feat: add overlay string function

e2e_test/batch/functions/overlay.slt.part

@@ -0,0 +1,31 @@
+query T
+SELECT OVERLAY('abcdef' PLACING '45' FROM 4);
+----
+abc45f
+
+query T
+SELECT OVERLAY('yabadoo' PLACING 'daba' FROM 5);
+----
+yabadaba
+
+query T
+SELECT OVERLAY('yabadoo' PLACING 'daba' FROM 5 FOR 0);
+----
+yabadabadoo
+
+query T
+SELECT OVERLAY('babosa' PLACING 'ubb' FROM 2 FOR 4);
+----
+bubba
+
+statement error
+SELECT OVERLAY('abc', 'xyz');
+
+statement error
+SELECT OVERLAY('abc' PLACING 'xyz');
+
+statement error
+SELECT OVERLAY('abc' PLACING 'xyz' FOR 2)
+
+statement error
+SELECT OVERLAY('abc' PLACING 'xyz' FOR 2 FROM 1)

proto/expr.proto

@@ -74,6 +74,7 @@ message ExprNode {
     BOOL_OUT = 228;
     OCTET_LENGTH = 229;
     BIT_LENGTH = 230;
+    OVERLAY = 231;
 
     // Boolean comparison
     IS_TRUE = 301;

src/expr/src/expr/build_expr_from_prost.rs

@@ -25,8 +25,10 @@ use crate::expr::expr_binary_nonnull::{new_binary_expr, new_like_default};
 use crate::expr::expr_binary_nullable::new_nullable_binary_expr;
 use crate::expr::expr_case::{CaseExpression, WhenClause};
 use crate::expr::expr_in::InExpression;
+use crate::expr::expr_quaternary_bytes::new_overlay_for_exp;
 use crate::expr::expr_ternary_bytes::{
-    new_replace_expr, new_split_part_expr, new_substr_start_end, new_translate_expr,
+    new_overlay_exp, new_replace_expr, new_split_part_expr, new_substr_start_end,
+    new_translate_expr,
 };
 use crate::expr::expr_unary::{
     new_length_default, new_ltrim_expr, new_rtrim_expr, new_trim_expr, new_unary_expr,
@@ -76,6 +78,24 @@ pub fn build_nullable_binary_expr_prost(prost: &ExprNode) -> Result<BoxedExpress
     ))
 }
 
+pub fn build_overlay_expr(prost: &ExprNode) -> Result<BoxedExpression> {
+    let (children, ret_type) = get_children_and_return_type(prost)?;
+    ensure!(children.len() == 3 || children.len() == 4);
+
+    let s = expr_build_from_prost(&children[0])?;
+    let new_sub_str = expr_build_from_prost(&children[1])?;
+    let start = expr_build_from_prost(&children[2])?;
+
+    if children.len() == 3 {
+        Ok(new_overlay_exp(s, new_sub_str, start, ret_type))
+    } else if children.len() == 4 {
+        let count = expr_build_from_prost(&children[3])?;
+        Ok(new_overlay_for_exp(s, new_sub_str, start, count, ret_type))
+    } else {
+        unreachable!()
+    }
+}
+
 pub fn build_repeat_expr(prost: &ExprNode) -> Result<BoxedExpression> {
     let (children, ret_type) = get_children_and_return_type(prost)?;
     ensure!(children.len() == 2);

