Add pipes_as_concat_mode (#2252)

This commit will add a new sql mode named MODE_PIPES_AS_CONCAT:
Description:
1、If this mode is active, '||' will be handled different from the original way ('||' and 'or' are seen as the same symbols in Doris) that it can be used to concat two exps and returns a new string. For example, 'a' || 'b' = 'ab' and 1 || 0 = '10'.
2. User can active this mode by "SET sql_mode = PIPES_AS_CONCAT", and deactive it by "SET sql_mode = '' ".

docs/documentation/cn/administrator-guide/sql-mode.md

@@ -60,7 +60,9 @@ show session variables
 
 ## 已支持mode
 
-（后续补充）
+1. `PIPES_AS_CONCAT`
+
+	在此模式下，'||'符号是一种字符串连接符号（同CONCAT()函数），而不是'OR'符号的同义词。(e.g., `'a'||'b' = 'ab'`, `1||0 = '10'`)
 
 ## 复合mode
 

docs/documentation/en/administrator-guide/sql-mode_EN.md

@@ -60,7 +60,9 @@ show session variables
 
 ## supported mode
 
-(Work in progress)
+1. `PIPES_AS_CONCAT`
+	
+	Treat '||' as a string concatenation operator (same as CONCAT()) rather than as a synonym for OR. (e.g., `'a'||'b' = 'ab'`, `1||0 = '10'`)
 
 ## combine mode
 

fe/src/main/cup/sql_parser.cup

@@ -210,7 +210,7 @@ terminal String KW_ADD, KW_ADMIN, KW_AFTER, KW_AGGREGATE, KW_ALL, KW_ALTER, KW_A
     KW_LOCAL, KW_LOCATION,
     KW_MAX, KW_MAX_VALUE, KW_MERGE, KW_MIN, KW_MIGRATE, KW_MIGRATIONS, KW_MODIFY,
     KW_NAME, KW_NAMES, KW_NEGATIVE, KW_NO, KW_NOT, KW_NULL, KW_NULLS,
-    KW_OBSERVER, KW_OFFSET, KW_ON, KW_ONLY, KW_OPEN, KW_OR, KW_ORDER, KW_OUTER, KW_OVER,
+    KW_OBSERVER, KW_OFFSET, KW_ON, KW_ONLY, KW_OPEN, KW_OR, KW_PIPE, KW_ORDER, KW_OUTER, KW_OVER,
     KW_PARTITION, KW_PARTITIONS, KW_PATH, KW_PRECEDING,
     KW_PASSWORD, KW_PLUGIN, KW_PLUGINS,
     KW_PRIMARY,
@@ -294,6 +294,7 @@ nonterminal Expr expr, non_pred_expr, arithmetic_expr, timestamp_arithmetic_expr
 nonterminal Expr set_expr_or_default;
 nonterminal ArrayList<Expr> expr_list, values, row_value, opt_values;
 nonterminal ArrayList<Expr> func_arg_list;
+nonterminal ArrayList<Expr> expr_pipe_list;
 nonterminal String select_alias, opt_table_alias;
 nonterminal ArrayList<String> ident_list, opt_using_partition;
 nonterminal ClusterName cluster_name;
@@ -428,6 +429,7 @@ precedence left KW_NOT, NOT;
 precedence left KW_BETWEEN, KW_IN, KW_IS, KW_EXISTS;
 precedence left KW_LIKE, KW_REGEXP;
 precedence left EQUAL, LESSTHAN, GREATERTHAN;
+precedence left KW_PIPE;
 precedence left ADD, SUBTRACT;
 precedence left AT, STAR, DIVIDE, MOD, KW_DIV;
 precedence left BITAND, BITOR, BITXOR, BITNOT;
@@ -3500,6 +3502,11 @@ non_pred_expr ::=
   /* Since "IF" is a keyword, need to special case this function */
   | KW_IF LPAREN expr_list:exprs RPAREN
   {: RESULT = new FunctionCallExpr("if", exprs); :}
+  /* For the case like e1 || e2 || e3 ... */
+  | expr_pipe_list:exprs
+  {:
+    RESULT = new FunctionCallExpr("concat", exprs);
+  :}
   | cast_expr:c
   {: RESULT = c; :}
   | case_expr:c
@@ -3538,6 +3545,21 @@ non_pred_expr ::=
   {: RESULT = new BoolLiteral(false); :}
   ;
 
