feat:implement sql style 'substr_index' string function

datafusion/expr/src/built_in_function.rs

@@ -302,6 +302,8 @@ pub enum BuiltinScalarFunction {
     OverLay,
     /// levenshtein
     Levenshtein,
+    /// substr_index
+    SubstrIndex,
 }
 
 /// Maps the sql function name to `BuiltinScalarFunction`
@@ -470,6 +472,7 @@ impl BuiltinScalarFunction {
             BuiltinScalarFunction::ArrowTypeof => Volatility::Immutable,
             BuiltinScalarFunction::OverLay => Volatility::Immutable,
             BuiltinScalarFunction::Levenshtein => Volatility::Immutable,
+            BuiltinScalarFunction::SubstrIndex => Volatility::Immutable,
 
             // Stable builtin functions
             BuiltinScalarFunction::Now => Volatility::Stable,
@@ -773,6 +776,9 @@ impl BuiltinScalarFunction {
                     return plan_err!("The to_hex function can only accept integers.");
                 }
             }),
+            BuiltinScalarFunction::SubstrIndex => {
+                utf8_to_str_type(&input_expr_types[0], "substr_index")
+            }
             BuiltinScalarFunction::ToTimestamp => Ok(match &input_expr_types[0] {
                 Int64 => Timestamp(Second, None),
                 _ => Timestamp(Nanosecond, None),
@@ -1235,6 +1241,14 @@ impl BuiltinScalarFunction {
                 self.volatility(),
             ),
 
+            BuiltinScalarFunction::SubstrIndex => Signature::one_of(
+                vec![
+                    Exact(vec![Utf8, Utf8, Int64]),
+                    Exact(vec![LargeUtf8, LargeUtf8, Int64]),
+                ],
+                self.volatility(),
+            ),
+
             BuiltinScalarFunction::Replace | BuiltinScalarFunction::Translate => {
                 Signature::one_of(vec![Exact(vec![Utf8, Utf8, Utf8])], self.volatility())
             }
@@ -1486,6 +1500,7 @@ fn aliases(func: &BuiltinScalarFunction) -> &'static [&'static str] {
         BuiltinScalarFunction::Upper => &["upper"],
         BuiltinScalarFunction::Uuid => &["uuid"],
         BuiltinScalarFunction::Levenshtein => &["levenshtein"],
+        BuiltinScalarFunction::SubstrIndex => &["substr_index", "substring_index"],
 
         // regex functions
         BuiltinScalarFunction::RegexpMatch => &["regexp_match"],

datafusion/expr/src/expr_fn.rs

@@ -916,6 +916,7 @@ scalar_expr!(
 
 scalar_expr!(ArrowTypeof, arrow_typeof, val, "data type");
 scalar_expr!(Levenshtein, levenshtein, string1 string2, "Returns the Levenshtein distance between the two given strings");
+scalar_expr!(SubstrIndex, substr_index, string delimiter count, "Returns the substring from str before count occurrences of the delimiter");
 
 scalar_expr!(
     Struct,
@@ -1203,6 +1204,7 @@ mod test {
         test_nary_scalar_expr!(OverLay, overlay, string, characters, position, len);
         test_nary_scalar_expr!(OverLay, overlay, string, characters, position);
         test_scalar_expr!(Levenshtein, levenshtein, string1, string2);
+        test_scalar_expr!(SubstrIndex, substr_index, string, delimiter, count);
     }
 
     #[test]

datafusion/physical-expr/src/functions.rs

@@ -862,6 +862,29 @@ pub fn create_physical_fun(
                 ))),
             })
         }
+        BuiltinScalarFunction::SubstrIndex => {
+            Arc::new(|args| match args[0].data_type() {
+                DataType::Utf8 => {
+                    let func = invoke_if_unicode_expressions_feature_flag!(
+                        substr_index,
+                        i32,
+                        "substr_index"
+                    );
+                    make_scalar_function(func)(args)
+                }
+                DataType::LargeUtf8 => {
+                    let func = invoke_if_unicode_expressions_feature_flag!(
+                        substr_index,
+                        i64,
+                        "substr_index"
+                    );
+                    make_scalar_function(func)(args)
+                }
+                other => Err(DataFusionError::Internal(format!(
+                    "Unsupported data type {other:?} for function substr_index",
+                ))),
+            })
+        }
     })
 }
 

datafusion/physical-expr/src/unicode_expressions.rs

@@ -455,3 +455,68 @@ pub fn translate<T: OffsetSizeTrait>(args: &[ArrayRef]) -> Result<ArrayRef> {
 
