alamb commented on code in PR #9849:
URL: https://github.com/apache/arrow-datafusion/pull/9849#discussion_r1544540980
##########
datafusion/functions/src/unicode/mod.rs:
##########
@@ -82,6 +96,21 @@ pub mod expr_fn {
pub fn rpad(args: Vec<Expr>) -> Expr {
super::rpad().call(args)
}
+
+ #[doc = "finds the position from where the `substring` matches the
`string`"]
+ pub fn strpos(string: Expr, substring: Expr) -> Expr {
+ super::strpos().call(vec![string, substring])
+ }
+
+ #[doc = "substring from the `position` to the end"]
+ pub fn substr(string: Expr, position: Expr) -> Expr {
+ super::substr().call(vec![string, position])
+ }
+
+ #[doc = "substring from the `position` with `length` characters"]
Review Comment:
thanks for bringing both forms of substr along
##########
datafusion/functions/src/unicode/substr.rs:
##########
@@ -0,0 +1,392 @@
+// 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::max;
+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, 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 SubstrFunc {
+ signature: Signature,
+}
+
+impl SubstrFunc {
+ pub fn new() -> Self {
+ use DataType::*;
+ Self {
+ signature: Signature::one_of(
+ vec![
+ Exact(vec![Utf8, Int64]),
+ Exact(vec![LargeUtf8, Int64]),
+ Exact(vec![Utf8, Int64, Int64]),
+ Exact(vec![LargeUtf8, Int64, Int64]),
+ ],
+ Volatility::Immutable,
+ ),
+ }
+ }
+}
+
+impl ScalarUDFImpl for SubstrFunc {
+ fn as_any(&self) -> &dyn Any {
+ self
+ }
+
+ fn name(&self) -> &str {
+ "substr"
+ }
+
+ fn signature(&self) -> &Signature {
+ &self.signature
+ }
+
+ fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
+ utf8_to_str_type(&arg_types[0], "substr")
+ }
+
+ fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> {
+ match args[0].data_type() {
+ DataType::Utf8 => make_scalar_function(substr::<i32>,
vec![])(args),
+ DataType::LargeUtf8 => make_scalar_function(substr::<i64>,
vec![])(args),
+ other => exec_err!("Unsupported data type {other:?} for function
substr"),
+ }
+ }
+}
+
+/// 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'
+/// The implementation uses UTF-8 code points as characters
+pub fn substr<T: OffsetSizeTrait>(args: &[ArrayRef]) -> Result<ArrayRef> {
+ match args.len() {
+ 2 => {
+ let string_array = as_generic_string_array::<T>(&args[0])?;
+ let start_array = as_int64_array(&args[1])?;
+
+ let result = string_array
+ .iter()
+ .zip(start_array.iter())
+ .map(|(string, start)| match (string, start) {
+ (Some(string), Some(start)) => {
+ if start <= 0 {
+ Some(string.to_string())
+ } else {
+ Some(string.chars().skip(start as usize -
1).collect())
+ }
+ }
+ _ => None,
+ })
+ .collect::<GenericStringArray<T>>();
+
+ Ok(Arc::new(result) as ArrayRef)
+ }
+ 3 => {
+ let string_array = as_generic_string_array::<T>(&args[0])?;
+ let start_array = as_int64_array(&args[1])?;
+ let count_array = as_int64_array(&args[2])?;
+
+ let result = string_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<GenericStringArray<T>>>()?;
+
+ Ok(Arc::new(result) as ArrayRef)
+ }
+ other => {
+ exec_err!("substr was called with {other} arguments. It requires 2
or 3.")
+ }
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use arrow::array::{Array, StringArray};
+ use arrow::datatypes::DataType::Utf8;
+
+ use datafusion_common::{exec_err, Result, ScalarValue};
+ use datafusion_expr::{ColumnarValue, ScalarUDFImpl};
+
+ use crate::unicode::substr::SubstrFunc;
+ use crate::utils::test::test_function;
+
+ #[test]
+ fn test_functions() -> Result<()> {
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::from(0i64)),
+ ],
+ Ok(Some("alphabet")),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("joséésoj")),
+ ColumnarValue::Scalar(ScalarValue::from(5i64)),
+ ],
+ Ok(Some("ésoj")),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("joséésoj")),
+ ColumnarValue::Scalar(ScalarValue::from(-5i64)),
+ ],
+ Ok(Some("joséésoj")),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::from(1i64)),
+ ],
+ Ok(Some("alphabet")),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::from(2i64)),
+ ],
+ Ok(Some("lphabet")),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::from(3i64)),
+ ],
+ Ok(Some("phabet")),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::from(-3i64)),
+ ],
+ Ok(Some("alphabet")),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::from(30i64)),
+ ],
+ Ok(Some("")),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::Int64(None)),
+ ],
+ Ok(None),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::from(3i64)),
+ ColumnarValue::Scalar(ScalarValue::from(2i64)),
+ ],
+ Ok(Some("ph")),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::from(3i64)),
+ ColumnarValue::Scalar(ScalarValue::from(20i64)),
+ ],
+ Ok(Some("phabet")),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::from(0i64)),
+ ColumnarValue::Scalar(ScalarValue::from(5i64)),
+ ],
+ Ok(Some("alph")),
+ &str,
+ Utf8,
+ StringArray
+ );
+ // starting from 5 (10 + -5)
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::from(-5i64)),
+ ColumnarValue::Scalar(ScalarValue::from(10i64)),
+ ],
+ Ok(Some("alph")),
+ &str,
+ Utf8,
+ StringArray
+ );
+ // starting from -1 (4 + -5)
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::from(-5i64)),
+ ColumnarValue::Scalar(ScalarValue::from(4i64)),
+ ],
+ Ok(Some("")),
+ &str,
+ Utf8,
+ StringArray
+ );
+ // starting from 0 (5 + -5)
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::from(-5i64)),
+ ColumnarValue::Scalar(ScalarValue::from(5i64)),
+ ],
+ Ok(Some("")),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::Int64(None)),
+ ColumnarValue::Scalar(ScalarValue::from(20i64)),
+ ],
+ Ok(None),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::from(3i64)),
+ ColumnarValue::Scalar(ScalarValue::Int64(None)),
+ ],
+ Ok(None),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("alphabet")),
+ ColumnarValue::Scalar(ScalarValue::from(1i64)),
+ ColumnarValue::Scalar(ScalarValue::from(-1i64)),
+ ],
+ exec_err!("negative substring length not allowed: substr(<str>, 1,
-1)"),
+ &str,
+ Utf8,
+ StringArray
+ );
+ test_function!(
+ SubstrFunc::new(),
+ &[
+ ColumnarValue::Scalar(ScalarValue::from("joséésoj")),
Review Comment:
❤️
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