+expr_pipe_list ::=
+  expr:e1 KW_PIPE expr:e2
+  {:
+    ArrayList<Expr> list = new ArrayList<Expr>();
+    list.add(e1);
+    list.add(e2);
+    RESULT = list;
+  :}
+  | expr_pipe_list:list KW_PIPE expr:e
+  {:
+    list.add(e);
+    RESULT = list;
+  :}
+  ;
+
 func_arg_list ::=
   expr:item
   {:

fe/src/main/jflex/sql_scanner.flex

@@ -31,6 +31,7 @@ import java.util.ArrayList;
 
 import org.apache.doris.analysis.SqlParserSymbols;
 import org.apache.doris.common.util.SqlUtils;
+import org.apache.doris.qe.SqlModeHelper;
 
 %%
 
@@ -352,7 +353,7 @@ import org.apache.doris.common.util.SqlUtils;
         keywordMap.put("with", new Integer(SqlParserSymbols.KW_WITH));
         keywordMap.put("work", new Integer(SqlParserSymbols.KW_WORK));
         keywordMap.put("write", new Integer(SqlParserSymbols.KW_WRITE));
-        keywordMap.put("||", new Integer(SqlParserSymbols.KW_OR));
+        keywordMap.put("||", new Integer(SqlParserSymbols.KW_PIPE));
    }
     
   // map from token id to token description
@@ -547,6 +548,11 @@ EndOfLineComment = "--" !({HintContent}|{ContainsLineTerminator}) {LineTerminato
   Integer kw_id = keywordMap.get(text.toLowerCase());
   /* Integer kw_id = keywordMap.get(text); */
   if (kw_id != null) {
+    // if MODE_PIPES_AS_CONCAT is not active, treat '||' symbol as same as 'or' symbol
+    if ((kw_id == SqlParserSymbols.KW_PIPE) &&
+      ((this.sql_mode & SqlModeHelper.MODE_PIPES_AS_CONCAT) == 0)) {
+      return newToken(SqlParserSymbols.KW_OR, text);
+    }
     return newToken(kw_id.intValue(), text);
   } else {
     return newToken(SqlParserSymbols.IDENT, text);

fe/src/test/java/org/apache/doris/analysis/SqlModeTest.java

@@ -0,0 +1,79 @@
+// 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.
+
+package org.apache.doris.analysis;
+
+import org.apache.doris.qe.SqlModeHelper;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.StringReader;
+
+public class SqlModeTest {
+
+    @Test
+    public void testScannerConstructor() {
+        String stmt = new String("SELECT * FROM db1.tbl1 WHERE name = 'BILL GATES'");
+        SqlParser parser = new SqlParser(new SqlScanner(new StringReader(stmt)));
+        SelectStmt selectStmt = null;
+        try {
+            selectStmt = (SelectStmt) parser.parse().value;
+        } catch (Exception e) {
+            Assert.fail(e.getMessage());
+        }
+        Assert.assertEquals("SELECT  FROM `db1`.`tbl1` WHERE `name` = 'BILL GATES'", selectStmt.toSql());
+
+        parser = new SqlParser(new SqlScanner(new StringReader(stmt), SqlModeHelper.MODE_DEFAULT));
+        try {
+            selectStmt = (SelectStmt) parser.parse().value;
+        } catch (Exception e) {
+            Assert.fail(e.getMessage());
+        }
+        Assert.assertEquals("SELECT  FROM `db1`.`tbl1` WHERE `name` = 'BILL GATES'", selectStmt.toSql());
+    }
+
+    @Test
+    public void testPipesAsConcatMode() {
+        // Mode Active
+        String stmt = new String("SELECT 'a' || 'b' || 'c'");
+        SqlParser parser = new SqlParser(new SqlScanner(new StringReader(stmt), SqlModeHelper.MODE_PIPES_AS_CONCAT));
+        SelectStmt selectStmt = null;
+        try {
+            selectStmt = (SelectStmt) parser.parse().value;
+        } catch (Exception e) {
+            Assert.fail(e.getMessage());
+        }
+        Expr expr = selectStmt.getSelectList().getItems().get(0).getExpr();
+        if (!(expr instanceof FunctionCallExpr)) {
+            Assert.fail("Mode not working");
+        }
+        Assert.assertEquals("concat('a', 'b', 'c')", expr.toSql());
+
+        // Mode DeActive
+        parser = new SqlParser(new SqlScanner(new StringReader(stmt), SqlModeHelper.MODE_DEFAULT));
+        try {
+            selectStmt = (SelectStmt) parser.parse().value;
+        } catch (Exception e) {
+            Assert.fail(e.getMessage());
+        }
+        expr = selectStmt.getSelectList().getItems().get(0).getExpr();
+        if (!(expr instanceof CompoundPredicate)) {
+            Assert.fail();
+        }
+        Assert.assertEquals("(('a') OR ('b')) OR ('c')", expr.toSql());
+    }
+}