src/expr/src/expr/expr_quaternary_bytes.rs

@@ -0,0 +1,101 @@
+// Copyright 2022 Singularity Data
+//
+// Licensed 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.
+
+//! For expression that accept 4 arguments + 1 bytes writer as input.
+
+use risingwave_common::array::{I32Array, Utf8Array};
+use risingwave_common::types::DataType;
+
+use crate::expr::template::QuaternaryBytesExpression;
+use crate::expr::BoxedExpression;
+use crate::vector_op::overlay::overlay_for;
+
+pub fn new_overlay_for_exp(
+    s: BoxedExpression,
+    new_sub_str: BoxedExpression,
+    start: BoxedExpression,
+    count: BoxedExpression,
+    return_type: DataType,
+) -> BoxedExpression {
+    Box::new(QuaternaryBytesExpression::<
+        Utf8Array,
+        Utf8Array,
+        I32Array,
+        I32Array,
+        _,
+    >::new(
+        s, new_sub_str, start, count, return_type, overlay_for
+    ))
+}
+
+#[cfg(test)]
+mod tests {
+    use risingwave_common::array::{DataChunk, Row};
+    use risingwave_common::types::{Datum, ScalarImpl};
+
+    use super::*;
+    use crate::expr::LiteralExpression;
+
+    fn test_evals_dummy(expr: BoxedExpression, expected: Datum, is_negative_len: bool) {
+        let res = expr.eval(&DataChunk::new_dummy(1));
+        if is_negative_len {
+            assert!(res.is_err());
+        } else {
+            assert_eq!(res.unwrap().to_datum(), expected);
+        }
+
+        let res = expr.eval_row(&Row::new(vec![]));
+        if is_negative_len {
+            assert!(res.is_err());
+        } else {
+            assert_eq!(res.unwrap(), expected);
+        }
+    }
+
+    #[test]
+    fn test_overlay() {
+        let cases = vec![
+            ("aaa", "XY", 1, 0, "XYaaa"),
+            ("aaa_aaa", "XYZ", 4, 1, "aaaXYZaaa"),
+            ("aaaaaa", "XYZ", 4, 0, "aaaXYZaaa"),
+            ("aaa___aaa", "X", 4, 3, "aaaXaaa"),
+            ("aaa", "X", 4, -123, "aaaX"),
+            ("aaa_", "X", 4, 123, "aaaX"),
+        ];
+
+        for (s, new_sub_str, start, count, expected) in cases {
+            let expr = new_overlay_for_exp(
+                Box::new(LiteralExpression::new(
+                    DataType::Varchar,
+                    Some(ScalarImpl::from(String::from(s))),
+                )),
+                Box::new(LiteralExpression::new(
+                    DataType::Varchar,
+                    Some(ScalarImpl::from(String::from(new_sub_str))),
+                )),
+                Box::new(LiteralExpression::new(
+                    DataType::Int32,
+                    Some(ScalarImpl::from(start)),
+                )),
+                Box::new(LiteralExpression::new(
+                    DataType::Int32,
+                    Some(ScalarImpl::from(count)),
+                )),
+                DataType::Varchar,
+            );
+
+            test_evals_dummy(expr, Some(ScalarImpl::from(String::from(expected))), false);
+        }
+    }
+}

src/expr/src/expr/expr_ternary_bytes.rs

@@ -19,6 +19,7 @@ use risingwave_common::types::DataType;
 
 use crate::expr::template::TernaryBytesExpression;
 use crate::expr::BoxedExpression;
+use crate::vector_op::overlay::overlay;
 use crate::vector_op::replace::replace;
 use crate::vector_op::split_part::split_part;
 use crate::vector_op::substr::substr_start_for;
@@ -92,6 +93,23 @@ pub fn new_split_part_expr(
     )
 }
 
+pub fn new_overlay_exp(
+    s: BoxedExpression,
+    new_sub_str: BoxedExpression,
+    start: BoxedExpression,
+    return_type: DataType,
+) -> BoxedExpression {
+    Box::new(
+        TernaryBytesExpression::<Utf8Array, Utf8Array, I32Array, _>::new(
+            s,
+            new_sub_str,
+            start,
+            return_type,
+            overlay,
+        ),
+    )
+}
+
 #[cfg(test)]
 mod tests {
     use risingwave_common::array::{DataChunk, Row};
@@ -208,4 +226,35 @@ mod tests {
             test_evals_dummy(expr, Some(ScalarImpl::from(String::from(expected))), false);
         }
     }
+
+    #[test]
+    fn test_overlay() {
+        let cases = vec![
+            ("aaa__aaa", "XY", 4, "aaaXYaaa"),
+            ("aaa", "XY", 3, "aaXY"),
+            ("aaa", "XY", 4, "aaaXY"),
+            ("aaa", "XY", -123, "XYa"),
+            ("aaa", "XY", 123, "aaaXY"),
+        ];
+
+        for (s, new_sub_str, start, expected) in cases {
+            let expr = new_overlay_exp(
+                Box::new(LiteralExpression::new(
+                    DataType::Varchar,
+                    Some(ScalarImpl::from(String::from(s))),
+                )),
+                Box::new(LiteralExpression::new(
+                    DataType::Varchar,
+                    Some(ScalarImpl::from(String::from(new_sub_str))),
+                )),
+                Box::new(LiteralExpression::new(
+                    DataType::Int32,
+                    Some(ScalarImpl::from(start)),
+                )),
+                DataType::Varchar,
+            );
+
+            test_evals_dummy(expr, Some(ScalarImpl::from(String::from(expected))), false);
+        }
+    }
 }

src/expr/src/expr/mod.rs

@@ -27,6 +27,7 @@ mod expr_input_ref;
 mod expr_is_null;
 mod expr_literal;
 mod expr_nested_construct;
+mod expr_quaternary_bytes;
 mod expr_ternary_bytes;
 pub mod expr_unary;
 mod template;
@@ -102,6 +103,7 @@ pub fn build_from_prost(prost: &ExprNode) -> Result<BoxedExpression> {
         Substr => build_substr_expr(prost),
         Length => build_length_expr(prost),
         Replace => build_replace_expr(prost),
+        Overlay => build_overlay_expr(prost),
         Like => build_like_expr(prost),
         Trim => build_trim_expr(prost),
         Ltrim => build_ltrim_expr(prost),