     Ok(Arc::new(result) as ArrayRef)
 }
+
+/// Returns the substring from str before count occurrences of the delimiter delim. If count is positive, everything to the left of the final delimiter (counting from the left) is returned. If count is negative, everything to the right of the final delimiter (counting from the right) is returned.
+/// SUBSTRING_INDEX('www.apache.org', '.', 1) = www
+/// SUBSTRING_INDEX('www.apache.org', '.', 2) = www.apache
+/// SUBSTRING_INDEX('www.apache.org', '.', -2) = apache.org
+/// SUBSTRING_INDEX('www.apache.org', '.', -1) = org
+pub fn substr_index<T: OffsetSizeTrait>(args: &[ArrayRef]) -> Result<ArrayRef> {
+    if args.len() != 3 {
+        return internal_err!(
+            "substr_index was called with {} arguments. It requires 3.",
+            args.len()
+        );
+    }
+
+    let string_array = as_generic_string_array::<T>(&args[0])?;
+    let delimiter_array = as_generic_string_array::<T>(&args[1])?;
+    let count_array = as_int64_array(&args[2])?;
+
+    let result = string_array
+        .iter()
+        .zip(delimiter_array.iter())
+        .zip(count_array.iter())
+        .map(|((string, delimiter), n)| match (string, delimiter, n) {
+            (Some(string), Some(delimiter), Some(n)) => {
+                let mut res = String::new();
+                match n {
+                    0 => {
+                        "".to_string();
+                    }
+                    _other => {
+                        if n > 0 {
+                            let idx = string
+                                .split(delimiter)
+                                .take(n as usize)
+                                .fold(0, |len, x| len + x.len() + delimiter.len())
+                                - delimiter.len();
+                            res.push_str(if idx >= string.len() {
+                                string
+                            } else {
+                                &string[..idx]
+                            });
+                        } else {
+                            let idx = (string.split(delimiter).take((-n) as usize).fold(
+                                string.len() as isize,
+                                |len, x| {
+                                    len - x.len() as isize - delimiter.len() as isize
+                                },
+                            ) + delimiter.len() as isize)
+                                as usize;
+                            res.push_str(if idx >= string.len() {
+                                string
+                            } else {
+                                &string[idx..]
+                            });
+                        }
+                    }
+                }
+                Some(res)
+            }
+            _ => None,
+        })
+        .collect::<GenericStringArray<T>>();
+
+    Ok(Arc::new(result) as ArrayRef)
+}

datafusion/proto/proto/datafusion.proto

@@ -641,6 +641,7 @@ enum ScalarFunction {
   ArrayExcept = 123;
   ArrayPopFront = 124;
   Levenshtein = 125;
+  SubstrIndex = 126;
 }
 
 message ScalarFunctionNode {

datafusion/proto/src/logical_plan/from_proto.rs

@@ -55,9 +55,9 @@ use datafusion_expr::{
     lower, lpad, ltrim, md5, nanvl, now, nullif, octet_length, overlay, pi, power,
     radians, random, regexp_match, regexp_replace, repeat, replace, reverse, right,
     round, rpad, rtrim, sha224, sha256, sha384, sha512, signum, sin, sinh, split_part,
-    sqrt, starts_with, string_to_array, strpos, struct_fun, substr, substring, tan, tanh,
-    to_hex, to_timestamp_micros, to_timestamp_millis, to_timestamp_nanos,
-    to_timestamp_seconds, translate, trim, trunc, upper, uuid,
+    sqrt, starts_with, string_to_array, strpos, struct_fun, substr, substr_index,
+    substring, tan, tanh, to_hex, to_timestamp_micros, to_timestamp_millis,
+    to_timestamp_nanos, to_timestamp_seconds, translate, trim, trunc, upper, uuid,
     window_frame::regularize,
     AggregateFunction, Between, BinaryExpr, BuiltInWindowFunction, BuiltinScalarFunction,
     Case, Cast, Expr, GetFieldAccess, GetIndexedField, GroupingSet,
@@ -551,6 +551,7 @@ impl From<&protobuf::ScalarFunction> for BuiltinScalarFunction {
             ScalarFunction::ArrowTypeof => Self::ArrowTypeof,
             ScalarFunction::OverLay => Self::OverLay,
             ScalarFunction::Levenshtein => Self::Levenshtein,
+            ScalarFunction::SubstrIndex => Self::SubstrIndex,
         }
     }
 }
@@ -1716,6 +1717,11 @@ pub fn parse_expr(
                         .map(|expr| parse_expr(expr, registry))
                         .collect::<Result<Vec<_>, _>>()?,
                 )),
+                ScalarFunction::SubstrIndex => Ok(substr_index(
+                    parse_expr(&args[0], registry)?,
+                    parse_expr(&args[1], registry)?,
+                    parse_expr(&args[2], registry)?,
+                )),
                 ScalarFunction::StructFun => {
                     Ok(struct_fun(parse_expr(&args[0], registry)?))
                 }

