branch-2.1: [fix](Nereids) fix fe folding constant of string function…

…s and add more cases #45233 (#46523)

pick: #45233
Issue Number: #44666
Related PR: #40441

Problem Summary:
- select substring_index('哈哈哈AAA','A', 1); String.split function has
second parameter 'limit', which is default zero. When 'limit' is zero,
it means it would remove trailing empty strings split of '哈哈哈AAA', which
would be '哈哈哈' only. But what we expect is '哈哈哈', '','','' when part
function is used by substring index. So we should change splitpart limit
to -1 to enable trailing empty character in splitpart list
- reorganize fold constant of string functions in fe and add more cases

---------

Co-authored-by: Mryange <[email protected]>

fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/executable/StringArithmetic.java

@@ -115,7 +115,7 @@ public static Expression substringVarcharIntInt(StringLikeLiteral first,
      */
     @ExecFunction(name = "length")
     public static Expression lengthVarchar(StringLikeLiteral first) {
-        return new IntegerLiteral(first.getValue().length());
+        return new IntegerLiteral(first.getValue().getBytes(StandardCharsets.UTF_8).length);
     }
 
     /**
@@ -319,7 +319,20 @@ public static Expression right(StringLikeLiteral first, IntegerLiteral second) {
      */
     @ExecFunction(name = "locate")
     public static Expression locate(StringLikeLiteral first, StringLikeLiteral second) {
-        return new IntegerLiteral(second.getValue().trim().indexOf(first.getValue()) + 1);
+        return new IntegerLiteral(second.getValue().indexOf(first.getValue()) + 1);
+    }
+
+    /**
+     * Executable arithmetic functions Locate
+     */
+    @ExecFunction(name = "locate")
+    public static Expression locate(StringLikeLiteral first, StringLikeLiteral second, IntegerLiteral third) {
+        int result = second.getValue().indexOf(first.getValue()) + 1;
+        if (third.getValue() <= 0 || !substringImpl(second.getValue(), third.getValue(),
+                second.getValue().length()).contains(first.getValue())) {
+            result = 0;
+        }
+        return new IntegerLiteral(result);
     }
 
     /**
@@ -334,12 +347,14 @@ public static Expression instr(StringLikeLiteral first, StringLikeLiteral second
      * Executable arithmetic functions Ascii
      */
     @ExecFunction(name = "ascii")
-    public static Expression ascii(StringLikeLiteral first) {
+    public static Expression ascii(StringLikeLiteral first) throws UnsupportedEncodingException {
         if (first.getValue().length() == 0) {
             return new IntegerLiteral(0);
         }
-        char firstChar = first.getValue().charAt(0);
-        return new IntegerLiteral(firstChar);
+        String character = first.getValue();
+        byte[] utf8Bytes = character.getBytes("UTF-8");
+        int firstByteAscii = utf8Bytes[0] & 0xFF;
+        return new IntegerLiteral(firstByteAscii);
     }
 
     /**
@@ -584,7 +599,7 @@ public static Expression fieldVarchar(StringLikeLiteral first, VarcharLiteral...
     }
 
     private static int findStringInSet(String target, String input) {
-        String[] split = input.split(",");
+        String[] split = input.split(",", -1);
         for (int i = 0; i < split.length; i++) {
             if (split[i].equals(target)) {
                 return i + 1;
@@ -634,6 +649,10 @@ public static Expression reverseVarchar(StringLikeLiteral first) {
      */
     @ExecFunction(name = "space")
     public static Expression space(IntegerLiteral first) {
+        // when it is too large for fe to make result string, do not folding on fe, limit 1 MB
+        if (first.getValue() > 1000000) {
+            throw new AnalysisException("space too large to fold const by fe");
+        }
         StringBuilder sb = new StringBuilder();
         for (int i = 0; i < first.getValue(); i++) {
             sb.append(' ');
@@ -646,7 +665,7 @@ public static Expression space(IntegerLiteral first) {
      */
     @ExecFunction(name = "split_by_char")
     public static Expression splitByChar(StringLikeLiteral first, StringLikeLiteral second) {
-        String[] result = first.getValue().split(second.getValue());
+        String[] result = first.getValue().split(second.getValue(), -1);
         List<Literal> items = new ArrayList<>();
         for (int i = 1; i < result.length; i++) {
             items.add((Literal) castStringLikeLiteral(first, result[i]));
@@ -673,16 +692,16 @@ public static Expression splitPart(StringLikeLiteral first, StringLikeLiteral ch
             if (".$|()[{^?*+\\".contains(separator) || separator.startsWith("\\")) {
                 separator = "\\" + separator;
             }
-            parts = sb.reverse().toString().split(separator);
+            parts = sb.reverse().toString().split(separator, -1);
         } else {
             if (".$|()[{^?*+\\".contains(separator) || separator.startsWith("\\")) {
                 separator = "\\" + separator;
             }
-            parts = first.getValue().split(separator);
+            parts = first.getValue().split(separator, -1);
         }
 
         if (parts.length < Math.abs(number.getValue()) || number.getValue() == 0) {
-            if (parts.length == Math.abs(number.getValue()) - 1) {
+            if (parts.length == Math.abs(number.getValue())) {
                 if (number.getValue() < 0 && first.getValue().startsWith(chr.getValue())
                         || number.getValue() > 0 && first.getValue().endsWith(chr.getValue())) {
                     return castStringLikeLiteral(first, "");
@@ -702,7 +721,10 @@ public static Expression splitPart(StringLikeLiteral first, StringLikeLiteral ch
      */
     @ExecFunction(name = "substring_index")
     public static Expression substringIndex(StringLikeLiteral first, StringLikeLiteral chr, IntegerLiteral number) {
-        String[] parts = first.getValue().split(chr.getValue());
+        if (chr.getValue().isEmpty()) {
+            return chr;
+        }
+        String[] parts = first.getValue().split(chr.getValue(), -1);
         if (Math.abs(number.getValue()) >= parts.length) {
             return first;
         }
@@ -871,6 +893,9 @@ public static Expression urlDecode(StringLikeLiteral first) {
      */
     @ExecFunction(name = "append_trailing_char_if_absent")
     public static Expression appendTrailingCharIfAbsent(StringLikeLiteral first, StringLikeLiteral second) {
+        if (second.getValue().length() != 1) {
+            return new NullLiteral(first.getDataType());
+        }
         if (first.getValue().endsWith(second.getValue())) {
             return first;
         } else {
@@ -899,13 +924,13 @@ public static Expression extractUrlParameter(StringLikeLiteral first, StringLike
             return castStringLikeLiteral(first, "");
         }
 
-        String[] urlParts = first.getValue().split("\\?");
+        String[] urlParts = first.getValue().split("\\?", -1);
         if (urlParts.length > 1) {
             String query = urlParts[1];
-            String[] pairs = query.split("&");
+            String[] pairs = query.split("&", -1);
 
             for (String pair : pairs) {
-                String[] keyValue = pair.split("=");
+                String[] keyValue = pair.split("=", -1);
                 if (second.getValue().equals(keyValue[0])) {
                     return castStringLikeLiteral(first, keyValue[1]);
                 }