src/expr/src/expr/template.rs

@@ -335,6 +335,7 @@ gen_expr_normal!(TernaryExpression, { IA1, IA2, IA3 }, { 'ia1, 'ia2, 'ia3 });
 gen_expr_bytes!(UnaryBytesExpression, { IA1 }, { 'ia1 });
 gen_expr_bytes!(BinaryBytesExpression, { IA1, IA2 }, { 'ia1, 'ia2 });
 gen_expr_bytes!(TernaryBytesExpression, { IA1, IA2, IA3 }, { 'ia1, 'ia2, 'ia3 });
+gen_expr_bytes!(QuaternaryBytesExpression, { IA1, IA2, IA3, IA4 }, { 'ia1, 'ia2, 'ia3, 'ia4 });
 
 gen_expr_nullable!(UnaryNullableExpression, { IA1 }, { 'ia1 });
 gen_expr_nullable!(BinaryNullableExpression, { IA1, IA2 }, { 'ia1, 'ia2 });

src/expr/src/vector_op/mod.rs

@@ -27,6 +27,7 @@ pub mod like;
 pub mod lower;
 pub mod ltrim;
 pub mod md5;
+pub mod overlay;
 pub mod position;
 pub mod repeat;
 pub mod replace;

src/expr/src/vector_op/overlay.rs

@@ -0,0 +1,92 @@
+// Copyright 2022 Singularity Data
+//
+// Licensed 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 risingwave_common::array::{BytesGuard, BytesWriter};
+
+use crate::Result;
+
+#[inline(always)]
+pub fn overlay(s: &str, new_sub_str: &str, start: i32, writer: BytesWriter) -> Result<BytesGuard> {
+    // If count is omitted, it defaults to the length of new_sub_str.
+    overlay_for(s, new_sub_str, start, new_sub_str.len() as i32, writer)
+}
+
+#[inline(always)]
+pub fn overlay_for(
+    s: &str,
+    new_sub_str: &str,
+    start: i32,
+    count: i32,
+    writer: BytesWriter,
+) -> Result<BytesGuard> {
+    let count = count.max(0) as usize;
+
+    // If start is out of range, attach it to the end.
+    // Note that indices are 1-based.
+    let start = ((start - 1).max(0) as usize).min(s.len());
+
+    let remaining = start + count;
+
+    let mut writer = writer.begin();
+    writer.write_ref(&s[..start])?;
+    writer.write_ref(new_sub_str)?;
+
+    if remaining < s.len() {
+        writer.write_ref(&s[remaining..])?;
+    }
+
+    writer.finish().map_err(Into::into)
+}
+
+#[cfg(test)]
+mod tests {
+    use risingwave_common::array::{Array, ArrayBuilder, Utf8ArrayBuilder};
+
+    use super::*;
+
+    #[test]
+    fn test_overlay() {
+        let cases = vec![
+            ("aaa__aaa", "XY", 4, None, "aaaXYaaa"),
+            // Place at end.
+            ("aaa", "XY", 4, None, "aaaXY"),
+            // Place at start.
+            ("aaa", "XY", 1, Some(0), "XYaaa"),
+            // Replace shorter string.
+            ("aaa_aaa", "XYZ", 4, Some(1), "aaaXYZaaa"),
+            ("aaaaaa", "XYZ", 4, Some(0), "aaaXYZaaa"),
+            // Replace longer string.
+            ("aaa___aaa", "X", 4, Some(3), "aaaXaaa"),
+            // start too small or large.
+            ("aaa", "XY", -123, None, "XYa"),
+            ("aaa", "XY", 123, None, "aaaXY"),
+            // count too small or large.
+            ("aaa", "X", 4, Some(-123), "aaaX"),
+            ("aaa_", "X", 4, Some(123), "aaaX"),
+        ];
+
+        for (s, new_sub_str, start, count, expected) in cases {
+            let builder = Utf8ArrayBuilder::new(1);
+            let writer = builder.writer();
+            let guard = match count {
+                None => overlay(s, new_sub_str, start, writer),
+                Some(count) => overlay_for(s, new_sub_str, start, count, writer),
+            }
+            .unwrap();
+            let array = guard.into_inner().finish().unwrap();
+            let v = array.value_at(0).unwrap();
+            assert_eq!(v, expected);
+        }
+    }
+}

src/frontend/src/binder/expr/function.rs

@@ -121,6 +121,7 @@ impl Binder {
                 "lower" => ExprType::Lower,
                 "trim" => ExprType::Trim,
                 "replace" => ExprType::Replace,
+                "overlay" => ExprType::Overlay,
                 "position" => ExprType::Position,
                 "ltrim" => ExprType::Ltrim,
                 "rtrim" => ExprType::Rtrim,