move Left, Lpad, Reverse, Right, Rpad functions to datafusion_functions

datafusion/expr/src/built_in_function.rs

@@ -111,18 +111,8 @@ pub enum BuiltinScalarFunction {
     EndsWith,
     /// initcap
     InitCap,
-    /// left
-    Left,
-    /// lpad
-    Lpad,
     /// random
     Random,
-    /// reverse
-    Reverse,
-    /// right
-    Right,
-    /// rpad
-    Rpad,
     /// strpos
     Strpos,
     /// substr
@@ -220,12 +210,7 @@ impl BuiltinScalarFunction {
             BuiltinScalarFunction::ConcatWithSeparator => Volatility::Immutable,
             BuiltinScalarFunction::EndsWith => Volatility::Immutable,
             BuiltinScalarFunction::InitCap => Volatility::Immutable,
-            BuiltinScalarFunction::Left => Volatility::Immutable,
-            BuiltinScalarFunction::Lpad => Volatility::Immutable,
             BuiltinScalarFunction::Radians => Volatility::Immutable,
-            BuiltinScalarFunction::Reverse => Volatility::Immutable,
-            BuiltinScalarFunction::Right => Volatility::Immutable,
-            BuiltinScalarFunction::Rpad => Volatility::Immutable,
             BuiltinScalarFunction::Strpos => Volatility::Immutable,
             BuiltinScalarFunction::Substr => Volatility::Immutable,
             BuiltinScalarFunction::Translate => Volatility::Immutable,
@@ -264,17 +249,8 @@ impl BuiltinScalarFunction {
             BuiltinScalarFunction::InitCap => {
                 utf8_to_str_type(&input_expr_types[0], "initcap")
             }
-            BuiltinScalarFunction::Left => utf8_to_str_type(&input_expr_types[0], "left"),
-            BuiltinScalarFunction::Lpad => utf8_to_str_type(&input_expr_types[0], "lpad"),
             BuiltinScalarFunction::Pi => Ok(Float64),
             BuiltinScalarFunction::Random => Ok(Float64),
-            BuiltinScalarFunction::Reverse => {
-                utf8_to_str_type(&input_expr_types[0], "reverse")
-            }
-            BuiltinScalarFunction::Right => {
-                utf8_to_str_type(&input_expr_types[0], "right")
-            }
-            BuiltinScalarFunction::Rpad => utf8_to_str_type(&input_expr_types[0], "rpad"),
             BuiltinScalarFunction::EndsWith => Ok(Boolean),
             BuiltinScalarFunction::Strpos => {
                 utf8_to_int_type(&input_expr_types[0], "strpos/instr/position")
@@ -361,28 +337,9 @@ impl BuiltinScalarFunction {
             BuiltinScalarFunction::Coalesce => {
                 Signature::variadic_equal(self.volatility())
             }
-            BuiltinScalarFunction::InitCap | BuiltinScalarFunction::Reverse => {
+            BuiltinScalarFunction::InitCap => {
                 Signature::uniform(1, vec![Utf8, LargeUtf8], self.volatility())
             }
-            BuiltinScalarFunction::Lpad | BuiltinScalarFunction::Rpad => {
-                Signature::one_of(
-                    vec![
-                        Exact(vec![Utf8, Int64]),
-                        Exact(vec![LargeUtf8, Int64]),
-                        Exact(vec![Utf8, Int64, Utf8]),
-                        Exact(vec![LargeUtf8, Int64, Utf8]),
-                        Exact(vec![Utf8, Int64, LargeUtf8]),
-                        Exact(vec![LargeUtf8, Int64, LargeUtf8]),
-                    ],
-                    self.volatility(),
-                )
-            }
-            BuiltinScalarFunction::Left | BuiltinScalarFunction::Right => {
-                Signature::one_of(
-                    vec![Exact(vec![Utf8, Int64]), Exact(vec![LargeUtf8, Int64])],
-                    self.volatility(),
-                )
-            }
 
             BuiltinScalarFunction::EndsWith | BuiltinScalarFunction::Strpos => {
                 Signature::one_of(
@@ -580,11 +537,6 @@ impl BuiltinScalarFunction {
             BuiltinScalarFunction::ConcatWithSeparator => &["concat_ws"],
             BuiltinScalarFunction::EndsWith => &["ends_with"],
             BuiltinScalarFunction::InitCap => &["initcap"],
-            BuiltinScalarFunction::Left => &["left"],
-            BuiltinScalarFunction::Lpad => &["lpad"],
-            BuiltinScalarFunction::Reverse => &["reverse"],
-            BuiltinScalarFunction::Right => &["right"],
-            BuiltinScalarFunction::Rpad => &["rpad"],
             BuiltinScalarFunction::Strpos => &["strpos", "instr", "position"],
             BuiltinScalarFunction::Substr => &["substr"],
             BuiltinScalarFunction::Translate => &["translate"],

