp/src/arrow/compute/kernels/scalar_arithmetic.cc
##########
@@ -233,6 +235,184 @@ struct DivideChecked {
}
};
+struct Power {
+ template <typename T, typename Arg0, typename Arg1>
+ static enable_if_signed_integer<T> Call(KernelContext* ctx, Arg0 left, Arg1
right) {
+ if (right < 0) {
+ ctx->SetStatus(
+ Status::Invalid("integers to negative integer powers are not
allowed"));
+ }
+ if (left == 0 && right != 0) {
+ return 0;
+ }
+ Arg0 result = 1;
+ for (Arg1 i = 0; i < right; i++) {
+ MultiplyWithOverflow(result, left, &result);
+ }
+ return result;
+ }
+
+ template <typename T, typename Arg0, typename Arg1>
+ static enable_if_unsigned_integer<T> Call(KernelContext* ctx, Arg0 left,
Arg1 right) {
+ if (left == 0 && right != 0) {
+ return 0;
+ }
+ Arg0 result = 1;
+ for (Arg1 i = 0; i < right; i++) {
+ MultiplyWithOverflow(result, left, &result);
+ }
+ return result;
+ }
+
+ template <typename T, typename Arg0, typename Arg1>
+ static enable_if_floating_point<T> Call(KernelContext* ctx, Arg0 left, Arg1
right) {
+ if (std::isnan(left) || std::isnan(right)) {
+ return NAN;
+ }
Review comment:
I think pow() can handle this case.
##########
File path: cpp/src/arrow/compute/kernels/scalar_arithmetic.cc
##########
@@ -233,6 +235,184 @@ struct DivideChecked {
}
};
+struct Power {
+ template <typename T, typename Arg0, typename Arg1>
+ static enable_if_signed_integer<T> Call(KernelContext* ctx, Arg0 left, Arg1
right) {
+ if (right < 0) {
+ ctx->SetStatus(
+ Status::Invalid("integers to negative integer powers are not
allowed"));
+ }
+ if (left == 0 && right != 0) {
+ return 0;
+ }
+ Arg0 result = 1;
+ for (Arg1 i = 0; i < right; i++) {
+ MultiplyWithOverflow(result, left, &result);
+ }
+ return result;
+ }
+
+ template <typename T, typename Arg0, typename Arg1>
+ static enable_if_unsigned_integer<T> Call(KernelContext* ctx, Arg0 left,
Arg1 right) {
+ if (left == 0 && right != 0) {
+ return 0;
+ }
+ Arg0 result = 1;
+ for (Arg1 i = 0; i < right; i++) {
+ MultiplyWithOverflow(result, left, &result);
+ }
+ return result;
+ }
+
+ template <typename T, typename Arg0, typename Arg1>
+ static enable_if_floating_point<T> Call(KernelContext* ctx, Arg0 left, Arg1
right) {
+ if (std::isnan(left) || std::isnan(right)) {
+ return NAN;
+ }
+ if (left == 0 && right < 0) {
+ ctx->SetStatus(Status::Invalid("divide by zero"));
+ }
+ return pow(left, right);
+ }
+};
+
+struct PowerChecked {
Review comment:
I see many similar codes in this change. Should refine to keep code
concise.
##########
File path: cpp/src/arrow/compute/kernels/scalar_arithmetic.cc
##########
@@ -233,6 +235,184 @@ struct DivideChecked {
}
};
+struct Power {
+ template <typename T, typename Arg0, typename Arg1>
+ static enable_if_signed_integer<T> Call(KernelContext* ctx, Arg0 left, Arg1
right) {
+ if (right < 0) {
+ ctx->SetStatus(
+ Status::Invalid("integers to negative integer powers are not
allowed"));
+ }
+ if (left == 0 && right != 0) {
+ return 0;
+ }
+ Arg0 result = 1;
+ for (Arg1 i = 0; i < right; i++) {
+ MultiplyWithOverflow(result, left, &result);
Review comment:
Without checking the return value? So why bother this costly overflow
guarded multiplication?
PS: Looks old comment about a more efficient implementation is not
addressed. I'm okay to start with easier approach. Then optimize later.
##########
File path: cpp/src/arrow/compute/kernels/scalar_arithmetic.cc
##########
@@ -233,6 +235,184 @@ struct DivideChecked {
}
};
+struct Power {
+ template <typename T, typename Arg0, typename Arg1>
+ static enable_if_signed_integer<T> Call(KernelContext* ctx, Arg0 left, Arg1
right) {
+ if (right < 0) {
+ ctx->SetStatus(
+ Status::Invalid("integers to negative integer powers are not
allowed"));
+ }
+ if (left == 0 && right != 0) {
+ return 0;
+ }
+ Arg0 result = 1;
+ for (Arg1 i = 0; i < right; i++) {
+ MultiplyWithOverflow(result, left, &result);
+ }
+ return result;
+ }
+
+ template <typename T, typename Arg0, typename Arg1>
+ static enable_if_unsigned_integer<T> Call(KernelContext* ctx, Arg0 left,
Arg1 right) {
Review comment:
Is it possible to use a single function for integers, no matter signed
or unsigned?
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