Support starts_with (str, prefix) function (#2813)

Support starts_with function

be/src/exprs/string_functions.cpp

@@ -79,6 +79,16 @@ StringVal StringFunctions::right(
     return substring(context, str, IntVal(pos), len);
 }
 
+BooleanVal StringFunctions::starts_with(
+        FunctionContext* context, const StringVal& str, const StringVal& prefix) {
+    if (str.is_null || prefix.is_null) {
+        return BooleanVal::null();
+    }
+    re2::StringPiece str_sp(reinterpret_cast<char*>(str.ptr), str.len);
+    re2::StringPiece prefix_sp(reinterpret_cast<char*>(prefix.ptr), prefix.len);
+    return BooleanVal(str_sp.starts_with(prefix_sp));
+}
+
 BooleanVal StringFunctions::ends_with(
         FunctionContext* context, const StringVal& str, const StringVal& suffix) {
     if (str.is_null || suffix.is_null) {

be/src/exprs/string_functions.h

@@ -49,6 +49,9 @@ public:
     static doris_udf::StringVal right(
         doris_udf::FunctionContext* context, const doris_udf::StringVal& str, 
         const doris_udf::IntVal& len);
+    static doris_udf::BooleanVal starts_with(
+        doris_udf::FunctionContext* context, const doris_udf::StringVal& str,
+        const doris_udf::StringVal& prefix);
     static doris_udf::BooleanVal ends_with(
         doris_udf::FunctionContext* context, const doris_udf::StringVal& str,
         const doris_udf::StringVal& suffix);

be/test/exprs/string_functions_test.cpp

@@ -190,6 +190,39 @@ TEST_F(StringFunctionsTest, ends_with) {
     ASSERT_EQ(nullRet, StringFunctions::ends_with(context, StringVal::null(), StringVal::null()));
 }
 
+TEST_F(StringFunctionsTest, starts_with) {
+    doris_udf::FunctionContext* context = new doris_udf::FunctionContext();
+    doris_udf::BooleanVal falseRet = doris_udf::BooleanVal(false);
+    doris_udf::BooleanVal trueRet = doris_udf::BooleanVal(true);
+    doris_udf::BooleanVal nullRet = doris_udf::BooleanVal::null();
+
+    ASSERT_EQ(trueRet, StringFunctions::starts_with(context, StringVal(""), StringVal("")));
+
+    ASSERT_EQ(trueRet, StringFunctions::starts_with(context, StringVal(" "), StringVal(" ")));
+
+    ASSERT_EQ(trueRet, StringFunctions::starts_with(context, StringVal("hello"), StringVal("")));
+
+    ASSERT_EQ(falseRet, StringFunctions::starts_with(context, StringVal(""), StringVal("hello")));
+
+    ASSERT_EQ(trueRet, StringFunctions::starts_with(context, StringVal("hello"), StringVal("hello")));
+
+    ASSERT_EQ(falseRet, StringFunctions::starts_with(context, StringVal("hello"), StringVal(" ")));
+
+    ASSERT_EQ(falseRet, StringFunctions::starts_with(context, StringVal(" "), StringVal("world")));
+
+    ASSERT_EQ(trueRet, StringFunctions::starts_with(context, StringVal("hello world"), StringVal("hello")));
+
+    ASSERT_EQ(falseRet, StringFunctions::starts_with(context, StringVal("hello world"), StringVal("world")));
+
+    ASSERT_EQ(trueRet, StringFunctions::starts_with(context, StringVal("hello world"), StringVal("hello world")));
+
+    ASSERT_EQ(nullRet, StringFunctions::starts_with(context, StringVal("hello world"), StringVal::null()));
+
+    ASSERT_EQ(nullRet, StringFunctions::starts_with(context, StringVal::null(), StringVal("hello world")));
+
+    ASSERT_EQ(nullRet, StringFunctions::starts_with(context, StringVal::null(), StringVal::null()));
+}
+
 }
 
 int main(int argc, char** argv) {

docs/documentation/cn/sql-reference/sql-functions/string-functions/starts_with.md