datafusion/expr/src/expr_fn.rs

@@ -578,25 +578,11 @@ scalar_expr!(Atan2, atan2, y x, "inverse tangent of a division given in the argu
 scalar_expr!(Log, log, base x, "logarithm of a `x` for a particular `base`");
 
 scalar_expr!(InitCap, initcap, string, "converts the first letter of each word in `string` in uppercase and the remaining characters in lowercase");
-scalar_expr!(Left, left, string n, "returns the first `n` characters in the `string`");
-scalar_expr!(Reverse, reverse, string, "reverses the `string`");
-scalar_expr!(Right, right, string n, "returns the last `n` characters in the `string`");
 scalar_expr!(EndsWith, ends_with, string suffix, "whether the `string` ends with the `suffix`");
 scalar_expr!(Strpos, strpos, string substring, "finds the position from where the `substring` matches the `string`");
 scalar_expr!(Substr, substr, string position, "substring from the `position` to the end");
 scalar_expr!(Substr, substring, string position length, "substring from the `position` with `length` characters");
 scalar_expr!(Translate, translate, string from to, "replaces the characters in `from` with the counterpart in `to`");
-//use vec as parameter
-nary_scalar_expr!(
-    Lpad,
-    lpad,
-    "fill up a string to the length by prepending the characters"
-);
-nary_scalar_expr!(
-    Rpad,
-    rpad,
-    "fill up a string to the length by appending the characters"
-);
 nary_scalar_expr!(Coalesce, coalesce, "returns `coalesce(args...)`, which evaluates to the value of the first [Expr] which is not NULL");
 //there is a func concat_ws before, so use concat_ws_expr as name.c
 nary_scalar_expr!(
@@ -1028,13 +1014,6 @@ mod test {
         test_scalar_expr!(Gcd, gcd, arg_1, arg_2);
         test_scalar_expr!(Lcm, lcm, arg_1, arg_2);
         test_scalar_expr!(InitCap, initcap, string);
-        test_scalar_expr!(Left, left, string, count);
-        test_nary_scalar_expr!(Lpad, lpad, string, count);
-        test_nary_scalar_expr!(Lpad, lpad, string, count, characters);
-        test_scalar_expr!(Reverse, reverse, string);
-        test_scalar_expr!(Right, right, string, count);
-        test_nary_scalar_expr!(Rpad, rpad, string, count);
-        test_nary_scalar_expr!(Rpad, rpad, string, count, characters);
         test_scalar_expr!(EndsWith, ends_with, string, characters);
         test_scalar_expr!(Strpos, strpos, string, substring);
         test_scalar_expr!(Substr, substr, string, position);

