Update INITCAP scalar function to support Utf8View (#11888)

* Update INITCAP scalar function to support Utf8View

* Fix comments

* Fix comments

Author: xinlifoobar

datafusion/functions/src/string/initcap.rs

@@ -18,10 +18,10 @@
 use std::any::Any;
 use std::sync::Arc;
 
-use arrow::array::{ArrayRef, GenericStringArray, OffsetSizeTrait};
+use arrow::array::{ArrayRef, GenericStringArray, OffsetSizeTrait, StringArray};
 use arrow::datatypes::DataType;
 
-use datafusion_common::cast::as_generic_string_array;
+use datafusion_common::cast::{as_generic_string_array, as_string_view_array};
 use datafusion_common::{exec_err, Result};
 use datafusion_expr::{ColumnarValue, Volatility};
 use datafusion_expr::{ScalarUDFImpl, Signature};
@@ -45,7 +45,7 @@ impl InitcapFunc {
         Self {
             signature: Signature::uniform(
                 1,
-                vec![Utf8, LargeUtf8],
+                vec![Utf8, LargeUtf8, Utf8View],
                 Volatility::Immutable,
             ),
         }
@@ -73,6 +73,7 @@ impl ScalarUDFImpl for InitcapFunc {
         match args[0].data_type() {
             DataType::Utf8 => make_scalar_function(initcap::<i32>, vec![])(args),
             DataType::LargeUtf8 => make_scalar_function(initcap::<i64>, vec![])(args),
+            DataType::Utf8View => make_scalar_function(initcap_utf8view, vec![])(args),
             other => {
                 exec_err!("Unsupported data type {other:?} for function initcap")
             }
@@ -88,28 +89,41 @@ fn initcap<T: OffsetSizeTrait>(args: &[ArrayRef]) -> Result<ArrayRef> {
     // first map is the iterator, second is for the `Option<_>`
     let result = string_array
         .iter()
-        .map(|string| {
-            string.map(|string: &str| {
-                let mut char_vector = Vec::<char>::new();
-                let mut previous_character_letter_or_number = false;
-                for c in string.chars() {
-                    if previous_character_letter_or_number {
-                        char_vector.push(c.to_ascii_lowercase());
-                    } else {
-                        char_vector.push(c.to_ascii_uppercase());
-                    }
-                    previous_character_letter_or_number = c.is_ascii_uppercase()
-                        || c.is_ascii_lowercase()
-                        || c.is_ascii_digit();
-                }
-                char_vector.iter().collect::<String>()
-            })
-        })
+        .map(initcap_string)
         .collect::<GenericStringArray<T>>();
 
     Ok(Arc::new(result) as ArrayRef)
 }
 
+fn initcap_utf8view(args: &[ArrayRef]) -> Result<ArrayRef> {
+    let string_view_array = as_string_view_array(&args[0])?;
+
+    let result = string_view_array
+        .iter()
+        .map(initcap_string)
+        .collect::<StringArray>();
+
+    Ok(Arc::new(result) as ArrayRef)
+}
+
+fn initcap_string(string: Option<&str>) -> Option<String> {
+    let mut char_vector = Vec::<char>::new();
+    string.map(|string: &str| {
+        char_vector.clear();
+        let mut previous_character_letter_or_number = false;
+        for c in string.chars() {
+            if previous_character_letter_or_number {
+                char_vector.push(c.to_ascii_lowercase());
+            } else {
+                char_vector.push(c.to_ascii_uppercase());
+            }
+            previous_character_letter_or_number =
+                c.is_ascii_uppercase() || c.is_ascii_lowercase() || c.is_ascii_digit();
+        }
+        char_vector.iter().collect::<String>()
+    })
+}
+
 #[cfg(test)]
 mod tests {
     use crate::string::initcap::InitcapFunc;
@@ -153,6 +167,44 @@ mod tests {
             Utf8,
             StringArray
         );
+        test_function!(
+            InitcapFunc::new(),
+            &[ColumnarValue::Scalar(ScalarValue::Utf8View(Some(
+                "hi THOMAS".to_string()
+            )))],
+            Ok(Some("Hi Thomas")),
+            &str,
+            Utf8,
+            StringArray
+        );
+        test_function!(
+            InitcapFunc::new(),
+            &[ColumnarValue::Scalar(ScalarValue::Utf8View(Some(
+                "hi THOMAS wIth M0re ThAN 12 ChaRs".to_string()
+            )))],
+            Ok(Some("Hi Thomas With M0re Than 12 Chars")),
+            &str,
+            Utf8,
+            StringArray
+        );
+        test_function!(
+            InitcapFunc::new(),
+            &[ColumnarValue::Scalar(ScalarValue::Utf8View(Some(
+                "".to_string()
+            )))],
+            Ok(Some("")),
+            &str,
+            Utf8,
+            StringArray
+        );
+        test_function!(
+            InitcapFunc::new(),
+            &[ColumnarValue::Scalar(ScalarValue::Utf8View(None))],
+            Ok(None),
+            &str,
+            Utf8,
+            StringArray
+        );
 
