viirya commented on code in PR #2809:
URL: https://github.com/apache/arrow-rs/pull/2809#discussion_r990716175
##########
arrow-array/src/cast.rs:
##########
@@ -50,427 +62,183 @@ macro_rules! downcast_primitive_array {
($values:ident => $e:expr, $($p:pat => $fallback:expr $(,)*)*) => {
downcast_primitive_array!($values => {$e} $($p => $fallback)*)
};
-
- ($values:ident => $e:block $($p:pat => $fallback:expr $(,)*)*) => {
- match $values.data_type() {
- arrow_schema::DataType::Int8 => {
- let $values = $crate::cast::as_primitive_array::<
+ (($($values:ident),+) => $e:block $($($p:pat),+ => $fallback:expr $(,)*)*)
=> {
+ $crate::downcast_primitive_array!($($values),+ => $e $($($p),+ =>
$fallback)*)
+ };
+ (($($values:ident),+) => $e:block $(($($p:pat),+) => $fallback:expr
$(,)*)*) => {
+ $crate::downcast_primitive_array!($($values),+ => $e $($($p),+ =>
$fallback)*)
+ };
+ ($($values:ident),+ => $e:block $($($p:pat),+ => $fallback:expr $(,)*)*)
=> {
Review Comment:
The number of `$p:pat` might be different to `$values:ident` and that will
cause error. But the caller should take care of it.
##########
arrow-array/src/cast.rs:
##########
@@ -50,427 +62,183 @@ macro_rules! downcast_primitive_array {
($values:ident => $e:expr, $($p:pat => $fallback:expr $(,)*)*) => {
downcast_primitive_array!($values => {$e} $($p => $fallback)*)
};
-
- ($values:ident => $e:block $($p:pat => $fallback:expr $(,)*)*) => {
- match $values.data_type() {
- arrow_schema::DataType::Int8 => {
- let $values = $crate::cast::as_primitive_array::<
+ (($($values:ident),+) => $e:block $($($p:pat),+ => $fallback:expr $(,)*)*)
=> {
+ $crate::downcast_primitive_array!($($values),+ => $e $($($p),+ =>
$fallback)*)
+ };
+ (($($values:ident),+) => $e:block $(($($p:pat),+) => $fallback:expr
$(,)*)*) => {
+ $crate::downcast_primitive_array!($($values),+ => $e $($($p),+ =>
$fallback)*)
+ };
Review Comment:
What's the difference between this and below? With additional `(` `)`?
##########
arrow-array/src/cast.rs:
##########
@@ -20,6 +20,18 @@
use crate::array::*;
use crate::types::*;
+/// Repeats the provided pattern based on the number of comma separated
identifiers
+#[doc(hidden)]
+#[macro_export]
+macro_rules! repeat_pat {
+ ($e:pat, $v_:ident) => {
+ $e
+ };
+ ($e:pat, $v_:ident $(, $tail:ident)+) => {
+ ($e, $crate::repeat_pat!($e $(, $tail)+))
+ }
+}
Review Comment:
Oh, this is interesting. Nice. 👍
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