From 2bc8b54ba85af4ed976440372ec929c8ab9fbc69 Mon Sep 17 00:00:00 2001
From: Andrew Duffy <andreweduffy@gmail.com>
Date: Thu, 18 Jul 2024 17:44:00 +0100
Subject: [PATCH] undo substr

---
 datafusion/functions/src/unicode/substr.rs | 74 +---------------------
 1 file changed, 3 insertions(+), 71 deletions(-)

diff --git a/datafusion/functions/src/unicode/substr.rs b/datafusion/functions/src/unicode/substr.rs
index 58e39abea667b..9d15920bb6550 100644
--- a/datafusion/functions/src/unicode/substr.rs
+++ b/datafusion/functions/src/unicode/substr.rs
@@ -19,12 +19,10 @@ use std::any::Any;
 use std::cmp::max;
 use std::sync::Arc;
 
-use arrow::array::{ArrayRef, GenericStringArray, OffsetSizeTrait, StringViewArray};
+use arrow::array::{ArrayRef, GenericStringArray, OffsetSizeTrait};
 use arrow::datatypes::DataType;
 
-use datafusion_common::cast::{
-    as_generic_string_array, as_int64_array, as_string_view_array,
-};
+use datafusion_common::cast::{as_generic_string_array, as_int64_array};
 use datafusion_common::{exec_err, Result};
 use datafusion_expr::TypeSignature::Exact;
 use datafusion_expr::{ColumnarValue, ScalarUDFImpl, Signature, Volatility};
@@ -50,10 +48,8 @@ impl SubstrFunc {
             signature: Signature::one_of(
                 vec![
                     Exact(vec![Utf8, Int64]),
-                    Exact(vec![Utf8View, Int64]),
                     Exact(vec![LargeUtf8, Int64]),
                     Exact(vec![Utf8, Int64, Int64]),
-                    Exact(vec![Utf8View, Int64, Int64]),
                     Exact(vec![LargeUtf8, Int64, Int64]),
                 ],
                 Volatility::Immutable,
@@ -83,13 +79,6 @@ impl ScalarUDFImpl for SubstrFunc {
     fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> {
         match args[0].data_type() {
             DataType::Utf8 => make_scalar_function(substr::<i32>, vec![])(args),
-            DataType::Utf8View => match &args {
-                // [_, ColumnarValue::Scalar(_)]
-                // | [_, ColumnarValue::Scalar(_), ColumnarValue::Scalar(_)] => {
-                //     arrow_string::substring
-                // }
-                _ => make_scalar_function(substr_view, vec![])(args),
-            },
             DataType::LargeUtf8 => make_scalar_function(substr::<i64>, vec![])(args),
             other => exec_err!("Unsupported data type {other:?} for function substr"),
         }
@@ -100,63 +89,6 @@ impl ScalarUDFImpl for SubstrFunc {
     }
 }
 
-// TODO(aduffy): just return a manipulated Utf8View array by modifying the view only.
-pub fn substr_view(args: &[ArrayRef]) -> Result<ArrayRef> {
-    match args.len() {
-        2 => {
-            let string_view_array = as_string_view_array(&args[0])?;
-            let start_array = as_int64_array(&args[1])?;
-
-            let result = string_view_array
-                .iter()
-                .zip(start_array.iter())
-                .map(|(string_view, start)| match (string_view, start) {
-                    (Some(string), Some(start)) => {
-                        if start <= 0 {
-                            Some(string.to_string())
-                        } else {
-                            Some(string.chars().skip(start as usize - 1).collect())
-                        }
-                    }
-                    _ => None,
-                })
-                .collect::<StringViewArray>();
-
-            Ok(Arc::new(result))
-        }
-        3 => {
-            let string_view_array = as_string_view_array(&args[0])?;
-            let start_array = as_int64_array(&args[1])?;
-            let count_array = as_int64_array(&args[2])?;
-
-            let result = string_view_array
-                .iter()
-                .zip(start_array.iter())
-                .zip(count_array.iter())
-                .map(|((string, start), count)| match (string, start, count) {
-                    (Some(string), Some(start), Some(count)) => {
-                        if count < 0 {
-                            exec_err!(
-                                "negative substring length not allowed: substr(<str>, {start}, {count})"
-                            )
-                        } else {
-                            let skip = max(0, start - 1);
-                            let count = max(0, count + (if start < 1 { start - 1 } else { 0 }));
-                            Ok(Some(string.chars().skip(skip as usize).take(count as usize).collect::<String>()))
-                        }
-                    }
-                    _ => Ok(None),
-                })
-                .collect::<Result<StringViewArray>>()?;
-
-            Ok(Arc::new(result) as ArrayRef)
-        }
-        other => {
-            exec_err!("substr was called with {other} arguments. It requires 2 or 3.")
-        }
-    }
-}
-
 /// Extracts the substring of string starting at the start'th character, and extending for count characters if that is specified. (Same as substring(string from start for count).)
 /// substr('alphabet', 3) = 'phabet'
 /// substr('alphabet', 3, 2) = 'ph'
@@ -201,7 +133,7 @@ pub fn substr<T: OffsetSizeTrait>(args: &[ArrayRef]) -> Result<ArrayRef> {
                             )
                         } else {
                             let skip = max(0, start - 1);
-                            let count = max(0, count + (if start < 1 { start - 1 } else { 0 }));
+                            let count = max(0, count + (if start < 1 {start - 1} else {0}));
                             Ok(Some(string.chars().skip(skip as usize).take(count as usize).collect::<String>()))
                         }
                     }