         Ok(())
     }

datafusion/sqllogictest/test_files/string_view.slt

@@ -425,6 +425,50 @@ logical_plan
 01)Projection: starts_with(test.column1_utf8view, Utf8View("äöüß")) AS c1, starts_with(test.column1_utf8view, Utf8View("")) AS c2, starts_with(test.column1_utf8view, Utf8View(NULL)) AS c3, starts_with(Utf8View(NULL), test.column1_utf8view) AS c4
 02)--TableScan: test projection=[column1_utf8view]
 
+### Initcap
+
+query TT
+EXPLAIN SELECT
+  INITCAP(column1_utf8view) as c
+FROM test;
+----
+logical_plan
+01)Projection: initcap(test.column1_utf8view) AS c
+02)--TableScan: test projection=[column1_utf8view]
+
+# Create a table with lowercase strings
+statement ok
+CREATE TABLE test_lowercase AS SELECT
+  lower(column1_utf8) as column1_utf8_lower,
+  lower(column1_large_utf8) as column1_large_utf8_lower,
+  lower(column1_utf8view) as column1_utf8view_lower
+FROM test;
+
+# Test INITCAP with utf8view, utf8, and largeutf8
+# Should not cast anything
+query TT
+EXPLAIN SELECT
+  INITCAP(column1_utf8view_lower) as c1,
+  INITCAP(column1_utf8_lower) as c2,
+  INITCAP(column1_large_utf8_lower) as c3
+FROM test_lowercase;
+----
+logical_plan
+01)Projection: initcap(test_lowercase.column1_utf8view_lower) AS c1, initcap(test_lowercase.column1_utf8_lower) AS c2, initcap(test_lowercase.column1_large_utf8_lower) AS c3
+02)--TableScan: test_lowercase projection=[column1_utf8_lower, column1_large_utf8_lower, column1_utf8view_lower]
+
+query TTT
+SELECT
+  INITCAP(column1_utf8view_lower) as c1,
+  INITCAP(column1_utf8_lower) as c2,
+  INITCAP(column1_large_utf8_lower) as c3
+FROM test_lowercase;
+----
+Andrew Andrew Andrew    
+Xiangpeng Xiangpeng Xiangpeng
+Raphael Raphael Raphael
+NULL NULL NULL
+
 # Ensure string functions use native StringView implementation
 # and do not fall back to Utf8 or LargeUtf8
 # Should see no casts to Utf8 in the plans below
@@ -586,18 +630,6 @@ logical_plan
 02)--Projection: CAST(test.column2_utf8view AS Utf8) AS __common_expr_1, test.column1_utf8view
 03)----TableScan: test projection=[column1_utf8view, column2_utf8view]
 
-
-## Ensure no casts for INITCAP
-## TODO https://github.com/apache/datafusion/issues/11853
-query TT
-EXPLAIN SELECT
-  INITCAP(column1_utf8view) as c
-FROM test;
-----
-logical_plan
-01)Projection: initcap(CAST(test.column1_utf8view AS Utf8)) AS c
-02)--TableScan: test projection=[column1_utf8view]
-
 ## Ensure no casts for LEVENSHTEIN
 ## TODO https://github.com/apache/datafusion/issues/11854
 query TT