@@ -0,0 +1,46 @@
+<!--
+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.
+-->
+
+# starts_with
+## description
+### Syntax
+
+`BOOLEAN STARTS_WITH (VARCHAR str, VARCHAR prefix)`
+
+如果字符串以指定前缀开头，返回true。否则，返回false。任意参数为NULL，返回NULL。
+
+## example
+
+```
+MySQL [(none)]> select starts_with("hello world","hello");
++-------------------------------------+
+| starts_with('hello world', 'hello') |
++-------------------------------------+
+|                                   1 |
++-------------------------------------+
+
+MySQL [(none)]> select starts_with("hello world","world");
++-------------------------------------+
+| starts_with('hello world', 'world') |
++-------------------------------------+
+|                                   0 |
++-------------------------------------+
+```
+##keyword
+STARTS_WITH

docs/documentation/en/sql-reference/sql-functions/string-functions/starts_with_EN.md

@@ -0,0 +1,47 @@
+<!--
+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.
+-->
+
+# starts_with
+## Description
+### Syntax
+
+`BOOLEAN STARTS_WITH (VARCHAR str, VARCHAR prefix)`
+
+It returns true if the string starts with the specified prefix, otherwise it returns false.
+If any parameter is NULL, it returns NULL.
+
+## example
+
+```
+MySQL [(none)]> select starts_with("hello world","hello");
++-------------------------------------+
+| starts_with('hello world', 'hello') |
++-------------------------------------+
+|                                   1 |
++-------------------------------------+
+
+MySQL [(none)]> select starts_with("hello world","world");
++-------------------------------------+
+| starts_with('hello world', 'world') |
++-------------------------------------+
+|                                   0 |
++-------------------------------------+
+```
+##keyword
+STARTS_WITH

gensrc/script/doris_builtins_functions.py

@@ -506,6 +506,8 @@ visible_functions = [
         '15FunctionContextERKNS1_9StringValERKNS1_6IntValE'],
     [['ends_with'], 'BOOLEAN', ['VARCHAR', 'VARCHAR'],
         '_ZN5doris15StringFunctions9ends_withEPN9doris_udf15FunctionContextERKNS1_9StringValES6_'],
+    [['starts_with'], 'BOOLEAN', ['VARCHAR', 'VARCHAR'],
+        '_ZN5doris15StringFunctions11starts_withEPN9doris_udf15FunctionContextERKNS1_9StringValES6_'],
     [['space'], 'VARCHAR', ['INT'],
         '_ZN5doris15StringFunctions5spaceEPN9doris_udf15FunctionContextERKNS1_6IntValE'],
     [['repeat'], 'VARCHAR', ['VARCHAR', 'INT'],

gensrc/script/doris_functions.py

@@ -107,6 +107,7 @@ functions = [
   ['String_Left', 'VARCHAR', ['VARCHAR', 'INT'], 'StringFunctions::left', ['strleft', 'left']],
   ['String_Right', 'VARCHAR', ['VARCHAR', 'INT'], 'StringFunctions::right', ['strright', 'right']],
   ['String_Ends_With', 'BOOLEAN', ['VARCHAR', 'VARCHAR'], 'StringFunctions::ends_with', ['ends_with']],
+  ['String_Starts_With', 'BOOLEAN', ['VARCHAR', 'VARCHAR'], 'StringFunctions::starts_with', ['starts_with']],
   ['String_Length', 'INT', ['VARCHAR'], 'StringFunctions::length', ['length']],
   ['String_Lower', 'VARCHAR', ['VARCHAR'], 'StringFunctions::lower', ['lower', 'lcase']],
   ['String_Upper', 'VARCHAR', ['VARCHAR'], 'StringFunctions::upper', ['upper', 'ucase']],