datafusion/proto/src/logical_plan/to_proto.rs

@@ -1573,6 +1573,7 @@ impl TryFrom<&BuiltinScalarFunction> for protobuf::ScalarFunction {
             BuiltinScalarFunction::ArrowTypeof => Self::ArrowTypeof,
             BuiltinScalarFunction::OverLay => Self::OverLay,
             BuiltinScalarFunction::Levenshtein => Self::Levenshtein,
+            BuiltinScalarFunction::SubstrIndex => Self::SubstrIndex,
         };
 
         Ok(scalar_function)

datafusion/sqllogictest/test_files/functions.slt

@@ -877,3 +877,78 @@ query ?
 SELECT levenshtein(NULL, NULL)
 ----
 NULL
+
+query T
+SELECT substr_index('www.apache.org', '.', 1)
+----
+www
+
+query T
+SELECT substr_index('www.apache.org', '.', 2)
+----
+www.apache
+
+query T
+SELECT substr_index('www.apache.org', '.', -1)
+----
+org
+
+query T
+SELECT substr_index('www.apache.org', '.', -2)
+----
+apache.org
+
+query T
+SELECT substr_index('www.apache.org', 'ac', 1)
+----
+www.ap
+
+query T
+SELECT substr_index('www.apache.org', 'ac', -1)
+----
+he.org
+
+query T
+SELECT substr_index('www.apache.org', 'ac', 2)
+----
+www.apache.org
+
+query T
+SELECT substr_index('www.apache.org', 'ac', -2)
+----
+www.apache.org
+
+query ?
+SELECT substr_index(NULL, 'ac', 1)
+----
+NULL
+
+query T
+SELECT substr_index('www.apache.org', NULL, 1)
+----
+NULL
+
+query T
+SELECT substr_index('www.apache.org', 'ac', NULL)
+----
+NULL
+
+query T
+SELECT substr_index('', 'ac', 1)
+----
+(empty)
+
+query T
+SELECT substr_index('www.apache.org', '', 1)
+----
+(empty)
+
+query T
+SELECT substr_index('www.apache.org', 'ac', 0)
+----
+(empty)
+
+query ?
+SELECT substr_index(NULL, NULL, NULL)
+----
+NULL

docs/source/user-guide/sql/scalar_functions.md

@@ -637,6 +637,7 @@ nullif(expression1, expression2)
 - [uuid](#uuid)
 - [overlay](#overlay)
 - [levenshtein](#levenshtein)
+- [substr_index](#substr_index)
 
 ### `ascii`
 
@@ -1152,6 +1153,23 @@ levenshtein(str1, str2)
 - **str1**: String expression to compute Levenshtein distance with str2.
 - **str2**: String expression to compute Levenshtein distance with str1.
 
+### `substr_index`
+
+Returns the substring from str before count occurrences of the delimiter delim.
+If count is positive, everything to the left of the final delimiter (counting from the left) is returned.
+If count is negative, everything to the right of the final delimiter (counting from the right) is returned.
+For example, `substr_index('www.apache.org', '.', 1) = www`, `substr_index('www.apache.org', '.', -1) = org`
+
+```
+substr_index(str, delim, count)
+```
+
+#### Arguments
+
+- **str**: String expression to operate on.
+- **delim**: the string to find in str to split str.
+- **count**: The number of times to search for the delimiter. Can be both a positive or negative number.
+
 ## Binary String Functions
 
 - [decode](#decode)