chore: Cleanup "!is_valid(i)" -> "is_null(i)" (#20453)

## Which issue does this PR close?

N/A

## Rationale for this change

This makes the code easier to read; per suggestion from @Jefffrey in
code review for a different change.

## What changes are included in this PR?

## Are these changes tested?

Yes.

## Are there any user-facing changes?

No.

Author: neilconway

datafusion/common/src/scalar/mod.rs

@@ -3588,7 +3588,7 @@ impl ScalarValue {
     /// Converts a value in `array` at `index` into a ScalarValue
     pub fn try_from_array(array: &dyn Array, index: usize) -> Result<Self> {
         // handle NULL value
-        if !array.is_valid(index) {
+        if array.is_null(index) {
             return array.data_type().try_into();
         }
 

datafusion/physical-expr-common/src/binary_view_map.rs

@@ -275,7 +275,7 @@ where
             let hash = self.hashes_buffer[i];
 
             // handle null value via validity bitmap check
-            if !values.is_valid(i) {
+            if values.is_null(i) {
                 let payload = if let Some(&(payload, _offset)) = self.null.as_ref() {
                     payload
                 } else {

datafusion/physical-expr-common/src/datum.rs

@@ -189,14 +189,14 @@ pub fn compare_op_for_nested(
             (false, false) | (true, true) => NullBuffer::union(l.nulls(), r.nulls()),
             (true, false) => {
                 // When left is null-scalar and right is array, expand left nulls to match result length
-                match l.nulls().filter(|nulls| !nulls.is_valid(0)) {
+                match l.nulls().filter(|nulls| nulls.is_null(0)) {
                     Some(_) => Some(NullBuffer::new_null(len)), // Left scalar is null
                     None => r.nulls().cloned(),                 // Left scalar is non-null
                 }
             }
             (false, true) => {
                 // When right is null-scalar and left is array, expand right nulls to match result length
-                match r.nulls().filter(|nulls| !nulls.is_valid(0)) {
+                match r.nulls().filter(|nulls| nulls.is_null(0)) {
                     Some(_) => Some(NullBuffer::new_null(len)), // Right scalar is null
                     None => l.nulls().cloned(), // Right scalar is non-null
                 }

datafusion/physical-expr/src/expressions/cast.rs

@@ -336,7 +336,7 @@ mod tests {
             for (i, x) in $VEC.iter().enumerate() {
                 match x {
                     Some(x) => assert_eq!(result.value(i), *x),
-                    None => assert!(!result.is_valid(i)),
+                    None => assert!(result.is_null(i)),
                 }
             }
         }};
@@ -388,7 +388,7 @@ mod tests {
             for (i, x) in $VEC.iter().enumerate() {
                 match x {
                     Some(x) => assert_eq!(result.value(i), *x),
-                    None => assert!(!result.is_valid(i)),
+                    None => assert!(result.is_null(i)),
                 }
             }
         }};

datafusion/physical-expr/src/expressions/try_cast.rs

@@ -206,7 +206,7 @@ mod tests {
             for (i, x) in $VEC.iter().enumerate() {
                 match x {
                     Some(x) => assert_eq!(result.value(i), *x),
-                    None => assert!(!result.is_valid(i)),
+                    None => assert!(result.is_null(i)),
                 }
             }
         }};
@@ -260,7 +260,7 @@ mod tests {
             for (i, x) in $VEC.iter().enumerate() {
                 match x {
                     Some(x) => assert_eq!(result.value(i), *x),
-                    None => assert!(!result.is_valid(i)),
+                    None => assert!(result.is_null(i)),
                 }
             }
         }};

datafusion/sqllogictest/src/engines/datafusion_engine/normalize.rs

@@ -186,7 +186,7 @@ macro_rules! get_row_value {
 ///
 /// Floating numbers are rounded to have a consistent representation with the Postgres runner.
 pub fn cell_to_string(col: &ArrayRef, row: usize, is_spark_path: bool) -> Result<String> {
-    if !col.is_valid(row) {
+    if col.is_null(row) {
         // represent any null value with the string "NULL"
         Ok(NULL_STR.to_string())
     } else {