datafusion/functions/src/unicode/left.rs

@@ -0,0 +1,236 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use std::any::Any;
+use std::cmp::Ordering;
+use std::sync::Arc;
+
+use arrow::array::{ArrayRef, GenericStringArray, OffsetSizeTrait};
+use arrow::datatypes::DataType;
+
+use datafusion_common::cast::{as_generic_string_array, as_int64_array};
+use datafusion_common::exec_err;
+use datafusion_common::Result;
+use datafusion_expr::TypeSignature::Exact;
+use datafusion_expr::{ColumnarValue, ScalarUDFImpl, Signature, Volatility};
+
+use crate::utils::{make_scalar_function, utf8_to_str_type};
+
+#[derive(Debug)]
+pub(super) struct LeftFunc {
+    signature: Signature,
+}
+
+impl LeftFunc {
+    pub fn new() -> Self {
+        use DataType::*;
+        Self {
+            signature: Signature::one_of(
+                vec![Exact(vec![Utf8, Int64]), Exact(vec![LargeUtf8, Int64])],
+                Volatility::Immutable,
+            ),
+        }
+    }
+}
+
+impl ScalarUDFImpl for LeftFunc {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    fn name(&self) -> &str {
+        "left"
+    }
+
+    fn signature(&self) -> &Signature {
+        &self.signature
+    }
+
+    fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
+        utf8_to_str_type(&arg_types[0], "left")
+    }
+
+    fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> {
+        match args[0].data_type() {
+            DataType::Utf8 => make_scalar_function(left::<i32>, vec![])(args),
+            DataType::LargeUtf8 => make_scalar_function(left::<i64>, vec![])(args),
+            other => exec_err!("Unsupported data type {other:?} for function left"),
+        }
+    }
+}
+
+/// Returns first n characters in the string, or when n is negative, returns all but last |n| characters.
+/// left('abcde', 2) = 'ab'
+/// The implementation uses UTF-8 code points as characters
+pub fn left<T: OffsetSizeTrait>(args: &[ArrayRef]) -> Result<ArrayRef> {
+    let string_array = as_generic_string_array::<T>(&args[0])?;
+    let n_array = as_int64_array(&args[1])?;
+    let result = string_array
+        .iter()
+        .zip(n_array.iter())
+        .map(|(string, n)| match (string, n) {
+            (Some(string), Some(n)) => match n.cmp(&0) {
+                Ordering::Less => {
+                    let len = string.chars().count() as i64;
+                    Some(if n.abs() < len {
+                        string.chars().take((len + n) as usize).collect::<String>()
+                    } else {
+                        "".to_string()
+                    })
+                }
+                Ordering::Equal => Some("".to_string()),
+                Ordering::Greater => {
+                    Some(string.chars().take(n as usize).collect::<String>())
+                }
+            },
+            _ => None,
+        })
+        .collect::<GenericStringArray<T>>();
+
+    Ok(Arc::new(result) as ArrayRef)
+}
+
+#[cfg(test)]
+mod tests {
+    use arrow::array::{Array, StringArray};
+    use arrow::datatypes::DataType::Utf8;
+
+    use datafusion_common::{Result, ScalarValue};
+    use datafusion_expr::{ColumnarValue, ScalarUDFImpl};
+
+    use crate::unicode::left::LeftFunc;
+    use crate::utils::test::test_function;
+
+    #[test]
+    fn test_functions() -> Result<()> {
+        test_function!(
+            LeftFunc::new(),
+            &[
+                ColumnarValue::Scalar(ScalarValue::from("abcde")),
+                ColumnarValue::Scalar(ScalarValue::from(2i64)),
+            ],
+            Ok(Some("ab")),
+            &str,
+            Utf8,
+            StringArray
+        );
+        test_function!(
+            LeftFunc::new(),
+            &[
+                ColumnarValue::Scalar(ScalarValue::from("abcde")),
+                ColumnarValue::Scalar(ScalarValue::from(200i64)),
+            ],
+            Ok(Some("abcde")),
+            &str,
+            Utf8,
+            StringArray
+        );
+        test_function!(
+            LeftFunc::new(),
+            &[
+                ColumnarValue::Scalar(ScalarValue::from("abcde")),
+                ColumnarValue::Scalar(ScalarValue::from(-2i64)),
+            ],
+            Ok(Some("abc")),
+            &str,
+            Utf8,
+            StringArray
+        );
+        test_function!(
+            LeftFunc::new(),
+            &[
+                ColumnarValue::Scalar(ScalarValue::from("abcde")),
+                ColumnarValue::Scalar(ScalarValue::from(-200i64)),
+            ],
+            Ok(Some("")),
+            &str,
+            Utf8,
+            StringArray
+        );
+        test_function!(
+            LeftFunc::new(),
+            &[
+                ColumnarValue::Scalar(ScalarValue::from("abcde")),
+                ColumnarValue::Scalar(ScalarValue::from(0i64)),
+            ],
+            Ok(Some("")),
+            &str,
+            Utf8,
+            StringArray
+        );
+        test_function!(
+            LeftFunc::new(),
+            &[
+                ColumnarValue::Scalar(ScalarValue::Utf8(None)),
+                ColumnarValue::Scalar(ScalarValue::from(2i64)),
+            ],
+            Ok(None),
+            &str,
+            Utf8,
+            StringArray
+        );
+        test_function!(
+            LeftFunc::new(),
+            &[
+                ColumnarValue::Scalar(ScalarValue::from("abcde")),
+                ColumnarValue::Scalar(ScalarValue::Int64(None)),
+            ],
+            Ok(None),
+            &str,
+            Utf8,
+            StringArray
+        );
+        test_function!(
+            LeftFunc::new(),
+            &[
+                ColumnarValue::Scalar(ScalarValue::from("joséésoj")),
+                ColumnarValue::Scalar(ScalarValue::from(5i64)),
+            ],
+            Ok(Some("joséé")),
+            &str,
+            Utf8,
+            StringArray
+        );
+        test_function!(
+            LeftFunc::new(),
+            &[
+                ColumnarValue::Scalar(ScalarValue::from("joséésoj")),
+                ColumnarValue::Scalar(ScalarValue::from(-3i64)),
+            ],
+            Ok(Some("joséé")),
+            &str,
+            Utf8,
+            StringArray
+        );
+        #[cfg(not(feature = "unicode_expressions"))]
+        test_function!(
+            LeftFunc::new(),
+            &[
+                ColumnarValue::Scalar(ScalarValue::from("abcde")),
+                ColumnarValue::Scalar(ScalarValue::from(2i64)),
+            ],
+            internal_err!(
+                "function left requires compilation with feature flag: unicode_expressions."
+            ),
+            &str,
+            Utf8,
+            StringArray
+        );
+
+        Ok(())
+    }
+}